Abstract: The mergence of VoIP and WLAN created a new wireless platform for voice service delivery, VoWLAN. This paper figured out the capacity bottleneck of VoWLAN, and analyzed the problems in current solutions such as M-M. A novel unicast based multiplexing scheme (U-M, Unicast Multiplexing) to improve the capacity and performance of VoWLAN was proposed. Both theoretical and simulation results showed that this scheme improved the voice capacity to nearly 100% comparing to the traditional un-multiplexed scheme, and reduced the packet lost ratio by 10% compared with the M-M scheme. Meanwhile, the U-M scheme is a power-saving scheme in the voice-oriented application as well. Therefore the proposed U-M scheme is an effective solution to increase the voice capacity of WLAN and improve the performance of VoIP service.

Key words: VoIP, WLAN, MAC, packet loss rate, ETE delay

摘要： VoIP（IP语音）与WLAN（无线局域网）两者结合，产生了一种新型的无线话音传送平台：VoWLAN。针对WLAN的研究热点，分析了VoWLAN中存在的容量瓶颈，指出现有解决方案（M-M）存在的问题，提出一种基于单播方式提高VoWLAN话音容量的方案（U-M，Unicast Multiplexing），对VoIP业务性能进行了理论分析和仿真验证。结果显示，U-M方案相对于传统方案提高系统话音容量近一倍，相对于M-M方案丢包率降低10％左右，较好地保证了VoIP业务的服务质量。该方案在以话音业务为主的VoWLAN中节省了系统的功耗，是一种性能优良 的提高VoWLAN系统话音容量的方案。

关键词: IP语音, 无线局域网, 媒体访问控制, 丢包率, 时延特性