A Multimedia and VoIP-Oriented Cell Search Technique for the IEEE 802.11 WLANS

Abstract

With the development and widespread of diverse wireless network technologies such as wireless local area networks (WLANs), the number of mobile internet users keeps on growing. This rapid increase in mobile internet users records a phenomenal growth in the deployment of the IEEE 802.11 WLANs (IEEE Std 802.11, 1999) in various environments like universities (Corner et al., 2010; Hills & Johnson, 1996), companies, shopping centers (Bahl et al., 2001) and hotels. This category of networks then will be the underlying basis of ubiquitous wireless networks by decreasing infrastructure costs and providing stable Internet connectivity at anytime and anywhere (Kashihara et al., 2011; Kunarak & Suleesathira, 2011). Hence many believe that are expected to be part of the integrated fourth generation (4G) network. At the same time, voice over IP (VoIP) is expected to become a core application in the ubiquitous wireless networks, i.e., the next generation cell-phone. Recently, many users have easily used VoIP communication such as Skype (Skype, 2003) in wireless networks. However, in the mobility context WLANs become not appropriate to the strict delay constraints placed by many multimedia applications, and Mobile Stations (MSs) cannot seamlessly traverse the 802.11 Access Points (APs) during VoIP communication due to various factors such as the inherent instability of wireless medium and a limited communication area. MSs are required to find and then to associate with another AP with acceptable signal quality whenever they go beyond the coverage area of the currently associated AP. The overall process of changing association from one AP to another is called handoff or handover process and the latency involved in the process is termed as handoff latency.