The Research On Cross Layer Design For Wireless Ad Hoc Network

Wireless Ad hoc networks consist of wireless mobile devices which form temporary networks without of the aid of established infrastructure or central administration. Nodes can not only as a host but also as routers when two nodes can not directly link each other. They assemble the network themselves, adaptively allocate resource to performance degradation, manage technology variations of nodes and respond to network requirements and task diversifications. The wireless, distributed and self-configuring natures of Ad hoc networks make them suitable for a wide variety of applications such as military and business.Wireless Ad hoc networks are a complex system, in which the contents of the research are very extensive. The original network layering structure can't adapt the demand of wireless Ad hoc networks, Because of its limited resources, the dynamic topology of network and the changeable capacity of wireless channel along with the control parameter and environment of the network. This text aims at a special characteristics of wireless Ad hoc network and mainly studies Cross layer design of wireless network. Include of cross layer design of broadcast, multi-path route protocol congestion control and simulates them. The details are as follows:In order to accelerate the development of various applications and high-performances in Ad hoc wireless networks, cross layer design has been discussed and is becoming an important and difficult research problem for wireless Ad hoc network. First cross layer design is defined, the motivations and the advantages of cross layer design are analyzed in the paper. Secondly, all important approaches of cross layer design are depicted and discussed according to different categories: passing information across layers,joint design cooperated layers,merging adjacent layers and layering as optimization decomposition. At the same time the paper evaluates and compares them with performance and complexity. At last the challenges of cross layer design are discussed and the future research work is proposed.Broadcasting is a common operation in Ad hoc wireless networks with severe resource constraints. The problem of broadcasting storm aggravated the resource consumption in Ad hoc networks. We propose a cross layer assisted broadcasting strategy for Ad hoc networks which is made use of 1-hop neighbor knowledge to decide to rebroadcast, and information of physical layer and MAC layer to differentiate time of rebroadcast at MAC layer. The different time of rebroadcast is adjusted adaptively by the density of transmitter node. We propose energy efficient broadcasting strategy without collision for Ad hoc networks which is made use of 2-hop neighbor knowledge, the surplus energy of a node and the degree of node to decide to rebroadcast. The nodes in forward node list are divided into several independent subsets which can rebroadcast simultaneously without collision. The different time of rebroadcast is set adaptively by the density of independent subset node.This paper presents an energy-balanced cross-layer multi-path routing algorithm (EBCLMRA) for Ad hoc wireless networks. In order to improve energy efficiency of Ad hoc networks, EBCLMRA combines the cross-layer information of networks such as the remained energy of nodes, the distance of neighbor node, the length of packets in sending buffer and the delay of the packets in node to find multiple node-disjoint paths in Ad hoc wireless networks. The sending nodes in the path selected power adaptively to reach the next hop according the distance of the sending and receiving to reduce interference and improve energy efficiency. The algorithm can balance the energy of node in the networks, reduce congestion in nodes, prolong the life time of networks and reduce the average delay of the network.This paper presents a load adaptive cross-layer multi-path routing algorithm (LACLMRA) for Ad hoc wireless networks. In order to improve performance of Ad hoc networks, LACLMRA combines the cross-layer information of networks such as the end to end delay of network, the number of re-transmission before success, the length of packets in sending buffer in nodes to find multiple node-disjoint paths in Ad hoc wireless networks. The sending node allocated rate for each path adaptively according the quality of routing path to improve performance. The algorithm can reduce congestion in nodes, reduce the average delay of the network and prolong the life time of networks. The results show that LACLMRA is able to reduce average delay, improve the throughput and prolong the life time of networks compared with SMR and AOMDV.This paper present a distributed congest control algorithm that couples with existing transmission control protocols (TCPs) and MAC protocols to increase end-to-end throughput and energy efficiency of the network. Under the rigorous framework of nonlinearly constrained, this paper presents a step toward a systematic understanding of "layering" as "optimization decomposition," where the overall communication network is modeled by a generalized network utility maximization problem, each layer corresponds to a decomposed subproblem, and the interfaces among layers are quantified as the optimization variables coordinating the subproblems. In the case of the transport and link layers, link congestion prices turn out to be the optimal "layering prices" to cooperate transport layer and link layer. There no modifies in tcps and no probes in networks. Congestion can be controlled by local information.