1. 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 < >.

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

3. 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

4. ACK Channel Structure(2)
When the DLRU contains 2 tiles, 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

5. 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

6. 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.

7. 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)

8. 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:
(5)
(6)
(7)
(8)

9. Simulation parameter Parameter value Carrier Frequency 2.5GHz
Antenna configuration
1Tx,2Rx
Channel Model
ITU(PB,VA),TU
Mobile speed
3km/h,120km/h
UL symbol
18(one frame)
HARQ feedback transmission unit num
30(one frame)
6*2
Detect method
Semi-Coherent
Pilot boosting
2.5dB
ACK/NACK format
BPSK/QPSK

10. 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.

11. Proposal text 11.9.2.2UL HARQ Feedback Control Channel
Text proposed for IEEE C802.16m-08/003r4
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 resource allocation unit. The
structure DLRU is 6 continue OFDM in time by 18 sub-carriers in frequency.
The DLRU is composed of two non-adjacent tiles(tile1 and tile2). Tile2 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 two tiles from the same
DLRU.
Each tile in the HARQ feedback channel transmission unit is divided into two parts as in
figure4, one is for effective data transmission which contain all the subcarrier of the
1,3,4,6th symbols while the rest of tile is for pilots.

12. Proposal text (cont)
mapping between HARQ feedback channel and sequence
12 HARQ feedback channel is CDM multiplexed in each UL HARQ feedback region, that is to say,6 times spread in frequency domain and 2 times spread in time domain.
Each HARQ feedback channel corresponding one data spread sequence in frequency domain with the length of 6 and one data spread sequence in time domain with the length of 4.
Each HARQ feedback channel corresponding one pilot sequence in frequency domain with the length of 6 and one pilot sequence in time domain with the length of 4.
is chosen one of the 6 orthogonal sequence in , is chosen as one of the 2 orthogonal sequence in , is chosen as one of the 6 orthogonal sequence in , is chosen as one of the orthogonal sequence in

13. Proposed text (cont) Figure 4 Tile structure in DLRU
Figure 5 structure of a tile
Figure 6 data and pilot sequence mapping

14. Proposed Text (cont) 11.9.2.2.2.2 Data spread sequence
The generate of is TBD.
The choice of from is TBD.
The choice of from is TBD.
11.x pilot sequence
The choice of from is TBD.
The choice of from is TBD.

15. Proposed Text (cont)
data modulation and sequence mapping
The feedback message on th UL HARQ feedback channel of a HARQ
feedback region is modulated with BPSK/QPSK signals.
Then is spread in the frequency domain firstly as ,and the this sequence is
multiplied by before mapping into all subcarrier of the th symbol in
the data zone of a tile, so the data modulated in the th subcarrier of the th symbol in
the data zone is
The pilot frequency sequence is multiplied by before mapping into all the
subcarrier of the th symbol in the pilot zone of a tile, so the signal modulated
In the th subcarrier of the th symbol in the pilot zone is
end of proposed text
(11.x )
(11.x )