环境信息激励的无源后向散射长距离低功耗通信系统研究

Low-power backscatter communication technology provides possibilities for wide-area IoT applications. However, Passive backscatter communication technologies based on commercial device signals face the dilemma of limited transmission distance (hundred meters) and lack of energy supply. Based on this, the project explores a passive long-range and low power backscatter communication system, which utilizes the signal of commercial LoRa device as carrier source. To overcome the challenges of power consumption constraint and distance limits, first, we leverages the undersampling analog-to-digital conversion and correlation detection methods to detect the accurate carrier signal. Then, based on the frequency shift keying(FSK), signal frequency splicing, frequency isolation and anti-interference based on signal shifting and blind modulation, we propose the long-range and low-power backscattering transmission systems. For the challenge of insufficient energy supply for backscattered transmission systems, we propose multiple energy heterogeneous energy harvesting by selecting energy efficiency interval and distributed capacitor banks; By designing current gate based on finite state machine, the energy storage detection and global energy saving can be achieved. To satisfy the requirements of some typical scenarios and complex application, we explore the comprehensive evaluation indicators, evaluation methods, and implementation methods of the hardware and software prototype of the communication system. The project aims to explore the intrinsic relationship between long-range backscatter communication efficiency and power consumption, and find the ways to implement low power and long-range backscatter communication systems, providing valuable theoretical basis and technical reference for next-generation Internet of Things (IoT), envisioning ubiquitous and cheap connectivity among humans, machines, and objects.

基于商用设备信号的无源后向散射通信技术面临着传输距离受限（百米范围）和能源供给缺乏的困境。本项目探索以LoRa商用设备信号为载波的无源后向散射长距离低功耗通信系统实现方法。针对低功耗、长距离传输挑战，探索采用欠采样模数转换与相关性检测相结合的载波检测方法，移频键控和频带拼接结合的调制手段，以及基于信号搬移、随机多频跳的频率隔离抗干扰，实现长距离、低能耗后向散射传输；针对后向散射传输系统能量供给不足的挑战，利用最优能效区间求解和分布式电容池实现多元异质能量高效收集，采用基于有限状态机的电流闸方法实现储能检测和全局能耗优化；针对典型场景和复杂应用需求，研究所提通信系统的综合评测指标、评测方法和软硬件原型系统实现方法。项目旨在探索长距离后向散射通信效率与功耗之间的内在关系，寻求长距离后向散射通信系统的低功耗实现方法，为缺乏稳定供电环境的大规模物联网应用提供有价值的理论依据和技术参考。

针对基于商用激励源的无源后向散射系统因通信距离受限难以广泛应用、节点能源供给匮乏而难以支持无源节点连续工作的现状，项目以LoRaWAN信号为载波，面向广域通信的无源后向散射低功耗系统实现方法。通过设计基于轻量级BP神经网络加速器的RF信号检测模块，解决环境弱载波信号的检测与帧结构识别问题；通过码表综合产生的细粒度频移信号实现基于FSK调制的可变吞吐量通信；通过散射场波束赋形技术，实现弱射频信号的远距离散射传输；通过研究基于电容池的高效集能和全局能量优化，实现无源节点的按需实时工作；最后，针对典型场景和野外复杂应用需求，提出了所研究设计的无源通信系统的综合评测指标、软硬件原型系统的验证和测试方法。项目通过探索电磁波信号在空间传播中的特征变换规律、能量传递耗散过程及其在空间不同方向传播建立不同传播路径的物理原理，寻求面向广域通信的环境载波激励的长距离后向散射系统解决办法，为少源、低成本物联网应用提供了理论依据、技术参考和原型设计。