New Bit-Selection Method Suitable for Adaptive HARQ

IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number:

IEEE C802.16m-09/0999Date Submitted:

2009-04-27Source:

Chiwoo Lim , Seunghoon Choi, Sung-Eun Park, Songnam Hong, Jaeweon Cho, Jaehee Cho, Heewon Kang, Hokyu ChoiE-mail: {chiwoo.lim, seunghoon.choi, se.park, sn7955.hong, jaeweon.cho, jaehee1.cho, hkang, choihk} @samsung.comSamsung Electronics, Co., Ltd.416 Maetan-3, Suwon, 443-770, Korea

Venue: Category: AWD comments / Area: Chapter 15.3.12 (Channel coding HARQ-PHY) “Comments on AWD 15.3.12 Channel coding HARQ-PHY” Base Contribution:

NonePurpose:

To be discussed and adopted by TGm for 802.16m amendmentNotice:

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InstructionInstruction

• Adaptive HARQ is mandatory in the downlink of IEEE 802.16m.

• IEEE 802.16e’s bit selection method results in the serious problem in adaptive HARQ

• It is very hard to get IR gain if the amount of retransmissions is too small compared with that of initial transmission

• Starting positions should be determined as maximizing IR gain as possible under adaptive HARQ

..

Proposed Bit SelectionProposed Bit Selection

The benefits of the design is as follows:

SPID = 0 ensure systematic bits are transmitted

SPID = 1 minimizes the code rate if used in conjunction with SPID = 0

SPID = 2 and SPID = 3 are placed such that 4 SPIDs are equally placed in the buffer to ensure equal opportunity for all coded bits to be transmitted

Proposed Bit SelectionProposed Bit Selection

SPID Starting position

0 0,0 kP

1

24

24

mod k FB_Buffer,k CTC,,1

NNP k

2 2448

kFB_Buffer,,2

NP k

3

2424

mod2 k FB_Buffer,k CTC,

kFB_Buffer,

,2

NNN

P k

Simulation ParametersSimulation Parameters

Parameters Assumption

Channel code CTC

Modulation QPSK for each transmission

HARQ mode Adaptive

Channel model AWGN

Code Length 480 bits

# of coded bits for each transmission 960bits

Number of retransmission 1

Samsung SPID=0 for initial transmissionSPID=2 for first retransmission

ZTE SPID=0 for initial transmissionSPID=1 for first retransmission

Simulation Result

1.00E-02

1.00E-01

1.00E+00

-3.6 -3.4 -3.2 -3 -2.8 -2.6 -2.4 -2.2 -2 -1.8 -1.6 -1.4

SNR

PER

Samsung

ZTE

ConclusionConclusion

• We suggest this new bit selection method to be adopted for CTC IR HARQ in 16m.