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Adaptive Rate Control for IIAC Communication

This study explores optimizing quality of experience for IIAC through adaptive rate control. It addresses various parameters and operational ranges, aiming to find optimal solutions for different user needs and trade-offs. It also investigates the use of DCCP and Push-To-Talk mode for enhanced performance.

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Adaptive Rate Control for IIAC Communication

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  1. Rate Adaptation for the IETF IIAC Patrick Schreiner,Christian Hoene Universität Tübingen WSI-ICS 26. July 2010

  2. Problem Statement • The IIAC is likely to have many parameters: • Coding rate (kbit/s) • Sampling rate (kHz) • Packet length (ms) • DTX/VAD/music/speech mode • Complexity • Look-ahead (ms) • Channels (x) • The IIAC will have a broad range of operation • 8 till 192*x kbit/s • 8 till 48 kHz • 2 till 160ms delay • Many different devices • Many different link qualities on the Internet Problem: When to set which codec parameter how?

  3. Operational Range of Contributed Codecs

  4. Many different platforms (and interests)

  5. Goal: Optimize Quality of Experience • ITU-T P.10/G.100 defines “Quality of Experience” The overall acceptability of an application or ser-vice, as perceived subjectively by the end-user. • Extension at ITU-T G.RQAM Quality of experience includes the complete end-to-end system effects (client, terminal, network, services infrastructure, etc.). Overall acceptability may be influenced by user expectations and context.

  6. Advertising DCCP • Offering congestion control and fairness like TCP • but fast delivery (no retransmissions) • Easy application interface • API gives you currently available TX rate and RTT • Implementations available • user-space and Linux kernel • Supports variable packet sizes • important for VoIP • Does DCCP solve all problems? • No feedback on month-to-ear delay • which is important for QoE • No feedback on computational latency • Which important for predicting MtE delay and for low cost devices

  7. Report on running code(c) • Master Thesis of Patrick Schneider • Implemented DCCP+SBC+PLC(SBC as replacement for a not yet existing IIAC) • Supporting • Rate control without difficulties (Optimal parameter selection is not yet achiable) • Switches to Push-To-Talk mode • if link speed falls below coding rate • We conducted conversational-tests comparing • UDP+packet loss • DCCP+DTN

  8. Research Results • Using SBC mono with 16 to 48 kHz • Using a network simulator for bw limits and packet losses • AVoIP refers to DCCP plus Push to Talk mode

  9. Summary • IWAC+RTP+DCCP is useful combination • but need protocol support for (fast) control loop • feedback on complexity (computational delay) • month-to-ear delay (when frame have been play out) • in RTP payload format or RTP header extensions? • Vendor specific optimizations on parameter trade-off shall be possible • to adapt to different user needs • to find an „optimal“ solution • Push-To-Talk mode helps • for low bandwidth lines • also for short handover interruptions

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