Multihop

Multihop refers to a method of transmitting data across a network in which the source forwards packets to one or more intermediate nodes before reaching the destination. Unlike single-hop communication, where a direct link exists between endpoints, multihop relies on a chain of wireless or wired hops, which is common when direct connectivity is impractical due to distance, interference, or energy constraints.

It is a fundamental concept in wireless ad hoc networks, wireless sensor networks, and mesh networks. Multihop routing protocols select routes by stitching together multiple hops. Classic protocols include AODV, DSR, and OLSR for mobile ad hoc networks; BATMAN and HWMP are used in mesh networks. In low-power networks such as ZigBee, multihop communication enables city-scale coverage with relatively small devices.

Multihop offers several advantages: it extends network coverage beyond the range of a single transmission, enables lower transmit power per hop, and can improve reach in obstructed or dynamic environments. The approach also presents challenges: increased latency due to multiple forwarding steps, higher potential for packet loss if intermediate nodes fail, and additional protocol overhead for route discovery and maintenance. Throughput can be affected by interference and contention across multiple hops, and performance depends on the quality of each hop along the route.

Design considerations for multihop networks include energy efficiency, mobility, topology control, and security. Routes may be chosen to minimize hop count, balance energy consumption, or optimize link reliability. Systems may employ hierarchical, geographic, or opportunistic routing to adapt to changing conditions and scale to large networks.

Applications span wireless sensor networks for environmental monitoring, wireless mesh networks for community broadband, disaster response, and military communications, as well as Internet of Things deployments where direct connectivity is impractical.