Spectrum metrics for 2.4 GHz ISM band Cognitive Radio applications

A Wi-Fi COgnitive RAdio Learning (CORAL) platform is used to map the radio environment in the 2.4 GHz ISM band through a spectrum monitoring campaign. The measurement outcome, stored in a radio environment data base, is processed for metrics that are intended to be representative of spectrum congestion. We find that some metrics such as channel occupancy at specified signal thresholds indicate a high correlation to the actual congestion of the channel; RSSI itself seems to be less useful as a congestion metric. Other metrics such as number of distinct channel occupants and Wi-Fi transmission rate are examined as well. The environment mapping exercise outlined in this paper provides insight into the types of metrics and capabilities that could be considered in the design of Wi-Fi based cognitive routers and femtocells.