1. Bit selection method for IEEE 802.16m Document Number: IEEE C802.16m-09/0674 Date Submitted: 2009-03-09 Source: Seunghyun Kang, Sukwoo Lee Email: {sh_kang, sugoo} @lge.com LG Electronics RE: IEEE 802.16m-09/0012, “Call for Contributions on Project 802.16m Amendment Working Document (AWD) Content”. Target topic: “Channel Coding” Venue: IEEE Session #60, Vancouver, BC, Canada Purpose: To be discussed and adopted in the Amendment Working Document 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 located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. Legacy Bit selection method [1] Let the scrambled and selected bits be numbered from zero with the 0-th bit being the first bit in the sequence. Then, the index of the j-th bit for the k-th subpacket shall be: S k,j = ( F k +j ) mod 3N EP where j = 0 … L k -1 L k : The sub packet size for the k-th transmission F k : Starting points depending SPID k The starting points depending on SPID k and L k are:

3. IR HARQ with legacy bit selection method IR HARQ process Adaptive HARQ For the initial transmission (or 0-th transmission), the SPID 0 shall be 0 and F 0 = 0 in order to transmit the sub-packet of L 0 bits which includes the whole systematic bits. For the re-transmission, a starting point F k shall be decided to transmit a sub-packet of L k bits which does not include the transmitted bits in the previous transmissions as much as possible to maximize IR HARQ gain. Non-adaptive HARQ For the non-adaptive HARQ, the sub-packet size will not be changed IR HARQ gain can be perfectly obtained. Worst case scenario For the 0-th transmission, let’s assume that the sub-packet of L 0 bits is transmitted with SPID 0 =0. For the 1-st transmission, if the sub-packet size L 1 is less than a quarter of L 0, a sub-packet of L 1 bits with any SPID 1 will be only a part of the sub-packet of 0-th transmission  No more IR HARQ gain.

4. Baseline starting points [2] Almost equally spaced starting points DG baseline starting points in the circular buffer

5. Baseline starting points Worst case scenario If the flowing conditions are satisfied, there always exists overlap between two subpackets of 0-th and 1-st transmission. The overlap causes less IR HARQ gain and results in performance degradation [3].

6. Proposed starting points The proposed starting points The proposed starting points in the circular buffer

7. Proposed starting points IR HARQ with the proposed starting points Adaptive HARQ For the 0-th transmission, the SPID 0 shall be 0 in order to transmit the whole systematic bits first. For the 1-st transmission, IR HARQ gain is fully obtained by using SPID 1 =1 since the starting point of SPID 0 = 0 indicates the fist bit index of the circular buffer and last bit index of SPID 1 =1 is the last bit index of the circular buffer (3N EP -1) regardless of the sub-packet size L 1. Non-adaptive HARQ by using the proposed starting points, IR HARQ gain can be perfectly obtained since the starting points are equally spaced with the sub-packet size over the circular buffer.

8. Conclusion Advantages of the proposed starting points For the 1-st transmission, IR HARQ gain is fully obtained regardless of the sub-packet size. For the case of non-adaptive HARQ, the proposed starting points obtain IR HARQ gain perfectly as well as the legacy starting points. In this regard, we propose the new starting points for IEEE 802.16m bit selection method.

9. Reference [1] IEEE P802.16 Rev2/D8, “Draft IEEE Standard for Local and Metropolitan Area Networks: Air Interface for Broadband Wireless Access,” Dec. 2008. [2] IEEE C802.16m 09/0510, “Proposed Text of Channel Coding and HARQ for the IEEE 802.16m Amendment” Mar.2009 [3] IEEE C802.16m 09/0494, “Bit Selection for 16m Downlink Transmission and Simulation Result” Mar.2009

10. Proposed Text ---------------------------------------------------- Text Start ----------------------------------------------- 15.x.2.HARQ 15.x.2.1.IR HARQ HARQ IR is used in 802.16m, by changing the starting position, P i,k, of the bit selection for HARQ retransmissions. For downlink, it is determined as a function of SPID and the subpacket size N CTC,k for the following equation. For uplink, it is determined as a function of SPID for the following equation. ----------------------------------------------------- Text End ------------------------------------------------