Properties of Opportunistic and Collaborative Wireless Mesh Networks

While the cost of nodes in a wireless mesh network is decreasing, the price tag of the network as a whole is best minimized by deploying the fewest number of nodes that still achieves some target network connectivity. In this document, we study two techniques to improve the connectivity of the network without increasing the density, and thus the cost, of the network. The two techniques are opportunistic routing and collaborative forwarding. Opportunistic routing makes use of links which become temporarily available due to instantaneous radio conditions. Collaborative forwarding forms associations between small connected clusters to forward packets to nodes outside of the range of any node in the cluster. These techniques were introduced by others in earlier papers. However, their evaluation was performed mostly via simulation. The contribution of this paper is to define a mathematical framework using percolation theory to quantify the gain in network coverage achieved using these techniques. This document shows that both technique significantly decrease the critical connectivity threshold for the wireless mesh network, and thus provide significant connectivity gain. This means that fewer nodes are necessary to achieve the same coverage. We focus on analytical techniques to prove the results, and confirm them by performing a numerical evaluation.