Proposal for 802.16m E-MBS

Document Number: IEEE C802.16m-08/1056r2 Date Submitted: 2008-09-12

Source: Wei Xie, Delin Chen, Zhiping Xia, Chinese Academy of Broadcasting Sciences, Hongbing Shen, Tao tao, Qihong Ge, Timi TechnologyHuaning Niu, Yujian Zhang, Changlong Xu, Jeong julie Lee, Kamran Etemad, Hujun Yin, Intel Corp.

Email: xiewei@abs.ac.cn Venue:

IEEE Session #57, Kobe.Base Contributions:

NoneRe: Call for Contributions on Project 802.16m System Description Document (SDD): MAC aspects of enhanced MBSPurpose: Discussion and ApprovalNotice:

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Release:The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that

this contribution may be made public by IEEE 802.16.

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Content

• Design Requirements and Goals• Deployment Cases

– Mixed Carrier Only– Dedicated Carriers Only – Mixed and Dedicated carriers

• Frame and Control Channel Structure – Mixed carrier– Dedicated carrier– Mixed and Dedicated carrier

• Symbol structure– OFDM numerology– Resource allocation and pilot

• Additional features

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Requirements from SRD• Support E-MBS delivery via a dedicated carrier or mixed carrier.

– Shall support switching between broadcast and unicast services, including the case when broadcast and unicast services are deployed on different frequencies.

• Short channel interruption time:– Maximum channel reselection interruption time:

• Intra-frequency reselection mode: 1.0 s• Inter-frequency reselection mode: 1.5 s

• Large cell coverage: – May support large cells (e.g. 50 km).

• High spectrum efficiency– Minimum performance requirements for E-MBS, expressed in terms of

spectral efficiency (bps/Hz) over 95% coverage area (assuming MBSFN), is• 4 for 0.5 km inter-site distance• 2 for 1.5 km inter-site distance

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Design Requirements • Most clarifications and optimization concepts adopted in REV2 should be supported in 16m zone using the

new frame and control channel structure • Both Static and Dynamic Multicasting shall be supported• Single BS MBS as a special class of Multi-BS MBS

– Design is optimized for multi-BS MBS– Design should be optimized for SFN while allowing other reuse factors.

• Maximize power saving at MS– MBS Service to MS without leaving idle/sleep mode– Selective decoding/discard to save application processing of multichannel transmissions

• Optimized for mixed carriers– Consistent with unicast design. – Support dynamic MBS/Unicast mixed traffic allocation in mixed carrier

• Support for Dedicated carrier – Coexistent with unicast carrier- large guard band is needed to protect cellular system from the huge transmit power of

TV band – Signaling support for initial subscription and security association through a mixed carrier or through application layer

out of band signaling that is out of scope.• Feedback Channel

– Reliable ACK for Service confirmation• For some Services which require guaranteed delivery

– Support statistical channel feedback in UL to allow link adaptation and retransmission• MIMO support

– Minimum 2 Tx antenna for mixed carrier– Support hierarchical encoding

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Different Deployment Models

Unicast/Mixed Carrier(Primary)

RFC1

Unicast/Mixed Carrier(Primary)

RFC2

Unicast/Mixed Carrier(Primary)

RFC1

Unicast/Mixed Carrier(Primary)

RFC1

Multi-BS MBS SFN

Multi-BS MBS Non-SFN

Unicast/Mixed Carrier(Primary)

RFC1

Unicast/Mixed Carrier(Primary)

RFC1

Single BS MBS

Unicast/Mixed Carrier

(Primary) RFC1

Broadcast Optimized

Carrier RFC3Unicast/Mixed

Carrier(Primary)

RFC2

Unicast/Mixed Carrier

(Primary) RFC1

Mixed Carrier Combined with

Dedicated Broadcast Only Carriers

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Frame Structure - Mixed Unicast/MBS Carrier

• TDM MBS and Unicast traffic on sub-frame basis.

• SBCH indicate the position of MBS-zone which may span over multiple subframes

• MBS sub-frames are allocated with fixed pattern within super-frame

SB

CH

SC

H

Superframe

frame frame

subframe E-MBS subframe

E-MBS subframe

……

……

E-MBS Zone

MCCH MCCH: E-MBS Control Channel

……

MC

CH

Unicast

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Frame Structure – MBS-Dedicated Carrier

• SBCH indicate the essential information about the dedicated carrier such as frequency band, FFT size etc

• Interactive Signaling between MS and the network is carried outside this dedicated carrier. – Such L2 and Upper layer signaling to support MBS service may be exchanged using a unicast/mixed

carrier as a primary carrier. See Figure:

• Preamble on dedicated carrier is generated by repeating the 5M 16m preamble with different phase rotation to minimize the PAPR

SB

CH

SC

H

Superframe

frame frame

subframeE-MBS

Subframe Zone

……

……

MCCH MCCH: E-MBS Control Channel 1

……

MBS Transmission period T

SC

HM

CC

H

Unicast/Mixed Carrier(Primary)

Dedicated Broadcast Only Carrier

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Mixed/Unicast Carrier supporting Dedicated MBS Carrier

• An MBS deployment in which dedicated MBS carriers are combined with unicast/MBS mixed carriers.

• The Mixed carrier :– Carries Information about any MBS zones embedded in the same carrier

– It may also provide minimum radio configuration of dedicated MBS carrier to help with unicast/MBS mixed operation.

– It may also support interactive signaling between MS and the network to support subcription, authentication, session join and leave etc.

– Note: Out of band signaling for MBS subscription, registration/updates which require DL/UL exchanges may also be used when dedicated MBS only carriers are deployed. This is outside the scope of 802.16m specifications.

– The mixed carrier serves as primary carrier to the user whereas broad only carrier serves as secondary carrier, consistent with multicarrier definitions in SDD.

Unicast/Mixed Carrier

(Primary) RFC1

Broadcast Optimized

Carrier RFC3Unicast/Mixed

Carrier(Primary)

RFC2

Unicast/Mixed Carrier

(Primary) RFC1

Mixed Carrier Combined with Dedicated Broadcast Only

Carriers

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MBS Control Channel• PBCH:

– Indicates if a carrier is broadcast only or can not be used for MS’s entry to the network. This help with faster scanning and selection of mixed unicast/MBS carriers.

– Alternatively certain preamble indexes can be reserved for broadcast only carriers which can not used a primary carriers for access.

• SBCH– Points to the beginning of MBS zone and its PHY parameters in the current superframe– Helps with MS synchronization with MBS transmission cycle.

• MCCH (MBS Control Channel)– Indicates physical layer parameters of MBS data channels for each service using joint coding.– MCCH is transmitted at the beginning of MBS resource during one MBS transmission period.– MCCH can point to burst locations in up to N super-frames later within the transmission period

• Design advantages:– Minimize SBCH overhead.– Can exploit coding gain for MCCH since all controls are coded together.– No link adaptation issue since MCCH need cell-wide coverage.

Data

SBCH MCCH Data Burst 2 Data

Burst 1 Data Burst n

Burst 3

Period T

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Private Map for Power Saving

• In addition to MCCH transmission at the beginning of each every cycle a Private MAP mechanism is used to indicate the physical layer parameters and transmission time of the same service at next period.

• Using the Private MAP the MS can skip reading MCCH to save more power.

Private MAP Private MAP Private MAP Private MAP

MCCH Data Data MCCH Data Data

Burst 1 Burst n Burst 1 Burst n

Period n Period n+1

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OFDM Numerology

• OFDM numerology is the same as unicast service in mixed carrier

• Support of larger FFT size for MBSFN in dedicated carrier with long range– Much longer delay spread in MBSFN with 50km range

– Fixed CP length to assign subframe boundary

– For 10M bandwidth, support• 2K FFT – 3 OFDM symbols per subframe

• 4K FFT – 3 OFDM symbols every two subframes

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Resource Allocation

• Use 16m DL distributed allocation across subframe– One LRU is 18x6, which consists of subcarriers distributed

across whole band

– Same pilot overhead as DL. Common pilot for all MBS users

– Same permutation sequence as mapping subcarriers to LRU

– Support of interlaced pilot pattern for Single-BS MBS

• Subchannel allocation per MBS service is across multiple sub-frames within one MBS transmission period T for time diversity

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Pilot StructurePilot stream 1

Pilot stream 2

1

2

1

2

1

2

1

2

1

2

1

2

Pilot pattern for Multi-BS MBS network

1

2

1

2

1

2

1

2

1

2

1

2

1 3

2 4

5

6

1 3

2 4

5

6

13

24

5

6

1 3

2 4

5

6

1 3

2 4

5

6

1 3

2 4

5

6

1 3

2 4

5

6

1 3

2 4

5

6

13

24

5

6

1 3

2 4

5

6

1 3

2 4

5

6

1 3

2 4

5

6

(b) (c)(a)

Interlace pilot pattern for single-BS MBS network

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MBS Feedback

• Statistical NACK feedback– Statistical NACK feedback to support link adaptation and HARQ

• Improved performance in single-BS MBS • NACK-only feedback based on feedback transmission probability to reduce

feedback overhead

– Multiple short-bit contention slots are allocated for MBS UL feedback per MBS service

• Less overhead by allowing multiple feedbacks to be received over the contention channel assuring reliable and finer granule feedback counting

– BS estimates total number of NACK feedback by detecting code words received.

• Interested in only how many, not who sent what

• Delivery ACK– This ACK can be a higher layer ACK and may not need a PHY channel

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MBS Feedback Gain (Single-BS Access):Throughput vs. Coverage

Throughput increase with HARQ for 95% coverage

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MIMO Schemes

• 2 spatial streams multiplexing is supported– Higher throughout with small cell range

– SCW MIMO scheme

• Support hierarchical encoding though superposition coding– High priority traffic is transmitted with higher power

– Low priority traffic is transmitted with lower power

– Good users use IC scheme to get both high/low priority stream

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Large Code Size Support

• Large coding block is beneficial MBS – Particular useful in Multi-BS SFN without retransmission

– Additional coding gain and better time diversity

– Widely adopted in current broadcasting standard: DVB - T2, MediaFlo, CMMB

– block size up to 9126 bits

– Support LDPC optimized for large coding block size

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Review of text proposal

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Text Recommendations forSDD Section 15 (1)

15.x: EMBS frame structure for mixed carrier • Insert the figure “frame structure - mixed carrier”

here• For mixed carrier case, MBS and unicast traffic are

TDM multiplexed on subframe base. • SBCH indicates the positions of MBS-zone which

may span multiple subframes. SBCH may also indicate the physical layer parameters of MCCH.

• MBS subframes are allocated with fixed pattern across frame/super-frame.

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Text Recommendations forSDD Section 15 (2)

15.x: EMBS frame structure for dedicated carrier • Insert the figure “frame structure - dedicated

carrier” here• SBCH on a mixed carrier indicate the essential

information about the dedicated carrier such as frequency band, FFT size etc.

• Interactive Signaling between MS and the network is carried outside this dedicated carrier.

• Preamble on dedicated carrier can provide information on whether this is DL carrier only

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Text Recommendations forSDD Section 15 (3)

15.x: EMBS control channel

• Insert the figure “MBS – Control channel” here

• MBS Control Channel (MCCH) is a logical channel carrying following E-MBS related control information

• MCCH is transmitted at the beginning of MBS zone at each MBS transmission period. MCCH indicates MBS related control information such as the physical layer transmission parameters of each service. All MBS control information is jointly coded.

• To maximize power saving, data part can indicate the physical layer parameters of the same service at next period.

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Text Recommendations forSDD Section 15 (4)

15.x: EMBS subchannelization

• EMBS use the same DL unicast distributed subchannelization.

• 2K and 4K FFT is supported in dedicated carrier MBS zone

15.x: EMBS pilot pattern

• Insert the figure “pilot structure” here

• Common pilot across frequency band is used in MBS zone.

• Optional interlaced pilot patterns for single-BS MBS.

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Text Recommendations forSDD Section 15 (5)

15.x: MIMO scheme in EMBS • SCW open loop MIMO scheme is supported in MBS• Superposition coding of different data streams are supported

for hierarchical transmission15.x: Feedback channel• Statistical NACK feedback is supported in EMBS for HARQ

retransmission and link adaptation• Higher layer ACK is transmitted for service delivery

confirmation15.x: Large coding block • Support large coding block size up to 9126 bits• Optional LDPC optimized for large block size is supported

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Back Up

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MBS Feedback Code Detection Performance Fading Channel, Adjacent tone permutation

Detects 90 % when 25 contenders 80% when 50 contenders

88%

78%

3dB Power Control Error 6dB Power Control Error

Ease False Detection Probability to operate in a reasonable detection range

90%

80%

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MBSFN Support of Feedback:UL synchronization

• Unicast/MBS Mixed Scenario– MBS can benefit from the unicast ranging (initial

and periodic).

• Dedicated MBS Scenario

– No feedback is supported in dedicated MBS

– All the required feedbacks go through the unicast/mixed carrier.