November 2007 doc IEEE 802 11 -07 2766

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November 2007 doc. : IEEE 802. 11 -07/2766 r 0 Example of 802. 11 n device capabilities to deliver quality video Authors: Name Company Address Michael Livshitz Metalink, Inc Yakum, Israel mlivshitz@mtlk. com Leonid Epstein Metalink, Inc Yakum, Israel leonide@mtlk. com Submission Slide 1 Phone Email

November 2007 doc. : IEEE 802. 11 -07/2766 r 0 Outline • Substantiate PER requirements for video transmissions • Provide an example how 802. 11 n device can reach the required PER with retransmissions – Analyze the effect of retransmissions to delay variation budget – Take into account typical aggregation conditions and link adaptation behavior Submission Slide 2 Michael Livshitz, Leonid Epstein Metalink

November 2007 doc. : IEEE 802. 11 -07/2766 r 0 Requirements for PER based on error-free viewing • Packet error rate probabilities can be derived from the requirements for error-free video rendering – Assumed payload format LLC/IP/UDP/RTP/[7 x. MPEG 2 -TS]=1364 bytes – For example, PER of 3 e-7 is required for 30 min error-free viewing of 20 Mbps HD MPEG 2 video Submission Slide 3 Michael Livshitz, Leonid Epstein Metalink

November 2007 doc. : IEEE 802. 11 -07/2766 r 0 802. 11 n Video Transmission Parameters Video Required Rate, PER(1) Mbps Raw BER(2) PER Maximum Number of retransmissions(3) Number of Aggregated MPDUs Max Delay variation, ms 20 3 e-7 5 9 10. 5(4) 8 7 e-7 4 6 10. 3 5 1 e-6 4 4 9. 0 1. 2 5 e-6 3 2 10. 1 1 e-6 0. 076 Notes: PER (after retransmissions) needed for 30 min error-free video (2) This raw BER (before retransmissions) is a target BER of Rate Adaptation algorithm (3) Number of retransmissions necessary to reach required PER (4) See next slide for example calculation (1) Submission Slide 4 Michael Livshitz, Leonid Epstein Metalink

November 2007 doc. : IEEE 802. 11 -07/2766 r 0 Example delay budget for aggregated and retransmitted 11 n frame • Assumed parameters: – PHY rate is 108 Mbps (2 SS, 16 QAM, rate 1/2) – IP/UDP/RTP/(7 x. MPEG 2 -TS) – A-MPDU/BA, 9 MPDUs, 5 retransmission allowed – All retransmissions are within original Tx. OP – Video is AC_VI, under EDCA rules with default parameters Aggregation Delay, ms Media busy Delay, ms Media access delay, ms Media time with retransmissions, ms Total delay, ms Time waiting to receive other packets to be aggregated into AMPDU Time waiting for media becoming idle DIFS + Backoff RTS-CTS(A-MPDU/BA)+ [N x (A-MPDU*/BA)] Fixed portion Maximum variation min max 0 4. 21 0 1. 15 0. 034 0. 097 1. 15 6. 27 1. 19 10. 5 Submission max Slide 5 Michael Livshitz, Leonid Epstein Metalink

November 2007 doc. : IEEE 802. 11 -07/2766 r 0 Conclusion • Numeric example illustrates the possibility of delivering high quality video with 802. 11 n-based toolset • Retransmissions can drive media loss rate low enough to enable quality error-free viewing, while keeping delay variation bounded by relatively small threshold • Standard-based features that benefit video delivery: – High throughput, low interference: • 5 GHz band, 40 MHz-wide transmissions • Multiple Spatial Streams, Receive Antenna Diversity – Effective media usage: • Qo. S (WMM/EDCA) • A-MPDU Aggregation • Single Tx. OP retransmissions – Video quality Rate Adaptation • Targets low BER Submission Slide 6 Michael Livshitz, Leonid Epstein Metalink

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