Sleep or Transmit: Dual-Mode Energy-Efficient Design for NOMA-Enabled Backscatter Networks

TL;DR

This paper introduces a dual-mode energy-efficient uplink backscatter communication system using NOMA, optimizing energy use and spectral efficiency for dense IoT networks through a novel algorithm and mode analysis.

Contribution

It proposes a NOMA-enabled backscatter design with a joint optimization algorithm for energy efficiency, considering sleep and active modes in a bistatic IoT network.

Findings

Achieves up to 8% higher EE than fixed-power schemes

Attains 68% higher EE than no-sleep baselines

Delivers up to 127% EE gains over OMA

Abstract

The rapid growth of Internet-of-Things (IoT) devices demands communication systems that are both spectrally efficient and energy frugal. Backscatter communication (BackCom) is an attractive low-power paradigm, but its spectral efficiency declines in dense deployments. This paper presents an uplink BackCom design that integrates non-orthogonal multiple access (NOMA) and maximizes system energy efficiency (EE). In a bistatic network where multiple backscatter nodes (BNs) harvest RF energy and alternate between sleep and active modes, we formulate a fractional program with coupled time, power, and reflection variables and develop a Dinkelbach-based alternating optimization (AO) algorithm with closed-form updates. Analysis reveals two operating modes depending on power availability, circuit demands and propagation conditions. Simulations show the proposed design adapts the time allocation, achieving up to 8% higher EE than fixed-power and 68% than no-sleep baselines, and delivering up to 127% EE gains over orthogonal multiple access (OMA). These results establish NOMA-enabled BackCom as a scalable, energy efficient solution for large-scale IoT deployments.