Routing protocol and medium access protocol for mobile ad hoc networks

This dissertation deals with two major topics of mobile ad hoc networks---routing protocol and medium access protocol. A new routing protocol for ad hoc networks, called Zone-Based Hierarchical Link State Routing (ZHLS), is proposed. In this protocol, the network is divided into non-overlapping zones. Each node only knows the node connectivity within its zone and the zone connectivity of the whole network. The link state routing is performed on two levels: local node and global zone levels. This hierarchical characteristic reduces the communication overhead and the storage requirement of routing information in large networks. But unlike other hierarchical protocols, there are no cluster heads in this protocol. The zone level topological information is distributed to all nodes. This "peer-to-peer" manner mitigates traffic bottleneck, avoids single point of failure and simplifies mobility management. Simulation results confirm that the communication overhead of the proposed protocol is smaller than that of a flat one. The results also assert that the zone level topology is relatively stable. So, ZHLS provides a bandwidth efficient approach to accommodate the changing topology in mobile ad hoc networks.; In ZHLS, a node has to keep track of its physical location continuously in order to determine its affiliated zone. A new spread spectrum-based synchronization and geolocation method is presented. By using a spread spectrum technique, delays of processing handshaking messages and of switching transceivers from receiving mode to sending mode will not incur any inaccuracy.; A new set of medium access protocols for mobile ad hoc networks, called MACA/C-T and MACA/R-T, is presented. The new protocols distinguish from the others by combining the capabilities of Multiple Access with Collision Avoidance protocol and those of spread spectrum protocols. The Request-to-Send and Clear-to-Send message dialogue avoids the "hidden terminal" and the "exposed terminal" problems. The Request-to-Send and Negative-Clear-to-Send message dialogue and the Clear-to-Send timer mechanism are introduced to speed up the retransmission. The assignment of unique spreading spectrum channel to each user prevents any disruption on any ongoing transmission by an intruder. A mathematical analysis confirms that MACA/C-T and MACA/R-T achieve a high channel throughput even in dense networks.