1. AWD Text Modification to Non-adaptive precoding in DL MIMO Document Number: IEEE C80216m-09_0896 Date Submitted: 2009-04-27 Source: Kiran Kuchi, J. Klutto Milleth, Vinod R, Dileep M K, Divagar, Padmanabhan M S, Bhaskar R, Giridhar KVoice: CEWiT, IndiaE-mail: kkuchi@cewit.org.in, klutto@cewit.org.in Venue: Call for Comments on IEEE 802.16m-09/0010r1a IEEE 802.16m Amendment text/Area: Chapter 15.3.7 (DL-MIMO) Base Contribution: None Purpose: To discuss and adopt the proposed text in amendment text To discuss in TGm for appropriate action. 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. Suggested modification to Non- adaptive precoding The mandatory non-adaptive precoder which is defined in DL MIMO section 15.3.7.1.2.1 uses N1 cycling and the precoder W is fixed in time. The purpose of this method is to keep the precoder fixed for the duration of the sub-band and enable best-M scheduling With multiple frequency partitions, the number of sub-bands available in each frequency partition is insufficient to implement N1-cycling+best-M scheduling. For example in 5 M Hz BW, with 4-partitions, the number of subbands/partition is only one.  N1 cycling has no meaning in such scenarios Proposed change: For single frequency partition case, use N1 cycling  The precoder W does not depend on the subframe number  The precoder W changes every N1 PRUs in the same subframe For multiple frequency partitions, use 1D and/or 2D-POD  The precoder W changes with the subframe number  The precoder W changes every N2 PRUs in the same subframe

3. 1D Vs 2D POD with N2 cycling For multiple frequency partitions, reduced amount of BW available in each partition More users can be served if users are simultaneously scheduled over two subframes “1D-POD in time” suitable diversity mode for low-medium bit-rate users who are allocated 1- PRU in frequency, and allocation extended over two or more subframes. “1D-POD in frequency” useful diversity mode when the user is given multiple PRUs in same subframe 2D-POD gives extra diversity gain when resource allocation spans both frequency and time 2D-POD subsumes “1D-POD in time” and “1D-POD in frequency” as special cases. 2D-POD can only provide a benefit  2D-POD facilitates robust CQI computation (by virtue of special property of the DFT code book)  2D-POD can be used in conjunction with best-band scheduling

4. Non-Adaptive precoder Text for DL MIMO With non-adaptive precoding, the precoding matrix is an NtX Mt matrix W(k), where Nt is the number of transmit antennas, Mt is the number of streams, and k is the physical index of the subcarrier where W(k) is applied. The matrix W(k) is selected from a subset of size Nw precoders of a base code book for a given Mt. The matrix W changes every N Psc contiguous physical subcarriers according to equation (10). W belongs to a subset of the base code book specified in section 15.3.7.2.6.6.2.4.1. When a single frequency partition is used, the precoder W does not depend on the subframe number. The value of N is equal N1. The NtX Mt precoding matrix W(k) applied on subcarrier k is selected as the code word of index i in the open-loop codebook subset with Mt streams where i is given by  i=mod([k/(NPsc)]-1, Nw) When the frequency band is split into multiple frequency partitions, in each partition, the value of N is set equal to N2, Psc=18. The precoder W changes with the subframe number. The W is computed as element- wise multiplication of two vectors/matrices as: W=Cs(i).Cs(j) where i=mod([k/(NPsc)]-1, Nw) and j=mod(q,Nw) where q is the subframe number, and Cs is open-loop subset code book of size Nw=4..

5. OL code book subsets for Nw=4 The base 2-Tx OL code book uses the following entries from the C(2,1,3) code book. The subsets for Nw=4 are given by the entries of C(2,1,3,m) where the index m takes the following values m=0,4,6,2 in the specified order. The subset code book Cs is represented in Tabular form as 4-Tx OL code book subset for Nw=4 uses the following entries from the C(4,1,6) code book. The subset a for Nw=4 are given by the entries of C(4,1,6,m) where the index m takes the following values m=6,0,1, 2 in the specified order. The subset code book Cs is represented in Tabular form as index0123 0.7071 -0.7071 j0.7071 -j0.7071 index0123 0.5 -0.5 0.5 -0.5 0.5 -0.50.5-0.5