Effects of Multipath and Oversampling on Navigation Using Orthogonal Frequency Division Multiplexed Signals of Opportunity; Master's thesis

摘要

This research exploits the Orthogonal Frequency Division Multiplexed (OFDM) signal for the purpose of navigation. A transmitter and reference receiver, both at known locations, and a mobile receiver at an unknown location were used to conduct simulations of a transmitted OFDM signal in a Rayleigh- distributed multipath environment. The OFDM signal structure was exploited by using the cyclic prefix in a correlation process to find the first symbol boundary in each received signal. Statistical features about each symbol is calculated at both receivers and then correlated to find the difference in arrival times. The simulations were run for varying levels of multipath, and also for oversampling in an effort to gain more accurate results by decreasing the sample period. Results show that oversampling the signal only slightly reduces errors in the symbol boundary correlation process, while multipath has a significant impact on the performance of both correlation processes. It was also found that increasing the window size significantly improved the performance of the feature correlator and yielded promising results even in the presence of high multipath environments.