Improvement of TCP Vegas algorithm based on forward direction delay

Abstract

Satellite networks transmit data through the space communications protocol specification transport protocol and uses transmission control protocol (TCP) Vegas as the congestion control algorithm. However, TCP Vegas does not have a suitable solution for the asymmetric bandwidth of satellite networks. Therefore, the reverse link of asymmetric bandwidth frequently causes congestion in satellite networks. This issue is addressed by reducing the congestion window with the occurrence of reverse link congestion, thereby simultaneously reducing the forward link throughput of the satellite network. In this study, a forward congestion control algorithm for the TCP Vegas algorithm based on time delay, which is called Vegas_FDD (forward direction delay), is proposed to mitigate congestion by dividing it into different types (forward and backward) and to improve network bandwidth utilisation. The suitability and effectiveness of the proposed algorithm are verified through simulation on Opnet software.