Handoff management schemes for HCN/WLAN interworking

Recent trends in wireless technology indicate that the future wireless networks will be the integration of two dominant evolving technologies namely cellular network and wireless local area network (WLAN) offering public wireless broadband services to end users. Wireless mobile users want high quality of service (QoS). One of the factors directly affecting QoS is the number of call drops and therefore it has to be reduced or eliminated if possible to achieve high QoS. The number of call drops experienced by a system mainly depends on its channel assignment and handoff schemes. There are two types of handoffs in such integrated networks: (i) horizontal handoff - handoff between the cells in the same layer; and (ii) vertical handoff between the cells in different layers. Vertical handoff can be further divided into two types: downward vertical handoff handover from a cell in higher layer to a cell in lower layer; and upward vertical handoff - handover from a cell in lower layer to a cell in higher layer. WLANs are in the lowest layer of the interworking. In this short paper, first we propose two simple and efficient upward vertical handoff schemes for HCN/WLAN interworking. Then modifications to random walk mobility model are presented in order to closely emulate the realistic mobility in the systems. We also conducted a simulation study to observe the performance of our proposed handoff schemes. The results illustrate that these schemes reduce the number of handoffs and system overhead in HCN/WLAN interworking.