1. C80216m-08_215 ProjectIEEE 802.16 Broadband Wireless Access Working Group http://ieee802.org/16 Title16m Downlink Dedicated Pilot Structure for TDM Control Structure Date Submitted 2008-03-10 Source(s)Young Hoon Kwon, Yunsong Yang Zhigang Rong, Yang Tang Jungwoon Lee, Anthony Soong Jianming Lu Huawei E-mail: zrong@huawei.com Re:IEEE 802.16m-08/005: Call for Contributions on Project 802.16m System Description Document (SDD). Target topic: “ Pilot Structures as relevant to downlink MIMO ”. AbstractThis contribution describes the design principles for the dedicated pilots that supports the enhanced TDM based control design in a mini-frame. PurposeFor discussion and approval by TGm Notice This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “ Source(s) ” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. 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. Patent Policy The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. C80216m-08_215 2 Objectives In contribution IEEE C802.16m-08/211, we described an enhanced TDM based control design in a mini-frame In contribution IEEE C802.16m-08/214, we described a common pilot structure supporting this enhanced TDM based control structure in a mini- frame In this contribution, we describe the design principles for the dedicated pilots that supports this enhanced TDM based control design in a mini-frame –More detailed design of dedicated pilot patterns is pending on the decision of resource block size

3. C80216m-08_215 3 Proposed Control and Data Multiplexing Scheme within a Data Mini-frame Control zone occupies x subcarriers in the first 2 OFDM symbols –To gain the benefits of TDM based control structure Data zone occupies the remaining usable subcarriers in the first 2 OFDM symbols –To enhance bandwidth and power efficiency by adding FDM –The Control zone size (x) is modulated on Common Pilots in the control zone 3rd to 6th OFDM symbols are used for data zone –Cleaner design for the data zone and pilot structures

4. C80216m-08_215 4 Principles for Designing Dedicated Pilots Most users use the common pilots in the TDM ’ ed control zone for data demodulation and decoding –Don ’ t penalize every users just because of some users ’ specific needs Use Dedicated Pilots in data zone on per resource block base and only when needed in order to support –high mobility, long delay spread, or low SNR –various OL-MIMO, CL-MIMO/BF, and SFN transmissions Dedicated pilots allocation can be per-antenna or per-stream Dedicated pilot patterns are pre-defined and indexed The presence of dedicated pilots can be indicated by the scheduling grant messages or determined by the MIMO/SFN mode negotiated –MS may assist BS in determining the need and pattern of dedicated pilots by providing feedback Dedicated Pilots do not occupy the first two OFDM Symbols so that the dedicated pilot pattern is independent on the Control zone size

5. C80216m-08_215 5 Example of Signaling Operation

6. C80216m-08_215 6 Dedicated Pilot on-Demand – Example for Users with High Mobility, Long Delay Spread, or Low SNR TDM ’ ed common pilots cover a wide range of speed, delay spread, and SNR Users may also use the common pilots of the next Mini-frame to further enhance channel estimation –Can be up to user capability BS provides per-antenna dedicated pilots only for those users that common pilots are inadequate –For example, Users 1 and 2 are experiencing high mobility. User 2 (but not User 1) is capable to use the common pilots in the next subframe for channel estimation (users ’ capabilities are known to the BS). User 3 is experiencing low mobility. Example

7. C80216m-08_215 7 Dedicated Pilot on-Demand – Example for SFN SFN zone may be used for MBS and full Paging messages –Same dedicated pilots are used by all SFN BSs for estimating the composite channel –SFN zone is reserved and known to all MSs since non-cell-specific hopping is used on SFN zone –SFN zone occupies OFDM symbols #2~#5 The BS takes those subcarriers in the first two OFDM symbols into account when grouping the leftover subcarriers into CRBs so that no bandwidth is wasted Example

8. C80216m-08_215 8 * Pilot pattern shown here is just for illustration Dedicated Pilot on-Demand – Example for MIMO Precoding Dedicated pilots on-demand for MIMO schemes –Dedicated pilot is not necessarily assigned in every resource block for MIMO –In case dedicated pilots are not used, additional data symbols can be transmitted which increases the spectral efficiency –For example, in some MIMO/Beanforming mode such that a user can identify the precoding vector, the user can estimate the beamformed channel by using common pilots with the precoding information. Thus, no dedicated pilot is required. The channel estimation is done based on common pilot & precoding information.

9. C80216m-08_215 9 Dedicated pilot pattern can be differently assigned based on users ’ specific situation –Several dedicated pilot patterns are predetermined based on Occupied resource block size Channel status: SNR, frequency/time selectivity Number of streams –Specific dedicated pilot pattern is indicated via scheduling grant Dedicated Pilot Optimization

10. C80216m-08_215 10 Conclusions Using adaptive allocation of dedicated pilots, the performance of channel estimation & spectral efficiency can be optimized –Dedicated pilots on demand Per-antenna dedicated pilot structure Per-stream dedicated pilot structure Optimized pilot frequency spacing based on the size of contiguous resource blocks assigned the user The size of the control zone does not affect the dedicated pilot patterns

11. C80216m-08_215 11 Text Proposal Insert the following text in Chapter 11 (Physical Layer): 11.Z Downlink Pilot Structures … 11.Z.2 Dedicated Pilots For TDM-based downlink control/data multiplexing scheme: The dedicated pilots are provided in data zone on per resource block base and only when they are needed. Some examples of such need can be high mobility, long delay spread, low SNR, various OL-MIMO or CL-MIMO/BF, and SFN transmissions. The dedicated pilots allocation can be per-antenna or per-stream. Several dedicated pilot patterns are pre-defined and indexed for optimized performance. The presence of dedicated pilots can be indicated by the scheduling grant messages or determined by the MIMO/SFN mode negotiated between the BS and MS. The MS may assist the BS to determine the need and pattern of dedicated pilots by providing feedback. The dedicated pilots do not occupy the first two OFDM Symbols so that the dedicated pilot pattern is independent on the Control zone size.