1. Cooperative Relaying with Spatial Diversity and Multiplexing IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE S802.16m-07/164 Date Submitted:2007-09-17 Source: Wei Ni, Gang Shen, Shan JinVoice:+ 86 21 50554550-8039 Alcatel-Lucent Research and Innovation ShanghaiE-mail:{wei.a.ni, gang.a.shen, shan.jin}@alcatel-sbell.com.cnwei.a.ni, gang.a.shen, shan.jin}@alcatel-sbell.com.cn F. Boccardi, K. Yu, A. AlexiouVoice:+ 44 1793 776620 Bell Laboratories, Alcatel-Lucent E-mail:{fb, kaiyu, alexiou}@alcatel-lucent.comfb, kaiyu, alexiou}@ Venue: Call for Comments on SRD r3 - 80216m-07_002r3 Base Contribution: IEEE 802.16 Session #51, Malaga, Spain Base Contribution: IEEE C802.16m-07/164 Purpose: To drive standardization and introduction of cooperative relaying. 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. Cooperative Relaying with Spatial Diversity and Multiplexing Benefits of cooperative relaying –Significant improvement is provided owing to distributed MIMO (D-MIMO) processing –Higher throughput owing to spatial multiplexing Relaying radio resources can be saved –Better performance due to spatial diversity Uncorrelated propagation channels –Simplifying intra-cell mobility Application scenarios –Two or more hops Methods of cooperative relaying –Adaptive distributed pre-coding (ADP) –Data splitting algorithm (DSA) Base Station (BS) Relay Station (RS) Mobile Station (MS) Fig. 1: The definition of cooperative relaying

3. Adaptive Distributed Pre-coding (ADP) ADP constitutes of two work modes –Spatial diversity (SD) mode Centralized or distributed pre-coding is performed at multiple collaborative RSs Diversity or interference mitigation is expectable Joint design with space-time code (STC/SFC) provides higher diversity gain and array gain –Regular STC or Distributed STC (DSTC) is adaptively selected with pre-coding criteria and limited channel feedback –Sufficient channel feedback improves performance via pre-coding –Spatial multiplexing (SM) mode Collaborative RSs form a virtual BS with multiple antennas and a broadcast channel (BC) is between the virtual BS to multiple destinations Pre-coding methods can be implemented for multi- user diversity easily due to the medium to large number of virtual array elements Multi-user interference is mitigated via centralized or distributed pre-coding with channel feedback RS 2 Virtual BS BS RS 1 MS 1 MS 2 Fig 3: A 2-hop downlink example of SM-ADP Multi-user MIMO RS 2 Virtual BS BS RS 1 MS 1 Fig 2: A 2-hop downlink example of SD-ADP w 1,1 w 1,2 w 2,1 w 2,2

4. Data Splitting Algorithm (DSA) Basic idea of DSA –DSA is to send multiple independent spatial data streams via direct link between source- destination and/or different RSs, and to collect them at the destination –Spatial multiplexing gain is available to increase the data rate of a single terminal Two multi-user MIMO channels in DSA –Broadcast channel (BC) The point-to-multi-point (PTMP) hop constructs a BC channel Different data streams are transmitted to collaborative RSs independently by pre-coding techniques of multi-user MIMO, e.g., MET Interference between data streams is mitigated –Multiple access channel (MAC) It is a typical multi-point-to-point (MPTP) architecture like virtual or collaborative MIMO Distributed pre-coding of RSs can be optional for interference avoidance RS BS MS RS Broadcast channel (BC) Multiple Access Channel (MAC) Fig. 4: A 2-hop example of DSA

5. Summary Two schemes of cooperative relaying are proposed for different D-MIMO modes –ADP has two work modes SD-ADP is for spatial diversity and array gain, and works even with limited channel feedback SM-ADP is for multi-user spatial multiplexing and the throughput of the whole system is improved (due to SDMA) –DSA is for spatial multiplexing and the data rate of single terminal is improved significantly Cooperative relaying switched between the three D- MIMO modes provides either good signal qualities and robustness or data rate improvement