i2RES: Integrated Information Relay and Energy Supply Assisted RF Harvesting Communication
Abstract: To overcome finite lifetime bottleneck in the ubiquitous deployment of lowlow power wireless devices in Internet Internet-of-Things, Things, we propose a novel integrated information relay and energy supply (i2RES)-assisted assisted RF harvesting co-operative co communication model. i2RES aids the communication between two distant energy-constrained constrained wireless nodes by: 1) RF energy transfer to the source and 2) relaying source data alongg with supplying energy to the destination. To enable efficient i2RES-powered powered information transfer to the destination, we first derive and then maximize the delay delay-limited limited achievable throughput over Rician channels by jointly optimizing time allocation for information and energy transfer along with relative position of i2RES between source and destination. Although the throughput maximization problem is nonconvex and highly nonlinear, we prove its generalized-convexity convexity and obtain the global global-optimal optimal numerical solutions. To gain analytical insights, we also derive tight closed closed-form form approximation for the optimized solutions. Numerical results validate the analysis and demonstrate significant gain in throughput performance via our proposed optimization schemes under der practical hardware constraints. Finally, we discuss how the analysis and optimization results can be extended to general RF-EH RF system settings with relaxed constraints.