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

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SureCall: Towards Glitch-Free Real-Time Audio/Video Conferencing Amit Mondal, Northwestern University Ross Cutler, Microsoft Corporation Cheng Huang, Microsoft Research – PowerPoint PPT presentation

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


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 (Infonetics Research,
    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/che
    ngh/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. audiovideo
  • 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 gt80
and false positive rate lt 1 for T1T20.07.
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
WiFi Relay
  • Evaluated on SureCall platform
  • Simultaneous direct and overlay VoIP call
  • An apple-to-apple comparison

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
  • WiFi Relay
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