Abstract: The traditional RFID indoor positioning system based on the distance measurement of RSSI needs to use multiple antennas simultaneously, which makes the cost of RFID positioning system expensive. However, the RFID rotating antenna positioning method using only one antenna needs to long-term search for a tag to measure the maximum signal strength, which causes that the system is unable to operate stably for a long period of time. In order to solve the problem, the system obtains the equal signal strength of different angles by rotating RFID antenna. Then the intersection points of two elliptical models are obtained by traversal methods. In this way the positioning function is achieved. At last the performance of the proposed algorithm is tested on the hardware device. The result indicates that the error of position is 0.754?m. Compared with the traditional RSSI positioning algorithm, the cost of proposed RFID indoor positioning system can be reduced about 36.19%. At the same time, the problem of heating easily of the reader is solved.

Key words: Radio Frequency Identification（RFID）, indoor localization, rotable antenna, Received Signal Strength Indication （RSSI） distance measurement, three edge location algorithm

摘要： 传统的基于RSSI测距的RFID室内定位系统需要多台天线同时进行测量，使得定位系统部署成本昂贵。而目前只使用一个天线的RFID旋转天线定位方法由于需要测量最大信号强度的角度，需要长期搜索标签，导致系统无法长期稳定工作。为了解决上述问题，提出在天线旋转过程中，获得不同特定角度的等信号强度轨迹，再通过遍历方法求两个椭圆模型的交点，实现定位。最后将该算法在硬件装置上进行了实验，结果表明平均定位误差达到0.754?m，与传统RSSI定位算法相比可以减少36.19%左右的硬件部署成本，同时解决了读写器容易发热的问题。

关键词: 射频识别, 室内定位, 旋转天线, RSSI测距, 椭圆模型, 三边定位算法