Transmission probability of energy harvesting-based cognitive radio networks with directional antennas

In cognitive radio networks (CRNs), the transmissions of primary users (PUs) will cause interference to secondary users (SUs), consequently resulting in the less spectrum available at SUs. Instead of regarding the radio signals radiated by PUs as interference, these signals can be opportunistically harvested by SUs as energy. We name such cognitive radio networks with wireless energy harvesting technology as (WEH-CRNs). However, most of previous studies mainly consider using omni-directional antennas in WEH-CRNs (OMN-WEH-CRNs), consequently resulting in high interference. In this paper, we consider using directional antennas in WEH-CRNs (DIR-WEH-CRNs) to improve the performance of WEH-CRNs. We establish an analytical model to analyze the transmission probability of SUs in both DIR-WEH-CRNs and OMN-WEH-CRNs. Our simulation results show that our proposed model can accurately analyze the transmission probability of SUs in both DIR-WEH-CRNs and OMN-WEH-CRNs. Moreover, our results also show that the transmission probability of SUs depends on both the spectrum availability and the probability of SUs being charged. Compared with OMN-WEH-CRNs, DIR-WEH-CRNs can achieve higher transmission probability of SUs due to the reduced interference.