VoIP over WLAN: voice capacity, admission control, QoS, and MAC

Voice over Internet Protocol (VoIP) is one of the fastest growing Internet applications. It is a viable alternative to the traditional telephony systems due to its high resource utilization and cost efficiency. Meanwhile, Wireless Local Area Networks (WLANs) have become a ubiquitous networking technology that has been deployed around the world. Driven by these two popular technologies, Voice over WLAN (VoWLAN) has been emerging as an infrastructure to provide low-cost wireless voice services. However, VoWLAN poses significant challenges since the performance characteristics of wireless networks are much worse than that of their wireline counterparts, and the IEEE 802.11-based WLAN was not originally designed to support delay-sensitive voice traffic. In this paper, we provide a survey of recent advances in VoWLAN voice capacity analysis, call admission schemes, and medium access control (MAC) layer quality of service (QoS) enhancement mechanisms. Some open research issues are presented for further investigation. Copyright # 2006 John Wiley & Sons, Ltd.