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SureCall: Towards Glitch-Free Real-Time Audio/Video Conferencing

SureCall: Towards Glitch-Free Real-Time Audio/Video Conferencing. Amit Mondal, Northwestern University Ross Cutler, Microsoft Corporation Cheng Huang , Microsoft Research Jin Li, Microsoft Research Aleksandar Kuzmanovic, Northwestern University. Physical Presence or United Communications?.

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SureCall: Towards Glitch-Free Real-Time Audio/Video Conferencing

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  1. SureCall: Towards Glitch-FreeReal-Time Audio/Video Conferencing Amit Mondal, Northwestern University Ross Cutler, Microsoft Corporation Cheng Huang, Microsoft Research Jin Li, Microsoft Research Aleksandar Kuzmanovic, Northwestern University

  2. Physical Presence or United Communications? • Attending meeting in person is nice, but the overhead due to travel is high & unpredictable • Unified Communications promise • VoIP service double in next 4 years, with an annual growth rate of 26% (InfoneticsResearch, 2008) not being there, but better than being there

  3. Booming of Unified Communications • Widely validated in the consumer world • Gradually being adopted by enterprises • Cisco acquired WebEx • Google announced acquisition of GIPS, which powers • Microsoft Unified Communications

  4. Contributions • SureCall platform • A distributed measurement and experiment platform for audio/video conferencing • Quantitatively analyze the impact of network over a wide variety of scenarios in fine granularity • Validate new solutions

  5. SureCall Platform • A distributed measurement and experiment platform • SureCall agents installed on volunteers’ machines • Measurements & experiments driven by a master controller • Packet-level traces collected & analyzed • Agents upgradeable without user intervention • Available from http://research.microsoft.com/~chengh/SureCall/SureCall.htm

  6. SureCall Measurements • Emulated bidirectional audio/video sessions using UDP • 5-minute session per hour • Audio bitrate : 24 kbps • Video bitrate: 192 kbps • STUN NAT traversal protocol for home users • Network connectivity close to the clients • ICMP packet pair with TTL = 2 • Traceroute to at the beginning and end of each session • Environmental details on client machines • CPU load, network interface type

  7. SureCall Deployment • Microsoft global enterprise network & many residential networks • Current deployment status • 80 unique machines • Enterprise - 32 • Home – 20 • Both – 28 • Enterprise trace and Home trace • two separate master controllers (within the enterprise network and on the Internet)

  8. SureCall Data Set • 4,800 hours of packet traces • 4,100 from enterprise • 700 from home • 1,968 unique IP addresses • Enterprise - 1212 • Home -756 • Trace classification and stratification • Intra-continental vs. inter-continental • Wired vs. wireless • Audio-only vs. audio+video • Trace preprocessing • Clock skew removal 8 Clock skew in wild

  9. Jitter in Enterprise and Home Networks US-US, wired traces Inter-continental, wired traces Home networks have significantly higher jitter compared to enterprise networks and affected greatly by inter-continental links.

  10. Correlation between Loss Burst Length and Jitter Home Enterprise End-to-end jitter increases significantly before loss events in both enterprise and home networks(~ 80%) Increase in end-to-end jitter is not a great indicator of loss burst length in enterprise networks.

  11. Network Audio Diagnostics • Concealed: percent of packets interpolated or extrapolated due to unrecovered packet loss • Stretched: percent of packets stretched via time compression • Classifier operates as follows • Supervised training with ground-truth objectively determined by PESQ score

  12. Audio Classifier Performance The classifier achieves a true positive rate >80% and false positive rate < 1% for T1=T2=0.07.

  13. WiFi Relay • Wireless connections experience significantly more packet losses than wired connections • Heavy replication is a effective manner to hide packet losses in wireless channel • WiFi relay solution

  14. Evaluated on SureCall platform • Simultaneous direct and overlay VoIP call • An apple-to-apple comparison WiFi Relay WiFi relay greatly reduces packet loss and significantly improves VoIP quality for WiFi users

  15. Conclusion • SureCall, a distributed measurement and experimental platform, to address the challenges of audio/video communications. • Characterized enterprise and residential networks over a wide variety of network scenarios • Two applications of SureCall • Network audio diagnostics • WiFiRelay

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