ABSTRACT
In recent years, indoor positioning technology has been widely used in many fields. It changes people’s lives deeply, and has become a hot topic in the field of LBS research. This paper discusses the problem of signal tracking in the TC-OFDM (Time & Code Division-Orthogonal Frequency Division Multiplexing) indoor positioning receiver, which is based on ground mobile radio network. In the TC-OFDM indoor positioning system, due to the complex structure of the indoor environment, and serious signal attenuation, a great challenge is presented to the performance of the carrier tracking loop, and also the positioning accuracy is greatly affected. This paper refers to the high dynamic carrier tracking loop, designs a dynamic threshold carrier tracking loop based on FLL and PLL, which is equipment with multiple status to adapt to the requirements of carrier tracking in different situations. This carrier tracking loop is designed with a joint judged threshold based on the residual frequency offset of FLL and the residual phase offset of PLL, with the convergence of the loop. The carrier tracking loop will correspondingly change the work status to track the signal stably when the discriminator value of the FLL and PLL and the threshold meet a certain condition. In addition, we emulate the algorithm with the TC-OFDM positioning receiver, and it can significantly improve the stability of the signal tracking on the complex indoor environment.
