A guide to channel assignment and antenna placement in IEEE 802.11 based multi-channel multi-radio wireless networks

The use of multiple radios tuned to non-overlapped channels, can increase the throughput of a wireless network. However, equipping a node with multiple radios can cause a proximity problem between antennas. In this context, the leakage power generated from co-located antennas, which is known as inter-radio interference (or inter-antenna interference), causes throughput degradation. In order to prevent this throughput degradation, we have to consider the inter-radio interference in the assignment of channels to each radio and when designing the placement of the antenna at a node. In this paper, we verified the existence of inter-radio interference and its impact on the throughput via testbed experiments. We also investigated the change of the inter-radio interference given various channel separation and antenna distance combinations on a node. Furthermore, we put more emphasis on finding the relationship between the channel separation and antenna distance in terms of the inter-radio interference. Based on our findings, we present a useful guide to assigning channels and to designing antenna placement at a node.