Efficiency and fairness of new-additive increase multiplicative decrease congestion avoidance and control algorithm

When using of the Internet increased dramatically; the congestion avoidance problem became even more important. The congestion is usually caused by the multiplexing for packets when the packets are at the bottleneck links. Efficiency and fairness are the important metrics in the performance of congestion avoidance mechanisms. And also all of the researches for the congestion avoidance algorithms, interest about this parameters metrics to evaluate the performance of the algorithms. This research studied the performance of the New-Additive Increase Multiplicative Decrease (AIMD) algorithm as one of the core protocols for the TCP congestion avoidance and control mechanism. In addition, to evaluate the effect of using the AIMD algorithm after its development to measure the efficiency and fairness and find new enhancement results for our approach, which named as the New-AIMD algorithm. The NCTUns simulator is used to obtain the results after implementing the modifications to the mechanism

An enhanced TCP congestion avoidance scheme and its performance evaluation in high speed satellite networks

High speed satellite communication networks are emerging as part of the future global wireless communication systems. However, existing transmission control protocols for satellite networks do not provide satisfactory performance over high speed satellite links due to their inefficient congestion avoidance algorithms. This paper identifies the reason for low throughput of a widely used protocol Space Communications Protocol Specification (SCPS) in such networks and proposes a new Transmission Control Protocol (TCP) congestion avoidance algorithm to overcome the drawback of the congestion avoidance algorithm used in the SCPS protocol. Numerical results through simulations demonstrate that the proposed new algorithm can achieve significant throughput improvement over links with variable error rates, compared with its legacy counterpart

End-to-End Algebraic Network Coding for Wireless TCP/IP Networks

The Transmission Control Protocol (TCP) was designed to provide reliable transport services in wired networks. In such networks, packet losses mainly occur due to congestion. Hence, TCP was designed to apply congestion avoidance techniques to cope with packet losses. Nowadays, TCP is also utilized in wireless networks where, besides congestion, numerous other reasons for packet losses exist. This results in reduced throughput and increased transmission round-trip time when the state of the wireless channel is bad. We propose a new network layer, that transparently sits below the transport layer and hides non congestion-imposed packet losses from TCP. The network coding in this new layer is based on the well-known class of Maximum Distance Separable (MDS) codes.Comment: Accepted for the 17th International Conference on Telecommunications 2010 (ICT2010), Doha, Qatar, April 4 - 7, 2010. 6 pages, 7 figure

Enhancing Datagram Congestion Control Protocol for Efficient Long Delay Link

Most of the multimedia applications use the User Datagram Protocol (UDP) as a transport layer protocol because it is suitable for the delivery of multimedia data over the Internet. However, the use of UDP could endanger the stability of the network because there is no congestion control applied. To a certain extent, the network can collapse if too many applications deliberately use this protocol. Subsequently, instead of using the UDP, the applications have choices to use the Datagram Congestion Control Protocol (DCCP), which has a built-in congestion control that can provide a better network. Nevertheless, the congestion control mechanism in the CCID-2 TCP-like can cause problems when delivering multimedia data over a long delay link. To alleviate the problems, such as longer time taken for achieving maximum throughput, and throughput fluctuation during a congestion avoidance phase, two approaches have been used, i.e. setting of an appropriate slow-start threshold value and manipulating congestion window during a congestion avoidance phase. A new congestion control mechanism presented in this thesis, namely the "TCP-like Threshold Window (TCP-like TW)" is designed based on the advantages of the two approaches. It has been developed and modeled in the Network Simulator 2 (ns-2). The TCP-like TW has proven to enhance the performance of the DCCP when delivering multimedia data over long delay link networks, as well as over short delay. For a long delay link, the TCP-like TW congestion control mechanism is able to minimize the time taken to achieve the maximum throughput. It can smooth the fluctuation of throughput after achieving the maximum throughput. Furthermore, for the short delay link, the maximum throughput will be increased while maintaining the friendliness towards other congestion-controlled protocols