A Two-Stage Precoding Algorithm for Spectrum Access Systems with Different Priorities of Spectrum Utilization

In this paper, a two-stage precoding algorithm, termed as subspace-projection prioritized signal-to-leakage-and-noise ratio (SP-PSLNR) algorithm, is proposed for dynamic spectrum access systems with different priorities of spectrum utilization. In the first stage precoding, the interference from the secondary users (SUs) to the primary users (PUs) is canceled; while in the second stage precoding, we differentiate the interference protection and quality of service (QoS) among SUs with different priorities of spectrum access. For this purpose, we newly introduce a parameter called as “interference leakage weight (ILW)” to be used in the optimization of signal to leakage and noise ratio (SLNR). The simulation results show that the proposed method can increase SUs’ maximum allowed transmit power while maintaining protection to the PUs. Moreover, this method can jointly optimize the transmit power of SUs and minimize the interference among SUs. Furthermore, the QoS of SUs can be differentiated by adjusting the ILWs.