Research For Path Handoff Policies With MSCTP

With the development of wireless communication technology,it is an obvious trend that we can access to Internet using heterogeneous wireless access networks. Mobile terminals may be through a number of wireless access networks in the process of moving,so the paths in the association are dynamic change.So,dynamic path set management is repuried,including add paths,delete paths and so on.Therefor in the mobile environment,the dynamic path set management to multi-interface mobile terminal has become an important subject.Among them,the path handoff is one of the important reseaech issues.The path handoff based on an connectivity management scheme is analyzed.An connectivity management scheme is based on transport layer protocol mSCTP,and use multihoming and dynamic address extension and the key factor-decouple the congestion control for the whole data transmission with the flow control for each path.The connectivity management scheme is proposed to realize the integration of bandwidth aggregation and mobility supporting at transport layer.The major path management functions were defined and the path handoff procedure was introduced, The transmission path subset policy was proposed.The focus on influence of the path handoff in the connectivity management are analyzed in this paper first,and the question that the path handoff in the connectivity management has been put forward:(1)the objection,which solves paths’performance degradation which relies on packet loss is obvious.The objection leads to the increase of path handoff latency,degradation of capability on the path,decrease of the throughout on the network.(2)after the path handoff,the new path can only send two pac-kets at the beginning,then in RTT continue to send packets.As a result,The set decides that the transmission of the new path is very low.So,It leads that the throughout of the association is low. This paper analysis these two issues in-depth and points out the corresponding solutions:(1)In order to solve the problem exist in the path handoff in the case of the path’s performance deteriotation,the proposed schemes named Path Handoff Algorit-hm-Oriented QoS&RTT.The algorithm is based on QoS on the path and use back-to-back RTT.(2)After path handoff,the new paths’congestion window is small,the transmission speed of the new path is low.In order to solve the problem,the initial congestion window is expanded.The initial window of the new path is broadened to the half size of the minnum of the congestion windows of the former paths.So,the path’s transmission ratio and the throughout of the association are improved The simulation results are provided showing how the proposed scheme pvovides better performance to path handoff.Finally, the research is concluded with future work and the suggestions are proposed.