Evaluating Adjacent Channel Interference in IEEE 802.11 Networks

The performance of 802.11-based multi-channel wireless mesh networks is affected by the interference due to neighboring nodes operating on same or adjacent channels. In this paper, we have performed extensive measurements on our conducted testbed to evaluate the effects of adjacent channel interference (ACI) in 802.11 networks, under the exposed terminal and hidden terminal scenarios. By varying the path loss and the channel separation distance between two nodes, we investigate the effective attenuation needed in order to completely eliminate the ACI between the two nodes. Using node throughput as a metric, our results confirm that for low path loss between two 802.11 nodes, there still exists interference between the two nodes even though they are operating on non-overlapping channels. Our results also show that we require 37 dB - 45 dB less attenuation to completely eliminate the ACI between two nodes operating on non-overlapping channels, compared to when both nodes are operating on the same channel. Our results are useful to network planners in terms of the placement of mesh nodes and the assignment of channels on the nodes in an 802.11-based multi-channel wireless mesh network.