基于智能天线的无源UHF RFID系统的理论与关键技术研究

Theory and key technique of the passive UHF RFID system based on the smart antenna will be deeply researched. On the side of the reader, the smart antenna based on the switched-beam antenna array is used. A narrow beam with high gain is formed at one time and then a few different-directional beams are orderly steered according to adaptively control arithmetic. The technique of beam pattern synthesis which adapts to the RFID system and adaptively control arithmetic of the beam-switching will be proposed. The method that the read range is stretched by the power control for anti-collision will be researched. The reader based on the smart antenna and the switched-beam smart antenna will be researched and developed. On the side of the tag, the tag scheme with the smart two antennas is proposed. The two-port tag IC researched and developed by ourselves can intelligently select the antenna which receives more power between two orthogonally polarized antennas as the special antenna to receive power. The special antenna does not backscatter in the communication process so that the power received by the tag IC is increased. The proposed passive UHF RFID system based on the smart antenna does not require the modification of the existing standard and protocol, and it can double the read range, extend the read area, decrease the tag collision number, promote the large-scale application of the passive UHF RFID system, and bring huge social and economic benefit.

拟对基于智能天线的无源UHF RFID系统的理论与关键技术进行深入研究。在阅读器一端，采用波束切换型智能天线：在同一时刻形成一个高增益的窄波束，然后在时间上自适应控制地顺序产生多个指向不同的波束。提出适合于RFID系统的相控阵天线方向图综合技术、波束切换的自适应控制算法。提出基于功率控制缩放识别区域来防碰撞的方法。研制基于智能天线的阅读器和波束切换型智能天线系统。在标签一端，提出智能双天线标签方案：自行研制的双端口标签芯片智能地将两个正交极化的天线中接收功率较大的天线专用于接收能量，即在通信过程中不参与反向散射调制通信，从而增加标签芯片接收到的能量。拟研究的无源UHF RFID系统在应用智能天线技术之后，无需修改现有的标准及协议，可以使最大识别距离增加一倍，并可以扩展识别区域和减少碰撞，促进无源UHF RFID系统的大规模应用，产生巨大的社会效益和经济效益。

随着物联网的发展，射频识别（RFID）技术具有战略性的重大意义。针对“RFID的最大读写距离只能达到10米”和“防碰撞”问题，本课题将智能天线应用到无源UHF RFID阅读器系统中，并对其理论和关键技术进行深入研究。.在抗多径干扰方面，首先建立多径环境下通信模型，然后验证应用智能天线对多径干扰的抑制作用。.在防碰撞方面，首先提出基于功率控制的标签防碰撞算法模型，然后分别提出定步长功率控制ALOHA防碰撞算法（SPCA）和自适应功率控制ALOHA防碰撞算法（APCA）。.依据波束切换型智能天线的阅读器与标签通信的信道模型，分别提出固定驻留时间波束切换自适应控制算法和动态驻留时间波束切换自适应控制算法。.为了降低能耗，提出基于功率控制的波束切换自适应算法。通过控制阅读器的发射功率和波束切换，将识别区域划分成多个块状区域，并通过红黑树来管理这些块状区域的调度切换问题。.提出一种基于改进粒子群的波束赋形算法。研制一种相控阵天线，实现阅读器对空间区域的波束扫描和增加识别距离。对阵元的小型化处理来减小天线阵列的总尺寸。.研制一种基于智能天线的UHF RFID阅读器，该阅读器系统支持ISO/IEC18000-6C协议，最远识别距离可达20米。结合波束切换自适应控制算法和基于功率控制的标签防碰撞算法，阅读器系统能够实现扩展识别区域、减小碰撞、提高定位精度和抗干扰等优点，并能够降低阅读器识别所消耗的时间和能量。.提出一种具有智能选择功能的双端口标签方案。所设计的双端口标签芯片智能地将两个正交极化的天线中接收功率较大的天线专用于接收能量，即在通信过程中不参与反向散射调制通信，从而增加标签芯片接收到的能量。.另外，本课题扩展研究了其他的防碰撞算法、定位算法、带有传感器的RFID和无线传感器网络等相关内容。