Connectivity support in heterogeneous wireless networks

In this chapter we show how heterogeneous networks for next generation multimedia systems can cooperate in order to provide seamless mobility support to mobile users requiring high multimedia Quality-of-Service (QoS) constraints (Knightson et al., 2005). We describe the traditional techniques of Vertical Handover in heterogeneous wireless networks. Basically, in Section 2 we introduce the main characteristics of handover process and our effort is addressed on a first handover classification, which distinguishes between horizontal and vertical, hard and soft, upward and downward procedures, and more. We also give an overview of current IEEE 802.21 standard for seamless connectivity in heterogeneous environments. In Section 3 we describe different decision metrics for handover mechanisms. Various metrics triggering handover decisions, including multi-parameters QoS, and mobile terminal location information, will be described in detail. Moreover, a hybrid approach which exploits both power measurements and location information is presented. Finally, conclusions are drawn in Section 4.