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Digital Radio Planning Committee

Technical Sub-Committee

DAB+ Regional Planning

Technical Report

Document: DRPC-TSC-2016-72

September 2016

FINAL

V1.1(Redacted version with edits agreed by the DRPC and minor corrections)

DAB+ Regional Planning Technical Report DRPC-TSC-2016-72

The technical aspects of the planning of DAB+ for regional Australia have been examined in depth by the Technical Sub-Committee (TSC) of the Digital Radio Planning Committee (DRPC), which has representatives from the key stakeholder groups in the Australian radio industry.

The studies undertaken have provided a detailed understanding of the issues, compromises and limitations that the limited spectrum available to DAB+ in Australia has imposed.

The TSC recognises that there is existing legislation governing the deployment of DAB+ digital radio in Australia and where that legislation affects technical planning the issues have been discussed and addressed.

In order to define a viable planning methodology those issues and limitations have been studied along with a detailed investigation of the base level planning parameters and models. The result is a proposed set of planning principles which should provide an equitable approach for the design and implementation of a cost effective DAB+ network with appropriate performance and coverage for regional Australians.

Of particular importance in the planning principles is the requirement for compromise from all parties. The spirit of compromise will allow the most cost effective design for regional Australia and lead to the most rapid, and equitable, rollout of new digital radio services.

The TSC provides the following proposals and consideration for the DRPC to use to move regional DAB+ planning forward in Australia.

Capacity considerations refer section 1.8

Consideration 1 The maximum number of commercial licences in any regional licence area is four, giving a maximum standard access entitlement capacity requirement of 4/9th. This means there will be at least 1/9th excess capacity on any Cat 2 multiplex and at least 3/9th excess capacity on a Cat 1 multiplex. Even if all licensees in an area purchased excess capacity entitlements up to the cap, there is a possibility that some multiplex capacity would remain unable to be used unless it was purchased by a community or national broadcaster (the latter in the case of a Cat 2 multiplex only), or a new commercial digital licence was allocated. A change in legislation would be required to provide for additional capacity allowances for commercial broadcasters.

Principle 1 – Overall planning approach refer section 1.9

Proposal 1 The planning of a licence area should address the wider area through the development of a regional plan encompassing all areas which may be affected by the transmissions in the target licence area.

Principle 2 – Proposed frequency allotment planning approach refer section 1.10

Proposal 2 That the 6/2 frequency allotment scenario should be adopted with the national frequency blocks being 9C and 8B.

Consideration 2 A power limitation for all regional licence areas of 5kW nominal ERP should be used in determining the allotments and baseline interference levels. Higher power will be considered on a case by case basis if there is minimal additional interference to other areas. Note however that some areas may need to be even lower power (e.g. Katoomba) due to the local topography and proximity to other licence areas.

Executive Summary


Principle 3 – Licence area aggregation refer section 1.11

Consideration 3 The DRPC may consider whether the commercial & wide area community broadcasters in some specifically difficult planning areas should be contacted to discuss the potential for licence area aggregation approach.

NOTE: CRA will discuss potential licence area aggregation on 6 October 2016. The text of this consideration will be adjusted after feedback is received.

Consideration 4 The DRPC request DoCA to consider legislative amendments that would enable the ACMA to aggregate licence areas for the purpose of digital radio, noting that public interest, policy and legal considerations may necessitate constraints on flexibility in particular cases.

Principle 4 – Transmitter site selection refer section 1.12

Proposal 3 When selecting sites for main transmitters and repeaters the following rules should be followed:

a) Main transmitters (or repeaters) should be co-sited with local VHF DTV when it is used in a Licence Area wherever practical

b) Where there are multiple DAB+ transmissions in the same area the main transmitters should be co-sited wherever practical

c) Where transmitters and repeaters are proposed after the establishment of the first DAB+ multiplex operating in the area the licensee of any subsequent DAB+ multiplex should ensure that there is no interference into the established DAB+ multiplexes (earlier deployment has precedence)

d) Repeaters which are not co-sited with VHF television transmitters should as far as practical ensure that eithera. there is an alternative television source available e.g. UHF, orb. no VHF services are lost by existing consumers. Note that fortuitous

coverage is not included.

RF planning parameters and targets refer section Error: Reference source not found

Proposal 4 The planning of DAB+ in regional Australia will assume Protection Level EEP-3A (FEC code rate ½).

Proposal 5 The location variation standard deviation parameter be changed from 5.5dB to 4.0dB in line with the value used in the UK.

Proposal 6 The Height Gain parameter used to convert field strengths required at 1.5m to 10m be adjusted from 13dB to 10dB

Proposal 7 The antenna gain for mobile devices be changed from -5dBd to -10dBd

Proposal 8 The allowance for Man Made Noise and interference be adjusted to include interference at 1.5m

Proposal 9 Adjust the Rayleigh fading allowance from 5.6 to 4.6dB to change the minimum carrier to noise ratio required by a DAB+ receiver to provide error free audio for a typical Rayleigh channel from 13dB to 12dB.


Proposal 10 The planning field strengths be adjusted as follows:

Planning field strengths (dBμV/m)Mobile Suburban Urban

Location availability 99% 95% 95%Current planning field strength (1.5m) 49 56 62Proposed planning field strength (1.5m) 50 54 60Current planning field strength (10m) 63 70 76Proposed planning field strength (10m) 60 64 70

Proposal 11 Where possible avoid using frequency blocks 8A and 9D where VHF DTV is provided with no UHF alternative.

Proposal 12 Increase the adjacent channel interference protection ratio from the current value of -9dB to -5dB.

Proposal 13 The protection ratio for co-channel DAB+ to DAB+ interference be relaxed from 15dB to 12dB.

Consideration 5 In planning the rollout of DAB+ transmitters all licensees (and prospective licensees) are to be encouraged to collaborate with the other licensee(s) that will operate in the same area to minimise the potential for ACI/hole punching, with co-siting of transmitters and repeaters recommended as an effective way of preventing such.

The following next steps are recommended to complete current studies and allow the industry to move forward with the planning of DAB+ services in regional Australia.

1. Finalisation and adoption of the updated planning parameters and planning principles.2. Allotment planning for licence areas within 400km of the first to rollout areas (Canberra,

Darwin, Gold Coast and Hobart) a. Industry provides proposed sites, patterns and powersb. Industry and ACMA work to develop indicative regional allotment plans

3. If the DRPC wishes, further cost analysis based on specific reference LAs4. While the legislative provisions preventing discrimination between the technical

specifications of multiplexes have no impact on the first three target areas (Canberra, Hobart and Darwin) the TSC should review the technical implications on planning as part of the 400km around those first movers.

5. DRCP committee to consider trial licences, where appropriate to foster deployment, prior to the establishment of full commercial / national licences, e.g. the Gold Coast so a shared multiplex can go on air in time for the Commonwealth Games

The above tasks may be modified based on the adoption and feedback of the proposals made by the TSC within the DRPC.


Table of ContentsExecutive Summary............................................................................................................................... 2

1. Introduction.................................................................................................................................... 7

1.1. The Purpose of this Report....................................................................................................7

1.2. TSC role, responsibilities and objectives................................................................................7

1.3. Background............................................................................................................................ 7

1.4. TSC Members......................................................................................................................10

1.5. Structure of this report..........................................................................................................10

1.6. Terminology......................................................................................................................... 11

2. DAB+ Regional Radio Planning Principles..................................................................................12

2.1. Introduction..........................................................................................................................12

2.2. Capacity considerations.......................................................................................................13

2.3. Principle 1: Overall planning approach................................................................................14

2.4. Principle 2: Proposed frequency allotment planning approach............................................16

2.5. Principle 3: Licence area aggregation..................................................................................20

2.6. Principle 4: Transmitter site selection..................................................................................21

2.7. Discussion............................................................................................................................ 23

3. DAB+ RF Planning Parameters and Targets...............................................................................24

3.1. Introduction..........................................................................................................................24

3.2. Current Australian values and international trends..............................................................24

3.3. Error correction considerations............................................................................................25

3.4. Base planning parameter investigations..............................................................................26

3.4.1. Location variation standard deviation...........................................................................26

3.4.2. Height Gain.................................................................................................................. 26

3.4.3. Mobile antenna gain.....................................................................................................26

3.4.4. Man-made noise and interference................................................................................27

3.4.5. Rayleigh fading allowance...........................................................................................27

3.5. Planning field strengths........................................................................................................28

3.6. DTV interference considerations..........................................................................................28

3.7. DAB+ interference protection ratios.....................................................................................29

3.7.1. Co-channel interference...............................................................................................29


3.7.2. Adjacent channel interference......................................................................................29

3.8. Coverage, overspill and interference targets........................................................................30

3.9. Summary and discussion.....................................................................................................31

4. Cost Analysis and Impact Assessment........................................................................................32

4.1. Cost model overview............................................................................................................32

4.2. Cost analysis........................................................................................................................35

4.3. Summary.............................................................................................................................. 37

5. Conclusions................................................................................................................................. 38

6. Next steps.................................................................................................................................... 39

7. Appendix A: TSC Terms of Reference.........................................................................................40

8. Appendix B: Base Planning Parameter Studies...........................................................................42

8.1. Current Australian values and international trends..............................................................42

8.2. Error correction considerations............................................................................................44

8.2.1. Error protection and digital radio planning....................................................................44

8.2.2. CBAA research............................................................................................................44

8.2.3. Interference impact......................................................................................................46

8.2.4. Discussion and recommendations...............................................................................47

8.3. Base planning parameter investigations..............................................................................47

8.3.1. Location variation standard deviation...........................................................................47

8.3.2. Height Gain.................................................................................................................. 50

8.3.3. Mobile antenna gain.....................................................................................................52

8.3.4. Man Made Noise and Interference...............................................................................54

8.3.5. Rayleigh fading allowance...........................................................................................55

8.4. Planning field strengths........................................................................................................56

8.5. DAB+ Interference Protection Ratios...................................................................................58

8.5.1. Co-channel interference...............................................................................................58

8.6. Coverage and overspill targets............................................................................................59

9. References and Glossary............................................................................................................61

9.1. References........................................................................................................................... 61

9.2. Glossary............................................................................................................................... 62


1.1. The Purpose of this Report

This report is the output of the Technical Sub-Committee (TSC) of the Digital Radio Planning Committee (DRPC). It provides a number of options for High Level Planning Principles for the DRPC to consider. The options presented are supported by a summary of work undertaken by the TSC on a broad range of relevant radio planning topics.

1.2. TSC role, responsibilities and objectives

The DRPC provided the Terms of Reference for the TSC as shown in full in Section Error: Reference source not found. The critical tasks are summarised in the following points:

1. Develop draft recommendations for the Committee to consider and put to the ACMA on high level planning principles for the allotment of frequency blocks for digital radio. These principles would reference matters such as:

a. The scope of matters that should be included in a high level frequency block allotment plan;

b. The technical parameters that would apply to planning for, and operation of digital radio multiplex transmitters, including coverage overspill and interference limits and;

c. The treatment of national services in a high level frequency block allotment plan;

2. Consistent with the planning principles, prepare for consideration by the Committee and/or the ACMA:

a. An industry wide planning process for coverage and interference analysis; and;

b. Technical specifications including frequency block allotments for licence areas where broadcasters agree that it is economically feasible to provide ongoing digital radio services.

The Terms of Reference led to the establishment of a cross industry group to focus on technical issues related to radio frequency planning for regional digital radio. The scope is to plan at this current stage for ABC, SBS, Commercial and wide area community broadcasters. The full team is listed in Section 1.4

1.3. Background

Radio is still the most popular traditional electronic medium with 95% of Australians listening to radio and 80% of those listening to commercial radio.

DAB+ digital radio take up in the metropolitan areas has been impressive. In just seven years, Australia has 46.9% of people with access to a DAB+ digital radio and 26.4%1 of all listeners now listening to radio via broadcast DAB+.

1 GfK radio survey results, June 2016

1. Introduction


Of the 3.5m listeners on DAB, 1.4m listen to new digital only services, of which there are around 30 in each of the five mainland state capital cities. This is already 1.8m more than are listening to radio via streaming services which have been available for much longer.

There are now 2.57m DAB+ enabled devices in the market which continues to give the retail audio category a $7m a quarter boost The average selling price for a portable DAB+ receiver has dropped from over $140 at launch to below $80 now and have been seen on promotion as low as $17. All leading retailers support DAB+ and have entered into joint promotions of the product category during key retail periods, in exchange for industry backed marketing.

In Australia, one in three new vehicles (31%) has DAB+ as standard or optional fit.

There are now 33 automotive brands offering DAB+ solutions and 15 aftermarket solutions are available. Online retailers offer a DAB+ car adaptor from $64.

Desire to expand trials to permanent

In July 2015, the Department of Communications released its Digital Radio Report with a set of key recommendations including moving the DAB+ trials in Canberra and Darwin onto a permanent basis. The DRCP has spent significant effort looking at ways to achieve this in the shortest timeframe.

Desire to provide regional coverage

The entire radio industry remains strongly committed to fast tracking the rollout of DAB+ digital radio to regional centres ending the current digital divide between the diversity, quality and choice now available to metropolitan audiences and the lack of this diversity and choice for regional Australians as a result of the limitations imposed by analogue technologies.

Industry has actively taken up the Department’s suggestion to join the Digital Radio Regional Planning Committee (DRCP) to work with the Department and the ACMA on planning for regional roll out of DAB+ digital radio services. CRA has suggested that this initially is to population centres over 5000 people.

CRA now chairs the DRCP technical sub-committee and with significant work from the ACMA and all industry sectors, this paper aims to define the technical parameters to commence regional planning.

CRA, ABC, SBS and the CBAA have been asked to provide the DRCP with recommendations for priority regional centres in which to deliver digital radio services in the next 1-3 years.

CRA has consulted with its members and come up with a list of 39 priority markets; ABC and SBS are reviewing the list but have suggested they take up Category 3 licences in Canberra, Darwin and Hobart as a first step. CRA members in the Gold Coast and Sunshine Coast have also expressed interest in proceeding as a first mover. Under current legislation, community sector services are unable to initiate multiplexes implementation but in principle support implementation based on population priorities.

To allow regional communities to access DAB+ digital radio service the commercial radio industry has asked the Government to propose legislative changes to support regional rollout. .

In addition to the original five lighthouse licence areas another 19 major population centres, have expressed interest including, Mandurah Newcastle, Gosford, Wollongong, Geelong, Nambour, Ipswich, Townsville, Cairns, Bathurst, Albury, Ballarat, Bendigo, Wagga Wagga, Bundaberg, Launceston, Murray Bridge and Bunbury .

With these 24 added to the metropolitan population coverage – it is anticipated that by end 2021 85% of the population would have access to DAB+ digital radio.

Available frequencies

As part of the Digital Restack the ACMA were able to plan a 14MHz digital radio sub band in VHF band III. The band has DTV services above and below it and provides a total of eight frequency blocks on which to plan for DAB+ around Australia.


Compared to Europe where much of DTV is now in UHF, allowing DAB access to significantly more of Band III2, the Australian limitations are proving to cause significant technical constraints.

Three of the eight DAB frequency blocks (Ch 9A, 9B and 9C) are already allocated to high powered digital radio services in the five mainland state capital cities, restricting their ability to be reused nearby. The remaining five of the eight frequency blocks must be carefully planned to avoid interfering with existing DTV or adjacent DAB services in the band.

The fact that frequencies need to be reused impacts the antenna patterns and powers that can be planned in regional markets. The national broadcasters have also expressed a preference for planning to include, where possible, comprehensive coverage of the entire Australian population and a preference to operate on Cat.3 multiplexes in all markets to facilitate provision of equivalent services to that available in the current capital cities to all Australians.

All parties acknowledge that the task of planning for DAB+ in another 95 markets is a complex one and given the lack of available Band III spectrum, compromises are going to be necessary.

Legislative framework

Digital radio services are licensed, planned and operate under the provisions of the Broadcasting Services Act 1992 (BSA) and the Radiocommunications Act 1992. Amongst other things, the legislation sets the statutory basis for spectrum planning for digital radio, the allocation of digital radio multiplex transmitter (DRMT) licences and the access regime for multiplex capacity.

Commercial radio broadcasting licensees with a licence extant at the time the digital radio legislation was introduced have the right to apply for shares in joint venture companies formed to hold one or more ‘foundation’ DRMT licences for a licence area. In addition, each incumbent commercial licensee has, through the access regime, a standard access entitlement to 1/9th of the gross capacity of a multiplex to provide commercial radio broadcasting services. Each commercial broadcaster also has the right to bid for any excess capacity on the multiplex, up to an additional 1/9th of capacity.

Designated eligible wide-area community broadcasting licensees may jointly access 2/9 th of gross multiplex capacity reserved for their exclusive use, with the allocation of this capacity to be decided by a community digital radio representative company. The community digital radio representative company may also choose to be a shareholder in the DRMT licensee joint venture company.

Relevantly for this report, the legislation requires the ACMA to prepare digital radio channel plans (DRCPs) that allot frequency channels (‘frequency blocks’) in each licence area for use by DRMT transmitter licensees. The DRCP must also specify the number and category of DRMT licences to be issued for the licence area. The ACMA must ensure it issues sufficient DRMT licences to satisfy the standard access entitlements of commercial broadcasters in the licence area. In regional licence areas, given the maximum number of commercial licenses in any market is four, commercial licensees will only need to access one DRMT. The ACMA must also reserve a frequency block for digital national broadcasting, whether or not a national DRMT transmitter is subsequently licensed on this block.

In preparing a DRCP, the ACMA must, as far as practicable, ensure that it does not discriminate between DRMT licensees in relation to the technical specifications of multiplex transmitters.

The licensing regime provides for some flexibility about how national services may be delivered. Instead of, or in addition to, a stand-alone multiplex transmitter licensed to national broadcasters, the ACMA may issue a “Category 2” DRMT licence in which 1/9th of the gross multiplex capacity is reserved for each national broadcaster (national broadcasters may transfer their access entitlement to the other national broadcaster).

A detailed description of each category of DRMT licence and the relevant reserved capacity is set out in the Terminology section 1.6.

Legislative changes were enacted in February 2016 to simplify the regulatory framework and facilitate the rollout of digital radio in regional licence areas. Further changes are currently being developed 2 For example the UK has 14 frequency blocks in use, while Norway has 22 frequency blocks either in use or planned.


with the aim of reducing the statutory timeframes associated with the planning and licensing of digital radio services.

In a number of places in this report, proposals are made which, if agreed, would necessitate – or would be supported by – further changes to the legislative provisions.

1.4. TSC Members

The following organisations were represented in the TSC.

The Australian Broadcasting Corporation The Australia Communications and Media Authority Commercial Radio Australia Community Broadcasting Association of Australia The Department of Communications and the Arts The Special Broadcasting Service Corporation

1.5. Structure of this report

This report is constructed as a main report and a set of Appendices. The main report presents a set of High Level Planning Principles as well as a summary of findings and proposals for DAB+ RF planning parameter changes while the appendices provide the details of the investigations undertaken.

Section Error: Reference source not found presents the proposed Planning Principles, while Section Error: Reference source not found provides the Planning Parameters and Targets that are proposed to be used as the technical planning basis. Section Error: Reference source not found provides a summary of the cost analysis of regional digital radio implementation, and conclusions are drawn in section 5.

The appendices provide:

A. The TSC Terms of ReferenceB. The details of the base technical parameter investigations

The report contains two forms of feedback to the DRPC:

Proposal A proposal is a recommendation for the DRPC to consider

Consideration A consideration is a specific topic for the DRPC to review

1.6. TerminologyAdjacent Channel Interference (ACI) – Interference caused to a wanted service by an unwanted service on an adjacent DAB channel block or VHF Band III DTV channel.

Allotment – An allotment identifies the frequency block or channel to be used in a particular area.

CAPEX – The Capital Expenditure required to establish an operational DAB+ system


Category 1 digital radio multiplex transmitter licence means a licence for transmitting digital commercial radio broadcasting services and digital community radio broadcasting services.

Category 2 digital radio multiplex transmitter licence means a licence for transmitting digital commercial radio broadcasting services, digital community radio broadcasting services, and digital national radio broadcasting services.

Category 3 digital radio multiplex transmitter licence means a licence for transmitting digital national radio broadcasting services.

Channel – A channel is a defined segment of radiofrequency spectrum of a particularly width. The term channel is typically used for television broadcasting services and because digital radio services occupy similar spectrum to television the term ‘frequency block’ is formally used to describe the digital radio channels to avoid confusion between the two types. It should be noted, however, that when two digital radio services operate on the same frequency block, the term co-channel is used. Similarly, ‘adjacent channel’ is also used to describe the relationship to either another digital radio or digital television service in an adjacent frequency block.

Co-channel interference (CCI) – Interference caused to a wanted service by an unwanted service on the same channel or same frequency block.

Commercial broadcasting service – A radio broadcasting service operated as an independent commercial business.

Community broadcasting service – A radio broadcasting service operated as a community service.

Digital television (DTV) services – An audio/video service broadcast using the DVB-T standard on VHF or UHF frequencies.

Ensemble – In DAB+ the term ensemble describes the full set of services carried within a frequency block.

Frequency block – see the definition under Channel above

Multiplex – is the set of services carried within the ensemble. The term ‘multiplex’ is often used interchangeably with ‘ensemble’ and is often shortened to ‘mux’.

National broadcasting service – a service provided by either the ABC or SBS

OPEX – The Operating Expenditure required to operate and maintain a working DAB+ system.

Regional licence area – For the purposes of this report, regional licence areas means licence areas outside of the mainland state metropolitan areas where digital radio services are already in operation but not including remote licence areas.

Self-interference – In a single frequency network (SFN) all transmitters operate on the same frequency and providing they carry the same content then there should no interference between the transmitters. However, this is dependent on the distance between the transmitters, their power level and the relatively timing between the launch of signals at each site. Where the necessary conditions are not met interference can occur and this is termed ‘self-interference’.

Service – a continuous program stream carried within a digital radio ensemble. Service is also used in the context of particular categories of service specified in the BSA.


1.7. IntroductionThe Planning Principles provide a basis for the planning of DAB+ in regional Australia. Due to the very limited spectrum that is available to DAB+, i.e. eight frequency blocks across Australia, there are a number of criteria that need to be considered as these require trade-offs under different deployment scenarios:

1. Interferencea. The design of the Australia-wide DAB+ allotments , i.e. frequency allotments, requires

the careful balance of interference between target coverage areasb. Additionally both self-interference and interference with digital television services

(DTV) must also be consideredc. While lower power transmissions reduce interference there is an impact on the

coverage and cost of the network2. Spectrum Capacity

a. The capacity of regional DAB+ networks in terms of the number of frequency blocks that can be implemented in an area will be limited in a Multi-Frequency Network (MFN) design due to interference between transmissions in licence areas which use the same frequency block.

b. Closely spaced licence areas requiring different frequency allotments are more difficult to plan within the interference constraints

3. Coveragea. When interference limits dictate the use of lower power levels the coverage area will

reduce. This can be compensated through the use of repeaters, albeit at additional CAPEX and OPEX expense. A careful balance needs to be targeted to ensure cost effective service delivery.

b. Use of lower power levels and greater use of repeaters may not be sufficient to cover all population centres unless greater use of Single Frequency Networks (SFNs) are also made within a commercial licence area or national local area. Wider-area SFNs may require the amalgamation of broadcaster licence areas or national broadcaster local radio areas, and reduce the localisation that can be provided.

4. Costa. The reduction of transmission powers will reduce interference but also coverage. To

ensure suitable coverage some licence areas will need to deploy additional repeater sites. It is generally accepted that repeaters are a significant operating expense.

5. Localisationa. The design of a single multiplex for mixed commercial, national and community

broadcasting services has been shown to be technically feasible within the constraints, although a single multiplex will limit the number of services available. The addition of a second multiplex as required by the legislation is difficult with most options showing significant interference issues. This will cause compromises on the deployment of both multiplexes and hence the way local regional services are delivered.

6. Optimisationa. The sample designs undertaken and the allotment methods and planning parameters

may be able to be optimised further to allow later additional services. This will however take time to study the interference performance of the initial rollouts.

7. Deployment timeframea. The industry as a whole is keen to start the deployment of DAB+ in regional Australia.

It is important to ensure that the recommended planning approach does not result in significant delays to deployment.

Each of the Planning Principles presented address each of the above criteria.

2.DAB+ Regional Radio Planning Principles


1.8. Capacity considerations

There are 95 regional3 commercial radio licence areas currently planned in Australia. The graph below shows the distribution of the number of commercial broadcasting licensees within these markets.

Figure 2-1: Distribution of commercial licensees

The Radiocommunications Act 1992 (Cth) currently provides a single fixed formula for the sharing of a Category 1 multiplex between commercial and community broadcasters, and Category 2 multiplex between national, commercial and community broadcasters. A Category 3 multiplex is for the exclusive use of national broadcasters. The multiplex sharing rules are set out below:

Under a 1 Category multiplex, each incumbent commercial broadcaster is eligible to receive a standard access entitlement of 1/9 th of the capacity (up to 7/9 th in total for commercial broadcasters) and the community broadcasters are eligible to share amongst themselves 2/9th

of multiplex capacity reserved for their exclusive use. Under a Category 2 multiplex, each incumbent commercial broadcaster is eligible to receive

1/9 th of the capacity (up to 5/9 th in total for commercial broadcasters), each incumbent national broadcaster similarly is eligible to receive 1/9 th, and the community broadcasters are eligible to share 2/9 th amongst them, reserved for their exclusive use,.

Under a Category 3 multiplex, the national broadcasters share the total multiplex capacity. Once the standard access entitlements of the incumbent commercial broadcasters have been

satisfied, the multiplex transmitter licensee may allocate any excess capacity in accordance with the legislation. In summary, the licensee must auction the capacity if demand exceeds supply. Relevantly, the incumbent commercial licensees may only access an additional 1/9th of multiplex capacity each, giving a total capacity cap of 2/9th per commercial radio broadcasting licence. Community broadcasters in the licence area are also able to bid for excess capacity entitlements. National broadcasters may also bid for excess capacity entitlements on a Category 2 multiplex.

The following table outlines the generic entitlements:

3 Canberra, Darwin and Hobart included in this total but the remote licence areas are excluded.


Category 1 multiplex Category 2 multiplex

Commercial broadcasting licences for the licence area 4 3 2 1 4 3 2 1

Total commercial broadcaster standard access entitlements 4/9 3/9 2/9 1/9 4/9 3/9 2/9 1/9

ABC standard access entitlement nil nil nil nil 1/9 1/9 1/9 1/9

SBS standard access entitlement nil nil nil nil 1/9 1/9 1/9 1/9

Designated community broadcasters combined access entitlement 2/9 2/9 2/9 2/9 2/9 2/9 2/9 2/9

Excess capacity 3/9 4/9 5/9 6/9 1/9 2/9 3/9 4/9

Multiplex capacity unable to be allocated to incumbent commercial broadcasters4 in the licence area due to capacity cap

0/9 1/9 3/9 5/9 0/9 0/9 1/9 3/9

Table 2-1: Current Cat.1 and Cat.2 capacity entitlements

Consideration 1: The maximum number of commercial licences in any regional licence area is four, giving a maximum standard access entitlement capacity requirement of 4/9th. This means there will be at least 1/9th excess capacity on any Cat 2 multiplex and at least 3/9th excess capacity on a Cat 1 multiplex. Even if all licensees in an area purchased excess capacity entitlements up to the cap, there is a possibility that some multiplex capacity would remain unable to be used unless it was purchased by a community or national broadcaster (the latter in the case of a Cat 2 multiplex only), or a new commercial digital licence was allocated. A change in legislation would be required to provide for additional capacity allowances for commercial broadcasters.

The TSC makes the following observations about the current spectrum entitlements:

The current legislative settings limit the planning options available to the TSC and representatives of the Department of Communications have kept themselves informed of these by attending the regular TSC meetings.

Some options for adjusting the legislative settings were made in the paper Transitioning Canberra and Darwin to multiplex licencing and industry provided feedback on the various options.

Under a Category 3 multiplex, there is an option that in smaller markets where there is only one or two existing commercial radio stations, it may be more economically sensible in the first instance for the commercial broadcasters and the national broadcasters to share one multiplex on a Category 2 licence, however the law would need to change to allocate to national broadcasters more than the currently allocated 1/9 th each.

1.9. Principle 1: Overall planning approachThe TSC considered two alternative approaches to planning regional digital radio services. The short-term or ‘first mover’ approach is to only identify the frequency blocks to be used in an area when the licensees in the area are ready to commence a service. The long-term approach will require the development of an overarching plan identifying the (two) frequency blocks to be used in every area either nationally or, as a minimum, across an area extending at least 400 km from any area that is ready to commence a service. Thus the long-term approach requires either a national plan or a series

4 This capacity is available to other eligible broadcasters for the licence area


of interlinked ‘regional plans’. Such plans would be indicative and able to be adjusted if necessary until such time as proposed allotments are incorporated in a legislative instrument (a Digital Radio Channel Plan).

As part of its contribution to the work of the TSC the ACMA undertook extensive studies to evaluate the options for allotting frequency blocks in the region within 400 km of Sydney. The results of these studies clearly showed that the outcomes are very dependent upon the maximum transmission power allowed for each licence area. Even with reduced power levels it is difficult to identify suitable frequency allotments which will provide acceptably low levels of interference. Adopting a ‘first mover’ approach would not allow for the balancing of transmission parameters and interference across all areas and would therefore lead to inequitable use of the available frequency block capacity.

Metrics Overall planning approachFirst Mover Regional plans

Interference By planning only for the first mover markets, subsequent markets are likely to experience high levels of interference

By developing a plan to cater for all areas there should be better control of interference levels

Capacity Less overall capacity is likely as early markets are likely to constrain subsequent markets (unless powers can be adjusted retrospectively)

Sufficient capacity would be planned for all markets

Coverage Potentially better coverage for early markets, but subsequent markets may have poor coverage due to interference constraints or may not be able to be covered at all.Uncoordinated approach may lead to key population centres missing out on DAB+

Coverage of early markets may be lower but coverage of other markets should be better due to improved control of interference.Coordinated approach is more likely to maximise audience access to DAB+.

Cost Lower for early markets, but potentially higher for subsequent markets

Costs are likely to be higher as making provision for all markets will require lower power levels which will require additional repeater sites in some LAs

Localisation A few early markets will be able to have two ensembles that operate independently from other markets and therefore a high degree of localism. However, subsequent rollout planning may need to consider aggregation of markets to make best use of remaining capacity leading to less localism.

It is likely that the national broadcasters (Cat.3 mux) will need to implement regional SFNs across multiple markets. Some limited aggregation of commercial/community (Cat.1 mux) may be necessary.

Optimisation No difference between options No difference between optionsDeployment May lead to early deployment in first

mover marketsAdditional time will be required to develop regional plans, and this may delay rollouts.

Table 2-2: Overall planning approach options

The studies undertaken clearly show that to ensure a long-term viable planning regime where future deployments are not disadvantaged by the initial deployments careful wide area planning is needed, through the development of several indicative allotment plans for extensive regional areas or one indicative national allotment plan.

While the development of regional indicative allotment plans is likely to take longer than planning for digital radio rollout in a small number of individual licence areas, this difference is not expected to be especially large. In undertaking the Sydney region allotment studies for the TSC, the ACMA has


developed techniques that allow allotments to be determined for a region of around 25 licence areas reasonably quickly which should not add significantly to the overall planning process of developing the legislative digital radio channel plans. The key to being able to undertake the planning studies quickly is for industry to be in a position to provide details of the proposed transmission parameters (including transmission sites, powers and antennas) for all licence areas in the relevant region(s).

Proposal 1: The planning of a licence area should address the wider area through the development of a regional plan encompassing all areas which may be affected by the transmissions in the target licence area.

1.10. Principle 2: Proposed frequency allotment planning approach

The ACMA studies referred to in the previous section initially studied an allotment approach whereby the Cat.1 and Cat.3 multiplexes for each licence area were allotted frequency blocks that were essentially equivalent in terms of transmission parameters and interference levels by considering the allotment of pairs of frequency blocks. This approach is equivalent to allotting frequency blocks to the Cat.1 mux from a pool of four frequency blocks and to the Cat.3 mux from another pool of four frequency blocks. The initial studies indicated such an approach would lead to very high interference levels so studies examined alternative scenarios. The effect of reducing the size of the Cat.3 pool (and increasing the Cat.1 pool) was studied. This is made possible because the national broadcasters’ local radio areas do not coincide with commercial licence areas and this would allow Category 3 multiplexes in adjacent licence areas to be allotted the same frequency block which would need to be operated as a wide area SFN5. At the extreme with just one frequency block in the Cat.3 pool, the SFN would need to cover the entire state.

The details of the methods and studies undertaken are provided in a separate report by the ACMA titled ‘Regional digital radio planning – Results of prediction and allotment studies for areas within 400 km of Sydney’ [15].

The studies considered 4/4, 5/3, 6/2, 7/1 allotment scenarios where the first number reflects the number of frequency blocks available in the pool for allotment to the Cat.1 mux and the second number the size of the allotment pool for the Cat.3 mux. Hence a 6/2 scenario results in six frequency blocks being available for allotment to a Cat.1 mux in each licence area and two frequency blocks available for the deployment of Cat.3 national services in a flexible manner across multiple licence areas. The 6/2 scenario is illustrated in Figure 2-2.

5 The carriage of local services within a wide area SFN is addressed in Table 2-4


Figure 2-2: Maps illustrating hypothetical 6/2 allotments

The studies initially were conducted with transmission power levels of up to 50kW effective radiated power (ERP) for many of the main transmitter sites. As the high power levels resulted in high levels of interference under all allotment scenarios, the effect of reducing or capping the maximum transmission power permitted in any licence area (to 5kW) was examined for each allotment scenario. Despite the reduced power levels, the 4/4 scenario results still showed unacceptably high levels of interference for the reduced power analysis conducted with both the standard planning parameters and the proposed revised planning parameters and for this reason the 4/4 scenario is not considered in the comparison of scenarios that follows. A summary table of the total interference results across the study area for each of the scenarios is presented in Table 2-3. The aggregate population base for the study area (NSW) is 10.97 million6.

Allotment Scenario

Standard Planning Parameters

Revised Planning Parameters

High ERP Reduced ERP Reduced ERP4/4 1,237,503 968,448 551,089

5/3 887,860 616,107 284,667

6/2 545,886 346,311 135,965

7/1 312,629 214,311 65,852Table 2-3: Summary of overall interference for study area

The overall results of the various studies undertaken indicate that through a combination of power caps and a greater pool of frequency blocks for the Cat.1 multiplexes at the expense of frequency blocks for the Cat.3 multiplexes, It may be possible to achieve a full rollout with acceptable interference levels. It should be noted that the need to cap power levels will increase costs through the need for additional repeater sites, or will alternatively lead to poorer coverage – particularly in-building coverage or both.

For the Cat.3 mux, the need to operate a wide area SFN will also mean that power levels need to be kept as low as practicable to control self-interference within the SFN which will also increase costs and impact on coverage. The reduced number of frequency blocks will also prevent the national broadcasters providing current levels of localism on a Cat 3 multiplex.

All of the allotment pool scenarios are theoretically possible if the power cap is sufficiently low. It should be noted however, that due to the uneven distribution of licence areas a particular allotment scenario might present no difficulties for allotments to most licence areas but leads to high levels of interference for a few licence areas. Therefore, in some areas it may be necessary to aggregate some licence areas for the chosen allotment scenario to provide all areas with a technically acceptable and cost effective outcome.

6 The relevant population is the sum of the populations of each licence area, which includes double-counting both Sydney licence areas as well as any overlaps between licence areas. Any interference from one area is considered in each other licence area individually and then summed, including interference; hence, each of the commercial Sydney multiplexes is potentially interfered with and the Sydney population is counted twice if so.


Ultimately, there is a need to strike a balance between the costs and trade-offs for the Cat.1 multiplexes and those for the Cat.3 multiplexes. Hence the following three options should be considered:

Option Principle 2a: That the 5/3 allotment scenario should be used when allotting frequency blocks to Cat.1 and Cat.3 multiplexes

Option Principle 2b: That the 6/2 allotment scenario should be used when allotting frequency blocks to Cat.1 and Cat.3 multiplexes

Option Principle 2c: That the 7/1 allotment scenario should be used when allotting frequency blocks to Cat.1 and Cat.3 multiplexes

The advantages and disadvantages of the three options are shown below.

Metrics Frequency allotment scenarios5/3 6/2 7/1

Interference Greater interference for Cat.1 mux, less for Cat.3 mux

Less interference for Cat.1 mux, greater for Cat.3 mux

Least interference for Cat.1 mux, greater for Cat.3 mux

Spectrum capacity

Every licence area7 would be allotted a frequency block for a Cat.1 mux. 3 frequency blocks for Cat.3 mux.

Every licence area8 would be allotted a frequency block for a Cat.1 mux. 2 frequency blocks for Cat.3 mux.

Every licence area8 would be allotted a frequency block for a Cat.1 mux. 1 frequency block for Cat.3 mux.

Coverage Cat.1 coverage likely to be lower due to lower powers or greater interference. Cat.3 coverage likely to be higher.

Cat.1 coverage likely to be higher due to lower interference levels. Cat.3 coverage likely to be better than for 7/1.

Cat.1 coverage likely to be best due to higher powers or lower interference. Cat.3 coverage likely to be worst due to SFN self-interference.

Cost Higher costs for Cat.1 but lower for Cat. 3 (compared to 6/2)

Costs for Cat.1 lower than 5/3 and higher than 7/1. Costs for Cat.3 higher than 5/3 but lower than 7/1.

Lowest costs for Cat.1 but highest for Cat.3

Localisation Aggregation of licence areas most likely to be needed for some Cat.1 muxs. Cat.3 mux should have a fair degree of freedom to provide localism within the Cat.3 mux.

Slightly less localisation than 5/3 due to the need to aggregate licence areas for the Cat.1 muxs.Cat.3 mux would have some scope /freedom to provide localism within the Cat.3 mux. Large Cat.3 wide area SFNs could carry multiple ‘local’ ABC services.Cat.2 muxs (in lieu of Cat.1) could be used so national broadcasters can provide localism, although this would be at an increased cost for national broadcasters, which

Aggregation of licence areas less likely to be needed for Cat.1 muxs. Cat.3 mux would be state wide SFN with no scope for localism.Cat.2 muxs (in lieu of Cat.1) could be used so national broadcasters can provide localism.

7 With the exception of licence areas that are to be aggregated which would share one allotment.


Metrics Frequency allotment scenarios5/3 6/2 7/1

would potentially have to contribute towards both multiplexes.

Optimisation More likely to be able to optimise coverage and interference

More likely to be able to optimise coverage and interference

Less likely

Deployment Power caps on Cat.1 mux most stringent and may require more repeaters.Requires SFNs across a small number of licence areas for the Cat.3 mux. No need to change any metro mux.

Power caps on Cat.1 mux fairly stringent and may require more repeaters. There might be scope to relax power cap on case by case basis.Requires very large SFNs for Cat.3 mux, but provides scope to use different frequency blocks at state borders without the need to change any metro mux.

Power caps on Cat.1 mux least stringent. May not require as many repeaters. There might be scope to relax power cap on case by case basis.Requires state-wide SFNs for Cat.3 and would require the existing Sydney and Adelaide Cat.3 to change frequency blocks.

Table 2-4: Frequency allotment scenarios options

Proposal 2: : That the 6/2 frequency allotment scenario should be adopted with the national frequency blocks being 9C and 8B.

Allotments should be determined with the following consideration.

Consideration 2: A power limitation for all licence areas of 5kW nominal ERP should be used in determining the allotments and baseline interference levels. Higher power will be considered on a case by case basis if there is minimal additional interference to other areas. Note however that some areas may need to be even lower power (e.g. Katoomba) due to the local topography and proximity to other licence areas.

1.11. Principle 3: Licence area aggregation While licence area aggregations for DAB+ are not seen by the commercial radio industry as a viable option due to business reasons, the frequency allotment challenges discussed above clearly indicate the need for a limited number of aggregations. These aggregations would reduce interference to acceptable levels (both in the aggregated areas and across the general region) and also enable national, commercial and wide area community broadcasters to provide reasonable levels of localism.

In DAB+ a wider area transmission which covers several commercial licence areas can be constructed through the operation of SFNs. This has the significant advantage of allowing better spectrum efficiency and reducing interference particularly where the density of licence areas is greatest – typically around the capital cities.

Additionally, the infrastructure that is required for aggregated areas will be shared across a greater number of licensees, so the CAPEX and OPEX burden would be lower. This may be offset slightly by the total aggregated area being larger than the individual licence areas which would require more transmission sites than each individual licence area. The biggest advantage would be where large licence area overlaps currently exist as aggregation would avoid the duplication of transmission sites that would be required if each licence area were to operate an independent multiplex.

Depending on one’s perspective a potential disadvantage (or advantage) is that all services will be available in the larger aggregated area. While this may be a disadvantage for the licensees due to


greater competition it is likely to be an advantage for listeners who would be able to listen to their favourite service across a larger area, which they may already do due to licence area overlaps or fortuitous overspill of analogue signals (although not technically of an adequate field strength for planning purposes such fortuitous signals may still be of sufficient quality to continue listening).

In deciding which licence areas to aggregate consideration will need to be given to technical factors such as coverage and interference as well as to non-technical factors such as community of interest, existing licence area overlaps, differential population in the licence areas and the number of commercial licences in operation. Legislative change would be required to allow for the aggregation of commercial licence areas for the purpose of digital radio and to address the restrictions on licence ownership that might arise as a consequence

The extent of aggregation will in part depend upon the allotment scenario selected. That is a 5/3 scenario will require greater levels of aggregation than a 7/1 allotment scenario with 6/2 in between. The ACMA allotment studies considered two aggregation case studies under the 5/3 and 6/2 allotment studies. These studies demonstrated that the aggregations considered resulted in significant reductions in interference. Refer to Table 15 of the ACMA report [15] and Table 5 of Addendum 1 to that report [17].

The ability to consider and incorporate licence area aggregation into the frequency allotment planning will require legislative amendments.

Metrics Extent of aggregationNo licence area aggregation Limited licence area aggregation

Interference Higher interference to the point some areas may not be worth operating

Aggregation would be used to reduce interference to acceptable levels where it would otherwise not be practicable to operate a digital radio service

Spectrum capacity

Minimal difference in options Minimal difference – may assist in opting for an allotment scenario with fewer Cat.1 frequency blocks and more Cat.3 blocks.

Coverage Coverage will be lower due to higher levels of interference and the consequent need for lower power levels

Better coverage, lower interference

Cost Higher LowerLocalisation No impact for Cat.1. May be worse

for Cat.3 as may need to choose 7/1 allotment scenario.

No loss of localism in the short to medium term as the analogue licence areas would not be affected. Any simulcast of the analogue services on digital would still be focused on the analogue market area.Better for Cat.3 as 6/2 allotment scenario may be more practicable. A 5/3 allotment scenario may be possible with higher levels of aggregation.

Optimisation Greater optimisation needed to minimise interference

Less optimisation needed to minimise interference

Deployment Higher overall costs as less infrastructure sharing

Lower overall cost due to infrastructure sharing

Table 2-5: Licence area aggregation options

It is not possible to identify all areas that may be candidates for licence area aggregation in advance of the detailed planning however work to date has indicated that licence areas with extensive licence area overlaps, are close to the metropolitan area or are in an area where there is a greater density of licence areas would be strong candidates for aggregation. Aggregations considered in the allotment studies included:

Campbelltown, Katoomba, Lithgow,


Gosford, Newcastle Nowra, Wollongong Bathurst, Orange

It is important for the planning of areas around Sydney, Brisbane and Melbourne/central Victoria that the scope for licence area aggregation be addressed.

Consideration 3: The DRPC may consider whether the commercial & wide area community broadcasters in some specifically difficult planning areas should be contacted to discuss the potential for licence area aggregation approach.

NOTE: CRA will discuss potential licence area aggregation on 6 October 2016. The text of this consideration will be adjusted after feedback is received.

Consideration 4: The DRPC request DoCA to consider legislative amendments that would enable the ACMA to aggregate licence areas for the purpose of digital radio, noting that public interest, policy and legal considerations may necessitate constraints on flexibility in particular cases.

1.12. Principle 4: Transmitter site selection

Co-siting of DAB+ transmission sites is essential for the minimisation of interference between both VHF Digital Television (DTV) and other DAB+ transmissions.

Transmissions are considered to be co-sited if their antenna systems are less than 1 km apart. This usually relates to specific geographical locations such as mountains or hill tops where the antenna systems are either on the same structure or if separate tower structures are used they are typically less than 100m or so apart.

If DAB+ transmissions, particularly the main transmissions in an area, are not co-sited with VHF DTV there is a significant probability that the DAB+ signal will interfere with VHF DTV reception. Such interference is generally limited to a specific area and can usually be overcome through the use of DTV masthead filters as was done to address this issue during the metro DAB+ rollout8.

The same issue arises for DAB+ repeater sites, and in some cases can be worse as repeater sites are usually closer to the area covered by the DTV services even though they are also lower power than the main transmission site.

For DAB+ the frequency blocks adjacent to DTV have a higher protection ratio (of -5dB rather than non (immediately) adjacent which have a PR of -30dB [1].

Similar effects can occur with DAB+ to DAB+ adjacent channel interference if co-siting is not used. The critical example is when a high power main site is used to cover multiple licence areas which each have their own lower power main sites. In this case, which is representative of a national wide area transmission overlaying local commercial area transmissions, the local commercial transmission may cause ACI into the national transmission. The current ACI protection ratio value is -40dB and is discussed in section 1.20.2.

The options considered here are

1. Co-siting preferred : in this case all broadcasters will be required through the “Technical Planning Guidelines” to co-site their transmission with DTV and other DAB+ services where practical

a. Situations which are not considered to be practical arei. There is no available aperture on the DTV towerii. there is no space for additional towersiii. it is cost prohibitive to use the same tower due to site operator monopolistic pricing

8 Notch filters were provided by Hills Industries.


2. Uncoordinated: in this case broadcasters are free to choose the transmission site, however there are some encumbrances

a. The newly established DAB+ transmission must not interfere with existing DTV or DAB+ transmissions

Uncoordinated sites will be required to be used for some repeater sites as VHF DTV repeaters are not commonly deployed close to population centres.

Metrics Transmitter sitingCo-Siting Preferred Uncoordinated

Interference Minimised potential areas of ACISpectrum capacity

Maximum Reduced

Coverage Maximum ReducedCost per LA Minimum More due to additional transmission sites

to overcome areas of interferenceLocalisation No impact Potential loss of coverage unless

interference areas are corrected with additional transmission sites

Optimisation No optimisation needed to minimise interference

Optimisation needed to minimise interference

Deployment Minimum cost and time Increased cost and time due to additional transmission sites to overcome interference

Table 2-6: Transmitter siting options analysis

Proposal 3: When selecting sites for main transmitters and repeaters the following rules should be followed:

a) Main transmitters (or repeaters) should be co-sited with local VHF DTV when it is used in a Licence Area wherever practical

b) Where there are multiple DAB+ transmissions in the same area the main transmitters should be co-sited wherever practical

c) Where transmitters and repeaters are proposed after the establishment of the first DAB+ multiplex operating in the area the licensee of any subsequent DAB+ multiplex should ensure that there is no interference into the established DAB+ multiplexes (earlier deployment has precedence)

d) Repeaters which are not co-sited with VHF television transmitters should as far as practical ensure that either

i. there is an alternative television source available e.g. UHF, orii. no VHF services are lost by existing consumers. Note that fortuitous coverage is

not included.

1.13. Discussion

A significant amount of study has been undertaken by the TSC members to determine what allotment planning options are technically feasible. The results of the studies showed that in order to deploy DAB+ across regional Australia with suitable operational characteristics a number of compromises will be required by all broadcasters. In particular it has been shown that the very limited number of frequency blocks forces a reduction in transmission power to reduce interference between areas to workable levels. The 6/2 model proposed provides the best compromise between capacity availability and transmission power while still keeping the cost of deployment within realistic limits.

Given the complexities of the planning process, particularly the impact of interference, the TSC has proposed that planning should be undertaken in large regions, e.g. 400 km around the existing mainland state capital cities. This approach is seen as equitable to all broadcasters and realistic in the time taken to determine the allotments. As discussed in the Next Steps this is the next essential part of the planning process.


The density of commercial licence areas has been shown to be of critical significance around the metro cities, particularly so around Sydney. It was further shown that the aggregation of some limited licence areas will have a big impact on the feasibility of planning cost effective DAB regional networks. While such aggregations may be considered by some broadcasters negatively there are a number of commercial benefits that the broadcasters may gain.

The TSC also examined the implications of co-siting transmissions. While there may be perceived cost savings in using wide area national overlays these should be tempered by the planning complexities and long term deployment impact that they may produce. Consequently it is proposed that the use of wide area overlay transmissions be factored into the planning process from the start to ensure that all broadcasters understand the impact and that they can be addressed early to prevent any long term negative impacts.


1.14. Introduction

The analysis of radio frequency interference and coverage are the key aspects of allotment planning. The network designer strives to achieve a balance where the inter-area interference is below a target threshold while the coverage within the target area is maximised at minimum cost (usually minimum sites).

The methods used to undertake this process naturally rely on a range of parameters which allow the assessment of quality metrics such as the number of people who will receive a minimum field strength in an area, or the number of people who are expected to receive interference for a specified percentage of time.

The parameters which form the basis for planning are currently being reviewed internationally as it has been observed that different countries, over time, have updated their planning parameters from those originally developed and published by the two leading bodies, the ITU and the EBU, e.g. [2], [4].

Additionally, since the time of publication of those documents, which in some cases is well over 10 years ago, planning and propagation modelling tools have made significant technical advances, for example 10 years ago it was typical for coverage planning to be done with terrain data which had a resolution of 100m or more while today it is common to use 20m or less terrain data and associated detailed clutter information. Additionally the models for coverage planning have migrated from empirical models to more deterministic models which have been shown to provide improved accuracy in the local planning area.

Given these changes in situation the TSC embarked a number of investigations to review the current parameters and where appropriate make recommendations for adjustments. This section provides an overview of the outcomes and reasoning, the details can be found in Section Error: Reference source not found and associated reference documents.

1.15. Current Australian values and international trends

There are several critical base level parameters which are used to determine the planning field strengths. These values vary from country to country and between standards and regulatory organisations. The critical base level parameters studied by the TSC and reported here are the standard deviation of location variation, height gain, man-made noise and interference allowances, receiver antenna gain and DAB+ to DAB+ co-channel interference Protection Ratios. The findings are presented in this section while the details of the investigations can be found in section Error: Reference source not found.

Other than the protection ratios, these base level parameters directly influence the minimum field strength assumed in planning predictions and interference studies to be necessary for adequate reception.

A summary of Australian and international planning field strengths is shown in Table 3-7.

3.DAB+ RF Planning Parameters and Targets


Country Minimum reception field strength (dBμV/m) Comments

Mobile

(99% of locations)

Suburban

(95% of locations)

Urban

(95% of locations)

1.5m 10m 1.5m 10m 1.5m 10m

Australia 49 63 56 70 62 76 From [5]

UK 44 54 53 63 60 70 Urban is considered as dense urban by UK OFCOM

Norway 48 58 54 64 60 70

Germany 48 60 56 68 62 74

Switzerland 48 66

Italy 60 66

ITU 48 60 54 66 - - RRC06

EBU 43 50 From [2]

Table 3-7: Current international and Australian planning field strengths

1.16. Error correction considerations

Forward Error Correction (FEC) is an essential part of digital communications providing the ability to correct errors that are received and consequently provide more robust and power efficient transmission. DAB+ has 5 available FEC code rates each of which have different error correcting capabilities and impact on the overall capacity of the multiplex – the stronger the protection the lower the multiplex capacity. The details of those trade-offs are provided in section 1.27.

It is widely adopted that the use of Protection Level EEP-3A (FEC code rate ½ coding) is the most balanced approach between protection and capacity and is used almost exclusively in DAB+ planning. While the use of weaker codes can appear to be advantageous due to the higher capacity that it provides it is considered to be a risky strategy to plan extensive DAB+ networks based on weaker code rates which will generally only be used in specific circumstances. The additional capacity also comes at a higher price due to the need for increased transmission powers or increased transmitter site density to cover the target area. In addition the co-channel interference protection ratio must also be increased making planning much more difficult.

Proposal 4: The planning of DAB+ in regional Australia will assume Protection Level EEP-3A (FEC code rate ½).


Note that this does not preclude the use of other protection levels / code rates with either stronger or weaker protection due to specific operational circumstances.

1.17. Base planning parameter investigations

1.17.1.Location variation standard deviation

The results of CRA field testing for the analysis of the location variation standard deviation (SD) are provided in section 1.28.1. Although the CRA study is not yet complete early indications are that the current value of 5.5dB is too high and will result in unnecessarily high target field strengths. This conclusion is also supported by the results of the UK trials in 2012 [7] which lead the UK to adopt an SD of 4.0 dB which they considered to be a conservative figure.

Proposal 5: The location variation standard deviation parameter be changed from 5.5dB to 4.0dB in line with the value used in the UK.

1.17.2.Height Gain

The results of CRA / ABC testing have shown that the Height Gain (HG) at most sites is less than 10dB. The detailed field test results shown in section 1.28.2 that 90% of measurements are less than 11dB. Further, both the UK and Norway use values of 10dB while Germany uses 12dB which is most likely derived from the ITU-R Geneva-06 regional plan. Given the results and international trend away from the historic 13dB used in [2] which has not been updated from the initial planning documents the following is proposed.

Proposal 6: The Height Gain parameter used to convert field strengths required at 1.5m to 10m be adjusted from 13dB to 10dB

1.17.3.Mobile antenna gain

Studies of the performance of antennas used in mobile environments for vehicles have shown that both the gain and antenna patterns can be compromised and significantly less than the value currently used to determine the minimum field strength for mobile environments, see section 1.28.3.

The vehicle antennas were shown to particularly suffer from pattern notching due to the location of the antenna, e.g. window mounted antennas, and rooftop mounted antennas which are close to the window edge. Some antenna types such as “shark’s fin” have low gain even though their overall pattern is reasonably circular.

Many handheld mobile receivers including smartphones use the unit’s headphones as an antenna. While this solution is convenient for the user it results in highly variable patterns and gain performance


dependant on the orientation of the antenna with respect to both the listener’s body and the radio signal field. Such solutions are generally accepted to have a low gain performance.

Proposal 7: The antenna gain for mobile devices be changed from -5dBd to -10dBd

1.17.4.Man-made noise and interference

Consideration of current international allowances for man-made noise and interference (MMNI) and changes in the interference environment are provided in section 1.28.4.

While MMNI does appear to be increasing, given that there has not been any extensive testing in this area reported and the CRA tests have been indicatory only it is suggested that the only change to the current budgetary allowance is to include the Interference allowance for 1.5m as well as 10m. This effectively applies a MMNI allowance of 2dB in line with Germany.

Proposal 8: The allowance for Man Made Noise and interference be adjusted as follows

Man Made Noise Interference

Current allowance (1.5m) 1dB 0dB

Proposed allowance (1.5m) 1dB 1dB

Current allowance (10m) 1dB 1dB

Proposed allowance (10m) 1dB 1dB

1.17.5.Rayleigh fading allowance

The Rayleigh channel model is used to account for received signal fading when there is no line-of-sight signal component from the transmitter. This is the main reception scenario for both mobile e.g. vehicle and portable indoor receivers. The allowance for Rayleigh fading was originally based on DAB and set to 5.6dB which is added to the Gaussian CNR or 7.4dB for DQPSK reception. DAB+ has a different error protection structure to DAB: DAB+ uses Equal Error Protection convolutional coding and an outer Reed-Solomon code which is provides better overall error protection than the single Unequal error protection coding used in DAB. The difference in performance in a Rayleigh environment is generally considered to be between 1 and 2dB, see [10] and the CRA receiver bench testing results [12] which both report a 1.5dB improvement for a typical urban environment9. We also note that the UK OFCOM / BBC / Arqiva report [11] uses a Rayleigh implementation margin of 4.6dB.

Proposal 9: Adjust the Rayleigh fading allowance from 5.6 to 4.6dB to change the minimum carrier to noise ratio required by a DAB+ receiver to provide error free audio for a typical Rayleigh channel from 13dB to 12dB.

9 Based on the TU25 channel simulation model


1.18. Planning field strengths

Considering the investigations undertaken and international trends in base parameters as detailed above and in section 1.28 the following is proposed:

Proposal 10: The planning field strengths should be adjusted as follows:

Planning field strengths (dBμV/m)

Mobile Suburban Urban

Location availability 99% 95% 95%

Current planning field strength (1.5m) 49 56 62

Proposed planning field strength (1.5m) 50 54 60

Current planning field strength (10m) 63 70 76

Proposed planning field strength (10m) 60 64 70

1.19. DTV interference considerations

There is a potential for viewers of VHF television transmissions to receive interference from digital radio transmissions under particular circumstances. Overall the potential problem is small but manageable. The potential for interference is greatest when the radio and television transmissions aren’t co-sited and/or when the digital radio transmissions are on frequency blocks 8A and 9D, directly adjacent to digital television channels 8 and 10. Television receiving systems that incorporate a mast-head amplifier will be more likely to be affected than those that do not.

In undertaking the frequency allotment studies the ACMA calculated the population that may be affected by interference to VHF television in the areas surrounding each digital radio transmission site that had been assumed in the allotment modelling. Affected populations were calculated for the more critical DAB+ frequency blocks of 8A and 9D as well the other non-adjacent DAB+ frequency blocks. An assessment of whether the potentially affected viewers had an alternative source of television signals on the UHF band was also made and an adjusted figure of the potentially affected population was arrived at. These figures of the potentially affected population were then used in the automated allotment algorithm to reduce the likelihood that and area with VHF television reception would be allotted a DAB+ frequency adjacent to TV channels 8 and 10.

The ACI protection ratios used in the study for DAB+ interference to DTV were -5dB for the worst case of DAB+ transmissions on blocks 8A or 9D. Calculations for the non-adjacent frequency blocks used a protection ratio of -30dB.


In developing regional indicative allotment plans similar considerations should be made to assess and minimise the potential for interference to television reception.

The ACMA’s Technical Planning Guidelines (TPGs) currently specify a digital radio to digital TV adjacent channel protection ratio of -9 dB based on measurements undertaken by the ACMA in 2007. However, the digital television signal used in those measurements had an FEC (Forward error correction) of 2/3, whereas broadcasters now use 3/4 FEC. Measurements for the 3/4 FEC case also undertaken in 2007 indicate the protection ratio should be -5dB and this more stringent value was used in the studies.

Proposal 11: Where possible avoid using frequency blocks 8A and 9D where VHF DTV is provided with no UHF alternative.

Proposal 12: Increase the adjacent channel interference protection ratio from the current value of -9dB to -5dB.

1.20. DAB+ interference protection ratios

1.20.1.Co-channel interferenceThe value used for DAB+ to DAB+ co-channel interference protection, i.e. the protection ratio, in Australia is currently 15dB. This value was sourced from the ITU-R Geneva 2006 regional plan (GE-06) [18] When compared with the values used elsewhere this is high, e.g. the UK use the Rayleigh CNR as the protection ratio value which is 13dB for DAB but will be reduced by 1 to 2dB for DAB+, e.g. 12dB. Both ITU-R Rec. BS. 1660 [4] and EBU TR 021 [2] planning documents specify 10dB co-channel protection for DAB, which is below the accepted CNR and is considered to be low.

CRA undertook bench testing of a number of receivers to gain knowledge of typical CCI protection ratio needs in modern receivers.

The results show an average PR of 12dB across the input signal level range which is approximately the same as the Rayleigh CNR value as proposed and used by OFCOM UK. Consequently we propose:

Proposal 13: The protection ratio for co-channel DAB+ to DAB+ interference be relaxed from 15dB to 12dB.

1.20.2.Adjacent channel interference

In this section adjacent channel interference (ACI) between DAB frequency blocks is considered.

When adjacent frequency blocks are transmitted from the same site, e.g. from the same antenna, no ACI issues will be experienced. This is the case for both main sites and repeaters.

ACI can occur when transmissions on adjacent channels occur from different sites in the same area.

A typical scenario is when a high power transmitter is used to cover a wide area while a repeater is used on an adjacent channel is used to provide additional coverage within that wide area. This can occur both within a single licence area or when a high power transmission is used to cover multiple commercial LAs. In these cases the signal from local area transmitter can have sufficient local field


strength to ‘over power’ the wider area transmission. When this occurs, receivers in that area will not be able to decode the wider area signal with the result of loss of audio output from all services on the wider area multiplex. This effect will occur for an area around the local transmitter/repeater and is referred to as a coverage “hole”. The size of the hole that is punched in the wider area transmission is dependent on the relative powers of the wider area and local transmitter/repeater and the distances and terrain between them.

This similar scenario can occur between licence areas where a local repeater near the boundary of a licence area could cause ACI into the coverage of the adjacent licence area.

In the single licence area case the ACI issue is overcome by ensuring that both/all frequency blocks are transmitted by the repeater.

The current Australian DAB-to-DAB ACI protection ratio is 40dB, i.e. receivers can tolerate up to 40dB power difference between the wanted and interfering received frequency blocks. If at any location the interfering signal has a signal power which is more than 40dB greater than the wanted signal power most receivers cannot decode and present the wanted audio service. Given the large value of the ACI protection ratio any holes, that could be punched in the wide area transmission will generally be localised around the commercial LA transmitter, the lower the power, e.g. low power repeaters in towns, the smaller the hole. Such holes may be a few tens of metres for low power repeaters or up to hundreds of metres possibly even kilometres for main sites.

At this stage the TSC does not propose any changes to the existing arrangement where new transmissions should not cause loss of reception within existing transmission areas, the TSC does however suggest the following approach to be equitable.

Consideration 5: In planning the rollout of DAB+ transmitters all licensees (and prospective licensees) are to be encouraged to collaborate with the other licensee(s) that will operate in the same area to minimise to potential for ACI/hole punching, with co-siting of transmitters and repeaters recommended as an effective way of preventing such.

The above approach is consistent with Proposal 3:

1.21. Coverage, overspill and interference targetsThe TSC has had a robust debate on the introduction of specific coverage, overspill and interference targets and limits. Currently there are no specific targets or limits with the ACMA effectively making a judgement call on what is considered to be fair and reasonable for all parties involved in a planning application dispute.

There are no specific targets for population coverage. The national broadcasters undertake to provide coverage to as much of the Australian population as is practical given their internal cost-benefit analysis and their mission statements. The commercial broadcasters cover the population within their licence areas as is required to provide a viable business. Each community broadcast service seeks coverage consistent with best providing a service to its respective community of interest. The TSC agreed that the current approach should be continued.

In 2008 as part of the metro DAB rollout planning the ACMA produced draft guidelines on overspill as shown in section 1.31. While the draft guidelines have not been formally adopted they are used as a basis for the analysis of overspill. The TSC discussed the use of specific overspill limits with the following discussion points

Overspill situations are very driven by the local terrain Overspill population counts can be distorted when a town is located on a licence area

boundary The establishment of s ‘hard’ overspill population limit will encourage broadcasters to

establish transmissions which are ‘just under’ the limit to maximise their coverage of adjacent licence areas.

Given these issues the TSC decided that current practice should be continued.


Co-channel interference targets are also very difficult to set a hard limit for. This is particularly the case at present when trying to fit all licence areas into a national DAB+ plan with only 8 frequency blocks. The TSC agreed that the best method was to try to achieve the most sensible overall operating balance between capacity access and cost rather than using a specific target which may not be suitable in all situations.

1.22. Summary and discussion

The RF planning parameters have been studied through a combination of field trials and discussions with international colleagues. There is an international consensus that the planning basis for DAB+ needs to be re-examined and updated given new information and planning techniques. This has culminated in the reformation of the EBU Broadcast Network Planning group with the mission to update the EBU planning recommendations.

In this section the TSC has made a number of recommendations based on the details provided in section Error: Reference source not found.

The TSC proposes the modification of the parameters examined to improve the accuracy of DAB+ planning in Australia.

While the proposed changes should provide improvements the Australian broadcast industry and the ACMA need to continue to monitor international developments and where possible work with our international colleagues, as we currently are in the EBU BPN group meetings.

There are still a number of issues to be studied and possibly updated including in-building penetration losses where Australia tends to have lower values than Europe and in general propagation model improvements and tools capabilities.

As Australia in just embarking on regional planning there is an ideal opportunity to further tune our methodology, models and parameters though on-going field testing of new deployments. Such activities are essential to not only improving our planning accuracy but also demonstrating to the broadcast industry in general the level of confidence in the planning approach. Confidence in turn will lead to faster detailed planning and lower planning and deployment costs.


A number of the decisions which result from the present study have the potential to impact the overall cost of the deployment of DAB+ networks for both commercial licence areas and wide area SFN transmissions. This section reviews the components of DAB+ transmission systems and examines cost sensitivities.

A key issue affecting planning is the number of repeater sites required to reach the desired target market as repeaters have a significant impact on the initial capital required to establish the network and the ongoing operating costs.

1.23. Cost model overview

Digital radio systems require use of infrastructure shared between service providers operating using capacity within each transmission multiplex.

Legislation sets out pricing principles and an access regime overseen by the ACCC with the intention that the total cost of operating each multiplex transmitter is reasonable and apportioned in accord with each service provider’s pro-rata use of capacity.

Figure 4-3 and Figure 4-4 show conceptual diagrams of the flow of data in a DAB+ system. There are many combinations of where the physical systems are located, those locations being dependant on many financial and operational requirements.

Figure 4-3 shows the key components of a Cat.2 multiplex where the common components are shared by all service providers, commercial, community and national. For clarity, the overview is simplified and does not show redundancy and/or monitoring and control systems.

Figure 4-3: Example regional Licence Area DAB+ system – Cat.2

4.Cost Analysis and Impact Assessment


Figure 4-4 shows the separation of key components for separate Cat.1 commercial/community and Cat.3 national multiplexes. The example shows the case of a shared site and shared antenna to reduce overall costs as is the case in some metro cities, e.g. Sydney. The use of co-siting is discussed above in section 1.12.

Figure 4-4: Example regional Licence Area DAB+ system – Cat.1 and Cat.3

In this example deployment each broadcast service is first encoded by DAB+ audio encoder and meta-data is inserted for each service through the Data Server. While there are several possible configuration variations a typical deployment scenario has the audio encoders and systems located at the studio while the multiplexer, multiplexer controller and data server are located at the transmitter site. The studio equipment communicates with the ‘central’ multiplexer through IP links which may be provided in several different forms such as microwave links or Telco circuits.

The multiplexer controller manages the partitioning of capacity for each service provider (usually a group of stations) within each multiplex. Each service provider is free to configure that allocated capacity as they wish without any interference or observation from the other service providers (apart from what can be observed in the on-air signal).

The encoding and multiplexing equipment along with their controllers and data servers are collectively known as the “head-end” system. The head-end system can have varying levels of redundancy from none to a full 1+1 redundancy scheme dependent on the service availability targets required.

While the head-end system is a significant part of the base cost of deployment they are independent of the cost of the main site transmitter system and any repeaters which are collectively known as the “transmission system”. The cost of the transmission system is dependent on the target coverage area size and terrain as well as any power limitations.

As depicted in Figure 4-5, it is not uncommon to require several repeaters irrespective of main site power to ensure suitable population coverage. Repeaters can be required due to several reasons including:

Target coverage area is shadowed from the main transmitter by terrain, typically mountains The target coverage area is too distant from the main transmitter to receive adequate field

strength


The target coverage area is shadowed by buildings, e.g. within CBDs and the area on the opposite side of the CBD, or large buildings, to the transmitter site.

Figure 4-5: Licence area transmission sites

Further, the number of repeaters can also be influenced by system level decisions such as:

Maximum power limits due to CCI management between LAso The TSC studies have clearly shown that there is a very strong relationship between

co-channel interference between licence areas and the transmission powers within those licence areas. As the transmission power used in a LA is increased so does the interference caused to those LAs using the same frequency block. Given a required maximum level of CCI each transmitter on the same frequency block has a maximum power that can be used in the direction of the LAs using the same frequency block. The transmission power used at a site can be varied from the maximum allowed for an omnidirectional antenna through the use of antenna patterns and down-tilt although these capabilities add cost and complexity relative to simple omnidirectional antennas.

The use of different protection levelso The protection level chosen strongly influences the number of transmitter sites and

the power of those sites, see section 1.27 for details of capacity and protection/power trade-offs. Relative to Protection Level EEP-3A weaker levels such as EEP-3B or EEP-4A will require either higher transmission powers and/or more transmission sites to cover the same area. Consequently planning based on the use of weaker PLs will result in a more expensive system in terms of both the capital and operational costs while stronger PLs will result in an overall cheaper solution.

The required population and area coverage o Population distribution in most regional markets is based around one or more major

towns/cities where the majority of the population resides. Generally broadcast systems are designed to service the population centres first and then the rest of the population in a region. Main transmitter sites are usually placed as close as possible to the largest population centre in a market and when necessary repeaters are added to service the remaining population and infrastructure, particularly main roads.


Consequently the cost of implementation increases as the population coverage requirement increases with the incremental cost of coverage being disproportionately larger for the last 20%.

o For example a theoretical LA may consist of 3 main towns, town A-50% of the population, town B with 20% and town C with 10%, i.e. the urban areas contribute 80% of the population in the LA, the other 20% is spread out across the LA in relatively sparse clumps. To cover the 3 main towns a main site and 2 repeaters can be used but to cover the majority of the remaining 20%, a further 3 or more repeaters sites may be required.

The number of repeaters required to cover an area, whether a commercial licence area or a national ‘local area’ is strongly influenced by the size and terrain in that area. The TSC studies, particularly [15], have shown that terrain can have a much stronger influence over coverage than power with a number of licence areas shown to have only slight coverage reductions when the main site transmitter power is reduced significantly, e.g. by half or more. In a number of cases when the number of repeaters did not change the overall population coverage only reduced by less than 5%. This is due to the transmissions being focused on the main population centres.

While the population coverage did not reduce significantly with the use of lower power main sites, as has been shown to be a necessity in a number of areas due to interference, the area covered will reduce and hence has an impact on outlying and sparse population areas and road coverage. To compensate for the loss of area coverage additional repeaters may be required. The number of additional repeaters that will be required will differ between target coverage areas due to the specific terrains and population distributions involved.

1.24. Cost analysis

CRA has undertaken cost analysis of regional DAB+ systems over some years and has established a cost database for all main components. While the cost database can be used to provide an indication of the costs involved with the deployment and operation of a DAB+ network it should be borne in mind that any such cost analysis will be generalised and represent indicative trends only. Accurate cost analysis requires the details of the target deployment to be established and current pricing to be obtained. This is especially important when bulk purchasing is to be employed as significant discounts can be obtained.

Cost basis

The cost analysis is based where possible on budgetary prices provided by equipment suppliers. CRA has conducted a number of Requests For Pricing requests over several years. The figures used in the cost analysis below are based on responses for the main equipment items received after January 2015.

Cost estimates provided below are for the lowest cost solution that is considered to be usable from a commercial perspective considering that the initial installation will be targeting a very low listener base with most licence areas having only a few receivers if any in the market. There are exceptions in the form of the DAB+ trials cities of Canberra and Darwin.

The “Low Cost” analysis assumes that the initial deployment will target only the major population centres within a licence area and only provides coverage for population centres with greater than 5,000 people. This often leads to a reduced number of repeaters than will be required to cover over (say) 95% of the population and also results in reduced road and wide area coverage.

Once the listener base has reached what the broadcasters consider to be a critical amount then additional repeaters can be added and equipment redundancy levels increased to ensure suitable service availability.


The equipment considered in the cost analysis, its redundancy level and its inclusion for both an initial low cost deployment and a full service deployment are shown in Table 4-8.

Equipment Initial Low Cost deployment Full service deploymentInclusion Redundancy Inclusion Redundancy

Transmit antenna and feeder

Y N Y Y, typically split antenna system

Filter or Diplexer Y N Y YMain Transmitter Y N, some inherent

redundancy is inbuilt in modern transmitter power amplifier systems

Y Y, typically redundant exciters, although some main sites may have redundant transmitters

Transmitter Redundancy switch

N N/A Y Y

Multiplexer Y N Y YHead-end system apart from multiplexer (Encoders, controllers, data servers, PAD server)

Y N, generic spares are carried in case of system failure

Y Y

Ancillary systems including power, NMS, IP etc

Partial, only IP

N Y Y, likely redundant IP, non-redundant NMS or UPS

Signal monitoring (ETIM, TXMN, Service Monitor, Logger)

POff-air logger only

N, likely to be simple commercial receivers

Y N

Building works incl. power, A/C

Y N Y N

Genset support N N Y NInterference Management

Y N/A Y N/A

System design, project management and installation

Y N/A Y N/A

Table 4-8: Equipment and configurations considered in cost analysis

CAPEX

This section has been redacted to protect commercially sensitive information.

OPEX

This section has been redacted to protect commercially sensitive information.


1.25. Summary

The cost analysis presented shows that DAB+ systems can be deployed in a cost sensitive manner where the initial deployment uses no redundancy and the minimum number of repeaters to cover the primary population centres within a licence area or local area. Operating expenses can similarly be kept to a minimum in the initial years of the deployment while the listener base is being built by utilising existing broadcaster resources.

As the listener base increases and in particular for commercial broadcasters the delivered content starts to attract advertising revenue, then service availability and reach can be improved through the addition of redundancy and repeaters as well as more sophisticated maintenance and monitoring regimes. When designing a DAB+ network for a target area it is important to plan the full system which will used in the long term including all transmitters and repeaters, redundancy, monitoring and other support system. The broadcasters (or JVC) then have a clear understanding the long term costs and can then scale the system back for a low cost entry to the target if desired.

While the above analysis has been based on actual sites and expected coverage requirements there is still a significant amount of coverage planning to be undertaken to establish the most appropriate main site powers and patterns, particularly considering the CCI issues identified, as well as the most appropriate number of repeaters. Once that has been completed then a detailed and accurate cost analysis can be undertaken for specific target areas.

The above analysis is intended to provide guidance to the DRPC in terms of the order of magnitude of costs to establish markets as well as trends involved. The most significant trend is that both CAPEX and OPEX are very sensitive to the number of repeaters which are required to cover a target area. The use of low main site power to mitigate CCI issues will in some cases require additional repeaters to provide the necessary area and/or population coverage.


The technical aspects of the planning of DAB+ for regional Australia have been examined in depth by the Technical Sub-Committee of the Digital Radio Planning Committee, which has representatives from the key stakeholder groups in the Australian radio industry.

The studies undertaken have provided a detailed understanding of the issues, compromises and limitations that the limited spectrum available to DAB+ in Australia has imposed.

The TSC recognises that there is existing legislation governing the deployment of DAB+ digital radio in Australia and where that legislation affects technical planning the issues have been discussed and addressed.

In order to define a viable planning methodology those issues and limitations have been studied along with a detailed investigation of the base level planning parameters and models. The result is a proposed set of planning principles which should provide an equitable approach for the design and implementation of a cost effective DAB+ network with appropriate performance and coverage for regional Australians.

Of particular importance in the planning principles is the requirement for compromise from all parties. The spirit of compromise will allow the most cost effective design for regional Australia and lead to the most rapid, and equitable, rollout of new digital radio services.

5.Conclusions


The following next steps are recommended to complete current studies and allow the industry to move forward with the planning of DAB+ services in regional Australia.

1. Finalisation and adoption of the updated planning parameters and planning principles.2. Allotment planning for licence areas within 400km of the first to rollout areas (Canberra,

Darwin, Gold Coast and Hobart) a. Industry provides proposed sites, patterns and powersb. Industry and ACMA work to develop indicative regional allotment plans

3. If the DRPC wishes, further cost analysis based on specific reference LAs4. While the legislative provisions preventing discrimination between the technical

specifications of multiplexes have no impact on the first three target areas (Canberra, Hobart and Darwin) the TSC should review the technical implications on planning as part of the 400km around those first movers.

5. DRCP committee to consider trial licences, where appropriate to foster deployment, prior to the establishment of full commercial / national licences, e.g. the Gold Coast so a shared multiplex can go on air in time for the Commonwealth Games

The above tasks may be modified based on the adoption and feedback of the proposals made by the TSC within the DRPC.

The following areas have been suggested for further study:

1. Network density cost modelling and site optionso The level of the proposed cost analysis is to be agreed, for the most accurate result

actual sites in a target LA will need to be considered.2. DAB ‘windowing’ as an option for the inclusion of local radio in a state-wide Cat.3 SFN

o The use of DAB Local Windowing has not been widely accepted due to the interference issues that arise. There have been some suggestions to help overcome interference particularly in the FIC through specific FIG time alignment, e.g.[16] however no equipment that supports this technique is known.

3. Review of existing DRPC templates as a result of analogue TV closure and DTV restack 4. Review of RadComms 44A regarding discriminatory coverage (i.e. lifting of DRCP coverage

template restrictions for national broadcasters)

6.Next steps


Digital radio planning committee for regional Australia

Technical Sub-Committee

Terms of Reference

BackgroundOn 18 September 2015, the inaugural meeting of the Digital Radio Planning Committee (the Committee) was convened in Pyrmont at the offices of the Australian Communications and Media Authority (the ACMA). The terms of reference of the Committee authorise the formation of select sub-committees to deal with specific issues as they arise.

At the inaugural meeting of the Committee it was decided that an informal meeting should take place to discuss technical matters. The informal meeting was held on Wednesday 7 October 2015 at Commercial Radio Australia’s offices in Sydney. During the meeting, Commercial Radio Australia proposed that the formation of a Technical Sub-Committee should be put to the Committee to assist its deliberations. Terms of referenceConsistent with the terms of reference of the Committee, the Technical Sub-Committee will:

1. Develop draft recommendations for the Committee to consider and put to the ACMA on high level planning principles for the allotment of frequency blocks for digital radio. These principles would reference matters such as:

a. The scope of matters that should be included in a high level frequency block allotment plan;

b. The technical parameters that would apply to planning for, and operation of digital radio multiplex transmitters, including coverage overspill and interference limits and;

c. The treatment of national services in a high level frequency block allotment plan;

2. Consistent with the planning principles, prepare for consideration by the Committee and/or the ACMA:

a. An industry wide planning process for coverage and interference analysis; and;

b. Technical specifications including frequency block allotments for licence areas where broadcasters agree that it is economically feasible to provide ongoing digital radio services.

3. Develop draft recommendations to the Committee on an implementation timeline and project plan for the licensing and commencement of digital radio services in roll out areas.

7.Appendix A: TSC Terms of Reference


4. Provide a forum for discussing detailed technical and operational issues for broadcasters in the lead up to the commencement of digital radio broadcasting in regional Australia.

Sub-Committee Establishment

The Sub-Committee is constituted under the terms of reference of the Committee. Sub-Committee Membership

Commercial Radio Australia (Chair)

Australian Communications and Media Authority

Department of Communications and the Arts

Australian Broadcasting Corporation

Special Broadcasting Service

Community Broadcasting Association of Australia

Other appropriate stakeholders as determined by the Chair from time to timeSub-Committee Chair and decision making process

It is proposed that Commercial Radio Australia or its nominee will chair the Sub-Committee.

It is proposed that the Sub-Committee will make recommendations to the Committee on a consensus basis.

Frequency of meetings

Meetings of the Sub-Committee will be held on an ‘as required’ basis, at the discretion of the relevant chair and in consultation with Committee or Sub-Committee members.

Meetings will be ideally attended in person, although, where unavoidable, attendance may be facilitated by telephone or videoconference.

Sub-Committee Secretariat arrangementsSecretariat support for the Sub-Committee will be provided by Commercial Radio Australia. Commercial Radio Australia will ensure that:

agendas and supporting papers are circulated in a timely manner in advance of meetings

draft minutes/meeting notes are circulated to sub-committee members within 5 business days of each meeting

The ACMA will provide an external facing SharePoint site of sub-committee documents to facilitate record-keeping and sharing of all agendas, papers, minutes/meeting notes and action items.


This section reviews current planning parameters used in Australia and internationally and then describes the studies undertaken to assess the appropriateness of some values. A number of changes are proposed and the impact discussed.

1.26. Current Australian values and international trends

A summary of the planning parameters used in Australia and Europe along with the current ITU and EBU planning documents is provided in Table 8-10.

The values used vary quite considerably between countries and the ‘nominal standards’ (ITU and EBU) having generally different values for critical parameters such as Location Factor Standard Deviation, Height Gain (or Height Allowance), in building penetration losses and man made noise and interference.

Both the main ITU and EBU documents, [4] and [2] respectively deal exclusively with DAB with no mention of DAB+ even though they were updated in 2012 and 2013 respectively.

In 2011/12 OFCOM in conjunction with the BBC and Arqiva (the national commercial multiplex provider and major transmission site owner) undertook a number of studies to reassess planning levels and procedures for DAB in the UK, e.g. [7] and [11], although DAB+ was not covered as it was not introduced into (partial) service until 2016.

The large number of differences between the base planning parameters has led the TSC to investigate further. Indeed discussions with the EBU revealed that they also have concerns and have reformed the Broadcast Network Planning (BNP) group to review the current planning guideless and recommendations. The TSC was invited to attend the technical meetings and presented field test results.

The base level parameters are used to calculate the minimum median field strengths required to support a particular percentage of the population with error free DAB+ coverage. The calculation of minimum median field strengths is described in section 1.29 and Table 8-17. The values target specific environment types as described in Table 8-9:

Environment classification Examples Usage

Mobile outdoor Vehicles and road coverage

Handheld portable receivers

Baseline coverage

All countries

Portable indoor – suburban Spread out dwellings, typically 1 or 2 floors

Baseline indoor

All countries

8.Appendix B: Base Planning Parameter Studies


Portable indoor – urban Closely spaced dwellings, typically 1 to 3 floors

Australia, Norway, Germany

Portable indoor – dense urban Multi-storey apartments and offices

Norway, UK

Table 8-9: Target environment characteristics

Unit ITU EBUItaly Norway UK Germany Switzerland Hungary

Organisation / Representative

DAB Club Italia / Hans

Wolter

NRK/ Petter Hox

BBC / James Hamilton

CSA TDF

Media Broadcast / Thomas Wachter

SRG SSR / Thomas Sanner

NMHH / Ádám Vörös

DAB/DAB+DAB DAB DAB+ DAB & DAB+ DAB & DAB+

DAB+/ DMB

DAB+ band

DAB & DAB+

DAB & DAB+ DAB+

Reference documentsBS.1660-6

(2012)TR021 (2013)

poss GE06 based

GE06 - RPC5 and RPC4

OFCOM reports from

2011/12 BMCO BMCOunder review

GE06, TR021

Coverage levels height 10m 10m 1.5m 10m 10m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 10m- Mobile reception dBuV/m 58 58 50 63 60 48 44 54 53 48 48 60 - % of locations 99 99 99 99 99 99 99 99 99- Indoor reception (suburban) dBuV/m 63 57 70 66 54 54 / 60 56 66 66 - % of locations 95 95 95 95 80 / 95 95- Indoor reception (urban) dBuV/m 63 76 60 NA 67 63 62 - % of locations 95 95 95 95 95 95- Indoor reception (dense urban) dBuV/m NA NA 70 61 / 67 67 - % of locations 95 80 / 95 95Planning Height

- coverage metres 10 10

10 1.510m

planned, 1.5m infered

1.5 1.5 1.5 1.5

- CCI / ACI metres 10 1.5 10 10 1.5Planning models

- coverage 1546

IRT 3DUK Planning

Model (UKPM)

ITU-R 526 or 1812 or

1546

TDF model 1,5m

- CCI / ACI 1546, 1812IRT 3D

UK Planning Model (UKPM)

ITU-R 526 or 1546

TDF model 1,5m

Parameters- 1.5 to 10m height allowance dB 10 13 10 10 12 12- DAB-DAB CCI PR dB 10 10 15 13 15

- DAB-DAB ACI PR dB

-35 (1st adj), -40 (2nd adj), -45 (greater

sep)

-35 (1st adj), -40 (2nd adj), -45 (greater

sep)

-40

- DAB to DVB-T ACI dB

N/A N/A

- man-made noise allowance dB 0 1 0 0 3 2- interference allowance dB 0 0 0 0

- Location variation SD - outdoor dB 5.5 4 5.5 / 6.2 / 7

- In building penetration loss - suburban - loss dB 8 9 8 9 - suburban - SD dB 5.5 4.4 3 or 4 - urban - loss dB 12 11 / 15 - urban - SD dB 7.1 - dense urban - loss dB 15 15 - dense urban - SD dB 5.5 5

Country

CRA / Les SabelACMA / Alastair Gellatly

Australia

4.4

-40

-9 to immediate adjacent, -30 otherwise

11

5.5

54.411

15

CRA(WD report), TR021, BS.1660-6, others

DAB+

ACMA uses 10mCRA uses 1.5 m

10

No single model specified. ACMA uses

CRC Predict, 1546-1, 1812CRA uses

P.525/Deygout94 No single model

specified. ACMA uses multiple

13

France

Table 8-10: Summary of international planning parameters (mid 2016)

Planning tools, capabilities and methods have improved significantly over the last 20 years leading to a number of planning organisations to ‘re-think’ the best approach to deliver both accurate and timely advice. The rest of this chapter examines recent results regarding the base level planning parameters and the implications on the minimum median field strength targets to be used for DAB+ planning in regional Australia.


1.27. Error correction considerations

Digital radio provides a variety of error protection schemes to enable more robust delivery of data and content services to receivers. DAB+ uses equal error protection (EEP) over the entire data stream,

Four different protection levels are defined for DAB+. A and B schemes allow nett data rate increments for sub-channel services of 8 kbps and 32 kbps respectively. Digital radio services typically use a mid range value of error protection, Level 3 which corresponds to rate ½ convolutional coding and scheme A, i.e. FEC 3A, to provide 8kbps increments which is much more flexible that the B rate bit rate increments of 32kbps.

A lower numerical level provides a stronger degree of error protection for more robust reception but the nett capacity available for delivery of wanted content is reduced. Conversely, a numerically higher level provides weaker error protection and so enables delivery of more capacity for content services but with less robust reception. Values for error protection can be set on a per service basis. Services sharing a multiplex need not operate using the same error protection parameters.

1.27.1.Error protection and digital radio planning

The TSC considered the use of error protection schemes and what role this may play in the planning of multiplex capacity for regional digital radio services.

The SBS tabled a paper referencing an extract from an ‘Overview of the DAB+ System’, World DMB Technical Committee, 2013, Les Sabel. The table below, from that overview, compares error protection rates; shows the number of 64 kbps channels that can be carried on a single multiplex; and indicates the power, relative to the typical protection level E3A, required to achieve a given received error performance.

ProtectionLevel

ApproximateCode Rate

Nett Capacity (kbps)

Number of 64 kbps services

Approximate Power relative to E3A (dB)

EEP1A 1/4 576 9 -3 to -6EEP-2A 3/8 864 13 -2 to -3EEP-3A 1/2 1152 18 0EEP-3B 2/3 1536 24 +3EEP-4A 3/4 1728 27 +6

Table 8-11: DAB+ FEC Code Rate characteristics – Rayleigh channel

In the established five metropolitan cities with DAB+ two-ninths of gross Cat 1 multiplex capacity is reserved for community based services under the current Australian legislative framework for digital radio. This two-ninths is shared between all eligible community broadcasters.

Existing commercial broadcasters are each accorded one-ninth of gross multiplex capacity per existing (2008) analogue service.

1.27.2.CBAA research

The TSC noted that in some cities the overall two-ninths capacity limit for Community Radio is insufficient to provide for the demand and a variation to the service data rate has been required for some services. In order to accommodate all eligible services being able to take up digital radio as intended by the policy and legislative framework, some innovation was required.


Based on an involvement with, and an understanding of, digital radio transmission planning underway in 2009/10, the CBAA considered that it was likely there would be sufficient signal strength across each city to provide at least adequate reception even with reduced error protection. While reception of some services may be less robust, it was reasoned this may be manageable in the context of an emerging listener base and, over time, be assisted by in-fill coverage. Further, it was considered that listener benefit would be best served by maintaining perceived audio quality and that reception would, at least initially, be primarily to fixed location receivers.

It was considered important to verify how reduced error protection affects reception performance and to see what locations in each city would benefit from in-fill development.

During 2011/12 research and tests were conducted in each of the five capital cities: Sydney, Melbourne, Brisbane, Adelaide and Perth. The research investigated practical reception differences observed when using different error protection schemes. No research was done on the use of error protection schemes with stronger error protection than EEP-3A. All measurements were made in a mobile environment. No measurements were taken in buildings. It was expected that when field strength is reduced to fringe reception levels, similar effects would be evident.

RESULTS

The following table compares the range of measured differences to the theoretical difference in transmit power required to achieve the same reception performance as when using E3A.

Protection Level

Approx Code Rate

Nett Capacity (kbps)

Number of 64 kbps services

Approximate Power relative to EEP-3A (dB)

Gaussian Ricean Rayleigh MeasuredEEP1A 1/4 576 9EEP-2A 3/8 864 13EEP-3A 1/2 1152 18 0 0 0 0EEP-3B 2/3 1536 24 +1.8 +2.1 +3.0 +1 to +1.5EEP-4A 3/4 1728 27 +2.8 +3.2 +5.3 +2 to +3.5EEP-4B 4/.5 +3.4 +3.9 +7.6 +4 to +6

Table 8-12: CBAA findings on DAB+ FEC Code Rate characteristics

The results suggest a correlation that is close to the theoretical difference that might be expected in a Ricean model, with some Rayleigh effects. For example, it was found that to maintain successful reception of EEP-4A the additional C/N required was over a range 2 to 3.5dB. Using EEP-3B the range was 1 to 1.5dB. This fits with the expectation for mobile reception and for locations where the difference in error protection was evident in tests.

In the CBD and urban locations it was found that signal levels were sufficiently strong and few/no errors and/or no differential between EEP-3A and other schemes was observed. The fringe of coverage areas are rural and so where differences were observed there were usually minimal obstructions.

BrisbaneThe suburbs Springwood to Moreton Bay, around 30 km south-east of Brisbane, were areas of reception failure, where the signal is obstructed by hills north of Daisy Hill and reception is at sea-level. All services were lost, with only very few locations where E3A was able to decode.

AdelaideCoverage fringe areas such as the Barossa Valley in the north-east and low elevation coastal areas around Aldinga Beach were areas of reception failure. Aldinga Beach is approximately 40 km south of Adelaide. EEP-4B failed slightly more than EEP-4A typically in low elevation and cluttered areas. The typical pattern is that the EEP-3A receiver fails a few seconds later than the alternatives. In this scenario, there is almost no benefit in applying EEP-3A or EEP-3B over the less robust EEP-4A or EEP-4B schemes.

Perth


Coverage fringe areas Two Rocks in the north and Roleystone, 30 km to the south-east, were areas of reception failure. Around Roleystone EEP-4B fails marginally head of other schemes. EEP-3A failed almost in time with the EEP-3B scheme.

OTHER CONSIDERATIONS

It is important to note that these measurements were based on mobile measurements and testing. In a mobile situation, the difference in C/N required between error protection schemes is most often overwhelmed by variations in signal strength.

Meaningful reception differences could be observed when the signal was consistently approaching lower levels and the failure point of all DAB+ services, including EEP-3A.

When in medium to strong signal environments there is no significant difference between the performance of services using different error protection schemes. In line with that observation, reception performance in CBD environments was consistently successful.

EEP-3A shows a minor benefit for mobile reception as less robust schemes fail ahead of EEP-3A. However, EEP-3A usually fails very soon thereafter, typically seconds.

There was almost no difference between the failure point of EEP-3A and EEP-3B in mobile reception environments. Perhaps greater benefit from EEP-3A might be expected for fixed receiver locations and in situations where building penetration is at play.

In practice, the use of reduced error protection is likely motivated by a lack of multiplex capacity overall. Therefore, the capacity available for delivery of multi-media metadata is likely to be also limited. This leads to longer time being needed to deliver images. This longer time combined with reduced error protection can cause delivery failure and lack of timeliness. Triggered slideshow capability does however overcome this deficiency.

DIGITAL RADIO PLANNING IMPLICATIONS

There seems merit in acknowledging there can be flexibility in use of error protection and in how individual services may be configured on a digital radio multiplex. That flexibility can provide a means by which extra services might be provided where the imperative to do so outweighs the needs for robust reception. Use of EEP-3B seems the least likely to cause significant disparity in terms of robust reception compared to use of EEP-3A although service data rates are limited to multiples of 32kbps, typically forcing broadcasters to use either 32 or 64kbps.

While acknowledging flexibility, continued coverage planning on the basis of E3A seemssensible and appropriate.

Significant coverage and reception issues caused by obstruction are best addressed through the use of a multiple transmitter topology.

1.27.3. Interference impact

As discussed above the use of lower code rates provides additional capacity on a multiplex at the expense of reception robustness and coverage area. The use of weaker codes also has an impact on robustness against CCI. For EEP-3A the recommended CCI PR is 12dB (see sections 1.20.1 and 1.30.1). When the code rate is weakened the protection ratio must be adjusted to deliver the same level of protection from CCI. The CCI PR is set at the CNR for Rayleigh channels, this being 12dB for EEP-3A, and hence for EEP-3B and 4A the protection ratio would need to be increased, approximately +3 and +6dB respectively.


This has a two-fold effect as to achieve the same coverage area as EEP-3A with say EEP-4A the transmission power must be increased but at the same time the CCI PR is also increased resulting in a significantly increased frequency reuse distance.

For existing deployments which use weaker code rates this effect has the potential to deliver more variable reception when regional transmissions are established.

1.27.4.Discussion and recommendations

The range of FEC code rates defined in the DAB+ standard are provided to allow broadcasters to construct networks and deliver services with flexibility. There are clear situations where code rates other than EEP-3A can be used to great effect, albeit with the expected consequences. For example, the use of EEP-1A in the Darwin DAB+ trials has provided improved coverage relative to what would be achieved with EEP-3A and hence is the best choice given that the capacity required in Darwin for the trial is less than 576kbps.

Similarly, the use of weaker codes than EEP-3A can be used to provide additional services and capacity at the expense of the level of robustness of the transmission, with the typical areas of poor performance being shadowed coverage areas.

Discussions with DAB+ network planners in many countries however shows that the use of EEP-3A is the most balanced solution for network design. The use of code rates other than EEP-3A are then considered to be options that broadcasters may choose to exercise if there is a particular advantage for them to do so.

1.28. Base planning parameter investigations

1.28.1.Location variation standard deviationThe location variation is used in defining the amount of signal or field strength variability in an area. The variability is considered statistically by classifying the signal strength as a log-normal variable, i.e. a variable measured in dB which has a normal distribution. For field strength the measurement is in dBμV/m. The Standard Deviation (SD) of the field strength distribution is used as a measure of the amount of variability in a specified area. The value of the SD is then used to calculate the probability that the field strength at any point in the area will be greater than a predefined amount.

For mobile outdoor coverage the Australian planning rules have used a target field strength of 50dBμV/m with a probability of 99%, i.e. the field strength should exceeds 50dBμV/m at 99% of locations.

Field Trials

CRA has undertaken extensive field trials in Brisbane, Sydney and Canberra. The data was collected while mobile using a RadioScape Field Monitor (FMON) with an antenna base height of 1.5m in the centre of the vehicle roof.

Ideally the measurements would be taken for a specific pixel size in a homogeneous manner over the pixel area, i.e. in both latitude and longitude. As we were limited to travelling along roads we have used the alternative of a linear track through a pixel. We note that some pixels will have curves and 90 degree bends, indeed for larger pixels there could be several such bends.


The FMON measurements are taken with a period of 25mS, i.e. 40 measurements per second.

Here we focus on the Brisbane trials where areas to the north (Nambour), south (Gold Coast) and west (Ipswich) were examined along with the major highways connecting those areas with Brisbane.

Figure 8-6: Map of drive test field strength results on the main north-south highways through Brisbane

Figure 8-7: Map of drive test filed strength measurements in suburban Ipswich

Initially the location variation SD results used the raw measurements without any fast fading filtering (only low speed filtering was applied). The results are shown in Table 8-13 for 100m pixels.

SD Analysis Number of Points – 100m pixels

Brisbane 4.48 1211

Ipswich 4.60 3014

Gold Coast 3.99 3073


Nambour 4.40 1744Table 8-13: Initial location variation SD results when no fast fading filtering is applied

Discussion with the members of the EBU Broadcast Network Planning group indicated that filtering should be applied to remove the fast fading component which should not be present in the data used for the determination of the LF as the Rayleigh fast fading is already accounted for in the link budget as shown in Table 8-17.

Analysis

The data measured was processed in the following way

1. Each data point is analysed for the speed at the time of measurement, all points with a speed of less than 3kph are removed to ensure that static points do not bias the results

2. Fast fading filteringa. Initially a standard moving average filter was applied – see results below. This however

is not considered to be accurate enough as it applied a variable distance filter depending on the speed at the time of data capture and the samples are (in most cases) spaced more closely that 0.5 wavelengths and hence are considered to be correlated. The results presented below are consequently only a guide. Further study advised that we should apply the Lee criteria which overcomes both of these issues, as described in 2b below.

b. Lee Criteria filtering: The fast fading signal variations are filtered using the Lee Criteria [6], in this case 50 points are used over a distance of 40 wavelengths, the resulting average value is then used in place of the original value

3. The SD is calculated over different pixel sizes [20, 50, 100, 200, 500, 1000] metres. In this case only the Lee averaged points within a segment of the pixel size are used, there is no overlap or reuse of data points.

Results

At the time of writing the additional filtering using the Lee Criteria had not been completed. As a guide ONLY we show the results for the standard Moving Average filter for the data gathered from the routes shown in Figure 8-6 and Figure 8-7.

0 200 400 600 800 1000 12000

1

2

3

4

5

6

7

1359173365129

Distance Bin

SD

Figure 8-8: Location variation SD results using MA filtering from a section of Brisbane highway


0 200 400 600 800 1000 12000

1

2

3

4

5

6

7

Ipswich Part 1

1359173365129Series18

Bin Distance

SD

Figure 8-9: Location variation SD results using MA filtering from suburban Ipswich

As guide prior to the Lee Criteria filtering we can estimate the MA filter lengths given that the measurement vehicle was travelling approximately 80-100kph on the highway section and 40kph in the Ipswich suburbs. The resulting filter lengths are shown in Table 8-14.

# MA filter points40 80 120

1 0.278 0.556 0.8333 0.833 1.667 2.5005 1.389 2.778 4.1679 2.500 5.000 7.500

17 4.722 9.444 14.16733 9.167 18.333 27.50065 18.056 36.111 54.167129 35.833 71.667 107.500

filter length in m for speed in kph

Table 8-14: MA filter length as a function of measurement speed and the number of filter points

The Lee Criteria requires 40 wavelengths which for frequency block 9B with centre frequency of 204.640MHz is 1.47m resulting in a filter size of 58.8m. This indicates that the filter size is on the high side of the analysis to date and will result in a LF SD value for a 100m pixel of less than 2dB. This is a very low value, even comparing it to the results of the UK trials undertaken by the UK OFCOM, the BBC and Arqiva and reported in [7] which resulted in the choice of 4dB for the LF SD in 2012.

To date the results indicate that the value used for LF SD at 5.5dB is high. Given the ongoing nature of the investigation at the time of writing it is recommended to tentatively adopt the value used by the UK OFCOM, that being the most recent study data available.

1.28.2.Height Gain

Height Gain (HG) refers to the gain applied to a field strength at 1.5m to determine the representative field strength at 10m (or visa-versa). Australia currently uses a value of 13dB for HG, the values used


international vary between countries including UK and Norway: 10dB and Germany 12dB while the EBU guideline [2] recommends 13dB.

CRA in conjunction with the ABC undertook field testing in Sydney and Canberra to obtain a better understanding of HG, the test vehicles are shown in Figure 8-10.

Figure 8-10: Test vehicles for HG field trials

The test equipment was based on a RadioScape Field Monitor (FMON). The signal received at 10m was measured using a FMON antenna mounted at the centre of a 600x600m ground plane at the top of the mast. The 1.5m measurement was made using an identical antenna mounted on top of the 1.5m test vehicle (a Honda Jazz).

The initial testing was conducted in Sydney. It was discovered that the use of repeaters in the Sydney LA compromised the results and hence it was decided to repeat the testing in Canberra where there is a single transmission site at Black Mountain.

The results are shown below in Figure 8-11. There is a clear limit of the HG value with 90% of measurements being below 11dB. The outlying value at 18dB is also thought to have been due to a large shadowing influence at the edge of coverage further strengthening the thinking that 13dB is too high and that the UK and Norwegian value of 10dB is more suitable.

Additional observations:

Open areas and LOS areas relatively close to the transmitter reduce the difference in field strength measured at 1.5m and 10m.

Highly shadowed and multipath areas reduce the difference in field strength measured between 1.5m and 10m.

Measurements further away from the transmitter in regional open suburban areas provide greater differences in field measured at 1.5m and 10m.

Suburban and urban buildings can create a greater difference in field strength measured at 1.5m and 10m.

The result of the work to date is that the TSC are in favour of reducing the HG value from 13dB to be in line with the UK and Norway who both use 10dB.


Figure 8-11: Distribution of height gains found in the Canberra trials

1.28.3.Mobile antenna gain

When reviewing the target field strength budgets, as shown in section 1.29 an anomaly was observed in the form of the mobile antenna gain. This value has previously be set at -5dBd largely due to the assumption that the majority of mobile receivers will be cars with good antennas systems, particularly ¼ wavelength monopole whip antennas on a good ground plane. Such antennas were quite the norm around the year 2000 but have more recently been largely replaced in new cars which include DAB+ in favour of more aesthetically pleasing alternatives such as in-glass antennas and small shark’s fin units.

CRA undertook a comprehensive analysis of different types of antennas in 2011 where a number of different types of antennas and positions were examined in an RF anechoic chamber the results were reported in [8] and [9]. The results showed that different antenna types had widely varying performance which was further exacerbated by the position of the antenna and the frequency of operation.

The report [9] covers a range of automotive antenna types including reference monopole, slant monopole, sharks fin and onscreen antennas, a summary of the results for frequency block 9B are shown in Table 8-15. It is clear from the summary table and the example antenna patterns shown in Figure 8-12 through to Figure 8-14 that there is a wide range of gain in the patterns with most minima less than -2.85dBi, i.e. -5dBd as currently specified in the field strength target budget shown in Table 8-17).

Additionally, most handheld portable radios including smartphones use headphone antennas which also have very variable gain and patterns dependant on the ‘instantaneous’ alignment of the headphones with the signal field.

The results above clearly show that the current mobile antenna gain value of –5dBd is too high and that the value should be reduced. As the maximum gains of the antennas shown is still reasonable a compromise value is suggested of -10dBd (or -7.85dBi).


Table 8-15: Performance summary for frequency block 9B, from [9]

Figure 8-12: Slant Monopole antenna and pattern for frequency block 9B

Figure 8-13: Sharks fin antenna and pattern for frequency block 9B


Figure 8-14: Examples of on-glass antenna pattern for frequency block 9B – left close to drivers windscreen pillar, right in centre of windscreen

Figure 8-15: Examples of automotive windscreen antennas and hand portable receivers

Figure 8-16: Examples of automotive antennas and hand portable receivers

1.28.4.Man Made Noise and Interference

Current allowances for Man Made Noise and Interference vary between countries as shown in Table 8-16


Country Man Made Noise Interference Comments

Australia 1 1 The analysis in [5] only includes Interference for 10m values

UK 0 0

Norway 0 0

Germany 2 0

EBU 1 0 See [2]

Table 8-16: Man Made Noise and Interference allowances

Interference levels are generally accepted to be increasing due the proliferation of electronic devices across all areas of life, for example LED lighting in homes, CAN bus noise in vehicles, the increasing number of personal electronic devices and increase in the number of active systems in the home and workplace.

Tests in the CRA office showed a background noise level infrequency block 8D to be the equivalent of -90dBm in a 1.5MHz bandwidth, this is 10dB higher than claimed minimum signal levels for modern DAB+ modules and over 15dB above a typical thermal noise limit of -105dBm, e.g. the Frontier-Silicon Verona 2 module boasts an AWGN operating point of -100dBm and a Noise Figure of 4.7dB. Conversely measurements during Canberra field trials showed low levels of noise in rural areas.

The Canberra trail investigations also showed that there can be significant power leakage through the receiver front end filter from adjacent television channels. This can in turn manifest itself a additive noise at the front end of the receiver. This effect is however negated if the DAB and DTV transmissions emanate from the same location as both signal levels increase as the receiver approaches the transmission site effectively overcoming the DTV leakage noise. This demonstrates the importance of co-siting DAB+ and DTV transmissions wherever possible.

While MMNI does appear to be increasing, given that there has not been any extensive testing in this area reported and the CRA tests have been indicatory only it is suggested that the only change to the current budgetary allowance is to include the Interference allowance for 1.5m as well as 10m. This effectively applies a MMNI allowance of 2dB in line with Germany.

1.28.5.Rayleigh fading allowanceThe allowance for Rayleigh fading was originally based on DAB and set to 5.6dB which is added to the Gaussian CNR or 7.4dB for DQPSK reception. DAB+ has a different error protection structure to DAB: DAB+ uses Equal Error Protection convolutional coding and an outer Reed-Solomon code which is provides better overall error protection than the single Unequal error protection coding used in DAB. The difference in performance in a Rayleigh environment is generally considered to be between 1 and 2dB, see [10] and [12] which both report a 1.5dB improvement for a TU25 channel. We also note that the UK OFCOM / BBC / Arqiva report [11] uses a Rayleigh implementation margin of 4.6dB.

Given that DAB+ receiver performance is better than for DAB it is proposed to adjust the Rayleigh fading allowance from 5.6 to 4.6dB to change the required CNR for a typical Rayleigh channel from 13dB to 12dB.


1.29. Planning field strengths

The determination of target minimum median field strengths considering the changes proposed above is shown in Table 8-17. The results see the field strengths at 1.5m AGL for suburban and urban classes reduce by 2dB while the mobile class increases by 1dB. The increase in the mobile minimum value corresponds well with the findings of car receiver performance testing by CRA as reported in [13]. In those trials two cars with factory fitted DAB+ receivers were tests, the results indicated that a minimum field strength of 50dBμV/m was required to ensure sustained error free operation.

Parameter Unit Mobile Suburban Urban Mobile Suburban Urban

Frequency MHz 200 200 200 200 200 200

Wavelength m 1.50 1.50 1.50 1.50 1.50 1.50

Equvalent Noise Bandwidth MHz 1.536 1.536 1.536 1.536 1.536 1.536

Receiver Noise Figure dB 8 8 8 8 8 8Required Threshold C/N (for PL=3 in 1.54 MHz Gaussian channel)

Allowance for Rayleigh dB 5.6 5.6 5.6 4.6 4.6 4.6Required Threshold C/N (for PL=3 in 1.54 MHz Rayleigh channel)

Minimum Receiver Input Voltage dBuV 17.7 17.7 17.7 16.7 16.7 16.7

Antenna Gain (incl any feeder cable loss) dBd -5 -8 -8 -10 -8 -8

Antenna Factor dB 17.3 20.3 20.3 22.3 20.3 20.3

Minimum Field Strength dBuV/m 35.0 38.0 38.0 39.0 37.0 37.0

Location Availability Std Dev. dB 5.5 5.5 5.5 4.0 4.0 4.0

Location Availability % 99 95 95 99 95 95

Dist factor - 2.33 1.64 1.64 2.33 1.64 1.64

Building penetration loss Std Dev dB 0 4.4 4.4 0 4.4 4.4

Composite Std Dev (outdoor + building) dB 5.5 7.0 7.0 4.0 5.9 5.9

Location Availability Margin dB 12.8 11.6 11.6 9.3 9.8 9.8

Man made noise allowance dB 1 1 1 1 1 1

Interference allowance dB 1 1 1 1 1 1

Min Median equivalent FS @1.5 m dBuV/m 48.8 50.6 50.6 50.3 48.8 48.8

Building penetration loss dB 0 5 11 0 5 11

Min Median equivalent FS @1.5 m dBuV/m 48.8 55.6 61.6 50.3 53.8 59.8Rounded values dBuV/m 49 56 62 50 54 60Height Gain Allowance dB 13 13 13 10 10 10

Min Median equivalent FS @10 m dBuV/m 62.8 69.6 75.6 60.3 63.8 69.8Rounded values dBuV/m 63 70 76 60 64 70

12 12 12dB 13 13 13

Current Australian numbers Proposed updates

dB 7.4 7.4 7.4 7.47.4 7.4

Table 8-17: Calculation of target field strengths


Figure 8-17: Silence performance for a factory fit radio during the Brisbane field trials, 2015

Comparing the results with current international targets in Table 8-18 we see that the mobile target is slightly higher than European targets while the indoor suburban and urban targets are very close or the same as the UK and Norway.

Country Minimum reception field strength (dBμV/m) Comments

Mobile

(99% of locations)

Suburban

(95% of locations)

Urban

(95% of locations)

Australia (2008) 49

(63 at 10m)

56

(70 at 10m)

62

(76 at 10m)

From [5]

Australia (2016) 50

60 at 10m)

54

(64 at 10m)

60

(70 at 10m)

UK 44 53 60 Urban is considered as dense urban by UK OFCOM

Norway 48 54 60

Germany 48 56 62

Switzerland 48 66


Italy 60 66

ITU 48 54 RRC06

EBU 43 50 From [2]

Table 8-18: Current international and proposed 2016 Australian planning filed strengths at 1.5m AGL (unless otherwise specified)

Given the results of the technical investigations detailed in section 1.28 it is proposed to adjust the minimum median field strength targets for Australian DAB+ digital radio planning to the following.

Planning field strengths (dBμV/m)

Mobile Suburban Urban

Current planning field strength (1.5m) 49 56 62

Proposed planning field strength (1.5m) 50 54 60

Current planning field strength (10m) 63 70 76

Proposed planning field strength (10m) 60 64 70

1.30. DAB+ Interference Protection Ratios

1.30.1.Co-channel interference

The value used for DAB+ to DAB+ co-channel interference protection, i.e. the Protection Ratio, in Australia is currently 15dB. When compared with the values used elsewhere this is high, e.g. the UK use the Rayleigh CNR as the PR value which is 13dB for DAB but will be reduced by 1 to 2dB for DAB+, e.g. 12dB. Both the ITU and EBU planning documents refer to 10dB for DAB, which seems low.

CRA undertook bench testing of a number of receivers using the Rhode and Schwarz SFU test unit supplied by the ACMA.

The tests involved the determination of the level of a co-channel interfering signal which will cause the audio to fail (threshold of Audibility). The measurements were done over a range of wanted input signal levels.

The test unit used was a Frontier-Silicon Venus Colour Reference Platform. The Frontier-Silicon (F-S) DAB+ receiver modules are the dominant receiver product in consumer products with a claimed 80% of the market. All F-S module products use the same RF frontend technology hence there is high confidence that the testing was on a representative product.


Figure 8-18 shows the results for the no fading case as well as three different fading models as per the recommended test fading channels [14], the Typical Urban (TU) profile was at 25kph and the Rural Area (RA) was at 120kph, both at frequency block 9A (202.928MHz).

The results show an average PR of 12dB across the input signal level range which is approximately the same as the Rayleigh CNR value as proposed and used by OFCOM UK. Consequently we recommend changing the CCI PR value from 15dB to 12dB.

Figure 8-18: Measured PR for the Frontier Silicon Venus Colour Reference Platform using a Venice 6.2 module

The use of a lower CCI PR will reduce the apparent impact of one transmission on another using the same frequency block in a different area. The TSC considers this reduction to be low risk in terms of the probability of interference occurring and expects that the results will be more realistic (less pessimistic).

The PR value applies not only to the use of the same channel block by different broadcasters in different licence areas but also to situations where CCI may occur within a SFN, particularly wide area SFNs.

1.31. Coverage and overspill targets

A delicate balance needs to be struck regarding fair and reasonable coverage of a LA and overspill into adjacent LAs. To date these discussions have mainly focused on FM where a broadcaster expects to cover the vast majority of the population within their LA with stereo quality. The issue is then how far FM-mono travels in a usable form inside the adjacent LA. In some cases this can be quite significant, particularly if the transmitter site is high and the adjacent LA is low and flat. Additionally FM degrades from stereo to mono gracefully with the lack of stereo difficult to discern in some audio formats and mobile environments like in vehicles. Consequently there is a reasonable level of tolerance to “fortuitous overspill”.

As DAB+ uses digital modulation with error correction it has a very different reception characteristic relative to FM, that being the familiar “brick wall” reception performance i.e. reception is either good (no errors) or bad (no sound). This makes the overspill into adjacent LAs more manageable but also encourages the broadcaster in the target area to ensure that they always have sufficient field strength so as not to suffer from black spot areas especially at the edge of coverage.


The extract from the ACMA’s 2008 discussion paper below proposed that overspill in Urban Centres (UCs) be limited to less than “Suburban grade” (currently 70dBμV/m at 10m), where an Urban Centre is defined as a population centre with more than 1,000 residents. In practice this means that the target LA needs to be planned to ensure that there is no coverage greater than the threshold in those urban centres.

As the ACMA 2008 report notes, the overspill target may in some situations allow the target licence area transmission to reach well within the adjacent licence area at less than “Suburban grade” field strength thus providing some vehicle grade coverage. The TSC considers this the most pragmatic solution to ensure cost effective roll out and importantly, main road coverage between licence area boundaries.

Relevant excerpts from 2008 ACMA discussion paper with the correction of UCLs to Urban Centres:

Minimum signal level considerations

A key issue for broadcasters planning their networks and frequency planners determining channel plans is the minimum signal level that is needed to achieve adequate coverage.

A number of factors influence the minimum signal level. Examples are whether the target receiver is a mobile receiver or a portable receiver[1][1] and, if the receiver is portable, whether it operates outdoors or indoors. A further factor is the ‘location availability’ required for the digital radio signal. Location availability is a statistical concept associated with modelling radiofrequency signals. Analogue signals have been planned on the basis of 50% location availability at the edge of coverage. This means that within a small area (for example 200m by 200m) 50% of locations would receive more than the predicted signal level. Note that at locations closer to the transmitter the location availability increases. Due to the abrupt failure characteristic of digital signals much higher location availability is typically required. Mobile reception is often planned for a 99% location availability and portable reception for 95% location availability.

Commercial Radio Australia, in its October 2007 submission to the initial draft DRCPs proposed, and after careful consideration, ACMA adopted in finalising those DRCPs the following minimum field strengths:

Mobile (Car) devices, minimum median field strength of 63 dBuV/m. (Location availability: 99%, Standard deviation: 5.5 dB)

Indoor Suburban devices, minimum median field strength of 70 dBuV/m. (Location availability: 95%, Standard deviation: 7.0 dB)

Indoor Urban devices, minimum median field strength of 76 dBuV/m. (Location availability: 95%, Standard deviation: 7.0 dB)

Adopting 70 dBuV/m as the planning level permitted for Urban Centres and Localities (UCLs) at the designated BSA radio area[2][2] boundary may result in a reception environment similar to FM radio. That is, where it is practicable to achieve this level, good coverage is likely to be available within the designated BSA radio area for all types of receivers and car radio reception would be possible for some distance outside the designated BSA radio area.

Overspill considerations

[1][1] The term mobile receiver corresponds to a radio mounted in a car or other vehicle with an external antenna. A portable receiver generally refers to a ‘bench top’ or ‘kitchen radio’ that would operate on mains power and have a telescopic antenna. [2][2] In general terms the designated BSA radio area is equivalent to the licence area of the majority of commercial radio broadcasting licensees operating in the area (see section 5 of the RA).


In developing the draft variation to the DRCPs, ACMA has set an objective that where practicable the signal level in Urban Centres and Localities (UCLs) beyond the boundary of a designated BSA radio area should be limited to less than 70dBμV/m, the minimum target signal level for indoor reception in an suburban environment.

It should be noted that limiting the signal level from the main transmitter to less than 70dBμV/m in UCLs beyond the designated BSA radio area boundary is likely to result in mobile grade coverage being available beyond the boundary.

1.32. References

[1] ACMA, Broadcasting Services (Technical Planning) Guidelines 2007 (as amended in 2009)

[2] EBU TR 021, TECHNICAL BASES FOR T-DAB SERVICES NETWORK PLANNING AND COMPATIBILITY WITH EXISTING BROADCASTING SERVICES, October 2013

[3] EBU, TR 024. SFN FREQUENCY PLANNING AND NETWORK IMPLEMENTATION WITH REGARD TO T-DAB AND DVB-T, October 2013

[4] ITU-R BS.1660-6 Technical basis for planning of terrestrial digital sound broadcasting in the VHF band, 08/2012

[5] CRA report, “Planning Field Strength and derivation for T-DAB reception for mobile and indoor”, BTC Australia for CRA, January 2008

[6] William C. Y. Lee, “Estimate of Local Average Power of a Mobile Radio Signal”, IEEE Transactions on Vehicular Technology, February 1985

[7] OFCOM report Annex F, “Location Variation for a T-DAB signal in Band III”, April 2012[8] CRA presentation, “Antenna placement for great reception”, 2011[9] Vehicle DAB+ Antenna characteristics – Patterns and minimum F/S, BTC Aust for CRA,

Dec 2011[10] EBU TR 025,REPORT ON FREQUENCY AND NETWORK PLANNING PARAMETERS

RELATED TO DAB+, October 2013[11] OFCOM report Annex I, “Technical Parameters and Planning Algorithms for DAB

Coverage Calculations”, June 2011[12] CRA report, “FEC-SFN DAB+ Receiver Performance –Bench Testing”, June 2013 [13] CRA report, “Brisbane DAB+ Field Trials”, September 2015[14] BS EN 50248, “Characteristics of DAB Receivers”, 2001, also published as IEC

62104:2003 and reissued in 2015[15] ACMA study document, “DRPC-TSC-2016-71 DRAFT REPORT DAB prediction and

allotment studies within 400km of Sydney – 15 August”, August 2016 [16] VAD and Fraunhofer paper, Experiments with Local Windows in DAB, date unclear but

likely to be pre-2000[17] Addendum 1 to ACMA report [15][18] ITU-R Final Acts of the Regional Radiocommunication Conference for planning of the

digital terrestrial broadcasting service in parts of Regions 1 and 3, in the frequency bands 174-230 MHz and 470-862 MHz (GE-06)

9.References and Glossary


1.33. Glossary

Term Meaning

ABC Australian Broadcasting CorporationACI Adjacent Channel InterferenceACMA Australian Communications and Media AuthorityAGL Above Ground LevelASL Above Sea LevelBNP The EBU Broadcast Network Planning groupBSA Broadcasting Services ActCat-SLS Categorised SLS – advanced categorised imageCat abbreviation for Category, e.g. Cat.1 means Category 1 multiplexCBAA Community Broadcasters Association of AustraliaCCI Co-channel interferenceCNR Carrier to Noise Ratio, also abbreviated as C/NCRA Commercial Radio AustraliaDAB+ Digital Audio Broadcasting using the AAC+ audio encoderDLS Dynamic Label Segment, also called text message and scrolling textDRPC Digital Radio Channel PlanDTV Digital TelevisionEBU European Broadcasting UnionEP Ensemble ProviderFEC Forward Error Correction codeFM Frequency Modulation (analogue radio in RF Band II)HRP antenna Horizontal Radiation PatternITU International Telecommunications UnionLA Licence AreaLAP Licence Area Plan as defined by the ACMALF Location FactorLFR Link Fed RepeaterMOT Multimedia Object TransferMux or mux abbreviation for MultiplexOCR On-Channel RepeaterPAD Program Associated DataPC Propagation Correction marginPR Protection RatioSBS Special Broadcasting ServiceSD Standard DeviationSFN Single Frequency NetworkSLS Slide Show (images)SP Service ProviderTC WorldDMB Technical CommitteeTF WorldDMB Technical Committee Task ForceTSC Technical Sub-Committee (of the DRPC)UHF Ultra High Frequency : 300 - 3000MHzURL Universal Resource LocatorUTC Universal Time Coordinates (Greenwich Mean Time)VRP antenna Vertical Radiation PatternVHF Very High Frequency : 30 – 300MHzXPAD eXtra Program Associated Data

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