Signaling Overhead Reduction Technique for PMI Coordination Document Number: IEEE C80216m-09xx Date Submitted: 2009-07 Source: C80216m-09_1627 Shuangfeng Han, David Mazzarese, E-mail: shuangf.han@samsung.com, d.mazzarese@samsung.com    Sangwoo Lee, Heewon Kang, Hokyu Choi   Samsung Electronics Venue: IEEE Session #62 Re: AWD comment for multicell MIMO Base Contribution: C80216m-09_1625 Purpose: For TGm discussion and adoption of 802.16m AWD text. 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: <http://standards.ieee.org/guides/bylaws/sect6-7.html#6> and <http://standards.ieee.org/guides/opman/sect6.html#6.3>. Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and <http://standards.ieee.org/board/pat >.

Additional information feedback for conflict resolution in PMI coordination Conflicting PMI coordination requests Conflicting requests from MSs within one cell ABS makes decision to choose some requests based on additional feedback and exchange with corresponding adjacent ABSs Conflicts resolution purely based on ABS scheduling Conflicting requests from MSs in different cells Additional information needed to assist decision making Additional information feedback Normalized interference power: ratio of the average interference power from each dominant interfering cell to total received interference power. Frequent feedback not needed due to slow variation Similar SINR, request with higher NIP has higher priority, vice verse. Similar NIP, request with higher SINR has lower priority, vice verse. For overhead reduction, quantization of NIP can be above some threshold, e.g., ¼.

Overhead reduction for PMI subset feedback (1) Why we need PMI subset feedback? 1 PMI coordination (recommendation or restriction) PMI restriction brings smallest cell edge gain and smallest cell average degradation More restricted PMIs, more cell edge gain and more cell average degradation PMI recommendation brings largest cell edge gain and also largest cell average degradation More recommended PMIs, less cell edge gain and less cell average degradation PMI subset coordination is needed for tradeoff between cell edge and cell average performance, although optimal set size is not easy to obtain. How we feed back PMI subset? Subset determined by AMS based on channel conditions Subset represented by the worst or best PMI index + 1 additional bit to indicate 1 or 2 correlation levels How ABS knows PMI subset and downlink indicate? ABS can figure out which PMI subset is requested based on cross correlation between PMI ABS makes decision which PMI subset is used for DL tx and may use bitmap for DL indication

Overhead reduction for PMI subset feedback (2) Correlation levels (4 bit 16m base codebook)

Overhead reduction for PMI subset feedback (3) Relationship between channel power and correlation 1 receive antenna at AMS 2 receive antenna2 at AMS In correlated channels, this relationship is acceptable. Since we apply PMI coordination to rank 1 transmission only, this relationship can allow us to feedback PMI subset with reduced overhead.

Overhead reduction for PMI subset feedback (4) PMI subset representation: MIMO channel feedback header Example: how to determine n1 and n2? Table X3 - PMI_coordination_subset PMI_coordination_subset Value 0b0 n1 0b1 n2

Proposed Text See C80216m-09_1625

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