A mobility model for heterogeneous wireless networks

In this paper we derive an expression for hotspot residence time of multi-mode users in heterogeneous wireless networks (HWNs) based on the general distributions of cell residence time in wireless local area networks (WLANs) and cellular networks. The hotspot boundary crossing probability during a call for different types of users are also derived analytically using realistic distributions of multi-RAN cell residence times and call holding time. Analytical results are validated using simulation results under different hotspot scenarios. Finally two examples are given to demonstrate the use of hotspot boundary crossing probabilities for calculating vertical handoff (VHO) call arrival rates in HWNs.