A novel secondary user assisted relay mechanism in cognitive radio networks with multiple primary users

A relay-based mechanism is proposed in a multi-channel cognitive radio network, while the multiple primary users (PUs) are considered in each channel. This mechanism guarantees that PUs achieve rates increment due to the assistance of the secondary users (SUs) in their transmission, while the SUs acquire reserved leasing timeslot to access the spectrum. We carefully investigate the issue on how to assign SUs to assist PUs during primary timeslot, which can be formed as a binary combinatorial optimization problem. Furthermore, we propose a matching algorithm to solve this problem. Simulation results show that, the proposed matching algorithm can solve this problem efficiently. Besides, the proposed relay-based mechanism performs significantly better than the traditional underlay-based mechanism.