KNOWS: Cognitive Radio Networks Over White Spaces

FCC has proposed to allow unlicensed operations in the TV broadcast bands. This portion of the spectrum has several desirable properties for more robust data communication as compared to the ISM bands. However, there are a number of challenges in efficiently using the TV bands. For example, the available spectrum is fragmented, and its availability may vary over time. In this paper, we present a cognitive radio system, called KNOWS, to address these challenges. We present the design of our prototype, which includes a new hardware platform and a spectrum-aware Medium Access Control (MAC) protocol. We have implemented the MAC protocol in QualNet, and our results show that in most scenarios KNOWS increases the throughput by more than 200% when compared to an IEEE 802.11 based system.