A Novel Cooperative Mechanism for Cognitive Radio Networks

Abstract—As the demand on frequency spectrum grows rapidly, cognitive radio technique becomes a hot research prob-lem and a promising approach to increase the efficiency of spectrum utilization. In this paper, we consider the problem of spectrum sharing among one primary user and multiple secondary users and secondary user’s power control by a cooperating method, where the primary user select a proper set of secondary users to serve as the cooperative relays for its transmission; and in return lease portion of channel access time to the selected secondary users for their own transmission. Primary user should broadcast the portion of channel access time it will leave for secondary users, the selected secondary users have the right to decide their power level used to help primary user’s transmission in order to achieve proportional access time to the channel. We assume that the primary user and secondary users are rational and selfish, i.e., they only aim at maximizing their own utility. As secondary users ’ utility is in term of their own transmission rate and the power cost for primary user’s transmission, so secondary users will choose an optimal power level to meet the tradeoff between transmission rate and power cost. And primary user will choose a proper portion of channel access time for secondary users to attract secondary users to employ higher power level and maintain enough transmission time at the same time. We can formulate this model as a game between primary user and secondary users; and it is proved to converge to a unique optimal equilibrium. By employing a proper power control updating algorithm, we can achieve the optimal equilibrium point, which will be shown in the numeric results. I