THEMIS: Collusion-Resistant and Fair Pricing Spectrum Auction under Dynamic Supply

Spectrum auctions allow a spectrum owner to allocate scarce spectrum resources quickly to the users that value them most. Previous solutions, while enabling reusability-driven and truthful spectrum allocation, are also expected to provide collusion-resistance, price fairness for homogeneous channels, online auction with unknown and dynamic spectrum supply, and bounded system performance. Existing works, however, lack most of these desirable properties due to the inherent technically challenging nature in the spectrum auction design. In this paper, we focus on the problem of allocating idle channels to spectrum users with homogeneous demands in a setting where available channels are arriving in a dynamic and random order. Taking spectrum reusability into consideration, we first propose THEMIS-I: a novel and efficient spectrum auction algorithm that achieves fair pricing for homogeneous channels, online spectrum auction under dynamic spectrum supply and a log approximation to the optimal social welfare. To enhance the robustness of the system, we further propose THEMIS-II: a collusion-resistant design that can resist any number of coalition groups of small size while still possessing all the above desirable properties. We analytically show that THEMIS can achieve either truthfulness without collusion or t-truthfulness tolerating a collusion group of size t with high probability. To the best of our knowledge, we are the first to design truthful spectrum auctions enabling collusion-resistance and fair payments for homogenous channels simultaneously under dynamic spectrum supply. Experimental results show that THEMIS outperform the existing benchmarks by providing perfect fairness of pricing for both the no-collusion case and the collusion case.