A TCP Enhanced Scheme Based on Bottleneck Bandwidth Estimation for Satellite Links

Based on estimation to the bottleneck bandwidth, a TCP enhanced scheme for satellite link, TCP-BBE (TCP for bottleneck bandwidth estimation) which is improved upon TCP Reno, is brought forward. There are three key innovations in this scheme. Firstly, in the progress of bandwidth estimation, to avoid error caused by some ACK´s extra delay, more than two back-to-back packets are used by averaging their ACKs´ interval. Secondly, to avoid infecting the estimation precision by delay ACK, a reserved bit is used to reset the ACK delay send timer. Thirdly, because of packets burst in satellite link, to avoid pricking up the congestion impact by estimation packets, a small interval timer is used to space the estimation packets and the user packets. TCP-BBE modifies the congestion window and the slow start threshold in time by the estimation value. By comparing TCP-BBE to TCP Reno, the experiment result shows TCP-BBE improves the transmission efficiency obviously.