Dynamic mode management in cognitive radio networks with RF energy harvesting

In order to realize green communication, we consider a cognitive radio network where the secondary user (SU) is equipped with RF energy harvesting capability. The three-state Markov chain is used to model the primary user (PU) channel, which considers both the channel occupation information of the primary network and the channel quality information. We assume that the SU cannot execute RF energy harvesting and packet transmission at the same time. Consequently, at the beginning of each time slot, the SU should make the decision to harvest RF energy or to transmit a packet. The mode decision depends on the channel state and the available energy in the energy queue. We formulate the mode management problem of the SU as a Markov decision process (MDP) problem that can be solved using dynamic programming. The objective of the proposed strategy is to maximize the expected number of packets successfully transmitted. Simulation results are presented to demonstrate the effectiveness of the proposed strategy.