Abstract:
ince their emergence in the 1970s, wireless networks have become increasingly popular in the computing industry. This is particularly true within the past decade, which has seen wireless networks being adapted to enable mobility. There are currently two variations of mobile wireless networks. The first is known as the infrastructured network (i.e., a network with fixed and wired gateways). The bridges for these networks are known as base stations. A mobile unit within these networks connects to, and communicates with, the nearest base station that is within its communication radius. As the mobile travels out of range of one base station and into the range of another, a "handoff " occurs from the old base station to the new, and the mobile is able to continue communication seamlessly throughout the network. Typical applications of this type of network include office wireless local area networks (WLANs). The second type of mobile wireless network is the infrastructureless mobile network, commonly known as an ad hoc network. Infrastructureless networks have no fixed routers; all nodes are capable of movement and can be connected dynamically in an arbitrary manner. Nodes of these networks function as routers which discover and maintain routes to other nodes in the network. Example applications of ad hoc networks are emergency search-and-rescue operations, meetings or conventions in which persons wish to quickly share information, and data acquisition operations in inhospitable terrain. This article examines routing protocols designed for these ad hoc networks by first describing the operation of each of the protocols and then comparing their various characteristics. The remainder of the article is organized as follows. The next section presents a discussion of two subdivisions of ad hoc routing protocols. Another section discusses current table-driven protocols, while a later section describes those protocols which are classified as on-demand. The article then presents qualitative comparisons of table-driven protocols, followed by demand-driven protocols, and finally a general comparison of table-driven and on-demand protocols. Applications and challenges facing ad hoc mobile wireless networks are discussed; and finally, the last section concludes the article.
