Chapter 5 - VoWLAN Challenges

Abstract

This chapter discusses the challenges of Voice-over-802.11b networks because 802.11b is the most widely deployed wireless local area network (WLAN) standard today. The wide-scale deployment of 802.11 networks means that it is possible to implement a Voice-over-IP (VoIP) solution over a WLAN instead of a wired LAN like Ethernet and VoIP can, for the first time become a wireless solution. Given that the bandwidth requirement of a VoIP stream can be minimized to about 10 kbps, an 802.11b WLAN could support hundreds of VoIP sessions. The IEEE 802.11 group defined the point coordination function (PCF) to be used with real-time traffic. Admission control can be broadly classified into two categories of authentication-based and resources-based. Authentication-based admission control refers to a procedure in which the network ensures the authenticity of the user/endpoint before allowing it to access the network. Resource-based admission control has its roots in telephony networks like public switched telephone network (PSTN) and is related to the concept of quality of service (QoS). Security in 802.11 networks is a complex issue and has been a focus of a lot of attention. The chapter concludes that 802.11 power save mechanism requires that the access point (AP) buffer packets are destined for a dozing station and inform the station about buffered packets in the beacon.