Spectrum allocation and power control in OFDM-based cognitive radios with target SINR constraints

In this paper we consider OFDM-based cognitive radios (CR) with linear precoders at the transmitter and minimum mean square error (MMSE) filters at the receiver, and formulate joint spectral allocation and power control subject to specified target signal-to-interference+noise ratio (SINR) as a constrained optimization problem. We discuss necessary and sufficient conditions for the optimal solution of this problem and present an algorithm that incrementally adapts the OFDM transmitter to reach the optimal transmit precoder and power values where the specified target SINR is achieved with minimum power.