Abstract: Reliable end-to-end delivery of ...

Abstract:
Reliable end-to-end delivery of data over unreliable network can be achieved with help of Transmission Control protocol (TCP). Most of the TCP implementation or deployments have been designed with respect to wired networks and by ignoring the wireless properties of AD Hoc Networks can lead to poor performance. To implement TCP in AD Hoc network various improvements (ideas) have been proposed in literature. These ideas will help TCP to identify different types of losses which occur in wireless networks (Ad hoc).Losses happening in static or mobile Ad hoc network are not always due to network congestions (happen mostly in wired networks) .
In this paper we will see how mobility and lower layers protocol affects TCP and will see how to implement TCP in Ad hoc network (mobile and static).
Introduction:
A complex system which has wireless mobile or static nodes that can dynamically organize by it-self is called as Ad Hoc Networks. In Ad Hoc Networks device can interconnect with each other in areas where there is no existing infrastructure. New technologies like Bluetooth helped implementation of Ad Hoc easily for commercial purpose.
As we all know TCP is designed to provide reliable data transfer in unreliable networks. In theory TCP must not depend upon the underlying technology i.e. TCP should not care whether IP (Internet Protocol) is running over wired connection or wireless connection. But in practical implementation TCP has been specifically designed for wire networks by ignoring the wireless transmission properties. TCP is implemented in wireless network will lead to poor performance.
The main problem of TCP is performing congestion control in case of losses that are not created by network congestion. In wireless network there are various types of losses which are not related to congestion, making TCP not adapted to this environment. Over the last few years various ideas have been proposed to improve TCP performance over wireless networks. Various TCP versions like Tahoe, New-Reno, Reno and Vegas perform differently in Ad Hoc networks but all these version of TCP share a common problem i.e. inability to differentiate between packet losses due to congestion from losses due to the specific features of Ad Hoc networks.
There are major four problem of TCP performance over Mobile Ad Hoc Networks and Static Ad Hoc Networks. These problems are listed below.


Due to route failure and network congestion TCP is unable to distinguish between losses.


TCP will suffer from frequent route failure.


TCP contention on wireless channel.


TCP unfairness.


The first two problems are the main reason for the low performance of TCP in Mobile Ad Hoc Networks and the last two problems are the main reason for the low performance of TCP in Static Ad Hoc Networks. Based on these four problems there are various proposal ...