Secondary throughput in underlay cognitive radio network with imperfect CSI and energy harvesting relay

In this paper performance of a cognitive relay network (CRN) is studied under imperfect channel state information (CSI) where a secondary user (SU) transmits using a decode and forward (DF) relay. The DF relay is assumed to harvest energy from the radio frequency (RF) signal transmitted by SU. The performance is evaluated in terms of throughput in an underlay scenario with the energy harvesting relay. The CSI of the interfering links i.e. links from SU transmitter as well as from relay to the primary user (PU) receiver, available at the SU transmitter and the relay, are assumed to be imperfect. A scaling factor based power control is used for the SU and relay in order to protect the PU satisfying an outage constraint. The impact of energy harvesting time, imperfect CSI, PU outage constraint and interference threshold on the throughput of the SU network is indicated. Further the impact of the above parameters on the average transmit power of the relay is also indicated. The performance is assessed using a test bed developed in MATLAB.