Utility-based cross-layer scheduling design for OFDMA-based cognitive radio systems

Cognitive radio makes it possible for an unlicensed user to access a spectrum opportunistically on the basis of non-interfering with licensed users. In this paper, we investigate the performance of opportunistic scheduling in an OFDMA-based cognitive radio (CR) systems by taking into the CR user's raw sensing information (RSI). We shall rely on the joint design framework to optimize a system utility, which adapts the packet delay and the throughput across the secondary users (under an average interference and total available power constraint) to guarantee Quality of Service (QoS) of the whole system. By maximizing the delay and throughput-based utility function, we can get the optimal subcarrier selection policy, power and modulation allocation for each SU's packet. Simulation results are presented to demonstrate the effectiveness of the proposed scheme.