QoS Issues for VoIP over WLAN

1
QoS Issues for VoIP over WLAN

• ?7?
• R91725004 ???
• R91725028 ???
• R91725045 ???
• R91725046 ???

2
Outline

• Challenges
• Issues
• Service differentiation
• Admission control
• Mobility management
• Expected result
• Reference

3
Challenges

• High requirements of delay and jitter
• MAC mechanism (DIFS) and high error rate of WLAN
  are not appropriate for these requirements
• 
  
• Bandwidth
• The transmission of VoIP traffic is usually CBR.
• MAC of WLAN does not provide QoS-guarantee
  service for sensitive traffic in case of heavy
  load.
  

4
Challenges

• Handover
• Handover between access points can have
  significant impact on real-time applications.
• Packet loss occurs in existing WLAN because there
  is no any make-before-break handover protocol.
• Security
• DoS?eavesdropping?interception (But these are not
  our concerns in this term project.)

5
Issues (cont)

• Service differentiation
• Provides differentiated service for real-time and
  non-real time traffic over WLAN
• Admission control
• Fixed available bandwidth
• Let each admitted VoIP session smoothly
  communicate with others

6
Issues

• Mobility management
• Mobile IP
• Hierarchical Mobile IP
• Integration of layer 2 and layer 3

7
Expected Result

• A report that consists of above three issues and
  related possible solutions
• Our proposed solutions , if possible

8
Reference

• Issues concerning usability of 802.11 networks
  for real-time service transport, Kedmenec, D.
  Kedmenec, V. Gerencir, M. Video/Image
  Processing and Multimedia Communications, 2003.
• Selective Packet Prioritization for Wireless
  Voice over IP. Siemens AG, Information and
  Communication Mobile Networks.
• "A Framework for Call Admission Control and QoS
  Support in Wireless Environments", INFOCOM 1999

9
Reference

• Voice Over IP Improving the Quality Over
  Wireless LAN by Adopting a Booster Mechanism - An
  Experimental Approach Christian Hoene, Iacopo
  Carreras, and Adam Wolisz Proe. Of SPIE 2001
• Differentiation mechanisms for IEEE 802.11, Imad
  Aad and Claude Castelluccia, Infocom 2001