Cross Layer optimization for VoIP over WLAN [Yuan Liu Zhu]. A Presentation for Resilinets group Sarvesh Kumar Varatharajan Department of Electrical Engineering & Computer Science University of Kansas [email protected]. 23 September 2014. 23 September 2014. 1. 1. Abstract. - PowerPoint PPT Presentation
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Abstract
• Problems of VoIP over WLAN • Unacceptable voice delays when coexisting with other
applications• Low voice Capacity due to heavy headers from the
above layers
• Cross layer schemes to improve voice capacity • Voice stream enjoys fixed bandwidth.• Voice delay is minimum• Simulation at various PHY rates over various voice codec• Proposed scheme advances throughput of voice stream
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Introduction
• VoIP applications• Delay• Heavy packet headers from upper layers reduces voice
capacity• 802.11 can support only limited number of VoIP
connections• Capacity of G.711 VoIP using CBR model and a 20ms packet interval is only 12 calls[2]• A scheme is proposed where interaction with application
layer reduces delay• Time slot reuse method to increase capacity
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References
[1]YUAN Wen-peng, LIU Gan, ZHU Guang-xi,Cross-layer optimization for VoIP over WLAN,June 2007 Volume 1,No 1,Computer Technology and Application,ISSN1934-7332,USA
[2]LIN Y.-B. and Chlamtac, I. Wireless and Mobile Network Architectures, New York:Wiley,2001
[3]Chen D., Garg S., Kappes . And M. and Trivedi K. Supporting VBR VoIP traffic in IEEE 802.11 WLAN in PCF mode. Avaya Laboratories, Basking Ridge, NJ Tech. Rep. ALR-2002-026, 2002
[4]Veeraraghavan, M., Cocker, N. and Moors, T. Support of voice services in IEEE 802.11 wireless LANs Proc. INFOCOM ‘01 Apr. 2001, 1:488-497
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References
[5]Baldwin, R.O. Davis IV, N.J .Midkiff, S.F and Raines, R.A. Packetized voice transmission using RT-MAC, a wireless real- time medium access control protocol. Mobile Comput Commun. Rev 2001, 5(3):11-25
[6] Casner,S. and Jacobson, V. Compressing IP/UDP/RTP headers for low speed serial links. Proc. IETF RFC 2508, Feb 1999.