Uplink Control PHY Design for HARQ Tri-State Feedback Buffer Management IEEE Presentation Submission Template (Rev. 9) Document Number: IEEE S802.16m-09/0894 Date Submitted: Source: Zheng Yan-Xiu, Yu-Chuan Fang, Chang-Lan Tsai, Chung-Lien Ho, Hsi-Min Hsiao ITRI Venue: Re: IEEE m-09/0020, Call for contributions on 16m AWD content. Amendment Working Document (IEEE m-09/0010r1a). Chapter HARQ Feedback A-MAP IE Chapter UL HARQ feedback control channel Base Contribution: IEEE C802.16m-09/0894r4 Purpose: To be discussed and approval by IEEE m TG Notice: This document does not represent the agreed views of the IEEE 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 Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and. Further information is located at and.

Motivation This contribution shows the buffer management performance and related uplink control PHY structure for tri-state HARQ feedback The feedback facilitates HARQ buffer management by three states ACK/NACK/DROP The buffer management occurs for high throughput scenario and each HARQ process will carry large HARQ burst Since larger burst applied in this scenario, we can apply more resource for the tri-state HARQ feedback

Aggressive HARQ Transmission Buffer management is necessary to accommodate packet dropped on receiver side –Aggressive HARQ transmission releases buffer constraint from receiver side –HARQ entity can boost transmission rate beyond HARQ buffer capability –Receiver may not store the HARQ burst when buffer is full –Packet is dropped due to buffer outage –It further introduces HARQ failure and makes HARQ performance unpredicatible Tri-state HARQ mechanism –If decoded data is correct, MS feedbacks ACK –If decoded data is incorrect and the redundancy version can be stored in the HARQ buffer, MS feedbacks NACK –If decoded data is incorrect and redundancy version can not be stored in the HARQ buffer, MS feedbacks DROP –BS will retransmit the dropped packet when DROP is received, otherwise, BS will follow existing HARQ mechanism

Simulation Environments Three mechanisms are compared –Tri-State HARQ feedback –Two-State HARQ feedback with buffer constraint –Two-State HARQ feedback without buffer constraint Simulation Environments –HARQ burst = 600 bytes –Maximum 8 HARQ processes –Maximum 4 successful transmissions –HARQ buffer ranges from 10K~80K soft bits –Round trip delay=20ms –Peak rate= 1.92Mbps –No feedback error –PB 3km/hr, VA 30km/hr and 120km/hr –Aggregation buffer is applied

IR-HARQ with PB 3km/hr No CQI Report Error Transmission rate increases by 2~8 times for tri-state HARQ mechanism and two-state HARQ mechanism without buffer constraint Tri-state HARQ mechanism further provides throughput gain when buffer is insufficient Two-state HARQ mechanism introduces large HARQ failure rate when Buffer is insufficient

IR-HARQ with VA 30km/hr No CQI Report Error Transmission rate increases by 2~8 times for tri-state HARQ mechanism and Tri-state HARQ mechanism further provides throughput gain 30~80% throughput gain when HARQ buffer is below 20K soft bits Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60K soft bits

IR-HARQ with VA 120km/hr No CQI Report Error Transmission rate increases by 2~8 times for tri-state HARQ mechanism and Tri-state HARQ mechanism further provides throughput gain 30~80% throughput gain when HARQ buffer is below 20K soft bits Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60K soft bits

1-bit HARQ feedback Four orthogonal sequences indexes ACK/NACK Each MS chooses one sequence from even numbered channel or odd number numbered channel The MS sends the chosen sequence as the HARQ feedback Sequence indexOrthogonal sequence1-bit Feedabck 0 [ ]Even numbered channel ACK 1[ ]Even numbered channel NACK 2[ ]Odd numbered channel ACK 3[ ]Odd numbered channel NACK

Tri-State HARQ feedback Three sequences are chosen from orthogonal sequences. The power boosting level is identical to 1-bit HARQ feedback Sequence indexOrthogonal sequencesTri-state HARQ feedback 0[ ]ACK 1[ ]NACK 2[ ]DROP 3[ ]Reserved

Nine-State HARQ feedback Nine sequences constructed by orthogonal sequences with linear combination. Unified receiver architecture can be applied The power boosting level is identical to 1-bit HARQ feedback Sequence index SequencesNine-state HARQ feedback 0[ j j j j] ACK/ACK 1[ j j j j] ACK/NACK 2[ j j j j] ACK/DROP 3[ j j j j] NACK/ACK 4[ j j j j] NACK/NACK 5[ j j j j] NACK/DROP 6[ j j j j] DROP/ACK 7[ j j j j] DROP/NACK 8[ ] DROP/DROP

Simulation Environment HMT is referred to AWD Simulation parameters are referred to EVM Channel Bandwidth10MHz Over-sampling Factor28/25 FFT Size1024 Cyclic prefix (CP) ratio 1/8 Channel conditionPB3, VA120, VA350 The number of antennas Tx:1, Rx:2 ModulationBPSK/MPSK FMT size2x6 ReceiverHARQ FB: non-coherent detection, MLD

Performance Comparison Tri-State HARQ feedback provides similar performance to 1-bit HARQ feedback Nine-State HARQ feedback provides similar performance to 1-bit HARQ feedback

Conclusion Tri-state HARQ feedback enhances the HARQ throughput without HARQ failure The proposed tri-state HARQ feedback provides similar performance than 1-bit HARQ feedback Nine-state HARQ feedback provide similar performance to 1-bit HARQ feedback with identical radio resource

Text Proposal [Add the following subclause after ] Extended HARQ Feedback A-MAP IE includes two bits and corresponding value for HARQ ACK/NACK/DROP information is shown in Table XXX. If extended HF-A-MAP IE has the 0b00, 0b01 or 0b10, it shall be interpreted as ACK information, NACK information and DROP information, respectively. SyntaxSize (bit)Notes HF-A-MAP IE format { HF-A-MAP IE value20b00 : ACK feedback info. 0b01 : NACK feedback info. 0b10: DROP feedback info. 0b11: Reserved } Table XXX—Extended HF-A-MAP-IE

Text Proposal [Add the following subclause at the end of ] Extended HARQ feedback control channel To apply the HARQ buffer management by using tri-state feedback, e.g., ACK, NACK, and DROP, the mapping of the tri-state HARQ feedback to its corresponding feedback sequence are show in Table ZYX. Table ZYX––Orthogonal sequences for UL tri-state HARQ feedback channel Sequence index Orthogonal sequenceTri-state HARQ feedback 0[ ] ACK 1[ ] NACK 2[ ] DROP 3[ ] Reserved