Improving TCP performance over Mobile Ad Hoc Networks using an adaptive backoff response approach

Abstract

Mobile Ad Hoc Network (MANET) suffers from temporary link failures and route changes. Moreover, TCP performs poorly when most packet losses are due to congestion. Most of research performed for improving TCP performance over MANET requires feedback from lower layers. Several attempts have been proposed for a layered TCP improvement. Yet, their percentage enhancements are not satisfactory. In this paper, we explore a new approach to improve TCP performance using a TCP layered approach. The proposed methodology depends on beginning transmission as soon as a failed route is reestablished. It utilizes an adaptive back-off response strategy through which congestion window and slow start threshold values are decreased when an acknowledgement is received. The proposed technique does not require feedback from the network layer. Simulation results showed that this approach had achieved an average performance improvement of 170/0.

Improve TCP performance over mobile ad hoc network by retransmission timeout adjustment

“…If new RTT is larger, it signifies that discovered route is more congested than broken route. So, sending rate which is dependent on congestion window size must be decreased to prevent congestion formation (5). The number of hops can affect route capabilities since packet accommodation is directly proportional to the number of hops.…”

“…However, it uses smoothed Round Trip Time instead of RTT to set retransmission timeout. ABRA measures last_srtt, min_srtt and max_srtt and experimentally found out that following relation exists between these variable [5] RTO new …”

Enhancing Congestion Control To Address Link Failure Loss Over Mobile Ad-Hoc Network

“…Thus it is serious deficiency since route recovered but TCP remains idle unnecessarily. ABRA claims that new RTO is dependent on the smooth round trip time (SRTT) [5].…”