Handoff Decision Strategies And Algorithms In Heterogeneous Wireless Network

The integration of heterogeneous wireless networks is a trend for the future wireless communication system. As a variety of wireless access technologies coexist in a geographical area, the multimode terminal, which equipped with multiple heterogeneous network interfaces, can connect/switch to the most suitable network(s). In order to provide seamless mobility and session continuity, the handoff decision strategy in heterogenous wireless network is regarded as a significant and challenging issue. In this paper, many existing handoff decision strategies and algorithms have been reviewed, and the implementation of handoff has also been introduced.According to the characteristic of heterogeneous wireless networks, we proposed a handoff decision algorithm considering parallel transmission. In the proposed algorithm, the handoff decision problem is formulated with the MDP model with the objective of maximizing the expected total reward during the transmission. And the total reward is calculated with a tradeoff between the benefit function (QoS provided by link) and the penalty function (handoff cost or/and connection dropping). For both scenarios of stationary terminal and mobile terminal, the handoff decision algorithm is detailed. Many simulations have been run for verifying the proposed algorithm.For the scenario of group mobility, a flow-handoff based group handoff strategy was proposed. In this stategy, each service flow can select network independently. As a result, it may increase the satisfaction of users and the utilization of network resources. The problem can be formulated as a 0-1 integer linear programming with some restricted conditions, because that the handoff action for the terminal is restricted by the mobility and the number of wireless interfaces. Finally, simulation setting and numerical results are presented.