Research On The TDOA Estimation Of OFDM System

With the rapid development of wireless communication network technology, wireless communication network positioning technologies have been paid more and more attention to. Different location parameters which are used in a wireless position location technology, such as Time Difference of Arrival(TDOA), Time of Arrival(TOA), Angle of Arrival(AOA) and Received Signal Strength Indication(RSSI), makes different location methods and systems. In recent years, with the rapid development of TDOA location technology, location system based on TDOA positioning technology has shown a good performance in terms of positioning accuracy and system complexity, becoming a hot research direction of common concern.On the other hand, due to the advantage of the high utilization and strong bandwidth scalability, the Orthogonal Frequency Division Multiplexing(OFDM) system has been widely used in terms of navigation, ranging, remote sensing, telemetry, location, etc. In this paper, to study the article of TDOA estimation technique of OFDM system we will perform following areas of research according to the characteristics of OFDM system:1. Through the comparison of several classic TDOA estimation algorithms, analyze their mathematical models and apply them in OFDM system, perform the simulation analysis of the performance and the advantage and disadvantage of the various algorithms in the aspect of adding uncorrelated noise, correlated noise, multipath and other environments.And the comparison fully highlights the high performance of TDOA estimation using bispectrum method in complicated environments.2. Do research on the influence of TDOA on carrier frequency offset(CFO) and symbol timing offset(STO) problems in OFDM systems, and use synchronization technology to correct these two errors.3. For OFDM system, take advantage of the characteristics of OFDM signal cycle prefix, propose the TDOA estimation algorithm based on symbolic features. Analyze the performance of the algorithm in different SNR by using the four commonly used symbols: the average, variance, root-mean-square error and the average symbol phase. Compared with the traditional TDOA estimation algorithm, this algorithm greatly improves the bandwidth utilization in the context of guaranteeing the performance of TDOA estimation is excellent, greatly improve the bandwidth utilization.4. Based on frequency domain correlation, using OFDM in pilot information, the TDOA estimation algorithm introduces a disturbance signal interference elimination technique to restore and to eliminate the signal from the received signal, getting the useful signal to improve the performance of TDOA estimation through the channel estimation method.