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This document analyzes the performance of the 3c MAC protocol with frame errors and explores the impact of ACK policies with and without aggregation. The study aims to provide insights for IEEE 802.15.3c standard consideration.
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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Performance Issue in terms of ACK policies with/withoutAggregation] Date Submitted: [March 16, 2008] Source: [Wooyong Lee1, Jinkyeong Kim1, Yongsun Kim1, Kyeongpyo Kim1, Hyoungjin Kwon1, Seung-Eun Hong1,Kyungsup Kwak2, Seokho Kim2, Xizhi An2, Saurabh N. Mehta2, Sangkyoon Nam2, Bumjung Kim2 ] Company: [Electronics and Telecommunications Research Institute(ETRI)1,Inha University2] Address: [ETRI, 161 Gajeong-dong, Yuseong-gu, Daejeon, 305-700, Republic of Korea]1,[ 6-141B, Inha University, 253 Yonghyun-dong, Nam-gu, Incheon, 402-751, Republic of Korea]2 Voice: [], FAX: [], E-Mail: [kskwak@inha.ac.kr (other contributors are listed in “Contributors” slides)] Re: [] Abstract: [We analyze the performance of “3c” MAC when the frame error is introduced. The effects of ACK policies w/wo aggregation are considered. ] Purpose: [To be considered in IEEE 802.15.3c standard] Notice:This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. ETRI
Contributors ETRI
Case Study • 1080p video stream • 16 ms superframe size • Superframe Sizing Procedure for Uncompressed Video Traffic [doc.: IEEE 802.15-07-0897-02-003c] ETRI
Simulation Model (UM1) PNC Control/commands Beacon Uncompressed Video Streaming DEV-0 DEV 1 2000Mbps Common mode (48.5 Mbps) • Uncompressed Traffic Model :1080p 30f 20b • - 2200(1920+280)*1125(1080+45)*30*20 = 1.485 Gbps • - CBR traffic -> 44000bit (2200*20) / 29.63us ETRI
802.15.3cPerformance Metrics Throughput • measured in terms of bits per second, is the amount of data delivered successfully by the peer MAC-SAP. End-to-End Delay • measured in terms of second, is the amount of time taken for a MAC SDU to be transferred from the MAC-SAP of the transmitter to the peer MAC-SAP of the receiver. Memory usage (MAC) • Memory usage represent the minimum buffer size required for continuous video representation ETRI
Parameters Assumed • Use common mode beacon to 47.8 Mbps • Random packet error • Set video traffic to CBR traffic mode • One MAC SDU is composed of data bits transmitted in one horizontal line. • Assume no buffer delay due to higher data rate • Assume no propagation delay due to short distance ( < 10 meter) • Consider transmission delay in terms of Overhead & Payload Size • Simulate in the NS-2 ETRI
MAC Throughput without Aggregation • Superframe size = 16 ms, Preferred payload size = 5.5k ETRI
Conclusions • We present the performance comparison in terms of ACK polices with or without aggregation. • Numerical and simulation results show that the aggregation scheme can improve the throughput results to a large extend. • Different ACK policies result in different throughputs. • No ACK has the highest efficiency, but it can not provide reliable data transfer. • Imm-ACK has the lowest performance. • Dly-ACK can improve throughput. • Number of pending frames should not be small • On the other hand, delay jitter may be larger. ETRI
Suggestions for setting ACK policies • RT traffic (video streaming) • Constant bandwidth and stringent timing requirement • No ACK policy is preferred • Imm-ACK and Dly-ACK have poor throughput performance. • Retransmission is useless and broken frames are directly discarded. • If a frame error occurs, retransmission doubles the delay. • If n-Dly-ACK is applied, the delay due to retransmission is correspondingly increased n times. • High power consumption to insure that frame can be successfully transmitted and received. • NRT traffic (data transfer) • ACK and retransmission is needed to correct frame errors • n-Dly-ACK is preferred. • Very high reliability (packet delivery ratio is almost 100%), if delay jitter requirement is not strict. • Extend the coverage range or reduce the need for transmit power. • Bi-directional communication • Imp-ACK is preferred. ETRI
Appendix ETRI