Abstract
In this paper, we optimize both harvesting and sensing durations for cognitive radio networks (CRNs). There are a primary source and destination PS and PD. In the secondary network, there are a secondary source and destination SS and SD. There are three time slots in secondary network. In the first one, secondary source SS harvests energy from radio frequency (RF) signal received from another node A. Node A can be a base station or any other node transmitting RF signal. In the second time slot, secondary source senses the channel using the energy detector to detect primary source activity. When PS is idle, the secondary source transmits data to secondary destination SD in the last time slot. We optimize harvesting and sensing durations to maximize the throughput. Our results are valid for quadrature amplitude modulation (QAM), phase shift keying (PSK) and amplitude shift keying (ASK) in the presence of Rayleigh or Nakagami fading channels.