According to the FCC's final rule for the unlicensed use of TV white spaces, secondary users are required to query a geo-location database to determine whether a spectrum band is occupied or not. However, how to design a multi-cell infrastructure-based secondary network to dynamically access TV white spaces with the help of database is still an open issue. In this paper, we present the design and implementation of WhiteNet, a multi-cell infrastructure-based dynamic spectrum access system on TV white spaces. WhiteNet is compatible with the FCC's database architecture. In WhiteNet, the geo-location database is exploited to assist multi-AP coordination. A low-overhead distributed spectrum allocation algorithm is proposed to allocate spectrum among multiple APs in WhiteNet, considering the heterogeneous propagation property among various spectrum bands throughout TV white spaces. A novel AP discovery scheme is designed to enable users to discover and select the best access point to connect. We implement WhiteNet in a 7-node GNU Radio testbed, which demonstrates the feasibility of our system. Evaluation results show that our spectrum allocation algorithm can significantly increase total network throughput, besides, the AP discovery scheme is reliable and efficient.
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