UL HARQ Feedback Channel Performance Comparisons of tile Format Options
Document Number: C80216m-09_0158
Date Submitted: 2009-01-05
Source:
Zhu dengkui,Jerry Chow
E-mail: Zhu.dengkui@zte.com.cn
*<http://standards.ieee.org/faqs/affiliationFAQ.html>
Venue: To Response “Call for Contributions on Project 802.16m System Description Document (SDD) – pertaining to comment on entire
content of IEEE 802.16m-08/003r6.”, “section 11.9.2.2 UL HARQ Feedback Channel”
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Background
• There exist several possible multiplexing unit format
in the HARQ feedback channel:
– 2x6, 6x2, and 1x2 format
– Different pilot patterns
• Considerations
– Detection error performance vs. channel conditions
– Frequency selective, time selective
– FDM legacy support
UL Tile Structure Alternatives
Time
Time
Time
data
Fre
Fre
pilot
2*6 without pilot
data
pilot
2*6 with pilot
Fre
6*2 with pilot
Time
Time
Frequemny
Fre
6*2 without pilot
user 1
user 3
user 5
user 2
user 4
user 6
3
Simulation Setup
Parameters
Value
FFT Size
1024
Bandwidth
10 MHz
Carrier frequency
2.5 GHz
Number of transmit antennas
1
Number of receiver antennas
2
Resource block
18subcarriers x 6 OFDM symbols
Receiver Type
Coherent/Non-Coherent
Channel Model
Ped B – 3 km/h
Veh A – 120 km/h, 350 km /h
The correlation of channel
Antenna Interval: 4 λ, AS:5degree at BS
SNR
E/N0 per subcarrier
4
Performance Results – Veh A (120 km/h)
10
6*2w/ pliot
6*2w/o pliot
2*6w/o pliot
2*6w/ pliot
1*2w/o pliot
-2
PER
10
HARQ feedback channel performance:eITU VA120km/h
-1
10
10
-3
-4
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
SNR(dB)
5
Performance Results – Veh A (350 km/h)
10
PER
10
10
10
10
HARQ feedback channel performance:eITU VA350km/h
0
6*2w/pliot
6*2w/o pliot
2*6w/o pliot
2*6w/ pliot
1*2w/opliot
-1
-2
-3
-4
-6
-5
-4
-3
-2
-1
SNR(dB)
0
1
2
3
4
6
Observations & Conclusions
•
•
•
•
•
•
6x2 structure is equal to or better than 2x6 over all MS speeds
6x2 structure performs significantly better at very high MS
speeds.
6x2 is not compatible with FDM with PUSC mode of UL legacy
support.
For the format 1*2,although channels not changes notablely in
the 2 symbols at high mobile speed, its deadly because of its
short sequence, so the 1*2 shows a certain performance
degrade than the 6*2 tile structure.
Need 2x6 only for FDM legacy support but 6x2 should
supported for other UL configurations due to significant
performance advantages
In order to capture the frequency diversity gain, DRU is used
in HARQ feedback channel, where each tile of DRU is consist
of three FMTs.
7
Proposal Text
11.9.2.2.2 PHY structure
We suggest to change the following current description
“The UL HARQ feedback channel is comprised of three distributed UL feedback minitiles (FMT), where the UL FMT is defined as 2 contiguous subcarriers by 6 OFDM
symbols. A UL FMT of 6 contiguous subcarriers by 2 OFDM symbols is FFS. One
LRU consists of 9 FMTs and can be shared by multiple HARQ feedback channels.”
to
“The UL HARQ feedback channel is comprised of three distributed UL feedback
mini-tiles (FMT). One UL FMT is defined as 6 contiguous subcarriers by 2
OFDM symbols in the 16m-only frame or the mixed frame with UL TDM. And one
UL FMT of 2 contiguous subcarriers by 6 OFDM symbols is used in the mixed
frame with UL FDM. One LRU consists of 3 tiles where each tile consists of 3
FMTs, and can be shared by multiple HARQ feedback channels.