Wireless energy harvesting and information transfer in cognitive two-way relay networks

Energy harvesting is an efficient method for extending the lifetime of energy-constrained networks. In this paper, we develop a wireless energy harvesting and information transfer protocol in cognitive two-way relay networks, in which a secondary network scavenges energy from ambient signals of primary network while shares the spectrum by assisting the primary transmission. In particular, two primary users exchange information through an energy harvesting secondary user which firstly harvests energy from the received primary signals and then uses the harvested energy to forward the remaining primary signals along with the secondary signals. The exact expressions of the outage probabilities for the primary network are analytically formulated. Besides, we derive the lower and upper bounds of the outage probability for the secondary network. Following aforementioned deduction, we analyze the energy efficiency of the whole system. Simulation results show that we can achieve maximum energy efficiency if we set up proper parameters. Finally, numerical results verify our theoretical derivation and demonstrate that the proposed protocol enables the high-quality transmission for both the primary and secondary network without extra relay energy consumed.