Detecting spectrum misuse in wireless networks

In contrast to conventional static fixed-width channel allocation, on-demand dynamic variable-width channel allocation has shown that it can effectively improve the fairness, throughput, and spectrum efficiency of wireless networks. Air-time utilization (the percentage of time spent on transmissions) is often used to characterize the spectrum demand of networks. The higher the airtime utilization of a network is, the more spectrum the network should be allocated to. Normally, if all wireless devices in a network utilize spectrum effectively, the airtime utilization can faithfully reflect the spectrum usage. In practice, however, spectrum can be ineffectively used due to the misconfiguration of wireless devices, such as inappropriate bit rate configuration, conservative transmit power setting, or mismatch between channel-width and bit rate. The misconfiguration not only degrades the performance of its local network, but also causes the inflation of local network´s airtime utilization and thus results in an unfair spectrum allocation. To address the problem, we present Pinokio, a system that monitors spectrum usage at access points, detects spectrum misuse and improves spectrum efficiency. Our extensive evaluations suggest that Pinokio can accurately detect spectrum misuse, and limit the inflation of airtime utilization from more than 730% to less than 20%.