The Introduction of a Cross-Layer Approach to Increase the Efficiency of TCP in Mobile AD HOC Networks by the Physical Cross-Layer Interactions and Network Layer and its Simulation by NS-2 Network Simulator

4 Abstract: Congestion control is one of the classic issues in network, various strategies are presented until now and one of the main duties of Transport Control Protocol (TCP) is dealing with this issue. Today, with the advancement of computer networks of wired models to wireless fields, the functions are various protocols of the network are more consistent with these environments. One of the networks is Mobile Ad hoc network (MANET). The current study aimed to used cross-layer interactions and by the collaboration of physical cross-layer and network layer attempts to create an environment on which TCP can work well. Wireless networks were developed due to presenting the mechanisms to adapt TCP with the Mobile Ad hoc various applications and good services. These networks network that the protocol with the view of the network are increasing rapidly and their services are improved. can have acceptable function. In recent years, many An infrastructure less network or mobile network is a studies are carried out on this model of the networks and model of wireless networks in which there is no fixed wireless networks. Some of the researches considered structure and it is only consisting of mobile nodes and no TCP itself and by improving it attempted to cope with the wired connection. Each mobile node acts as both host and problems of the networks. Some others dealt with the mediating node in a wireless connection. In these lower layers and by taking cross-layer mechanisms and networks, the nodes are mobile and they have a dynamic lower layers information had better view to TCP that this topology and some phenomena as route failure and protocol can act in more consistent way based on the packet losses are occurred more. model applied in the lower layers of the network. TCP Nodes mobility and energy constraint of the nodes considers any error or losses due to the congestion in the are the issues creating some limitations in the networks. network and attempts to apply congestion control TCP is created based on wired model and most of the new mechanism. In Mobile Ad hoc network, other reasons characteristics of wireless models such as nodes mobility, except congestion can cause error and packets losses and high error rate in the environments, signal attenuation, a good behavior should be applied to deal with each noise, etc are not considered. Thus, working on these special error and calling the congestion control blindly networks, we are faced with many problems including can drop the efficiency of the network (1). congestion control mechanism. It is required to present