i2ER: Integrated information and energy relaying protocol for RF powered communication network

Performance of RF powered communication network is bottlenecked by short downlink energy transfer range and doubly-near-far problem faced in uplink information transfer to Hybrid Access Point (HAP). Theses problems can be resolved by cooperation of an RF energy harvesting node R present between HAP and RF energy harvesting information source S. However, there lies a dilemma at R on whether to transfer its harvested energy to S or to act as an information relay for transferring its data to HAP in a two-hop fashion. This paper resolves this dilemma of R by proposing a novel integrated information and energy relaying (i
²
ER) protocol. It also provides insights on the relay positions suited for either energy relaying (ER), or information relaying (IR), or where neither ER nor IR will be useful. In this regard, while considering Rician fading channels, we derive the expression for mean harvested dc power at S via energy transfer from HAP and ER from R. We also derive the closed-form outage probability expression for decode-and-forward relaying with maximal-ratio-combining at HAP over Rician channels. Finally numerical results validating the analytical results and providing insights on the relaying role (ER and/or IR) of RF harvesting helping node are presented.