1. Collaborative uplink MIMO techniques for IEEE 802.16m Document Number: C80216m-08/638 Date Submitted: 7/7/2008 Source: Mohamed Abdallah Mohammed Nafie Cairo University, Cairo, Egypt Venue: Call for contributions on project 802.16m SDD Session #56: Denver, USA Base Contribution: C80216m-08/638 Purpose: For discussion and approval by IEEE 802.16m group. 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. Collaborative MIMO Mobile stations (MS) can transmit at the same time in the same frequency –Improve system throughput by employing collaborate spatial multiplexing (CSM) Rate 2 by using 2 BS ant. x 1 MS ant. configuration. (adopted by IEEE 802.16e) Rate 4 by using 4 BS ant. x 2 MS ant. configuration. –Interference mitigation can be provided at the BS by Proper selection of the MSs based on channel conditions. Applying Precoding techniques at the MS.

3. Open Loop CSM 2 (M.S) x 4 (BS) OL collaborative spatial multiplexing (CSM) can achieve system throughput of rate 4 Matrix A used at each MS At the BS, the 4 streams can be separated given that the two MSs are chosen properly.

4. Closed Loop CSM Precoding techniques can be applied at the MS for the CSM. –Improve the performance of the CSM. At each MS, a precoding 2x2 matrix V is chosen from a codebook such that and are the 4x2 channel matrices between BS and MS1 and MS2, respectively. Due to the limited power constraint at the MS –The precoding matrix V should limit the power transmitted per antenna. –The joint selection of the matrix V and the corresponding MS are performed at the BS and fedback to the MSs.

5. Proposed SDD Text 11.x.x. MU MIMO –For open loop CSM mode, two MS with 2 transmit antenna can cooperate together by sending their data using matrix A to a 4 receive antennas at the BS. –For closed loop CSM mode, precoding is applied at each MS where the 2x2 matrix V is properly selected to separate the 2 streams of each MS efficiently at the 4 ant. BS.