Efficient handover scheme in wireless ATM networks

Abstract

The future mobile wireless communication networks are to be required to support not only voice but also various multimedia data. WATM network based on ATM networks is a candidate of the next generation wireless communication network to support broadband multimedia data services. There are some technical problems in order to support user mobility in WATM networks. One of them is the handover problem that the connection path must be rerouted to the new cell to which a mobile user moves. The crucial elements of the handover in WATM networks are the handover delay and the handover efficiency. Until now, the researches of the handover in WATM networks mostly focus on minimizing handover delay, so it results on the inefficiency of network resource. In larger size broadband Wireless ATM networks it is critical to network capacity. In this thesis, we research handover schemes that improve handover efficiency in WATM networks by considering handover delay and efficiency in the handover. Other handover schemes that focus on only handover delay worsen handover efficiency because the result path after the handover is longer than the shortest path of the connection during frequent handovers. This kind of schemes consequently requires more network resources, increases end-to-end delays in connections and decreases network efficiency. To resolve this problem, we propose new COS conditions of the partial path rerouting handover scheme, which are the delay limited COS condition that enables to handover within the tolerable delay and to improve handover efficiency and the efficiency guided COS condition that enable to keep the efficiency guideline and to reduce the handover delay. Furthermore, we proposed a new COS searching method: best-fit COS search method using two-step adaptive backtracking manner. This COS search method can search for the COS best satisfying the given COS condition among the COS candidates checked during backtracking. In addition, it determines the number...