1. Sunhun Lee and Kwangsue Chung School of Electronics Engineering, Kwangwoon University 22 nd International Conference on Advanced Information Networking and Application Joint Quality and Rate Adaptation Scheme for Wireless Video Streaming

2. Outline Introduction Background Cross-layer design Performance evaluation Conclusion

3. Introduction This paper proposed a new cross-layer design for video streaming over wireless network that jointly considers the application and the lower layers(PHY and MAC) to imporve the wireless link utilization by adapting the data transmission to the current channel condition. Quality adaptation scheme – Application Rate adaptation scheme – MAC and PHY

4. Background IEEE 802.11 WLAN DCF (Distributed Coordination Function) – CSMA/CA PCF (Point Coordination Function) – polling etc…(RTS/CTS) IEEE 802.11 PHY provides multiple data transmission modes. (ex.1, 2, 5.5 and 11 Mbps are support at 2.4GHz ISM band in 802.11b)

5. Background IEEE 802.11 WLAN Rate adaptation scheme Higher data rate does not yield a higher throughput. Basic idea of these scheme have been proposed is to estimate the channel quality and adjust the data transmission mode accordingly. 1. Statistics-based Maintain statistics about the data delivery such as the PER/BER (Packet Error Rate / Bit Error Rate). oARF (Auto Rate Fallback) oCARA (Collision-Aware Rate Adapation) 2. Quality-based Measure SNR (Signal to Noise Ratio) or SSI (Signal Strength Indicator). oRBAR (Receiver-Based Auto Rate)

6. Cross-layer design Overview

7. Cross-layer design Overview Rate adaptation scheme in our design This paper proposed a new scheme, called SARA (Sender-oriented Automatic Rate Adaptation) Quality-based RTS frame is used when the size of pending data is equal to or larger than the RTS threshold. RSSI (Received Signal Strength Indicator) instead of SNR

8. Cross-layer design Overview Rate adaptation scheme in our design

9. Cross-layer design Overview Rate adaptation scheme in our design Quality adaptation scheme in our design Rate limit is calculated based on the packet pair algorithm and periodically notified to the quality of video stream. Quality adaptation scheme uses the hierarchical encoding scheme, specifically the FGS (Fine Granularity Scheme) algorithm of MPEG-4 standards determined sending rate. This paper think that the hierarchical encoding scheme is not employed to streaming application because encoders with this capability are rare.

10. Performance evaluation NS-2 BSS mode (Include AP and Stations) CBR (Constant Bit Rate) traffic at a rate 4Mbps Simulation time 50s 10-30 low speed 30-40 medium speed 40-50 high speed

11. Performance evaluation

17. Quality adaptation

18. Conclusion This paper proposed a idea that combines the rate adaptation with the quality adaptation for providing improved wireless video streaming service. In future, they want to extend their design to the wired-cum- wireless convergence network environments.