Optimal Power Allocation for Wideband Cognitive Radio Networks Employing SC-FDMA

In this paper, we investigate the optimal power allocation (OPA) strategy of secondary user (SU) transmitters in wideband cognitive radio networks employing single-carrier frequency-division multiple access (SC-FDMA). To protect the link of the primary user, we study two types of constraints on the SUs: Individual per-tone interference power constraints (IPCs) for each SU and a joint aggregate IPC across all frequency tones and users. Using tools from convex optimization, we derive the sum rate optimal OPA across frequency tones for the SU transmitters for both types of constraints. Simulation results show that the proposed OPA schemes can considerably improve the achievable sum rate of SC-FDMA based SU systems compared to equal power allocation and conventional power allocation schemes.