SWARM: The Power of Structure in Community Wireless Mesh Networks

Community wireless networks (CWNs) have been proposed to spread broadband network access to underprivileged, underprovisioned, and remote areas. Research has focused on optimizing network performance through intelligent routing and scheduling, borrowing solutions from mesh networks. Surprisingly, however, there has been no work on how to make efficient use of multiple channels in CWNs in the presence of multiple gateways and a single radio per device. In fact, today´s deployments in underprivileged areas are primarily single-radio and do operate on a single channel. Frequency selection in such CWNs is very complex because it does not only determine the nodes´ channel of operation, but also the gateway and the routing tree to the gateway-a rather computationally intensive task. In this paper, we propose, design, implement, and evaluate SWARM, a practical system that allows a CWN to make effective use of the available wireless channels in order to offer globally optimal performance. SWARM improves performance versus current single-channel protocols by up to 7.7 × in our experiments. Moreover, while we should be expecting performance gains due to channel diversity, we clearly demonstrate that up to 3.7 × improvement is attributed to the network organization into efficient traffic distribution structures.