A Distributed Algorithm for Resource Allocation in OFDM Cognitive Radio Systems

We study the problem of allocating subchannels, bits, and powers for variable rate services in an OFDM based cognitive radio (CR) system, in which available system resources are highly dynamic. In a resource-limited situation under which the nominal rate requirements of users cannot be satisfied, it is desirable to provide fair degradation among users. In a situation with abundant resources, we may choose to maximize system throughput while ensuring that user nominal rate requirements are met. The problem is formulated as a single objective nonlinear optimization problem using techniques from goal programming. A distributed resource allocation algorithm is proposed and simulation results are obtained which show that the proposed distributed algorithm provides good fairness and aggregate bit rates close to (within 8% of) optimal values.