Interference Avoidance and Control

The throughput of a wireless network is often limited by interference caused by multiple concurrently active nodes. The conventional approach of using a “one-transmission-ata-time” MAC protocol to combat interference leads to a significant loss of achievable throughput compared to schemes such as interference cancellation that keep all transmitters active simultaneously. Unfortunately, interference cancellation incurs significant computational complexity, and cannot be implemented with commodity hardware. In this paper, we propose a practical approach for improving the throughput of interfering nodes using variable-width frequency allocation. We show that variable-width channels provide significant theoretical capacity improvements, comparable to interference cancellation for infrastructure networks. We design an algorithm that reduces interference by assigning orthogonal variable-width channels to transmitters. We evaluate a prototype implementation of this algorithm on an outdoor wireless network with ten long-distance links configured into point-to-point and point-to-multipoint topologies. We observe a throughput improvement of between 30% and 110% compared to the existing fixed-width channel allocation.