Simultaneous Wireless Information and Power Transfer for Decode-and-Forward Multi-Hop Relay Systems in Energy-Constrained IoT Networks

TL;DR

This paper proposes an optimal power splitting scheme for multi-hop relay systems in IoT networks that enables simultaneous wireless information and power transfer, improving energy efficiency and data throughput.

Contribution

It introduces a convex optimization-based method to find globally optimal power splitting ratios for energy harvesting and data relaying in multi-hop SWIPT systems.

Findings

Optimal PS ratios are derived in closed-form for both power minimization and rate maximization.

The proposed scheme outperforms fixed PS ratio schemes in numerical simulations.

The approach simplifies the design of energy-efficient multi-hop relay networks in IoT applications.

Abstract

This paper studies a multi-hop decode-and-forward (DF) simultaneous wireless information and power transfer (SWIPT) system where a source sends data to a destination with the aid of multi-hop relays which do not depend on an external energy source. To this end, we apply power splitting (PS) based SWIPT relaying protocol so that the relays can harvest energy from the received signals from the previous hop to reliably forward the information of the source to the destination. We aim to solve two optimization problems relevant to our system model. First, we minimize the transmit power at the source under the individual quality-of-service (QoS) threshold constraints of the relays and the destination nodes by optimizing PS ratios at the relays. The second is to maximize the minimum system achievable rate by optimizing the PS ratio at each relay. Based on convex optimization techniques, the globally optimal PS ratio solution is obtained in closed-form for both problems. By setting the QoS threshold constraint the same for each node for the source transmit power problem, we discovered that either the minimum source transmit power or the maximum system throughput can be found using the same approach. Numerical results demonstrate the superiority of the proposed optimal SWIPT PS design over conventional fixed PS ratio schemes.