Wireless Routing Protocol

The Wireless Routing Protocol (WRP) is a proactive unicast routing protocol for mobile ad-hoc networks (MANETs). WRP uses an enhanced version of the distance-vector routing protocol, which uses the Bellman-Ford algorithm to calculate paths. Because of the mobile nature of the nodes within the MANET, the protocol introduces mechanisms which reduce route loops and ensure reliable message exchange.

Each node implementing WRP keeps a table of routes and distances and link costs. It also maintains a message retransmission list (MRL). Routing table entries contain distance to a destination node, the previous and next nodes along the route, and is tagged to identify the route's state, for instance, whether it is a simple path, loop or invalid route. (Storing the previous and successive nodes assists in detecting loops and avoiding the counting-to-infinity problem - a shortcoming of Distance Vector Routing.) The link cost table maintains the cost of the link to its nearest neighbours (nodes within direct transmission range), and the number of timeouts since successfully receiving a message from the neighbour.

Nodes periodically exchange routing tables with their neighbours via update messages, or whenever the link state table changes. The MRL maintains a list of which neighbours are yet to acknowledged an update message, so they can be retransmitted if necessary. Where no change in the routing table, a node is required to transmit a 'hello' message to affirm its connectivity. When an update message is received, a node updates its distance table and reassesses the best route paths. It also carries out a consistency check with its neighbours, to help eliminate loops and speed up convergence.

WRP requires large memory storage and resources in maintaining its tables. The protocol is not suitable for large mobile ad hoc networks as it suffers from limited scalability.