Proposal for 802.16m E-MBS
Document Number: IEEE C802.16m-08/1056r1
Date Submitted: 2008-09-11
Source:
Wei Xie, Delin Chen, Zhiping Xia, Chinese Academy of Broadcasting Sciences,
Hongbing Shen, Tao tao, Qihong Ge, Timi Technology
Huaning 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:
None
Re:
Call for Contributions on Project 802.16m System Description Document (SDD): MAC aspects of enhanced MBS
Purpose:
Discussion and Approval
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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
2
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
3
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
–
–
•
Maximize power saving at MS
–
–
•
Consistent with unicast design.
Support dynamic MBS/Unicast mixed traffic allocation in mixed carrier
Support for Dedicated carrier
–
–
•
MBS Service to MS without leaving idle/sleep mode
Selective decoding/discard to save application processing of multichannel transmissions
Optimized for mixed carriers
–
–
•
Design is optimized for multi-BS MBS
Design should be optimized for SFN while allowing other reuse factors.
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
4
Different Deployment Models
Broadcast
Optimized
Carrier RFC3
Mixed Carrier
Combined with
Dedicated Broadcast
Only Carriers
Unicast/Mixed
Carrier
(Primary)
RFC1
Unicast/Mixed
Carrier
(Primary)
RFC2
Unicast/Mixed Carrier
(Primary)
RFC1
Unicast/Mixed Carrier
(Primary)
RFC1
Multi-BS MBS SFN
Unicast/Mixed
Carrier
(Primary)
RFC1
Unicast/Mixed Carrier
(Primary)
RFC1
Unicast/Mixed Carrier
(Primary)
RFC2
Multi-BS MBS
Non-SFN
Single BS MBS
Unicast/Mixed Carrier
(Primary)
RFC1
Unicast/Mixed Carrier
(Primary)
RFC1
5
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 superframe
E-MBS Zone
MCCH
MCCH: E-MBS Control Channel
Superframe
SCH
SBCH
……
frame
……
frame
M CCH
……
Unicast
subframe
E-MBS
subframe
E-MBS
subframe
6
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
MCCH
MCCH: E-MBS Control Channel
1
Superframe
SCH
SBCH
Unicast/Mixed Carrier
(Primary)
……
frame
frame
MCCH
SCH
subframe
……
……
E-MBS
Subframe
Zone
Dedicated Broadcast Only Carrier
MBS Transmission period T
7
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.
Broadcast
Optimized
Carrier RFC3
Unicast/Mixed
Carrier
(Primary)
RFC1
Unicast/Mixed
Carrier
(Primary)
RFC2
Mixed Carrier Combined with
Dedicated Broadcast Only
Carriers
Unicast/Mixed
Carrier
(Primary)
RFC1
8
MBS Control Channel
•
PBCH:
–
–
•
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 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.
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 cycle.
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
9
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.
MCCH
Private MAP
Private MAP
Data
Data
Burst 1
Burst n
Period n
MCCH
Private MAP
Private MAP
Data
Data
Burst 1
Burst n
Period n+1
10
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
11
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
12
Pilot Structure
Pilot stream1
Pilot stream2
1
1
1
2
2
1
2
2
1
1
2
1
1
2
2
2
1
1
2
1
1
2
2
1
2
(a)
3
5
1
3
5
1
3
5
1
3
5
4
6
2
4
6
2
4
6
2
4
6
2
5
1
3
5
1
3
5
1
3
5
1
3
2
4
6
2
4
6
2
4
6
2
4
6
3
5
1
3
5
1
3
5
1
3
5
1
2
4
6
2
4
6
2
4
6
2
4
(b)
6
(c)
Interlace pilot pattern for single-BS MBS network
Pilot pattern for Multi-BS MBS network
13
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
– BS estimates total number of NACK feedback by detecting
code words received.
• Delivery ACK
– This ACK can be a higher layer ACK and may not need a
PHY channel
14
MBS Feedback Gain (Single-BS Access):
Throughput vs. Coverage
Throughput increase with HARQ for 95% coverage
15
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
16
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
17
Review of text proposal
18
Text Recommendations for
SDD Section 11 (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.
19
Text Recommendations for
SDD Section 11 (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
20
Text Recommendations for
SDD Section 11 (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.
21
Text Recommendations for
SDD Section 11 (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.
22
Text Recommendations for
SDD Section 11 (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 transmission
15.x: Feedback channel
• Statistical NACK feedback is supported in EMBS for HARQ
retransmission and link adaptation
• Higher layer ACK is transmitted for service delivery
confirmation
15.x: Large coding block
• Support large coding block size up to 9126 bits
• Optional LDPC optimized for large block size is supported
23