Research On OFDM Ranging Techniques

Radio ranging is the key technique in ranging, navigation, location and wireless communication systems. Orthogonal Frequency Division Multiplexing (OFDM) is a preferred technique in wireless communication systems. OFDM systems need accurate frequency and timing synchronization, which provides good foundation for a novel ranging system established on highly precise time-of-arrival (TOA) measurements of OFDM signal.The paper mainly deals with the problems of wireless ranging technique based on OFDM transmission systems. First, based on the analysis of the pesudo-noise ranging and phase ranging methods, a novel OFDM based ranging technique is proposed for the ranging systems in the space by using the properties of OFDM in the time and frequency domains, and the simulation results reveal that the accuracy and the measurable range of the proposed ranging technique are highly improved. In order to improve the ranging accuracy, the paper also proposes a new ranging method in the space based on maximum likelihood algorithm. Furthermore, the TOA estimation algorithms for wireless channel are discussed. According to the principle of maximum likelihood algorithm, an iterative TOA estimation method is proposed, and the range of TOA estimation is highly improved. The method is not sensitive to timing error and can highly improve the TOA estimation performance. Finally, the OFDM ranging system is implemented on the TMS320C6713 DSP platform.