PSO-Based OFDM Adaptive Power and Bit Allocation for Multiuser Cognitive Radio System

The cognitive radio (CR) can take full advantage of the spectrum by enabling second user (SU) to access idle radio channel licensed by primary user (PU) to improve spectrum utilization. The orthogonal frequency division multiplexing (OFDM) provides a feasible network air interface scheme for CR with the flexibility of distributing power and bit to achieve tremendous data rate with the least power. And the mutual interference is a limiting factor that should be taken into account due to the non-orthogonality of their transmit signals. And in this paper we analyze the theoretical system capacity with available sub-channels, subject to interference tolerance and power ceiling appointed by PU in a downlink OFDM-Based CR multiuser scenario, and employ a particle swarm optimization-based (PSO) algorithm to achieve the resource allocation.