Performance evaluation of CoRe with consideration of CTC Bit Grouping
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-09/0743
Date Submitted:
2009-03-10
Source:
Hyungho Park, Sukwoo Lee
LG Electronics, Inc.
LG R&D Complex, 533 Hogye-1dong,
Dongan-gu, Anyang, 431-749, Korea
*< http://standards.ieee.org/faqs/affiliationFAQ.html
>
Voice: +82-31-450-1934
E-mail: hyunghopark@lge.com
, sugoo@lge.com
Re: IEEE 802.16m-09/0012, “Call for Comments on Amendment Working Document”
Target topic: “Channel Coding & HARQ” Section
Purpose:
To provide details on performance evaluation of constellation rearrangement with bit grouping
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– In 64 QAM and N
EP with multiple of 6, the interleaved bits is fed to QAM mapper as the bits are always mapped into the same bit reliability within a
QAM symbol
• This results in performance degradation in CTC trellis decoding.
– How many block sizes are relevant to such performance degradation
• Performance degradation depending on FEC block size, modulation order, code rate, and fading channel
– Relationship between Constellation Rearrangement and CTC Bit Grouping
• Performance evaluation in IR-HARQ is required with consideration of CoRe and Bit
Grouping

• How many block sizes can have performance improvement by BG (Bit Grouping)
– Only 34.8% of the total number of block sizes obtain Bit Grouping gain under 64 QAM and code rate < ½ (N
EP with multiple of 6)
– 65.2 % of the total are well bit-grouped with distribution of bit reliabilities
(N
EP with non-multiple of 6)
20
21
22
23
16
17
18
19
12
13
14
15
8
9
10
11
24
25
26
27
28
29
4
5
2
3
Inde x
0
1
6
7
N
FB
Inde x
720 90
736 91
752 92
768 93
776 94
800 95
824 96
848 97
872 98
888 99
912 100
936 101
960 102
984 103
1000 104
1024 105
1048 106
1072 107
1096 108
1112 109
1136 110
1160 111
1184 112
1216 113
1248 114
1280 115
1312 116
1336 117
1368 118
1392 119
N
FB
Inde x
328 60
344 61
352 62
360 63
368 64
376 65
384 66
400 67
416 68
432 69
440 70
456 71
472 72
480 73
496 74
512 75
528 76
544 77
552 78
568 79
584 80
600 81
608 82
624 83
640 84
656 85
664 86
680 87
696 88
712 89
N
FB
Inde x
48 30
64 31
72 32
80 33
88 34
96 35
104 36
120 37
128 38
136 39
144 40
152 41
160 42
176 43
184 44
192 45
200 46
208 47
216 48
232 49
240 50
248 51
256 52
264 53
272 54
288 55
296 56
304 57
312 58
320 59
FEC block size table for downlink and uplink data channels
N
FB
Inde x
1424 120
1448 121
1480 122
1504 123
1536 124
1560 125
1600 126
1640 127
1672 128
1712 129
1752 130
1784 131
1824 132
1864 133
1896 134
1920 135
1952 136
2000 137
2048 138
2096 139
2144 140
2192 141
2232 142
2280 143
2328 144
2368 145
2432 146
2496 147
2560 148
2624
N
FB
3904
3968
4096
4160
4224
4288
4352
4416
4544
4608
4672
4736
4800
3328
3392
3456
3520
3648
3712
3776
3840
2752
2816
2880
2944
3008
3072
3200
3264

• Simulation Parameters
Parameters
Bandwidth
Number of subcarrier
Frame length
Channel estimation
Channel code/HARQ
Modulation
MIMO configuration
Resource allocation
Channel model
MS mobility
Receiver type
Maximum number of retransmission
Retransmission latency
Assumption
10 MHz
1024
5ms
Perfect
CTC ½ / IR
QPSK, 16 QAM, 64 QAM
2 x 2 SM
Distributed resource allocation
VEH A
30km/h
Linear MMSE
1~4
10ms

• The impact of CTC block size to FER performance ( a multiple of 6 )
1
VEH A, 30km/h, 64 QAM, 1/2 CTC, Nep:720, Max Tx:1
0.1
16e BG
HMS BG
0.01
12 14 16 18
SNR
20 22 24
– In fading channel model, it’s unlikely for HMS Bit-Grouping to obtain significant performance improvement shown in AWGN. The gain is close to 0.3dB~0.4dB in spite of good simulation environment (64QAM, ½ CTC)
– HMS Bit Grouping has no performance gain under simulation environment of 16QAM and 64QAM with the block sizes which are not a multiple of 6, code rate>1/2)
HMS BG : Huawei/MediaTek/Samsung joint contribution for Bit Grouping (C802.16m-09/0665)

• The impact of CTC block size to FER performance ( non-multiple of 6 )
VEH A, 30km/h, 64QAM, 1/2 CTC, 2x2 SM, Max Tx:1 VEH A, 30km/h, 64 QAM, 1/2 CTC, Nep:640, Max Tx:1
1 1
0.1
0.1
0.01
12
16e BG (Nep:720)
HMS BG (Nep:720)
16e BG (Nep:640)
HMS BG (Nep:640)
14 16
0.01
HMS BG
16e BG
18
SNR
20 22 24 12 14 16 18
SNR
20 22 24
– N
EP
720 shows performance degradation close to 1dB over N sequence with same bit reliability.
EP
640 due to contiguous distribution of coded bit
– HMS Bit Grouping is not an enhanced scheme with an additional improvement in CTC decoding, it only plays a role to make up for performance degradation.

• CoRe gain separated from Bit Grouping in IR-HARQ
– Nep with a multiple of 6
VEH A, 30km/h, 64 QAM, 1/2 CTC, 2x2 SM, Nep:720, Max Tx:2
VEH A, 30km/h, 64QAM, 1/2 CTC, 2x2 SM, Nep:720, Max Tx:4
1
1
0.1
0.1
0.01
0.01
16e BG
HMS BG
16e BG + CoRe (LG)
HMS BG + CoRe (LG)
16e BG
HMS BG
16e BG + CoRe(LG)
HMS BG + CoRe (LG)
1E-3
6 7 8 9 10 11 12 13 14
2 3 4 5 6 7 8 9 10
SNR SNR
– From simulation results, we can know that Constellation Rearrangement has additional HARQ gain regardless of Bit Grouping method.

• CoRe gain separated from Bit Grouping in IR-HARQ
– Nep with non-multiple of 6
VEH A, 30km/h, 64QAM, 1/2 CTC, 2x2 SM, Nep:640, Max Tx:2 VEH A, 30km/h, 64QAM, 1/2 CTC, 2x2 SM, Nep:640, Max Tx:4
1
1
0.1
0.1
0.01
0.01
16e BG
HMS BG
16e BG + CoRe
HMS BG + CoRe
16e BG
HMS BG
16e BG + CoRe (LG)
HMS BG + CoRe (LG)
1E-3
1E-3
6 8 10 12 14 2 3 4 5 6 7 8 9 10
SNR SNR
– In case of N
EP
Bit Grouping. with non-multiple of 6, HMS Bit Grouping has the same or poor performance as 16e
– The HARQ retransmission gain by CoRe is irrelevant to Bit Grouping shown in simulation results above.