Cost sharing based truthful spectrum auction with collusion-proof

Spectrum auction is an important approach of spectrum distribution in cognitive radio networks. However, a single secondary user (SU) probably can't afford the price of spectrum. Multiple SUs grouping together to participate in the auction as a whole is helpful to increase purchasing power. However, SUs could suffer from a new group cheating problem, i.e., parts of users conspire to manipulate the auction by submitting untruthful bids. Existing auction mechanisms were mainly designed to be strategy-proof only for individual user and can't deal with group cheating. In this paper, a novel spectrum auction mechanism called COSTAG (COst Sharing based Truthful Auction with Group-buying) is proposed to address the group cheating problem. COSTAG consists of a grouping rule to perform grouping and a payment rule to determine the market-clearing price in the spectrum auction. Different from single-echelon pricing approach employed in existing works, a multi-echelon pricing strategy is designed to increase the transaction rate and optimize social profit for the auction. Comprehensive theoretical analysis shows that COSTAG can satisfy the crucial economic robustness properties, both individual and group truthfulness. Simulations demonstrate that comparing with existing works, COSTAG can improve the system performance significantly.