1. 1 A Multimedia Architecture for 802.11b network Berthou, P.; Gayraud, T.; Alphand, O.; Prudhommeaux, C.; Diaz, M.; Wireless Communications and Networking, 2003. WCNC 2003. 2003 IEEE, Volume: 3, 16-20 March 2003 Page(s): 1742 -1747 2003.11.19 NCNU CSIE MCL network group, Group Meeting

2. 2 Outline Introduction Introduction Multimedia Communication in 802.11 Multimedia Communication in 802.11 Wireless Networks Wireless Networks A Multimedia Architecture For 802.11b A Multimedia Architecture For 802.11b Performance Evaluation Performance Evaluation Conclusion Conclusion

3. 3 Multimedia Communication in 802.11 Wireless Networks Multimedia communication QoS requirements Multimedia communication QoS requirements Quality of service in 802.11b networks Quality of service in 802.11b networks (1) Dynamic Rate Shifting (1) Dynamic Rate Shifting (2) A difficult cohabitation btw low and (2) A difficult cohabitation btw low and high rates high rates (3) 802.11 drawbacks for multimedia (3) 802.11 drawbacks for multimedia communication communication

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10. 10 i.e. 0.848 Mbps/user for delivering the same amount of data (1534 bytes)

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12. 12 A Multimedia Architecture For 802.11b Disabling DRS in multimedia context Disabling DRS in multimedia context Performance Enhancing Proxy to restore QoS Performance Enhancing Proxy to restore QoS A strategic location A strategic location Limitation Limitation

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15. 15 Performance Evaluation testbed: testbed: 11 Mbps 802.11 WLAN + wire WAN 11 Mbps 802.11 WLAN + wire WAN network delay: network delay: WLAN: 10ms, WAN: 100ms WLAN: 10ms, WAN: 100ms every 10s, reliability decreased every 10s, reliability decreased (BER:0  10 -4 ) (BER:0  10 -4 ) TCP throughput: TCP throughput: # delivered packets /s # delivered packets /s

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19. 19 Conclusion The 802.11b dynamic rate shifting mechanism is proposed to be disabled and replaced by a Performance Enhancing Proxy at the wireless network edge. The 802.11b dynamic rate shifting mechanism is proposed to be disabled and replaced by a Performance Enhancing Proxy at the wireless network edge. This multimedia architecture could be a cheap solution for the already deployed 802.11b networks.