Bi-Criteria Optimisation for Energy Harvesting Relaying: Formulation and Algorithm Implementation

This paper proposes a bi-criteria optimisation frame-work that maximises both the network rate and the harvested energy, which are contradictory objectives. Using the practical non-linear energy harvesting (EH) model, we jointly optimise re-lay selection (RS), power splitting (PS) and power allocation (PA). We decouple the relay selection variables from the other resource allocation variables to convert the original mixed-integer non-linear programming (MINLP) problem into a tractable problem. For PS and PA, the well-known ∊-constraint method is applied to convert the bi-criteria problem into a convex problem. For RS, we propose a sub-optimal algorithm based on a selection order function with linear complexity. The simulation results indicate that the proposed schemes perform better than the benchmarks, drastically reducing computational complexity from exponential to polynomial.