Ergodic Capacity based Transmit Antenna Selection for Cogniitve Radio Network under Nakagami-m Fading

In Cognitive radio networks the performance of secondary users depends on the co-channel interference generated by both primary and secondary users. A transmit antenna selection (TAS) technique which increases the capacity of secondary user with less hardware has been dealt in literature for CRN. The subset of antenna was selected with the assumption that the secondary transmitter works under the tight constraints laid by primary receivers. However the aggregate interference at secondary receiver due to multiple secondary transmitters has not been considered in literature while selecting the antenna subset. In this paper, a single TAS technique is proposed based on the ergodic capacity of cognitive radio network under the impact of aggregate interference generated due to multiple secondary interference sources. The interference sources are assumed to be distributed as homogeneous spatial Poisson point process. To estimate the received signal to interference noise ratio, the characterization of aggregate interference is presented. Further the ergodic capacity of the secondary network is derived. The subset of antenna is selected which maximizes the ergodic capacity. The results show that the performance of the secondary improves due to proposed TAS system even operating at very small powers below the interference temperature of primary receiver under the aggregate interference scenario. The analysis is carried out under Nakagami-m fading distribution.