Joint precoder and power adaptation for cognitive radios in interference systems

In this paper we present a new approach for joint precoder and power adaptation applicable in multi-user spectrum sharing cognitive radio (CR) networks. In the proposed approach bandwidth use is expressed in terms of a finite set of discrete resources whose use is optimized by the CR transmitters in terms of system sum-rate under operating constraints that restrict the operation of secondary (unlicensed) CR transmitters to protect licensed primary user-transmissions. We formulate the optimal resource allocation for CR users as a constrained optimization problem and illustrate the proposed approach with numerical results obtained from simulations.