Multihop Wireless Networks

Abstract

In cellular and wireless local area networks, wireless communication only occurs on the last link between a base station and the wireless end system. In multihop wireless networks, there are one or more intermediate nodes along the path that receive and forward packets via wireless links. Multihop wireless networks have several benefits: Compared with networks with single wireless links, multihop wireless networks can extend the coverage of a network and improve connectivity. Moreover, transmission over multiple ‘‘short’’ links might require less transmission power and energy than that required over ‘‘long’’ links. Moreover, they enable higher data rates resulting in higher throughput and more efficient use of the wireless medium. Multihop wireless networks avoid wide deployment of cables and can be deployed in a costefficient way. In case of dense multihop networks, several paths might become available that can be used to increase robustness of the network. Unfortunately, protocols developed for fixed or cellular networks as well as the Internet are not optimal for multihop wireless networks. This is in particular the case for routing protocols, where completely new unicast, multicast, and broadcast routing protocols have been developed for (mobile) ad hoc and sensor networks. On the transport layer, the Transmission Control Protocol (TCP) is the de facto standard in the Internet, and, in order to allow interoperability, TCP must be supported in multihop wireless networks as well. However, many protocol mechanisms such as congestion control and error control based on acknowledgments do not work efficiently in multihop wireless networks due to various reasons such as contention and control packet overhead. Even on the application level, new concepts are required to support discovery of available applications and services.