A Probabilistic MAC for Cognitive Radio Systems with Energy Harvesting   Nodes
  In this paper, we consider a cognitive radio (CR) system where the secondary user (SU) harvests energy from both the nature resources and the primary user (PU) radio frequency(RF) signal. We propose an energy-based probabilistic access scheme in which SU probabilistically accesses and senses the primary channel. The decision is based on the available energy and the PU's activity. We investigate the problem of maximizing the SU's success rate provided that the PU average quality of service (QoS) constraint is satisfied. We also assume multi-packet reception (MPR) capability and sensing errors under a Rayleigh fading channel. Numerical results show the effectiveness of the proposed probabilistic access scheme. 
Ramy E. Ali, Fadel F. Digham, Karim G. Seddik, Mohammed Nafie, Amr   El-Keyi and Zhu Han
cs.NI cs.IT math.IT