Ping-pong avoidance algorithm for vertical handover in wireless overlay networks

In this paper, we propose a ping-pong avoidance algorithm capable of effectively alleviating the unnecessary vertical handovers between 3G cellular and WLAN hotspots. The proposed algorithm determine the appropriate time at which a terminal should initiate a handover. It can be classified into two major schemes: One is designed to separate the single vertical handover threshold; the other to estimate the transition of the beacon signal strengths received by the terminal from WLAN hotspots on the basis of the least square approach. The aim of this study is to prevent such performance degradations as the increase of the service interruption time which follows unnecessary vertical handovers.