Adaptive bit-loading in relay-aided cognitive radio network

In this work, we consider a joint power allocation and bit loading problem in an orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) network. The objective is to maximize the end-to-end rate in a relay aided dual hop transmission subject to individual power constraints at each transmission node. More specifically, an underlay CR transmission is considered, where the secondary nodes transmit simultaneously with the primary nodes subject to an interference protection criteria. An efficient algorithm is proposed which maximizes the overall throughput while meeting all the constraints. Simulations results are presented to validate the performance of our proposed scheme.