GSM RF Planning Concepts Ppt

RF Network Design

Network Planning

Introduction

• The high level life cycle of the RF network planning process can be summarised as follows :-

• To help the operator to identify their RF design requirement

• Optional• Discuss and agree

RF design parameters, assumptions and objectives with the customer

• Coverage requirement

• Traffic requirement• Various level of

design (ROM to detail RF design)

• Issuing of search ring

• Cand. assessment• Site survey,

design, approval• Drive test

(optional)

• Frequency plan

• Neighbour list• RF OMC data• Optimisation

Comparative Analysis

RF Design requirement

RF Design

Site Realisation

RF Design Implementation


• This is an optional step

• This is intended to :-o Help an existing operator in building/expanding their networko Help a new operator in identifying their RF network requirement,

e.g. where their network should be built

• For the comparative analysis, we would need to :-o Identify all network that are competitors to the customero Design drive routes that take in the high density traffic areas of

interesto Include areas where the customer has no or poor service and the

competitors have service


• The result of the analysis should include :-

• For an existing operatoro All problems encountered in the customer’s networko All areas where the customer has no service and a competitor

doeso Recommendations for solving any coverage and quality problems

• For a new operatoro Strengths and weaknesses in the competitors networko Problem encountered in the competitors network

RF Network Design Inputs

• The RF design inputs can be divided into :-o Coverage requirements

Target coverage areas Service types for the target coverage areas. These should be

marked geographically Coverage area probability Penetration Loss of buildings and in-cars

o Capacity requirements Erlang per subscriber during the busy hour Quality of service for the air interface, in terms GoS Network capacity

RF Network Design Inputs

• Available spectrum and frequency usage restriction, if any• List of available, existing and/or friendly sites that should be included

in the RF design• Limitation of the quantity of sites and radios, if any • Quality of Network (C/I values)• Related network features (FH, DTX, etc.)

Coverage Design Inputs by BSNL

• Coverage Thresholds o Indoor Coverage : Signal Level measured at street better than –65 dBm.

Indoor coverage to be provided in commercial complexes, hotels,technology parks etc.

o In Car Coverage: Signal Level measured at street better than –75 dBm. In Car coverage to be provided in residential areas, highways, tourist spots etc.

o Outdoor Coverage : Signal level measured at street better than –85 dBm. All remaining areas to be covered with Outdoor coverage.

o These are general guidelines for planning , specific areas not provided.

Capacity Design Inputs by BSNL

• Frequency spectrum available 6.2 MHz (31 channels).• Average traffic per sub for RF design : 50 mErlang.• Synthesizer frequency hopping can be used.• GOS: 2%• Existing network Database

o Total No. of sites with configurationo Site details eg location(Lat-Long), Antenna height ,azimuth, etc.

RF Network Design

• There are 2 parts to the RF network design to meet the :-o Capacity requiremento Coverage requirement

• For the RF Coverage Design

RF Coverage

Design

Link Budget

Propagation Model

Digitised DatabasesCW Drive

TestingCustomer

Requirements

CW Drive Testing

• CW drive test can be used for the following purposes :-o Propagation model tuningo Assessment of the suitability of candidate sites, from both

coverage and interference aspect• CW drive test process can be broken down to :-

Test Preparation

Propagation Test

Data Processing

• Equipment required

• BTS antenna selection

• Channel selection

• Power setting• Drive route planning• Test site selection

• Transmitter setup

• Receiver setup

• Drive test• Transmitter

dismantle

• Measurement averaging

• Report generation

CW Drive Testing - Test Preparation

• The test equipment required for the CW drive testing :-o Receiver with fast scanner

Example : HP7475A, EXP2000 (LCC) etc. The receiver scanner rate should conform to the Lee Criteria of

36 to 50 sample per 40 wavelength

o CW Transmitter Example : Gator Transmitter (BVS), LMW Series Transmitter

(CHASE), TX-1500 (LCC) etc.

o Base Station test antenna DB806Y (Decibel-GSM900), 7640 (Jaybeam-GSM1800) etc.

o Accessories Including flexible coaxial cable/jumper, Power meter, extended

power cord, GPS, compass, altimeter


• Base Station Antenna Selectiono The selection depends on the purpose of the testo For propagation model tuning, an omni-directional antenna is

preferredo For candidate site testing or verification, the choice of antenna

depends on the type of BTS site that the test is trying to simulate. For Omni BTS :

Omni antennas with similar vertical beamwidth For sectorised BTS

Utilising the same type of antenna is preferred Omni antenna can also be used, together with the special

feature in the post processing software like CMA (LCC) where different antenna pattern can be masked on over the measurement data from an omni antenna


• Test Site Selection

• For propagation model tuning, the test sites should be selected so that :-o They are distributed within the clutter under studyo The height of the test site should be representative or typical for

the specific cluttero Preferably not in hilly areas

• For candidate site testing/verification, the actual candidate site configuration (height, location) should be used.

• For proposed greenfield sites, a “cherry-picker” will be used.


• Frequency Channel Selectiono The necessary number of channels need to be identified from the

channels available With input from the customer

o The channels used should be free from occupation From the guard bands Other free channels according to the up-to-date frequency plan

o The channels selected will need to be verified by conducting a pre-test drive It should always precede the actual CW drive test to verify the

exact free frequency to be used It should cover the same route of the actual propagation test A field strength plot is generated on the collected data to

confirm the channel suitability


• Transmit Power Setting

• For propagation model tuning, the maximum transmit power is used

• For candidate site testing, the transmit power of the test transmitter is determined using the actual BTS link budget to simulate the coverage

• On sites with existing antenna system, it is recommended that the transmit power to be reduced to avoid interference or inter-modulation to other networks.

• The amount of reduction is subject to the possibility if separating the test antenna from the existing antennas


• Drive Route Determinationo The drive route of the data collection is planned prior to the drive test

using a detail road map Eliminate duplicate route to reduce the testing time

o For propagation model tuning, each clutter is tested individually and the drive route for each test site is planned to map the clutter under-study for the respective sites.

o It is important to collect a statistically significant amount of data, typically a minimum of 300 to 400 data points are required for each clutter category

o The data should be evenly distributed with respect to distance from the transmitter

o In practice, the actual drive route will be modified according to the latest development which was not shown on the map. The actual drive route taken should be marked on a map for record purposes.

• Transmitter Equipment Setupo Test antenna location

Free from any nearby obstacle, to ensure free propagation in both horizontal and vertical dimension

For sites with existing antennas, precaution should be taken to avoid possible interference and/or inter-modulation

o Transmitter installation

o A complete set of 360º photographs of the test location (at the test height) and the antenna setup should be taken for record

CW Drive Testing - Propagation Test


• Scanning Receiver Setup - HP 7475A Receiver Example

HP 7475A Receiver


• Scanning Receiver Setupo The scanning rate of the receiver should always be set to allow at least

36 sample per 40 wavelength to average out the Rayleigh Fading effect. For example: scanning rate = 100 sample/s test frequency = 1800 MHz therefore, to achieve 36 sample/40 wavelength, the max. speed is =

o It is recommended that :- Beside scanning the test channel, the neighbouring cells is also

monitored. This information can be used to check the coverage overlap and potential interference

Check the field strength reading close to the test antenna before starting the test, it should approach the scanning receiver saturation

CW Drive Testing - Propagation Test• Drive Test

o Initiate a file to record the measurement with an agreed naming convention

o Maintain the drive test vehicle speed according to the pre-set scanning rate

o Follow the pre-plan drive route as closely as possibleo Insert marker wherever necessary during the test to indicate

special locations such as perceived hot spot, potential interferer etc.

o Monitor the GPS signal and field strength level throughout the test, any extraordinary reading should be inspected before resuming the test.

• Dismantling Equipmento It is recommended to re-confirm the transmit power (as the pre-set

value) before dismantling the transmitter setup

Measurement Data Processing• Data Averaging

o This can be done during the drive testing or during the data processing stage, depending on the scanner receiver and the associated post-processing software

o The bin size of the distance averaging depends on the size of the human made structure in the test environment

• Report Generationo For propagation model tuning, the measurement data is exported

into the planning tool (e.g. Asset)o Plots can also be generated using the processing tool or using

MapInfoo During the export of the measurement data, it is important to take

care of the coordinate system used, a conversion is necessary if different coordinate systems are used.

Propagation Model• Standard Macrocell Model for Asset

o Lp (dB) = K1 + K2 log(d) + K3 Hm + K4 log(Hm) + K5 log(Heff) o + K6 log(Heff) log(d) + K7 Diffraction + Clutter factoro where Lp, Diffraction, Clutter factor are in dBo d, Hm, Heff are in mo It is based on the Okumura-Hata empirical model, with a number of

additional features to enhance its flexibilityo Known to be valid for frequencies from 150MHz to 2GHzo Applies in condition :-

Base station height : 30 - 200 m Mobile height : 1 - 10 m Distance : 1 - 20 km

o An optional second intercept and slope (K1, K2) for the creation of a two-piece model with the slope changing at the specified breakpoint distance.

Morphology Class

Link Budget

Link Budget Element of a GSM Network

BTS Antenna Gain Max. Path Loss Fade Margin

LNA (optional)

Feeder Loss

Diversity Gain

BTS Receiver

Sensitivity

ACELoss

BTS Transmit

Power

Penetration Loss

MS Antenna Gain, Body and Cable

Loss

Mobile Transmit

Power

Mobile Receiver

Sensitivity

Link Budget

• BTS Transmit Powero Maximum transmit powero GSM900 and 1800 networks use radios with 46dBm maximum transmit

power• ACE Loss

o Includes all diplexers, combiners and connectors.o Depends on the ACE configurationo The ACE configuration depends on the number of TRXs and combiners

used

Link Budget

• Mobile Transmit Powero GSM900 : Typical mobile class 4 (2W)o GSM1800 : Typical mobile class 1 (1W)

• Mobile Receiver Sensitivityo The sensitivity of GSM900 and GSM1800 mobile = -102 dBm

Link Budget• Diversity Gain

o Two common techniques used :- Space Polarisation

o Reduce the effect of multipath fading on the uplinko Common value of 3 to 4.5 dB being used

• BTS Receiver Sensitivityo Depends on the type of propagation environment model used,

most commonly used TU50 modelo BTS :-

Receiver Sensitivity for GSM900 = -107 dBm

Link Budget• Feeder Loss

o Depends on the feeder type and feeder lengtho The selection of the feeder type would depends on the feeder

length, I.e. to try to limit to feeder loss to 3 -4dB.

• BTS Antenna Gaino Antenna gain has a direct relationship to the cell sizeo The selection of the antenna type depends on :-

The morphology classes of the targeted area and coverage requirements

Zoning and Local authority regulations/limitationso Common antenna types used :-

65º, 90º, omni-directional antennas with different gains

Link Budget• Slow Fading Margin

o To reserve extra signal power to overcome potential slow fading.o Depends on the requirement of coverage probability and the

standard deviation of the fadingo A design can take into consideration :-

both outdoor and in-building coverage, which utilises a combined standard deviation for indoor and outdoor (Default value = 9dB)

Only outdoor coverage (Default value = 7dB) Pathloss slope used, 45dB/dec (Dense Urban), 42dB/dec

(Urban), 38dB/dec (Suburban) and 33dB/dec (Rural)

Link Budget

• Penetration Losso Penetration loss depends on the building structure and materialo Penetration loss is included for in-building link budgeto Typical value used for Asia-Pacific environment (if country specific

information is not available) :- Dense Urban : 20 dB Urban : 18 dB Suburban : 15 dB Rural : 9 dB

• Body Losso Typical value of 3dB body loss is used

• MS Antenna Gaino A typical mobile antenna gain of 2.2 dBi is used

Link Budget

• Link Budget Example (GSM900)

Antenna• Antenna Selection

o Gaino Beamwidths in horizontal and vertical radiated planeso VSWRo Frequency rangeo Nominal impedanceo Radiated pattern (beamshape) in horizontal and vertical planeso Downtilt available (electrical, mechanical)o Polarisationo Connector types (DIN, N)o Height, weight, windload and physical dimensions

Antenna

• The antenna selection processo Identify system specifications such as polarisation, impedance

and bandwidtho Select the azimuth or horizontal plane pattern to obtain the

needed coverageo Select the elevation or vertical plane pattern to be as narrow as

possible, consistent with practical limitations of size, weight and cost

o Check other parameters such as cost, power rating, size, weight, mounting capabilities, wind loading, connector types, aesthetics and reliability to ensure that they meet system requirements

Antenna

• System Specificationo Impedance and frequency bandwidth is normally associated with the

communication system usedo The polarisation would depends on if polarisation diversity is used

• Horizontal Plane Patterno Three categories for the horizontal plane pattern :-

Omnidirectional Sectored (directional) Narrow beam (highly directional)

• Elevation Plane Patterno Choosing the antenna with the smallest elevation plane beamwidth will

give maximum gain. However, beamwidth and size are inversely relatedo Electrical down tilto Null filling

Nominal RF Design

Link Budget

Maximum path loss

Propagation model

Typical site configuration

Site radiusNominal RF

Design (coverage)

Coverage requirements

Nominal site count

Coverage site count

• Transmit Power• Antenna

configuration (type, height, azimuth)

• Site type (sector, omni)

Traffic requirements

• Standard hexagon site layout

• Friendly, candidate sites

• Initial site survey inputs

Traffic site count

Traffic > Cov.

Cov. > Traffic

• Recalculate the site radius using the number of sites from the traffic requirement

• Repeat the nominal RF design

Traffic requirements

Nominal RF Design

• Calculation of cell radiuso A typical cell radius is calculated for each clutter environmento This cell radius is used as a guide for the site distance in the

respective clutter environmento The actual site distance could varies due to local terrain

• Inputs for the cell radius calculation :-o Maximum pathloss (from the link budget)o Typical site configuration (for each clutter environment)o Propagation model

Nominal RF Design

• There are different level of nominal RF design :-o Only using the cell radius/site distance calculated and placing

ideal hexagon cell layouto Using the combination of the calculated cell radius and the

existing/friendly sites from the customer

The site distance also depends on the required capacity• In most mobile network, the traffic density is highest within the CBD

area and major routes/intersections• The cell radius would need to be reduce in this area to meet the traffic

requirements

• BASED ON THE SITE DISTANCE & THE COVERAGE REQUIREMENTS CELL COUNT BASED ON COVERAGE IS CALCULATED.

Nominal RF Design

• Cell count based on traffic is derived based on capacity inputs:- Capacity requirements GOS Spectrum availability Freq. Hopping techniques

• If the total sites for the traffic requirement is more than the sites required for coverage, the nominal RF design is repeated using the number of sites from the traffic requiremento Recalculating the cell radius for the high traffic density areaso The calculation steps are :-

Calculate the area to be covered per site Calculate the maximum cell radius Calculate the site distance

Site Realisation

• After completion of Nominal design based on cell count ( coverage & capacity requirements) , search rings for each cell site issued.

• Nominal design is done , with the existing network in place(existing BTS). Existing site location remain unchanged , azimuth , tilts as per the new design requirements.

• Based on the search ring form physical site survey is undertaken.

Site Realisation

Search Ring Form• Site ID• Site Name• Latitude/Longitude• Project name• Issue Number and date• Ground height• Clutter environment• Preliminary configuration

o Number of sectoro Azimutho Antenna typeo Antenna height

• Location Map & SR radius

• Search ring objective• Approvals

Site Realisation

Release of Search Ring

Suitable Candidates?

Candidates Approved?

Arranged Caravan

All parties agreed at Caravan

Produce Final RF Design

Caravan next candidate

Exhausted candidates

Additional sites required

Cell split required

Candidate approved?

Driveby, RF suggest possible

alternative

Next candidate

Problem identifying candidate

Discuss alternative with

customer

Issue design change

Exhausted candidates

Y

N

Y Y

Y

Y

YY

NN

N

N

NN

YN

Site Realisation

• Candidate Assessment Report-Site Survey Formso Site survey Forms for all suitable candidates for the search ringo For each candidates :-

Location (latitude/longitude) Location map showing the relative location of the candidates

and also the search ring Candidate information (height, owner etc) Photographs (360º set, rooftop, access, building) Possible antenna orientations Possible base station equipment location Information for any existing antennas Planning reports/comments (restrictions, possibilities of

approval etc.)

Site Realisation-Site Survey Form

• Final RF Configuration Formo Base Station configuration

Azimuth Antenna height Antenna type Down tilt Antenna location Feeder type and length BTS type Transmit power Transceiver

configuration

Traffic Engineering

Spectrum Available

Reuse factor

Maximum numberof TRX per cell

No of TCH available

Traffic offered

Traffic Requirement

Subscriber supported

Channel loading

Traffic Engineering

• Traffic Requirement

• The Erlang per subscriber

• Grade of Service (GoS)o GoS is expressed as the percentage of call attempts that are

blocked during peak traffico Most cellular systems are designed to a blocking rate of 1% to 5%

during busy hour

Traffic Engineering• Frequency Reuse

o In designing a frequency reuse plan, it is necessary to develop a regular pattern on which to assign frequencies

o The hexagon is chosen because it most closely approximated the coverage produced by an omni or sector site

o Common reuse factor : 4/12, 7/21

Traffic Engineering• Channel Loading

o As the number of TRX increases, the control channels required increases accordingly

o The following channel loading is used for conventional GSM network

o For services such as cell broadcast, additional control channels might be required

Traffic Engineering

• After determining the number of TCH available and the traffic requirements, the traffic offered is calculated using the Erlang B tableo For example, for a 2% GoS and 3 TRX configuration, the traffic offered is

14 Erlango If the traffic per subscriber is 50mE/subscriber, then the total subscribers

supported per sector = 280

• For a uniform traffic distribution network, the number of sites required for the traffic requirement is :-

Traffic Engineering

• Erlang B Table

Traffic Engineering• If a traffic map is provided, the traffic engineering is done together with

the coverage design• After the individual sites are located, the estimated number of

subscribers in each sector is calculated by :-o Calculating the physical area covered by each sectoro Multiply it by the average subscriber density per unit area in that regiono The overlap areas between the sectors should be included in each

sector because either sector is theoretically capable of serving the area• The number of channels required is then determined by :-

o Calculating the total Erlangs by multiplying the area covered by the average load generated per subscriber during busy hour

o Determine the required number of TCH and then the required number of TRXs

o If the number of TRXs required exceeded the number of TRXs supported by the available spectrum, additional sites will be required

SWAP PLAN

• Why do we need a swap plan?To reduce mix of different vendor BTS within a large city/ area

o Reduce Inter MSC HO.o Better maintenance efficiency

Swap Strategyo No. of existing BTS sites with configuration known o No. of new sites with configuration known.

For Example BSNL UP(W) Circle

UP(W) Circle Network Diagram

Nokia BTS

Ericcsson BTS

All DHQ on Nokia

Muzaffarnagar

Meerut

AligarhMathura

Agra

Noida

Etah

Ghaziabad

Bijnor

Rampur

Pilbhit

Etawah

Mainpuri

Budaun

Bulandshahr

Saharanpur

Moradabad

Bareilly

Delhi

NCR

Uttaranchal

Haryana

Haryana

RajasthanUP(E)

Nepal

UP(W) Circle Network Distribution• Major Cities /SSA’s to be deployed on Nokia BTS

o DHQ of all SSA’so Meeruto Agrao Mathurao Noidao Ghaziabado Muzaffarnagaro Aligarho Bulandshahar

• SSA’s except DHQ’s deployed on Ericsson BTSo Bijnoro Bareillyo Moradabado Etaho Etawah o Rampuro Pilbhito Badaun o Mainpurio Saharanpur

Agra

Mathura

Mainpuri

Meerut

Muzaffarnagar

Saharanpur

Moradabad

BulandshaharBadaun

PilbhitBareilly

Etawah

Aligarh

Bijnor

Rampur

Ghaziabad

NoidaDelhi

Etah

69 Ericsson HW Site

56 Nokia HW Site

National HW

Railways

State Highway

District Border

Uttaranchal

Haryana

Haryana

RajasthanUP(E)

HW & Rly Plan for UPW

NH-58

NH-91NH-24

NH-02

NH-03

Nepal

SWAP SUMMARYSl NO SSA PH-IV PLANNED

NOKIASWAP

NOKIA WITH ERICSSON

EXISTING ERICSSON

SWAP ERICSSON

WITH NOKIA

TOTAL NOKIA

TOTAL ERICSSON

Highways Nokia

GRAND TOTAL

A B C D E F G H

(A+D-B) (C-D+B) (E+F+G)

1 Agra 74 2 43 37 109 8 8 125

2 Aligarh 40 4 27 19 55 12 1 68

3 Badaun 16 10 11 3 9 18 1 28

4 Bareilly 45 11 27 17 51 21 2 74

5 Bijnor 39 32 16 3 10 45 0 55

6 Bulandshahar 27 3 17 12 36 8 1 45

7 Etah 17 12 10 3 8 19 3 30

8 Etawah 29 21 16 4 12 33 0 45

9 Ghaziabad 27 1 15 9 35 7 0 42

10 Mainpuri 22 17 12 2 7 27 0 34

11 Mathura 34 1 22 17 50 6 7 63

12 Meerut 68 5 30 26 89 9 11 109

13 Moradabad 73 35 33 16 54 52 9 115

14 Muzaffarnagar 48 10 17 13 51 14 3 68

15 Noida 12 0 8 6 18 2 0 20

16 Pilbhit 11 6 6 2 7 10 5 22

17 Rampur 20 13 11 3 10 21 0 31

18 Saharanpur 31 18 16 9 22 25 5 52

Total 633 201 337 201 633 337 56 1026

• Before Swap 24volt’s (40) BTS statuso Agra – 9o Aligarh – 2o Bareilly – 5 o Mathura – 2o Meerut – 3 o Moradabad – 6 o Saharanpur – 4o Bijnor – 2o Bulandshahar – 2o Etah – 1o Etawah – 3o Pilibhit – 1

• Out of 40 sites 31 have been swapped too Bijnor – 16o Moradabad – 15

• Out of 40 sites 9 left as it is (No Swap)o Agra - 1o Moradabad – 1o Saharanpur – 1o Bijnor – 1o Bulandshahr – 1o Etah – 1o Etawah – 3

• After Swap 24volt’s (40) BTS statuso Agra – 1o Moradabad – 16o Saharanpur – 1o Bijnor – 17 o Etah – 1o Etawah – 3o Bulandshahr – 1

UP(W) Circle 24volt BTS Distribution

Advanced Network Planning Steps

Parameter Planning

• Parameter planning means creating a default set of BSS parameters.• The most important parameters to plan for:

o frequencieso BSICo LACo handover control parameterso adjacent cell definitions.

BSS Parameter

• Relevant BSS parameter for NW planningo frequency allocation plano transmit powero definition of neighbouring cellso definition of location areaso handover parameterso power control parameterso cell selection parameters

Handover Types

• Intracell same cell, other carrier or timeslot• Intercell between cells (normal case)• Inter-BSC between BSC areas• Inter-MSC between MSC areas • Inter- PLMN e.g. between AMPS and GSM systems

intracellintercell

inter-BSC

Handover Criteria

1. Interference, UL and DL2. Bad C/I ratio3. Uplink Quality 4. Downlink Quality 5. Uplink Level 6. Downlink Level 7. Distance8. Rapid Field Drop

9. MS Speed10. Better Cell, i.e. periodic check (Power Budget, Umbrella Handovers)11. Good C/I ratio12. PC: Lower quality/level thresholds (DL/UL)13. PC; Upper quality/level thresholds (DL/UL)

Location Area Design 1/2

• Location updating affects all mobiles in networko LocUp in idle modeo LocUp after call completion

• Location updating causes signalling and processing load within the network (international LocUpdate !)

• Avoid oscillating LocUpdate• Trade-off between Paging load

and Location Update signalling

Location area 1

Location area 2

major road

Location Area Design 2/2

• Different MSC can not use the same LAC.• Location areas are important input for transmission planners

o should be planned as early as possible.• Never define location area borders along major roads!• Dual band or microcellular networks require more attention on LAC

planningo co-located DCS and GSM cells are defined to the same LAC o same MSC to avoid too much location updates which would

cause very high SDCCH blockings

Network Optimisation

What is network optimisation?

• Improving network quality from a subscribers point of view.

• Improving network quality from an operators point of view.

Network Optimisation is:

What is network quality?

OPERATOR

CUSTOMER

NETWORK

SERVICES

MOBILE

COST

• Mail Box, Data, Fax, etc.

• Customer Care• Faulty H/W or S/W• Mobile Quality• Misuse of

Equipment

• H/W Failure• Network

Configuration• Network Traffic• Spectrum

Efficiency• Coverage yes/no• Service Probability• Quality• Call Set Up Time• Call Success Rate• Call Completion

Rate

H/W CostsSubscription/Airtime costsAdditional Services Costs

Network Equipment CostsMaintenance CostsSite Leasing CostsTransmission Link Costs

Overall Network Quality

Cell Planning Tools• Prediction• Simulation

Network Measurement Tools• Propagation • Drive test

Network Management System• Network configuration• BSS parameter data• Network performance

Tools for Optimisation

Performance Feedback

• Network is under permanent changeo ==> detect problems and symptoms early!

OMC

field tests

customer complaints

It´s far too late

when customerscomplain!

Optimize compared to what?

Key Performance Indicators, KPI

• KPIs are figures used to evaluate Network performance. o post processing of NMS data or o drive test measurements data

• Usually one short term target and one long term target. o check the network evolution and which targets are

achieved• KPIs calculated with NMS data

o network performance on the operator side. • KPIs from drive test

o performance on the subscribers side• Usually turn key projects are evaluated according to

some predefined KPIs figures like drop call rate

Network Performance Evaluation with NMS

• The most reliable KPIs to evaluate the network performance with NMS are:o SDCCH and TCH congestiono Blocking percentage [%]o Drop call rate [%]o Handover failure and/or success rateo Call setup success rate o Average quality DL and UL

• The targets are always defined by the customer but the following figures can be considered as satisfactory results:

Item limit Target Lowest acceptable Dropped calls: <2 % 4 % Handover success >98 % 96 % Good Qual samples (0..5) >98 % 95 %

Drive Test Measurements

• Evaluate network performance from the subscriber point of view• KPIs information:

o DL quality, call success rate, handover success rate, DL signal level

o not statistically as reliable as NMS information • Added value of drive test measurement :

o find out the geographical position of problems like bad DL quality to look for a possible interference source in the area

o compare the performance of different networks o display the signal level on the digital maps to individuate areas

with lack of coverage eventually improve the propagation model o verify the neighbour list parameter plan

Optimisation Process

• There are not strict processes for optimization because the activity is driven by the network evolution.

Optimisation Process: Young Network Case

• In a young network the primary target is normally the coverage. • In this phase usually there is a massive use of drive test

measurement o check the signal and o the performance of the competitors

GPS

NMSX

MMAC

Optimisation Process: Mature Network Case• In a mature network the primary targets are quality indicators

o drop call rate, average quality, handover failures. • Important use the information from NMS

o a general view of the network performance. • Drive test measurements are still used

o but not in a massive wayo in areas where new sites are on airo where interference and similar problems are pointed out by NMS

data analysis.

GSM RF Planning Concepts Ppt

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