"Signal level is high but throughput is low" is a common experience in WLAN networks without central management. That causes a lot of frustration, mainly because there is no easy way for users to OBSERVE the presence of interference at all.
In order to improve this situation we developed a patch for OpenWRT which makes interference from other sources visible and is able to display the current utilization-ratio (channel load). No additional hardware is required and no interruption of normal operation is necessary - because recent chipsets maintain internal counters for channel load tracking.