Enhancing the throughput of cognitive radio network in the presence of malicious cognitive radio user (MCRU) is addressed in this paper. We have considered the impact of MCRU on the sensing performance and achievable throughput of secondary network during two phases, namely, sensing phase (SP) and secondary user transmission phase (SUTP), respectively. This impact is mitigated by employing cognitive radio (CR) users equipped with multiple receiving antennas. We have performed diversity combining and have formulated the optimization problems with solutions during SP and SUTP. Moreover, the method of estimating the channel between MCRU and CR receiver is integrated into the solution. Simulation results show that this method achieves 89% detection and 3.5 bits/s/Hz of achievable throughput, while maximal ratio combining technique offers only 22% and 0.4 bits/s/Hz, respectively, when MCRU is active with ten times stronger power than the primary user. 
Enhancing the throughput of cognitive radio networks through malevolent presence