A traffic probing based handoff algorithm for heterogeneous networks

From the view of resource management, when a WLAN is overloaded, multimode mobile stations should not handoff to it even if the stations are entering the coverage area of the WLAN. We propose a novel handoff algorithm between a WLAN and WCDMA networks based on the traffic condition of the WLAN. Rather than taking the WLAN´s traffic condition as a priori information (e.g., traffic announcement from access points of WLANs), in the proposed algorithm a station is required to probe a WLAN´s traffic load. If the WLAN is overloaded, stations will give up the handoff to it. A mathematical model is used to analyze the probability that a station docs not handoff to a WLAN. Some numerical results are presented. It´s shown that the traffic condition of a WLAN has significant impact on the successful probability of the handoff to the WLAN. The effects of some systematic parameters, such as the number of max backoff stages and initial contention window size, are also investigated.