Research On Key Technologies Of Cross-layer Optimization In Wireless Ad Hoc Network

Wireless Ad Hoc networks are widely used in commercial, military, industry andother fields for its self-organizing, self-configuring, and non-infrastructure. Recently, thediversity of business of wireless Ad Hoc network is increasingly, such as data services,especially multimedia data services put forward higher requirements on networkperformance. However, the limited resources, channel fading, dynamic topology andmulti-hop interference in wireless Ad Hoc network make the network protocols designedby traditional hierarchical have poor performance. Although traditional layer reduces thecomplexity of network design, it does not allow information sharing between each layer ofthe protocol stack that accounts for using the limited spectrum and power resources withinefficiency. Cross-layer optimization designs and optimizes the network as a wholethrough exchanging information of the layers, which is a significant theory to improvewireless network performance. Cross-layer optimization should be considered whileproviding high-performance applications in wireless Ad Hoc network.In this dissertation, aiming at the wireless multi-radio multi-channel Ad Hoc network,cross-layer optimization is explored and researched, including channel and powerallocation, multicast rate control and power allocation, channel assignment andopportunistic scheduling, and routing and channel assignment in wireless Ad Hoc network.1. In order to improve the capacity of wireless multi-radio multi-channel Ad Hocnetwork and reduce interference of links, the optimization of joint channel and powerallocation is proposed in this dessertation which is transformed into a non-linearmixed-integer programming model. A two-stage iterative algorithm is proposed in thedissertation for joint optimization, which uses heuristic algorithm to assign the channel inthe first stage and distributed algorithm to allocate power in the second stage. The resultsof simulation show that the channel and power joint allocation has better performance thanthe fixed channel and greedy channel assignment; the two-stage iterative algorithm caneffectively reduce the interference between nodes to improve the network utility. 2. In order to improve the effectiveness of the energy of the wireless nodes and toprovide high-performance multicast data transmission in multi-radio wirelessmulti-channel Ad Hoc network, cross-layer optimization is proposed to address aggregateutility of multicast and power allocation. The problem is formulated as a no-convexoptiminzation. Through dual decomposition approach, optimization model is decomposedinto congestion control at source and power allocation at node. Using the the subgradientalgorithm, a distributed algorithm is designed, which can controlle flow rate at the sourceto avoid congestion and allocate power in the intermediate nodes, as a result it eliminatesthe link bottleneck. Simulation results show that the cross-layer optimization cansignificantly reduce the energy consumption of the node, and obtain better balancebetween the network performance and energy consumption.3. In order to improve the opportunistic scheduling performance in multi channelrelay network, the sub channel allocation, opportunity scheduling and relay selection arejointed to establish a cross-layer optimization model which address the network throughputand user fairness, and two rapid scheduling algorithms are proposed which can meet thereal-time scheduling requirements. Scheduling algorithms firstly select relay nods andassign sub channel for the established optimal path to reach the end-user, then selectoptimal end-user. Simulation results show that the opportunity scheduling can improvenetwork performance by selecting the optimal relay node.4. n order to effectively utilize the multi-radio multi-channel resources so as toprovide end to end quality of service, The dessertation studies interference-aware QoSrouting in wireless multi-radio multi-channel Ad Hoc network. Ia residual bandwidthestimation method in multi-channel network is designed. The routing algorithmdynamically allocates channel through the residual bandwidth in the process of routing, adistributed call admission control is integrated to prevent network overload and the optimalpath metric is used to establish interference-aware multi-channel QoS routing. Simulationresults show that the hybrid routing algorithm can reduce co-channel interference, improvenetwork performance and acceptance rate by assigning channels dynamically.