An Optimized Congestion Control Mechanism by using Anti-Congestion Topology Routing (ACTR) Protocol in MANET

Abstract

A Mobile Ad-Hoc Network is a self-configuring infra structure less network of mobile devices connected by wireless links. As the links are unstable, the link bandwidth keeps on changing in MANET environment. Each device in a MANET is free to move independently in any direction and therefore changes its links frequently. The primary challenge in building a MANET is equipping each device to continuously maintain the information required to properly route the traffic. In any network, when there is too much data traffic at a node due to which the network slows down or starts loosing the data, it is known as network congestion. It degrades quality of service and also can lead to network delays. The congestion problem in a network with shared resources, where multiple senders compete for link bandwidth, it is necessary to adjust the data rate used by each sender in order not to overload the network. Packets that arrive at a router and cannot be forwarded are dropped, consequently an excessive amount of packets arriving at a network bottleneck leads to many packet drops. In this paper, we aim at providing a solution to the problem of network congestion by designing a protocol that performs routing intelligently and minimizes the congestion while routing. For this we have proposed a protocol named as Anti-Congestion Topology Routing (ACTR) Protocol.
ACTR employs Circular topology restriction mechanism along with Constrained Shortest Path First (CSPF) algorithm. CSPF is an extension of normal Shortest Path First algorithm extended along with the constraints (conditions) to be satisfied like minimum bandwidth required per link, end-to-end delay, maximum number of links traversed can be considered as constraints in CSPF. For further enhancement of our proposed protocol, multiple constraints are considered in Constrained Shortest Path First (CSPF) Algorithm. The multiple constraints considered are minimum bandwidth and minimum hop count. The constraints are checked in prioritized manner. The ACTR protocol uses OSPF (Open Shortest Path First) & CSPF (Constrained Shortest Path First) protocols as the base protocol and adds-on the constrained circular routing technique to it. This proposed protocol will be compared with this two link state routing protocols and proved to be better in terms of End-to-End Delay.