Simulations on TCPW ABSE in Mobile Ad Hoc Networks

TCP Westwood (TCPW) is a TCP protocol relying on a continuous estimation of the packet rate of a connection. Based on the ACK reception rate, a sender computes the congestion window and slow start threshold settings after a congestion period in the network. Given that, TCP throughput greatly depends on how fast and accurate these estimates are made. In this paper, we study TCPW ABSE bandwidth estimation effectiveness. This study was performed using scenarios intended to recreate some ad hoc networks’ characteristics, especially ACK compression effects, nodes mobility and load changes. Results revealed that TCPW ABSE gives negative bandwidth estimates. The second remark is that those estimates oscillate on a large scale. We introduced an enhancement to TCPW ABSE operation to fix these problems and validate it via simulations.