Forward-only uni-directional routing

Wireless computer networks have properties that differ significantly from traditional wireline networks. One prominent difference is the presence of unidirectional channels. That is, it may be possible for a computer p to send a message to a neighboring computer q, but it may not be possible for computer q to send a message to computer p. This introduces significant changes in routing protocols. In particular, routing protocols that tolerate unidirectional links incur an O(N/sup 2/) message overhead between neighboring nodes, where N is the number of nodes in the network. This is significantly higher than the typical O(N) message overhead in some traditional routing protocols. We present a protocol with an O(N) message overhead even in the presence of unidirectional links. This low overhead comes at the price of not always finding the optimum path. However, the protocol is guaranteed to always find a path between each pair of nodes. Furthermore, the cost of this path is guaranteed not to exceed the cost of the optimal bidirectional path between the nodes.