HARQ Buffer Management for Aggressive HARQ transmission IEEE

HARQ Buffer Management for Aggressive HARQ transmission IEEE 802. 16 Presentation Submission Template (Rev. 9) Document Number: IEEE S 802. 16 m-09/0891 r 2 Date Submitted: 2009 -4 -30 Source: Zheng Yan-Xiu, Yu-Chuan Fang, Chang-Lan Tsai, Chung-Lien Ho, Hsi-Min Hsiao E-mail: zhengyanxiu@itri. org. tw. ITRI Venue: Re: IEEE 802. 16 m-09/0020, Call for contributions on 16 m AWD content. Amendment Working Document (IEEE 802. 16 m-09/0010 r 1 a). Chapter 15. 3. 6 DL control information elements Base Contribution: Purpose: To be discussed and approval by IEEE 802. 16 m TG 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: <http: //standards. ieee. org/guides/bylaws/sect 6 -7. html#6> and <http: //standards. ieee. org/guides/opman/sect 6. html#6. 3>. Further information is located at <http: //standards. ieee. org/board/pat-material. html> and <http: //standards. ieee. org/board/pat >.

Motivation • System can be optimized for single user – Controlling overhead: multiple HARQ bursts assignment – User throughput: aggressive HARQ transmission – Both can be done by A-MAP IE design and HARQ feedback IE

Multiple HARQ Bursts Assignment • Controlling overhead reduction: – Sharable overhead for multiple HARQ bursts • • A-MAP IE Type; 4 bits MEF: 2 bits Configuration of MEF: 1~4 bits Long TTI indicator: 1 bit MCRC: 16 bits HFA: 4 bits Reserved: X bits – We can save at least 28+X~31+X bits – The reduction is significant • Two bits HARQ feedback indication – At least 2. 5 d. B performance improvement in uplink control channel

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 10 K~80 K soft bits Round trip delay=20 ms Peak rate= 1. 92 Mbps No feedback error PB 3 km/hr, VA 30 km/hr and 120 km/hr Aggregation buffer is applied

IR-HARQ with PB 3 km/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 30 km/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 20 K soft bits Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits

IR-HARQ with VA 120 km/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 20 K soft bits Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits

Conclusions • • Tri-State HARQ mechanism guarantees HARQ reliability even there is package drop due to buffer overflow Tri-State HARQ mechanism can boosts throughput by 5~8 times Tri-State HARQ mechanism is recommended to adopted to 16 m to increase transmission rate with buffer constraint Recommend to adopt the proposed text #1 in C 802. 16 m-09/0894 r 2 Recommend to adopt the proposed text #2 in C 802. 16 m-09/0894 r 2 Recommend to adopt the proposed text #3 in C 802. 16 m-09/0894 r 2 Recommend to adopt the proposed text #4 in C 802. 16 m-09/0894 r 2 Recommend to adopt the proposed text #5 in C 802. 16 m-09/0894 r 2

APPENDIX

AGGRESSIVE IR-HARQ TRANSMISSION WITH 3 DB CQI REPORT ERROR

IR-HARQ with PB 3 km/hr 3 d. B CQI Report Error • • Transmission rate increases by 2~8 times for tri-state HARQ mechanism and two-state HARQ mechanism without buffer constraint At high SNR, aggressive HARQ mechanism provides more transmission rate 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 30 km/hr 3 d. B CQI Report Error • • Transmission rate increases by 2~8 times for tri-state HARQ mechanism Aggressive HARQ mechanism increases more throughput when SNR is high Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits or SNR is below than 16 d. B Two-state HARQ mechanism introduces less transmission rate due to high HARQ failure rate

IR-HARQ with VA 120 km/hr 3 d. B CQI Report Error • • Transmission rate increases by 2~8 times for tri-state HARQ mechanism Aggressive HARQ mechanism increases more throughput when SNR is high Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits or SNR is below than 16 d. B Two-state HARQ mechanism introduces less transmission rate due to high HARQ failure rate

AGGRESSIVE CC-HARQ TRANSMISSION WITH NO CQI REPORT ERROR

CC-HARQ with PB 3 km/hr No CQI Report Error • • • Transmission rate increases by 2~8 times for tri-state HARQ mechanism Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits Link reliability significantly decreases due to highly correlated channel condition

CC-HARQ with VA 30 km/hr No CQI Report Error • Transmission rate increases by 2~8 times for tri-state HARQ mechanism • Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits • Tri-State HARQ mechanism provides better link quality

CC-HARQ with VA 120 km/hr No CQI Report Error • Transmission rate increases by 2~8 times for tri-state HARQ mechanism • Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits • Tri-State HARQ mechanism provides better link quality

AGGRESSIVE IR-HARQ TRANSMISSION WITH 3 DB CQI REPORT ERROR

CC-HARQ with PB 3 km/hr 3 d. B CQI Report Error • • • Transmission rate increases by 2~8 times for tri-state HARQ mechanism Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits Link reliability significantly decreases due to highly correlated channel condition

CC-HARQ with VA 30 km/hr 3 d. B CQI Report Error • Transmission rate increases by 2~8 times for tri-state HARQ mechanism • Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits • Tri-State HARQ mechanism provides better link quality

CC-HARQ with VA 120 km/hr 3 d. B CQI Report Error • Transmission rate increases by 2~8 times for tri-state HARQ mechanism • Two-state HARQ mechanism introduces large HARQ failure rate when HARQ buffer is below than 60 K soft bits • Tri-State HARQ mechanism provides better link quality