Effects of Oversampling and Multipath on Navigation Using OFDM Signals of Opportunity

Christopher M. Schexnayder, John F. Raquet, Richard K. Martin

Abstract:	This research focuses on exploiting the Orthogonal Frequency Division Multiplexed (OFDM) signal for the purpose of navigation. An algorithm was developed to simulate a transmitter, receiver, channel noise, and multipath propagation. A transmitter and reference receiver, both at known locations, and a mobile receiver at an unknown location were used to conduct simulations with a transmitted OFDM signal in a Rayleigh-distributed multipath environment. The OFDM signal structure was exploited by using its cyclic prefix in a correlation process to find the first symbol boundary in each received signal. Each receiver calculates statistical features about each symbol in the received signal. These two sets of data are then correlated in order to find the difference in symbol arrival times. The simulations were run for varying levels of oversampling in an effort to gain more accurate results by decreasing the sample period. Results show that oversampling the signal only slightly reduces probability of error in the symbol boundary correlation process, while multipath has a significant impact on correlation performance. It was also found that increasing the window size significantly improved feature correlator performance and yielded promising results even in the presence of high multipath environments.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	1792 - 1803
Cite this article:	Schexnayder, Christopher M., Raquet, John F., Martin, Richard K., "Effects of Oversampling and Multipath on Navigation Using OFDM Signals of Opportunity," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 1792-1803.
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