Uplink HARQ Feedback Channel Design for IEEE802.16m Document Number: IEEE C802.16m-08/968 Date Submitted: Source: Dengkui Zhu Yanfeng Guan Ying Liu zhaohua Lu Xiangyu Liu ZTE Corporation Venue PHY: Text; in response to the TGm Call for Contributions and Comments m-08/033 for Session 57 Base Contribution Purpose To be discussed and adopted by TGm for use in the IEEE m SDD Notice This document does not represent the agreed views of the IEEE 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 Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: 7.html#6 and. Further information is located at and.

Overview ACK Channel resource structure ACK channel design Simulation results Proposal Text

ACK Channel Structure(1) The SDD Text of IEEE C80216m-08/003r4 has described ACK Channel is FDM with data and other control channel. We suggest the basic resource unit in UL HARQ feedback channel should be consistent with data and other control channel for the convenient of resource permutation and mapping,so the structure of 18*6(Freq*Time) of LRU is also for the ACK channel. In the ACK channel, Distributed LRU(DLRU) should be employed for the reason that frequency diversity gain would be captured. As in figure 1,all the UL HARQ feedback channel in one UL subframe make up of UL HARQ feedback region in which DLRU is the resource unit. Figure1 UL HARQ feedback region

ACK Channel Structure(2) the structure of tile is 6 by 6 as in figure2. Tile 2 &3 is the repeat of tile1 in order to capture the freq diversity gain. Figure2: the structure of DLRU in HARQ feedback region

ACK Channel Design(1) Each tile of a DLRU is composed of a data zone which contain all the subcarrier of symbol 1,3,4,6,and a pilot zone which contain all the subcarrier of symbol 2,4 as in figure. CDM is used to multiplexing ACK channels in each DLRU, where is the freq spreading nums and is the time spreading nums. Each ACK channel transmits one ACK/NAK message. Each ACK channel corresponds to a freq domain spreading sequence and a time domain spreading sequence Figure3 Tile structure in HARQ feedback resource unit

ACK Channel Design(2) Each ACK channel corresponds a freq domain pilot sequence and a time domain pilots spreading sequence. is chosen from orthogonal sequence set, and is chose from orthogonal sequence set, is chosen from orthogonal sequence set, and is chosen from orthogonal sequence set. Each feedback message is modulated with BPSK/QPSK signal. when BPSK is used, each HARQ feedback channel transmits one ACK/NAK messages. when QPSK is used, each HARQ feedback channel transmits two ACK/NAK messages as MCW is used in MIMO.

ACK Channel Design(3) -data spread sequence select() The sequence in is chosen from the column of DFT matrix or ZC sequence. E.g. is chosen from as follows: is generate as follows: is chosen from as follows (1) (2) (3) (4)

ACK Channel Design(4) -pilot sequence select is chosen from the ZC sequence, and they must satisfy the condition that any one of the sequence of is circular of the other one. E.g. is chosen from as follows: is generate as follows: is chosen from as follows: (5) (6) (7) (8)

Simulation parameter Parameter value Carrier Frequency2.5GHz Antenna configuration1Tx,2Rx Channel ModelITU(PB,VA),TU Mobile speed3km/h,120km/h UL symbol18(one frame) HARQ feedback transmission unit num 30(one frame) 6*2 Detect methodSemi-Coherent Pilot boosting2.5dB ACK/NACK formatBPSK/QPSK

Simulation results From the simulation results, the SNR for per =1% is about -10dB for ITU PB3km/h channel, and about -7dB for ITU PB120km/h.

Proposal text Text proposed for IEEE C802.16m-08/003r start of proposed SDD text UL HARQ Feedback Control Channel PHY Structure All the UL HARQ feedback channel In the UL subframe make up of a HARQ feedback region in which, Distributed LRU (DLRU) is the basic HARQ feedback channel resource allocation unit. the DLRU is composed of three non-adjacent tiles(tile1 and tile2 and tile3). Tile2 and tile3 is the repeat of tile1 so as to capture frequency diversity gain. The structure of the tile is 6 continue OFDM symbol by 6 adjacent subcarrier in frequency. A HARQ feedback channel transmission unit is compose of three tiles. Each tile in the HARQ feedback channel transmission unit is divided into two parts as figure4, one is for effective data transmission which contain the 1,3,4,6th symbols while the rest of tile is for pilots. 12 HARQ feedback channel is CDM multiplexed in each UL HARQ feedback resource unit, 6times spread in frequency domain and 2 times spread in time domain. Each HARQ feedback channel corresponding one data spread sequence in frequency domain and one data spread sequence in time domain. Each HARQ feedback channel corresponding one pilot sequence in freq and one pilot sequence in time

Proposed Text (cont) data modulation and sequence mapping The feedback message UL HARQ feedback channel is modulated with BPSK/QPSK signals. The feedback message is spread in freq and time using relative spreading sequences and then mapping to the data zone of tile, the pilots sequence in freq is spead in time and then mapping to The pilot zone of tile end of proposed text

Proposed text (cont) Figure 4 Tile structure in DLRU Figure 5 structure of a tile