TCP with Adaptive Delay and Loss Response for Heterogeneous Networks

Long propagation delays and high bit error rates in heterogeneous networks with geostationary earth orbit (GEO) satellite links have negative impact on the performance of Transmission Control Protocol (TCP). In this paper, we propose modifications to TCP by introducing adaptive delay and loss response (TCP-ADaLR) to mitigate the adverse effects of satellite link characteristics. The proposed modifications incorporate delayed acknowledgment (ACK) recommended for Internet hosts. TCP-ADaLR introduces adaptive window increase and loss recovery mechanisms to address TCP performance degradation in satellite networks. We evaluate and compare the performance of TCP-ADaLR, TCP SACK, and TCP NewReno, with delayed ACK enabled and disabled. In the absence of losses, TCP-ADaLR exhibits the shortest user-perceived latency for HTTP and FTP applications. In the presence of only congestion losses, TCP-ADaLR shows comparable performance to TCP SACK and TCP NewReno. In the presence of only error losses, TCP-ADaLR exhibits improvements up to 61% and 76% in throughput and utilization, respectively. In the presence of both congestion and error losses, TCP-ADaLR exhibits goodput and throughput improvements up to 43%. TCP-ADaLR exhibits the best performance in the absence of losses and in the presence of losses due to both congestion and errors. It also friendly to TCP NewReno, exhibits better fairness, and maintains TCP end-to-end semantics.