Research On Distributed Topology Control Algorithm For Interference Optimize In Ad Hoc Networks

Ad hoc networks have become increasingly important with the requirement forenhanced data and multimedia communications in wireless environments. Whilesingle hop wireless networks or infrastructure networks are common, there are agrowing number of applications require multi-hop wireless infrastructure which doesnot necessarily depend on any fixed base-station.Ad hoc network needs some special treatments as it intrinsically has its ownspecial characteristics and some unavoidable limitations compared with wirednetworks. For example, wireless nodes confronted with intricate wireless transmissionenvironment since ad hoc network share limited wireless channel, which leads toseries of new problems, particularly, interference. One way to reduce networkinterference is topology control. By adjusting wireless nodes’ transmission powerunder the primary of connectivity, topology control can construct sparse topologieswhich optimize the network interference, also make for optimized high-layersolutions. However, as a result of sparseness, another fatal problem comes: bottlenecknodes. As is well known, sparseness will increase bottleneck nodes in network and asa key impact on network performance, bottleneck nodes number should restricted asfar as we could. In order to improve performance instead of confining by bottlenecknode, routing algorithms are introduced as a way to relieve traffic load on bottlenecknodes, by establishing routes with links in nonadjacent selection from bottlenecknodes with certain rules. Nevertheless, links in ad hoc network are calculated bytopology control, without the assistance of topology control, routing algorithmsefficiency constraint to a limited level, while on the opposite stand point, anappropriate topology can raise route routing algorithms’ efficiency immensely.Existed topology control algorithms increase network bottleneck nodes becauseof sparseness while current solutions for bottleneck nodes are implemented in routingalgorithms whose efficiency rely on underlying topology. The contradiction betweensparseness and bottleneck nodes can resolve by topology control. In summary,topology control can calculate optimized topology to reduce network interferencewhile lessening bottleneck nodes number, not only improve network performance, butalso upgrade route routing algorithms efficiency. To our best knowledge, there haveno other work concerning about this. The main contributions of this paper are asfollows: (1)Introduce features of Ad hoc networks, describes related work and recentresearch status in interference-optimize topology control algorithms, classify existedinterference-optimize topology control algorithms and discuss the classical onesdetailed. By implementing the algorithms in JAVA, we discuss the impact of topologycontrol algorithms on network bottleneck nodes while it set a sparse graph. By a lot ofanalyze, we believe that the number of network bottleneck nodes would not decreasewhile network density increase. With a reasonable explanation, we claim that networkbottleneck nodes should be considered in topology control algorithms for networkoptimization(2)Several proposed interference model are introduced and analyzed in this paper,also we present a new interference model: quasi-bottleneck interference model, acorresponding optimization is also proposed in this paper. By employingquasi-bottleneck optimization into interference-optimize topology control algorithm,QIA and AQIA are proposed, also AQIA could adaptively adopt quasi-bottleneckoptimization according to current network traffic situations. Result shows, QIA candecrease the number of network bottleneck nodes, optimize network interference,increase network throughput while network traffic is heavy while AQIA can adapt allkinds of network traffic, build a better network topology.(3)Simulation on OPNET is expanded by using the EMA(External ModuleAccess) interface, now we can simulate large scale experiments. On the base of EMAinterface and fully support of protocol programming, kernel codes of OPNET aremodified in this paper to simulate AQIA. By Simulation, several parameters asthroughput, delay are compared.