Design And Implementation Of Experimental Platform For LTE Terminal Positioning

With the arrival of the age of information, the number of people using the mobile internet is in explosively growth. The demands to the application in wireless communication environment also grows rapidly. Among these demands, the needs of location based service are urgent. Most current positioning systems are based on GPS or Beidou system. Both of them have high positioning accuracy and ripened technology, but the drawback of them is that both of them cannot meet the application requirements of indoor environment. Therefore, the development of a high precision system which can be used in the indoor environment is important. In recent years, with the use of 4G network based on LTE mobile communication system in commercial area, the wireless communication in China has entered the 4G age. The number of customs who use the LTE network will increase fast. Therefore, the study of the location service in LTE framework will be the main direction in the future. This thesis mainly studies the high precision indoor positioning system based on LTE framework including the estimation of time delay, location algorithm, and the design and implementation of the system. Simulations to analyze the performance of the proposed positioning system are also done in this thesis.The main work of this paper are as following:1. The accuracy of the traditional system is limited by the sampling rate. In order to solve this problem, a two steps algorithm based on OFDM signal is proposed in this thesis. This algorithm gets the initial delay value through the traditional detection of the correlation peak. Then the algorithm transforms the signal to frequency domain to get the delay value less than one sampling interval by detecting the signal’s phase. This algorithm also improves the precision by using the character of OFDM signal.2. To solve the interference of the multipath in indoor environment, a time delay estimation algorithm based on sliding window function is proposed in this thesis. This algorithm can effectively resist the interference of the noise and the channel multipath effect. Simulation results indicate the performance of the algorithm is significantly better than the conventional peak detection method.3. This thesis proposes a location algorithm based on circular vector method. It can determine the position of the target node quickly and improve the position accuracy. Additionally, an improved algorithm based on the circular vector method and Taylor series method is put forward. The algorithm gets the position of the target node by the circular vector method and then uses the Taylor series to expand in this position and fix the position by iteration to obtain the final result.4. To fit the demand for the time synchronization of the TOA positioning system, a high precision clock source based on Beidou system is designed. The clock source can provide clock with a precision of "ns" level to the FPGA to implement the time synchronization among the anchor nodes.5. A high precision positioning system scheme based on LTE framework is designed At the same time, the performance of the designed system is evaluated and analyzed.