Providing Seamless Communication in Mobile Wireless Networks

This paper presents a technique to provide seamless communication in mobile wireless networks. The goal of seamless communication is to make the motion of a mobile host transparent to the applications executing on it. Active handoos (handoos during an active connection) cause pauses in communication between the mobile host and the xed network, resulting in applications seeing a substantial performance degradation. The motivation behind this study is to nd a cost eeective solution for minimizing impact of active handoos on connection throughput. Existing solutions either provide total guarantee for seamless communication, incurring heavy network bandwidth usage (multicast based approach), or do not provide any guarantee for seamless communication (unicast based approach). Some other solutions are tuned to give good performance for speciic protocols (e.g., fast-retransmit approach). This paper proposes a novel staggered multicast approach which provides a prob-abilistic guarantee for seamless communication independent of the communication protocol used. The main advantage of the staggered multicast approach is that it exploits the performance guarantees provided by the multicast approach and also provides the much required savings in the wired network bandwidth. 1 We present experimental results of performance improvements achieved by our scheme, for data transfer using TCP over a wireless network in the presence of active handoos. The conclusions however, are generic in that they apply to protocols other than TCP.