Power allocation in OFDM-based cognitive relay networks

This paper investigates power allocation in OFDM-based cognitive relay networks. Relay-assisted cognitive radio network (RCRN) combines diversity gain with spectral sharing technique and improves the spectrum utilization efficiency. A secondary user (SU) shares radio resources of a primary user (PU) under the condition that interferences from SU to PU is below a specific threshold. We formulate a power allocation optimization problem that maximizes the spectral efficiency of RCRN under total transmit-peak and total transmit-average interference power constrains. Numerical results show that RCRN provides significant performance improvement over single hop CRN (SCRN).