1. Constellation Rearrangement for IEEE802.16m IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE S802.16m-08/807 Date Submitted: 2008-7-15 Source: Hyungho Park, HanGuy Cho, Sungho Moon Voice:+82-31-450-1934 LG Electronic Inc.E-mail:hyunghopark@lge.com, hgcho@lge.com,hyunghopark@lge.comhgcho@lge.com LG R&D Complex, 533 Hogye-1dong, msungho@lge.com msungho@lge.com Dongan-gu, Anyang, 431-749, Korea * http://standards.ieee.org/faqs/affiliationFAQ.html Venue: Macau, China Re : IEEE 802.16m-08/024 – Call for Contributions on Hybrid ARQ (PHY aspects) Base Contribution: IEEE C802.16m-08/807 Purpose: To be discussed and adopted by TGm for 802.16m SDD Notice: This document does not represent the agreed views of the IEEE 802.16 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 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. HARQ mode for HARQ PHY structureHARQ mode for HARQ PHY structure –Both Chase HARQ and IR HARQ has been considered in IEEE802.16m –Chase HARQ can achieve power gain with low complexity, however it has performance loss as compared with IR HARQ operation. –For IR HARQ, the structure which is combined with the process of Partial IR and Full IR would be considered in 16m over retransmissions. Although higher coding gain may be achieved, its buffering overhead lay burden on a receiver side with decreasing mother code rate. Conventional CoReConventional CoRe –High cost effective solution for enhancement of 16m HARQ High additional HARQ gain regardless of MS’s mobility Low implementation complexity –Unequal bit error probability In case of high modulation order, the symbol has different bit reliabilities such as MSB, SB (64 QAM), and LSB. These kinds of bit reliability difference result in performance degradation in course of channel decoding Constellation Rearrangement [1]

3. –CoRe related Bitwise operations Swapping operation: Averaging out the difference of bit reliability between component bits (MSB, SB, LSB) within signal constellation. Inversion operation: Averaging out the difference of bit reliability candidate component bits Considerations on enhancement of CoRe for IEEE802.16mConsiderations on enhancement of CoRe for IEEE802.16m –High modulation order support Higher order modulated symbol has a larger potential gain from constellation rearrangement due to its increased number of component bits for bitwise rearrangement (up to 64 QAM) –Both Chase and IR HARQ support The performance of IR HARQ can be also improved by CoRe in the way that recursive systematic or parity bits adopt the bitwise operations such as swapping and inversion in order to average the reliability of coded bits –Incorporation of Multiple Antenna configuration MIMO related LLR combing is not straightforward because the symbols transmitted from each antenna interfere with each other. As the number of retransmission is increased, the interference is further aggravated in course of LLR combing. Constellation Rearrangement [2]

4. Constellation Rearrangement [3] Proposed Constellation RearrangementProposed Constellation Rearrangement –Horizontal bitwise mapping Swapping operation exchanges component bits (i 1, q 1, i 2, q 2 ) on signal constellation in order to average the difference of bit error probabilities. Inversion operation averages out error probabilities of candidate component bits by taking inversion of the corresponding bits on signal constellation –Vertical bitwise mapping perform to exchange component bits between transmit antennas for averaging the channel difference.

5. Constellation Rearrangement [4] Example of proposed CoRe for 16 QAMExample of proposed CoRe for 16 QAM –1 st retransmission Horizontal bitwise mapping: swapping bit reliability between MSB and LSB Vertical bitwise mapping : exchanging to average spatial channel difference between MSBs –2 nd retransmission Horizontal bitwise mapping: inversion of LSBs for averaging out the difference of bit reliabilities between candidate component bits(10, 11, 01, 00) Vertical bitwise mapping: exchanging to average spatial channel difference between LSBs

6. Performance comparison [1] Comparison of proposed CoRe and 16e Chase/IR HARQComparison of proposed CoRe and 16e Chase/IR HARQ –Proposed CoRe obtains approximately 2~3dB FER gain over 16e Chase HARQ regardless of MS’s mobility –Proposed CoRe shows little improvement in link performance gain over 16e CTC-IR HARQ Performance gain (10% FER) CoRe over Chase (30 km) CoRe over Chase (120 km) CoRe over IR, (30km) CoRe over IR (120 km) N re = 11.7 dB1.9 dB0.30 dB0.35 dB N re = 22.1 dB2.2 dB0.15 dB N re = 32.8 dB3.1 dB0.47 dB N re :Maximum number of retransmission

7. Performance comparison [2] Simulation ParametersSimulation Parameters ParametersAssumption Bandwidth10 MHz Number of subcarrier1024 Frame length5ms Channel estimationPerfect Channel codeCTC 1/2 Modulation16 QAM MIMO configurationTx: 2, Rx:2 Resource allocationPUSC Channel modelVEH A MS mobility30km/h, 120km/h Receiver typeLinear MMSE Maximum number of retransmission1, 2, 3 Retransmission latency10ms

8. Performance comparison [3] Chase HARQ w/ CoRe vs 16e Chase HARQChase HARQ w/ CoRe vs 16e Chase HARQ

9. Performance comparison [4] Chase HARQ w/ CoRe vs 16e IR HARQChase HARQ w/ CoRe vs 16e IR HARQ

10. Text Proposal for 802.16m SDD [1] x.x HARQ mode x.x.x. Constellation Rearrangement Constellation rearrangement considering both horizontal and vertical bitwise mapping shall be adopted for IEEE 802.16m. x.x.x.1. Horizontal bitwise mapping Horizontal bitwise mapping changes the bit position and its value on signal constellation in order to get temporal diversity gain during retransmissions through the following operations. A specific mapping rule is FFS. x.x.x.2 Vertical bitwise mapping Vertical bitwise mapping perform to exchange components bits between transmit antennas for averaging the channel difference. A specific bitwise mapping rule is FFS ------------------------------------------- Start of the Text ------------------------------------------------ -------------------------------------------- End of the Text ----------------------------------------------------