Spatial Throughput Analysis and Transmission Strategy Design in Energy Harvesting Cognitive Radio Networks

Abstract

In this paper, we consider an energy harvesting cognitive radio network where each secondary transmitter (ST) harvests radio frequency energy from ambient primary transmitters (PTs), and communicates with its secondary receiver (SR) which suffers co-channel interference from PTs. A positive correlation is observed between the harvested energy at the ST and the aggregate interference at the SR, which illustrates that an ST will have a higher probability to harvest enough energy if there is strong interference at the SR. To exploit the positive correlation, we propose an interference threshold-based transmission strategy for STs, so as to protect secondary transmissions as well as increase the amount of harvested energy. We model the battery level of each ST as a finite state discrete-time Markov chain and derive the expression of the secondary spatial throughput as a function of the transmission probability and coverage probability. We investigate the impact of interference threshold and density of PTs on the secondary spatial throughput, and provide guidelines in the optimal design of these two factors to maximize the spatial throughput. To further improve the spatial throughput of a secondary network, we consider the successive interference cancellation strategy at SRs, and reveal its superiority in the high density regime of PTs.