Ultra-low-power backscatter-based software-defined radio for intelligent and simplified IoT network

Abstract

The recent decade has witnessed an upsurge in the demands of intelligent and simplified Internet of Things (IoT) networks that provide ultra-low-power communication for numerous miniaturized devices. Although the research community has paid great attention to wireless protocol designs for these networks, researchers are handicapped by the lack of an energy-efficient software-defined radio (SDR) platform for fast implementation and experimental evaluation. Current SDRs perform well in battery-equipped systems, but fail to support miniaturized IoT devices with stringent hardware and power constraints. This paper takes the first step toward designing an ultra-low-power SDR that satisfies the ultra-low-power or even battery-free requirements of intelligent and simplified IoT networks. To achieve this goal, the core technique is the effective integration of µW-level backscatter in our SDR to sidestep power-hungry active radio frequency chains. We carefully develop a novel circuit design for efficient energy harvesting and power control, and devise a competent solution for eliminating the harmonic and mirror frequencies caused by backscatter hardware. We evaluate the proposed SDR using different modulation schemes, and it achieves a high data rate of 100 kb/s with power consumption less than 200 µW in the active mode and as low as 10 µW in the sleep mode. We also conduct a case study of railway inspection using our platform, achieving 1 kb/s battery-free data delivery to the monitoring unmanned aerial vehicle at a distance of 50 m in a real-world environment, and provide two case studies on smart factories and logistic distribution to explore the application of our platform.

摘要

近年来,对智能和简化、为众多小型化设备提供超低功耗的通信物联网(IoT)的需求激增。尽管科研人员已开始为这些网络设计通信协议,但缺乏一个低功耗、高能效软件无线电(SDR)开发平台实现快速实施和实验评估。现有SDR平台只能在有源场景下工作良好,但不适用于硬件条件和能量高度受限的小型化IoT设备。本文率先尝试实现一种超低功耗SDR平台,可满足超低功耗甚至无源物联网节点的通信研发需求。为实现这个目标,将μW级背向散射通信技术有效集成到SDR平台,避免使用高耗能有源射频前端器件。设计了一个包含能量收集和功率管理的新颖电路,并提出消除背向散射造成的谐波和镜像频率干扰方法。评估了不同调制方式下的SDR性能,实现了100 kb/s的高通信速率,该节点在唤醒状态能耗低于200μW,在睡眠状态下能耗为10μW。利用该平台进行一个铁路检查案例研究,在真实环境中且距离为50米时,实现1 kb/s的无源数据传输效率。此外,提供智能工厂和物流配送两个案例,探索所提平台的应用。