Freeze TCPv2: An enhancement of freeze TCP for efficient handoff in heterogeneous networks

The advancement of mobile communications for the last few years has accompanied an increasingly extensive and diverse array of environments for TCP applications, which has led to a host of wireless TCP approaches that may provide more stability and ensure higher performance. In a heterogeneous network, as opposed to conventional wireless networks, a mobile node performs a handoff to another network cells with a different bandwidth and latency. Conventional wireless TCP schemes, however, are not capable of properly addressing sudden changes in round trip time (RTT) and packet loss resulting from handoffs within a heterogeneous network and do experience such problems as the waste of available bandwidth and frequent packet loss. As a solution to these problems, this paper proposes Freeze TCP version 2 (v2), an enhancement of Freeze TCP designed to dynamically obtain the available bandwidth in a new network cell. Comprehensive simulation study is conducted by using a network simulator, ns-2, to compare the proposed scheme to a few other schemes, such as Freeze TCP, DEMO-Vegas, and TCP Vegas, in a heterogeneous network environment with vertical handoffs in terms of throughput per speed of the mobile node and per bit error rate of the wireless link.