Y.-T. Chen and L.-B. Hsu (Taiwan)
Wireless LAN, medium access control, and multimedia
In recent years, high-speed wirelesses LANs are widely deployed in airports, stations, hotels and street corners. Transmitting video and audio over wireless LANs becomes an important trend. Hence, service differentiation and throughput enhancement become important issues in multimedia wireless LANs. In this paper, we extend Distributed Coordinated Function (DCF) in IEEE 802.11e to provide alternatives for service differentiation, and improve throughput for live video and audio over error-prone wireless LAN. Backoff procedure becomes a performance bottleneck for Media Access Control (MAC) protocol in IEEE 802.11. Hence, we propose an adaptive two-stage backoff counter to reduce the overheads in blocking backoff counter. Furthermore, we explore the proactive frame drop policy to eliminate unnecessary retransmissions of video and audio frames under poor channel conditions. To investigate the performance of the proposed schemes, we run intensive computer simulation using ns-2, and compare performance with EDCF in IEEE 802.11e in terms of throughput and delay. .
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