Overview

A mobile ad hoc network, such as the one shown in Figure 12.1, is a collection of digital data terminals equipped with wireless transceivers that can communicate with one another without using any fixed networking infrastructure. Communication is maintained by the transmission of data packets over a common wireless channel. The absence of any fixed infrastructure, such as an array of base stations, make ad hoc networks radically different from other wireless LANs. Whereas communication from a mobile terminal in an infrastructured network, such as a cellular network, is always maintained with a fixed base station, a mobile terminal (node) in an ad hoc network can communicate directly with another node that is located within its radio transmission range. In order to transmit to a node that is located outside its radio range, data packets are relayed over a sequence of intermediate nodes using a store-and-forward multihop transmission principle. All nodes in an ad hoc network are required to relay packets on behalf of other nodes. Hence, a mobile ad hoc network is sometimes also called a multihop wireless network.

Figure 12.1: A Mobile Ad Hoc Network

Since no base stations are required, ad hoc networks can be deployed quickly, without having to perform any advance planning or construction of expensive network infrastructure. Hence, such networks are ideally suited for applications where such infrastructure is either unavailable or unreliable. Typical applications include military communication networks in battlefields, emergency rescue operations, undersea operations, environmental monitoring, and...