Several Key Issues In Wireless Ad Hoc Networks

Wireless ad hoc network is a temporary multi-hop self-organizing system composed of a group of nodes with wireless transceivers. As infrastructureless networks, ad hoc network, hotspot of current research, will have an expansive forefront in the field of military and civil applications. In recent years, several new research branches of ad hoc network have appeared. The thesis discusses some hotspots in the fields of wireless sensor network and vehicular ad hoc networks.In the first part, a routing protocol is designed for vehicular ad hoc network. Because of the unique locomotion mode, the routing protocols of traditional ad hoc network and wireless sensor network cannot work well in the vehicular ad hoc network. Based on the service mode and locomotion characteristic of vehicular ad hoc network, we proposed a service-orient distributed routing protocol. It builds route by reusing paths which have already detected by previous service discovery, and effectively integrates service discovery and routing establishment process, which makes it unnecessary to use special service discovery protocol over routing protocol. As well, we do use the distributed routing maintenance mechanism that nodes along the established route try to maintain the the integrality and validity of local links to insure the success of entire routing. Moreover, we have discussed the partition problem of vehicular ad hoc network. In order to solve the problem, store-to-retransmit scheme is proposed. In the last part, we examinate the feasibility and validity of our routing protocol by simulations.The second part focuses on the localization problem of multi-sink dynamic wireless sensor networks. With the requirements of applications, there appear multi-sink dynamic wireless sensor networks, where sensors are movable and there are multiple sinks. The multi-sink dynamic networks have some characterics different from the traditional sensor networks and make the localization schemes encounter big chanllenges. In this paper, an active layered localization mehtod is proposed for multi-sink dynamic wireless sensor networks. Different form the traditional localization methods of sensor networks, where the proactive localization scheme is taken, our method is event-driven and the sensor detecting event actively initializes the localization. As well, comparing with the traditional flat localization model, our method divides the localization into two two layers (sensor layer and sink layer) by taking advantage of the strong ability of sinks. Our method not only supports the node's movement, but also reduces the localization cost of sensor nodes which can extend the lifetime of network.The third part of the thesis addresses on the coverage and deployment problem of sensor network. Generally speaking, in sensor network, large amount of sensor nodes are randomly deployed throughout the sensor field to carry out the detecting task. Even in the case of densely deployment, there still exist the blind paths in the sensing field. Especially for the application that demands high reliability, the existence blind paths may make the network be disabled. In this thesis, the problem of the blind path is analyzed, and we propose a distribution scheme to solve the problem of detecting blind paths by using local cooperation among nodes. This scheme can effectively judge if the blindf paths existed in the network and gets rid of blind path if yes. In this part, the main contribution is to propose the distributed solves to detect and remove the blind paths.