Timer-based Protocols in Ad Hoc and Sensor Networks

Abstract

Wireless ad hoc and sensor networks present the next great challenge for distributed system research. In wireless ad hoc and sensor networks, each node participates the routing process that allows a packet to be forwarded from its source to the destination. Protocols that support communications in such networks have to take into account the mobility of the participants and the status of links between nodes.

In general, a distributed system is defined as a collection of autonomous components that are interconnected through a network and distributed middleware. A distributed system coordinates the events of components to share resources and give users the perception that the whole system is a single and integrated computing facility. According to this definition, wireless ad hoc and sensor networks can be considered as a special type of distributed systems where each node in the networks serves an autonomous component. In theory, the concepts involved in the design of distributed system should be easily adapted for wireless ad hoc and sensor networks.

In the design of a distributed system, the order of events plays an important role. To manipulate the order, one of the the well-known tools is the (defer) timer. Many distributed communication protocols have been designed using this tool.

In this dissertation, we investigated the use of the defer timer on the design of various protocols in wireless ad hoc and sensor networks. By properly setting up the defer timers, many difficult issues in ad hoc and sensor networks, such as the broadcast storm problem, the construction of a virtual backbone, and dynamic cluster formation can be easily addressed with only the help of simple localized information at each node. The simulations show the suggested timer-based protocols perform effectively in wireless ad hoc and sensor networks.