DEPLOYMENT OF FAIR SHARE AND SMART START TECHNIQUE FOR OPTIMAL USE OF AVAILABLE CAPACITY IN TCP CONGESTION CONTROL
Ganeshkumar P, K. Thyagarajah · International Journal on Information Sciences and Computing · 2009
TCP (Transmission Control Protocol) (1) was designed to provide reliable end-to-end delivery of data over unreliable networks.In theory, TCP should be independent of the technology of the underlying infrastructure.In particular, TCP should not care whether the Internet Protocol (IP) is running over wired or wireless connections.In practice, it does not matter because most TCP deployments have been carefully designed based on assumptions that are specific to wired networks.Ignoring the properties of wireless transmission can lead to TCP implementations with poor performance.In wireless and Ad hoc networks, the principal problem of TCP lies in performing congestion control in case of losses that are not induced by network congestion.Since bit error rates are very low in wired networks, nearly all TCP versions nowadays assume that packets losses are due to congestion.Consequently, when a packet is detected to be lost, either by timeout or by multiple duplicated acknowledgements (ACK), TCP slows down the sending rate by adjusting its congestion window.Unfortunately, wireless networks suffer from several types of losses that are not related to congestion, making TCP not adapted to this environment.Numerous enhancements and optimizations have been proposed over the last few years to improve TCP performance over wireless and Ad hoc Networks.These improvements include infrastructure based WLANs (2), (3), ( 4), (5), mobile cellular networking environments (6), (7), and satellite networks (8), ( 9).It is noted that the following TCP versions: Tahoe, Reno, Newreno, and Vegas perform differently in Ad hoc networks (10).However, all these versions suffer from the AbstractThe traditional TCP congestion control mechanism encounters a number of new problems and suffers in poor performance.In traditional TCP congestion control, slow start results in poor performance.During slow start the number of TCP segments transmitted per unit time is considerably small compared to the capacity of the Network.It increases gradually according to the RTT.In this paper, an attempt is made to increase the performance of the TCP by introducing a two new technique called Adaptive Fair Share of Congestion window size (AFSCOW) and Smart Start (SS).AFSCOW can be used for the new TCP connections emerging in the end systems having same sender and receiver.For an emerging new application in the sender the window size can be determined as the total of the current window sizes of the existing application divided by the total number of application including the new emerging application.In Fast Start the number of TCP segments transmitted is not doubled but it is increased three times the older window size which shows the optimum use network resources within minimum RTT.