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UDP Lite for Wireless Video Streaming

UDP Lite for Wireless Video Streaming. Amoolya Singh, Almudena Konrad, and Anthony Joseph University of California, Berkeley Jun 19, 2000. Idea. Problem Current Internet doesn’t support bit error resilient codecs Goal

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UDP Lite for Wireless Video Streaming

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  1. UDP Lite for Wireless Video Streaming Amoolya Singh, Almudena Konrad, and Anthony Joseph University of California, Berkeley Jun 19, 2000

  2. Idea • Problem • Current Internet doesn’t support bit error resilient codecs • Goal • Support real-time streaming applications over noisy channels, such as wireless • Proposed Solution • Provide link/transport layer alternatives to support error resilient video codecs

  3. Packetization RTP Testbed, Protocols, Tools IP PPP PSTN H.263+ Encoder Fixed Host Unix BSDi 3.0 GSM Base Station Mobile Host Unix BSDi 3.0 SocketDUMP SocketDUMP Socket Interface GSM Network UDP / UDP Lite RLPDUMP H.263+ Decoder De-packetization RTP MultiTracer Socket Interface RLP / non RLP RLP / non RLP UDP / UDP Lite Plotting & Analysis (MATLAB) IP PPP

  4. 0 7 8 15 source port # dest port # length / coverage checksum UDP Lite (Larzon, Degemark, and Pink) • Flexible checksumming scheme allows corrupted data to be transmitted to the application • “length” field in UDP header replaced by “coverage” field • Specifies how many bytes of payload to checksum • Implemented in BSDi 3.0 kernel (Keith Slower)

  5. Transparent Mode no error control mechanism Non-Transparent Mode Uses RLP (Radio Link Protocol), a semi-reliable ARQ protocol Link resets after N=7 number of re-transmissions Fixed frame size of 30 bytes (6 bytes header) Reliability at the cost of additional end-to-end delay Window size of 62 frames Error recovery mechanisms Select - Reject (initiated by receiver) Checkpointing (initiated by sender) Physical / Radio Link Layer (GSM 9.6 kb/s)

  6. Channel Simulator: WSim Wireless Error Trace Input Video Stream WSim Output Video Stream • Allows “easy” performance study of UDP-Lite, and error resilience functionalities • Simulates two protocol configurations: • UDP, non-RLP and UDP Lite, non-RLP • Uses 215 min of GSM wireless error traces collected in a poor channel environment

  7. Performance Analysis Experiment • Collect 4480 min of wireless video traces, (~4 min per video) • Bad channel conditions (signal strength ~2-3) • Three different network configurations • UDP, RLP • UDP, non-RLP • UDP-Lite, non-RLP • For each trace, we calculated metrics • end-to-end, inter-arrival time ,loss rate and throughput • For each metric, we calculated statistics • mean & std dev Simulation • Run Wsim on “mom” video stream using a wireless error trace of 1.5% BLER

  8. Experimental Results

  9. End to End Delay

  10. Inter-Arrival Time

  11. Packet Loss

  12. Video Screenshots Experiment UDP UDP Lite Simulation UDP UDP Lite

  13. Type of Application Example Protocol Choice intolerant & rigid* TCP / RLP UDP / RLP Interactive: telnet, web tolerant & daptive* Hard real-time: wb, v-conf UDP / RLP Adaptive real-time: vic, vat UDP Lite /non-RLP Discussion & Conclusions • Reliability at link layer causes delay • Strict checksumming of UDP causes poor “error resilience” at application • UDP Lite (with GSM in transparent mode) provides • less end to end delay • constant jitter • higher throughput • lower packet loss • … than UDP • In general, can choose protocol combination appropriate for application Batch: email, ftp

  14. Future Work • Provide real-time feedback on channel conditions • Provide rate control • Incorporate unequal error protection for MPEG4

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