无线供电反向散射多天线通信系统吞吐量优化理论与技术

In a backscatter communication system, the passive user device (e.g., RFID tag, sensors) uses the energy harvested from the incident RF signal to actvate itself, and it changes the amplitude and phase of the backscattered signal, by changing the impedence of antenna according to its information bits, achieving the information transmission from users to the base station (e.g., RFID reader). Backscatter communication enables users to work without batteries, and is thus practically important. However, this technique has not been widely used in Internet of Things (IoT), mainly due to the limited activating distance and lower throughput. As to the two limitations, this project studies the throughput optimization theory and key techniques for energy-beamforming-based wireless powered backscatter multi-antenna communication systems, including: 1) propose low-overhead and efficient channel estimation schemes for backscatter multi-antenna channels; 2) design the channel-estimation-based energy beamforming, and propose the resource allocation scheme to optimize the energy-transfer performance, in order to increase the activating distance; 3) establish the throughput optimization model which takes the user fairness into account, propose the joint optimization scheme for energy beamfoming design and resource allocation, and establish the optimal tradeoff theory between the system throughput and users’ energy requirement. This project can provide theoretical support for the development of next-generation RFID and sensors, and push the practical development of IoT.

在反向散射通信系统中，无源用户(如RFID标签、传感器)从入射无线信号中收集能量来实现激活，并根据信息比特切换天线阻抗，以改变反散信号的幅度和相位，实现用户向基站(如RFID读写器)的信息传输。反向散射通信可使用户摆脱电池的束缚，具有重大的应用价值。但是该技术目前还未在物联网中得到广泛应用，主要是因为用户激活距离受限和吞吐量较低。针对这两大局限性，本项目研究基于能量波束成形的无线供电反向散射多天线通信系统的吞吐量优化理论与关键技术，包括：1）提出低开销、高效率的反向散射多天线信道估计方法；2）设计基于信道估计的能量波束成形，提出优化能量传输性能的资源分配机制，以提高用户激活距离；3）建立考虑用户公平性的吞吐量优化理论模型，提出能量波束成形和资源分配的联合优化机制，并建立系统吞吐量与用户能量需求之间的最优折中关系理论。本项目能为新一代RFID和传感器的发展提供理论支撑，并推动物联网的实用化。

面向未来物联网低功耗高速率远距离通信的需求，本青年基金项目研究了无线供电反向散射多天线通信系统的吞吐量优化理论与关键技术，以解决现有反向散射通信系统激活距离受限和吞吐量较低的局限性。主要进展包括：1）提出了基于环境OFDM信号的反向散射通信收发机设计方法，实现有效消除强直接链路干扰，可对反向散射通信信号进行高效检测；2）提出了协作接收型环境反向散射多天线通信系统的最优和次优检测理论方法；3）提出了协作接收型环境反向散射多天线通信系统吞吐量优化技术；4）提出了全双工型环境反向散射通信系统吞吐量优化技术；5）提出了非正交多址接入辅助的反向散射多接收天线通信系统吞吐量优化技术；6）提出了无人机辅助的反向散射通信系统中路径规划和资源分配的优化机制；7）提出了智能反射表面辅助的下行非正交多址接入系统吞吐量优化技术。研究成果能够为新一代传感器和RFID的发展提供理论支撑，并推动物联网的实用化。本项目已发表（含已接收）论文共计17篇，包括国际期刊论文8篇（中科院大类二区及以上，SCI和EI检索）和国际会议论文9篇（EI检索），其中2篇期刊论文入选ESI高被引论文，1篇IEEE GLOBECOMM论文获得IEEE通信学会TAOS技术委员会最佳论文奖，申请中国发明专利9项，授权3项，超额完成既定任务。