A Survey of Unicast Routing Protocols in Mobile Ad Hoc Networks

Abstract

A mobile ad hoc network is a collection of mobile nodes that do not require any infrastructure for communication. The nodes co-operatively maintain network connectivity. These kinds of networks are very useful in emergency applications like battlefield communication, disaster recovery, traffic management etc. There exists an abstract electronic circle around each node within which the nodes can directly send information. This circle is called radio-circle and communication with the nodes residing within the radio-circle of a node is called single-hop communication. Radius of the radio-circle is called radio-range. The collection of nodes nj that reside within the radio-circle of one particular ode ni at time t, is called the set of downlink neighbours of ni at that time t. Similarly, the collection of nodes nj that contain ni within their radio-circle at time t, is called the set of uplink neighbours of ni at time t. For a communication session, if the destination resides within the radio-circle of the source then it is a single hop communication. On the other hand, if the destination is not within the radio-range of the source then a multi-hop steady path needs to be established. In this multi-hop path, several nodes act as bridge or routers that forward the packet of the source. Building such a multi-hop path from source to destination is very difficult due to random node dynamics in ad hoc networks. Design of routing protocols for ad hoc networks is very difficult due to inherent dynamism and frequent topology change. A huge number of research articles on unicast, multicast, broadcast and geocast protocols are available in the literature of ad hoc networks. Some of them are power-aware. Similarly, several clustering mechanisms as well as selfish and malicious activity detection and prevention techniques have evolved. In this paper a survey of unicast routing protocols in ad hoc networks is presented.