Analyzing TCP Performance in High Bit Error Rate Using Simulation and Modeling

While Transmission Control Protocol (TCP) works well with a low bit error rate (BER), the performance of TCP degrades significantly if the BER rises above a certain level. A study of the performance of TCP with high BER is required for the efficient design and deployment of such systems. In this paper, we address the problem of TCP performance in high BERs and analyze the issues by investigating the effect of BERs on system performance. We consider TCP Reno in our study to explore the system performance using extensive analysis of simulation and modeling. In the analysis, we consider the amount of datagram sent and retransmitted, mean throughput, link-layer overhead, TCP window size, FTP download response time, packet dropping and retransmission, and the TCP congestion avoidance mechanism. We validate simulation results by setting up a virtualized testbed using Linux hosts and a Linux router. The results obtained show that TCP throughput degrades significantly and eventually collapses at the packet drop probability of 10% (BER = 10−5). The FTP download response time is about 32 times longer than that of a perfect channel (no packet dropping). We found that TCP Reno cannot handle such a high BER to operate in wireless environments effectively. Finally, we provide recommendations for network researchers and engineers confronted with the challenge of operating TCP over noisy channels

Efficient Medium Access Control with IEEE 802.11 for Mobile Ad Hoc Networks

The IEEE 802.11 Medium Access Control (MAC) protocol has inherent weakness of channel wastage while operating a Mobile Ad hoc Network (MANET). In this paper, we therefore propose several new mechanisms we collectively name as Exhaustive MAC, to alleviate this problem and thus improve performance of IEEE 802.11 in MANETs. The basic principle of our proposals is to ensure utilization of channel capacity that is otherwise wasted. In addition to the concept of extra frame transmission during the wasted reservation period, our main contributions in this paper include (i) idea of RTS Release (RTSR), (ii) channel rescue and reuse, (iii) moving the state of the channel forward through ahead-of-time decrement of back-off timer. In addition, our proposed mechanisms are free from compatibility problems with standard IEEE 802.11

Efficient Medium Access Control with IEEE 802.11 for Mobile Ad Hoc Networks

The IEEE 802.11 Medium Access Control (MAC) protocol has inherent weakness of channel wastage while operating a Mobile Ad hoc Network (MANET). In this paper, we therefore propose several new mechanisms we collectively name as Exhaustive MAC, to alleviate this problem and thus improve performance of IEEE 802.11 in MANETs. The basic principle of our proposals is to ensure utilization of channel capacity that is otherwise wasted. In addition to the concept of extra frame transmission during the wasted reservation period, our main contributions in this paper include (i) idea of RTS Release (RTSR), (ii) channel rescue and reuse, (iii) moving the state of the channel forward through ahead-of-time decrement of back-off timer. In addition, our proposed mechanisms are free from compatibility problems with standard IEEE 802.11

TCP-LoRaD: A Loss Recovery and Differentiation Algorithm for Improving TCP Performance over MANETs in Noisy Channels

Mobile Ad hoc Networks (MANETs) are becoming popular technologies because they offer flexibility in setting up anytime and anywhere, and provide communication support on the go. This communication requires the use of Transmission Control Protocol (TCP) which is not originally designed for use in MANET environments; therefore, it raises serious performance issues. To overcome the deficiency of the original TCP, several modifications have been proposed and reported in the networking literature. TCP-WELCOME (Wireless Environment, Link losses, and Congestion packet loss ModEls) is one of the better TCP variants suitable for MANETs. However, it has been found that this protocol has problems with packet losses because of network congestion as it adopts the original congestion control mechanism of TCP New Reno. We also found that TCP-WELCOME does not perform well in noisy channel conditions in wireless environments. In this paper, we propose a novel loss recovery and differentiation algorithm (called TCP-LoRaD) to overcome the above-mentioned TCP problems. We validate the performance of TCP-LoRaD through an extensive simulation setup using Riverbed Modeler (formerly OPNET). Results obtained show that the proposed TCP-LoRaD offers up to 20% higher throughput and about 15% lower end-to-end delays than the TCP-WELCOME in a noisy channel under medium to high traffic loads

TCP-LoRaD: A Loss Recovery and Differentiation Algorithm for Improving TCP Performance over MANETs in Noisy Channels

Mobile Ad hoc Networks (MANETs) are becoming popular technologies because they offer flexibility in setting up anytime and anywhere, and provide communication support on the go. This communication requires the use of Transmission Control Protocol (TCP) which is not originally designed for use in MANET environments; therefore, it raises serious performance issues. To overcome the deficiency of the original TCP, several modifications have been proposed and reported in the networking literature. TCP-WELCOME (Wireless Environment, Link losses, and Congestion packet loss ModEls) is one of the better TCP variants suitable for MANETs. However, it has been found that this protocol has problems with packet losses because of network congestion as it adopts the original congestion control mechanism of TCP New Reno. We also found that TCP-WELCOME does not perform well in noisy channel conditions in wireless environments. In this paper, we propose a novel loss recovery and differentiation algorithm (called TCP-LoRaD) to overcome the above-mentioned TCP problems. We validate the performance of TCP-LoRaD through an extensive simulation setup using Riverbed Modeler (formerly OPNET). Results obtained show that the proposed TCP-LoRaD offers up to 20% higher throughput and about 15% lower end-to-end delays than the TCP-WELCOME in a noisy channel under medium to high traffic loads