Using cross-layer information to improve TCP performance with vertical handoffs

Abstract

this paper we study the performance of TCP with a vertical handoff between access networks with widely varying link characteristics. TCP being an end-to-end protocol has performance problems as its behaviour depends on the end-to-end path characteristics which are likely to be affected by a vertical handoff. We propose a set of enhancements to the TCP sender algorithm that leverage on explicit cross-layer information regarding the change in the access link delay and bandwidth. We apply our enhanced algorithms and carry out a systematic study comparing the performance of the regular TCP to the performance of the enhanced TCP algorithms in various handoff scenarios between access networks having widely different bandwidth and delay characteristics. Our experiments show that with cross-layer notifications TCP performance can be improved significantly in most vertical handoff scenarios.