Research On Energy-Efficient Routing Technology Of Mobile Ad Hoc Networks

The wireless ad hoc networks are product in combination with mobilecommunication and computer networks. A mobile ad hoc network is a self-organizingnetwork without any existing fixed communication infrastructure support. Comparedwith the traditional fixed networks and wireless mobile cell networks, the ad hocnetworks have some special characters such as instant deployment, strongenvironment adaptability and survivability and so on. So the ad hoc wirelessnetworking technology shows great potential and importance in many situations, suchas in military, disaster-relief, field investigation and industry field supervisionapplications. Because of the features of no existing fixed communicationinfrastructure support and dynamic changed network topology in ad hoc networks,there exist many problems and new challenges including routing, energy management,QoS (Quality of Service) guarantees, security and etc., which are different from thosein the traditional fixed networks.As a multi-hop autonomous system, the ad hoc networks are different from thetraditional wireless networks, in which each node acts as both host and router.However, traditional routing algorithms based on distance vector or link-state needexchange information between nodes and take long time to converge, which are notsuitable for mobile, dynamic changed topology ad hoc networks. So how to design asimple and efficient routing algorithm that can sense the change of network topology,maintain connectivity of network dynamically, update link state and find properroutes quickly is one of the key problems in ad hoc networks.In wireless communication system, energy consumption is a important metric tomeasure the system performance. In addition, low energy consumption can not onlyprolong operating time of the devices but also improve the system robustness.Moreover, through using lower power consumption to communicate can help peopleto release their anxiety for the health hazard from wireless communication. Theenergy problem also exists in ad hoc networks. Compared with other wirelesscommunication systems, it will influence not only on the performance of network butalso on "life-or-death" of the network. Therefore, energy conservation has becomethe key problem of ad hoc networks.This dissertation addresses the key technologies about energy conservation and routing in ad hoc networks and has made innovative progress in the followingrespects.1) A Distributed Broadcasting Algorithm for Ad Hoc Networks based onDistance and Counter ThresholdIn mobile ad hoc networks, many unicast and multicast protocols depend onbroadcasting mechanism to finish control and route establishment functionality. But astrightforward broadcasting in ad hoc networks will be easy to result the broadcaststorm problem. In order to deal with the broadcast storm problem in ad hoc networks,this dissertation proposes an efficient distributed broadcast algorithm which usescross-layer design manner. It changes the backoff defer in MAC layer according tothe receiving signal strength to estimate the distance from the sender. It alsoschedules the packet transmitting in network layer through inducing the distancethreshold and counter threshold. The simulation experiments have demonstrated thatthe proposed broadcast algorithm can lighten the broadcast storm problem andimprove the energy efficiency of broadcast.2) A Power Control Algorithm Based on Game Theory in Ad Hoc NetworksThis dissertation investigates the power control problem in ad hoc networks. Inmobile ad hoc networks, power control method is an efficient way to improve theefficiency of energy used to transmit data packets. However, it will also producenegative influence on the network connectivity, delay and capacity. So regarding asthe objectives of network connectivity, maximum network capacity and minimumnetwork delay, a distributed power control algorithm based on non-cooperative gametheory is proposed. The theoretical proving is given for the existing and uniqueness ofthe algorithm's Nash equilibrium. Simulation results show that the algorithm isefficient and has a good integrated performance.3) A Distributed Maximum Network Lifetime QoS Routing Protocol in MobileAd Hoc NetworksA mobile ad hoc network is composed of a group of mobile wireless nodeswhich form a network independently of any centralized administration. The nodes inthe network communicate with each other in a multi-hop manner. With thedevelopment of the network applications and the technology of Internet, it demands MANETs to support Quality of Service (QoS) in a certain extent. Since the mobilenodes are battery-powered and each mobile node in a MANET performs the routingfunctions, the "death" due to energy exhaustion of even a few nodes might cause thedisruption of the entire network. So for obtaining routes on a MANET, it is notsufficient to only consider about traditional QoS constrints. Power consumptionshould also be taken into consideration. And how to prolong the network lifetime hasbecome very an important objective for guaranteeing QoS in a MANET. Finally, inthis dissertation, a formulation is given to describe the problem of maximizing thenetwork lifetime with QoS routing which is also proved as the maximum flowproblem later. Referring to the idea of solving the maximum flow problem, adistributed maximum network lifetime QoS routing protocol (DMNLQRP) isproposed. The performance of the protocol is analyzed. The simulation results showthat DMNLQRP can not only prolong network lifetime but also improve data packetsdelivery rate and delay.