# Throughput Maximization in Two-hop DF Multiple-Relay Network with Simultaneous Wireless Information and Power Transfer

## TL;DR

This paper develops a comprehensive optimization framework for maximizing end-to-end throughput in a two-hop relay network with SWIPT, accounting for nonlinear energy harvesting, and derives globally optimal solutions.

## Contribution

It introduces a novel optimization approach for throughput maximization in SWIPT-enabled relay networks considering nonlinear energy harvesters and provides globally optimal solutions.

## Key findings

- Global optimal solutions are derived for the non-convex optimization problems.
- The proposed methods outperform baseline approaches in numerical simulations.
- A simple yet optimal solution is also identified in some cases.

## Abstract

This paper investigates the end-to-end throughput maximization problem for a two-hop multiple-relay network, with relays powered by simultaneous wireless information and power transfer (SWIPT) technique. Nonlinearity of energy harvester at every relay node is taken into account and two models for approximating the nonlinearity are adopted: logistic model and linear cut-off model. Decode-and-forward (DF) is implemented, and time switching (TS) mode and power splitting (PS) mode are considered. Optimization problems are formulated for TS mode and PS mode under logistic model and linear cut-off model, respectively. End-to-end throughput is aimed to be maximized by optimizing the transmit power and bandwidth on every source-relay-destination link, and PS ratio and/or TS ratio on every relay node. Although the formulated optimization problems are all non-convex. Through a series of analysis and transformation, and with the aid of bi-level optimization and monotonic optimization, etc., we find the global optimal solution of every formulated optimization problem. In some case, a simple yet optimal solution of the formulated problem is also derived. Numerical results verify the effectiveness of our proposed methods.