Multiantenna Spectrum Sensing Over Correlated Nakagami-$m$ Channels With MRC and EGC Diversity Receptions

Increasing number of antennas are closely packed in emerging multiantenna systems and correlation among them can no longer be ignored. In this paper, such a multiantenna spectrum sensing system is investigated considering dual, triple, four and up to infinite number of correlated antenna branches. Constant, arbitrary and exponential correlation among the antenna branches are considered. Closed form expressions for the detection probability, in terms of the confluent hypergeometric function, is derived assuming maximal ratio combining (MRC) and equal gain combining (EGC) diversity techniques in Nakagami-m multipath fading channel. Numerical results quantify the interbranch correlation that impacts the detector performance significantly. However, results also show that this effect could be compensated by employing the appropriate diversity combining technique and by increasing the diversity branches. Furthermore, we find that at high m values (Rician like channel), low false alarm probability and highly correlated environments, EGC which is a simpler scheme performs as good as MRC which is a more complex scheme.