Research On Key Techniques Of Routing In Wireless Ad Hoc Networks

A wireless ad hoc network is a special structure of the wireless communications network, in which the communications between the nodes rely on mutual collaboration in wireless multi-hop manner, and therefore the network is self-organized and self-managed without any infrastructure. The special type of networking makes wireless ad hoc networks not only applicable to military communications, but also useful for areas like environment monitoring, disaster rescue and etc. However, the dynamic network topology poses severe challenges to the design of routing protocols. Focused on the ad hoc routing, this paper discussed and analyzed the problems of routing protocol, neighbor management as well as energy-efficient algorithm and other related areas. The major contributions of this thesis are listed as follows:Chapter II presented the in-depth analysis of IEEE 802.11 from single-hop to multi-hop, then proposed a linkloss-tolerant Priority-Based Forwarding (PBF). Exploiting the idea of opportunistic routing, PBF selects the next hop on-the-fly based on both the realtime propagation instance and a predefined list of candidate forwarders, thereby reducing the influence of link loss on the routing protocols. One of the main features of PBF is to simplify the process of the list of candidate forwarders by utilizing of reference path generated previously by routing protocols, and therefore PBF exhibits more scalability. Route salvage is the other method of PBF. PBF allows some third-party node which meets the need of several demands take the responsibility of current packet forwarding while the packet is not received by all the candidates. Simulation results showed that PBF produced better throughput and delay than other common routing protocols.Chapter III introduced the neighbor model of ad hoc networks, targeted for the neighbor discovery in the general single-radio multi-channel ad hoc networks. Based on the mathematics model, this chapter proposed a Random Neighbor Discovery (RND) protocol which is adaptive to the common channel model, and two extended algorithms: DPF (Discovery Probability First) and WTF (Working Time First). Being similar to the model of Birthday protocols in single-channel environment, RND and its two extended algorithms, configure the transmitting and listening probability such that neighbor discovery can be performed at the low cost of time and operation. Simulation results were consistented with the theoretical calculation. Considering the neighbor management in general network model, we also proposed a Multiple-Announcement Neighbor Management (MANM) method. With MANM, each node generates multiple announcements including its neighbor and channel information, and periodically broadcastes each announcement in corresponding channel such that all the neighbors on all channels can collect the neighborhood information. Analysis and simulation results indicated that MANM is a promising method for discovering multi-channel neighbors as well as an extensible platform which provided basic support for various services in multi-channel ad hoc networks.In Chapter IV the study of existing energy-efficient algorithms based on the node sleep revealed the shortage consideration on routing algorithms for network, and proposed JRT (Joint Routing and Topology management). JRT promoted the prediction of traffic by conbine the on-demand routing protocol with node sleep. A conservative local-partition-avoiding method was introduced in JRT in order to keep the global connectivity of ad hoc networks. Motivated by energy-effiency, JRT scheduled node states under the condition of routing and topology management. Theoretical analysis and simulation results showed that JRT enhanced the effiency of energy-saving without degrading the capability of network services.Domain Name System from traditional Internet can not work well in Mobile Ad Hoc Network due to its lack of fixed infrastructure. This problem becomes more serious with the integration of ad hoc networks and Internet. Chapter V focused the on-demand Mobile Ad Hoc Network as the research object and...