Throughput of cognitive relay networks with energy-harvesting based primary user's interference

Abstract

In this paper, we analyze the throughput of secondary user (SU) in cognitive relay network under primary user (PU) interference. Relays are equipped with energy-harvesting devices which can assist SU to transmit information from SU source (SS) to SU destination (SD) in a decode and forward (DF) mode. The transmission power of relay is constrained by interference threshold of the PU destination (PD). Two kinds of protocols of energy harvesting and information transmission in relay are studied in this paper, time switching relaying (TSR) and power splitting relaying (PSR). In the consideration of interference caused by PU at relay node and energy harvesting process, we analyze the throughput of SU system. The effects of system's parameters (e.g. Numbers of relays, time switching coefficient or power splitting coefficient) to the throughput of SU system are analyzed based on the simulation results. The simulation results show that throughput of SU system in TSR protocol is better than that in PSR protocol in the condition of low time switching coefficient. Throughput of SU system in PSR protocol is better in high time switching coefficient condition. Throughput of SU system in TSR protocol is more sensitive to the variation of interference than in PSR protocol.