1. HARQ Bit Selection Algorithm
IEEE Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-09/0504r1
Date Submitted:
Source:
1Zheng Yan-Xiu, Yu-Chuan Fang, Chang-Lan Tsai, Chung-Lien Ho, Hsi-Min Hsiao, Ren-Jr Chen Chien-Yu Kao, Cheng-Ming Chen, Yu-Tao Hsieh, Jen-Yuan Hsu, Pang-An Ting 1
ITRI
Venue:
IEEE Session #60, Vancouver
Base Contribution: N/A
IEEE m-09/0012, “Call for Comments on Amendment Working Document” Target topic: “ Channel coding and HARQ”.
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2. Bit Selection: Cocktail Therapy
Bit Grouping: (Harmonization proposed by MediaTek, Huawei and Samsung)
Method:
Avoid mapping the encoded bits of the same indices onto the same bit level.
Map the contiguous encoded bits different bit levels in 16QAM and 64QAM.
Gain: provide better protection in the first transmission
Prioritized Circular Reading (PCR):
Method: control the prioritized code bits on MSB or LSB of a symbol and minimize complexity to the least
Gain: obtain diversity, e.g. frequency domain diversity
Priority Swapping (PS):
Method: retransmit coded bits in MSB to LSB to average modulation effect
Gain: acquire constellation diversity gain
Shifted IR Redundancy Version Selection (SIRRVS):
Method: improve performance by selecting code bits at first when complete code bits are selected
Gain: enhance code bits influence in the later transmission to acquire coding gain
Bit Inverting (BI):
Method: exclusive OR code bits
Gain: acquire more constellation diversity gain 2

3. Shifted IR redundancy version selection (SIRRVS)
To select parity bits, Y1 & Y2, at first, when complete code bits are selected.

4. Illustration for CC-HARQ (1/3)
16-QAM, R=1/2 BI
PCR PS

5. Illustration for CC-HARQ (2/3)
64-QAM, R=1/2

6. Illustration for CC-HARQ (3/3)
represents the coded bit sequence at the first transmission, whose length is Lk.
Fk represents the initial position of bit selection for the k-th subpacket, where k is the subpacket index and k = 0, 1, 2, 3. Thus the initial bit selected is denoted as
When the initial position is determined, the bits are accessed contiguously and circularly to generate the k-th subpacket for retransmissions. (k = 0 for the first transmission)

7. Definition of Parameters
Ex: NT = NDT + NPT
1 stream: =
2 streams: 108 =
4 streams: 108 = 7

8. Proposed bit selection for CC-HARQPS BI
PCR
Initial position
New address 8

9. Illustration for IR-HARQ (1/3)
16-QAM, R=1/2, NEP=12 PS
PCR
SIRRVS
length for Group #1
length for Group #2
2TX
3TX
4TX 9

10. Illustration for IR-HARQ (2/3)
64QAM, R=1/2, NEP=12
length for Group #1
length for Group #2
2TX
3TX
4TX

11. Illustration for IR-HARQ (3/3)
16QAM, R=3/4, NEP=12
length for Group #1
length for Group #2
2TX
3TX
4TX

12. Proposed bit selection for IR-HARQPS
PCR BI
PCR
SIRRVS 12

13. Procedure of channel interleaver
The modified channel interleaver for CTC comprises several parts.
Bit separation (16e)
Subbock interleaving (16e)
Bit grouping (16e[1] or MBG[6])
Bit selection (proposed algorithm)
[1] 16e represents the IEEE e.
[6] MBG (modified bit grouping) denotes the proposal of Huawei, Samsung and MTK, IEEE C802.16m-09/0665, “Proposed Text of CTC Bit grouping for IEEE m Amendment.”

14. Simulation scenario

15. Simulation cases

16. Simulation Results
In short, the simulation results show the combination of modified bit grouping (MBG) [6], prioritized circular reading (PCR) and priority swapping (PS) has the best performance, so only its results are shown in this contribution.

17. Fig. 7(a)
MBG (modified bit grouping) denotes the proposal of Huawei, Samsung and MTK, IEEE C802.16m-09/0665, “Proposed Text of CTC Bit grouping for IEEE m Amendment.”

18. Fig. 7(b)

19. Fig. 7(c)

20. Fig. 8(a)

21. Fig. 8(b)

22. Fig. 8(c)

23. Fig. 9(a)

24. Fig. 9(b)

25. Fig. 9(c)

26. Fig. 10(a)

27. Fig. 10(b)

28. Fig. 10(c)

29. Fig. 11(a)

30. Fig. 11(b)

31. Fig. 11(c)

32. Fig. 12(a)

33. Fig. 12(b)

34. Fig. 12(c)

35. Fig. 13(a)

36. Fig. 13(b)

37. Fig. 13(c)

38. Fig. 14(a)

39. Fig. 14(b)

40. Fig. 14(c)

41. Conclusions
The proposed bit selection algorithm improve the HARQ technique significantly regardless of the bit grouping methods.
The proposed bit selection cooperating with the modified bit grouping [6] has the better performance than with the 16e scheme.

42. References
[1] IEEE P Rev2 / D8, “Draft Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Broadband Wireless Access,” Dec
[2] IEEE m-08/003r7, “IEEE m System Description Document”
[3] IEEE m-07/002r7, “802.16m System Requirements”
[4] IEEE C802.16m-08/043, “Style guide for writing the IEEE m amendment”
[5] IEEE m-08/050, “IEEE m Amendment Working Document”
[6] IEEE C802.16m-09/0665, “Proposed Text of CTC Bit grouping for IEEE m Amendment”
[7] IEEE C802.16m-09/0573, “Bit Grouping Performance Comparison for Bit Priority Mapping and 16e Mapping in the 1st Transmission”