The CDMA Limits of C/A Codes in GPSApplications - Analysis and Laboratory Test Results

S. Raghavan, R. Kumar, S. Lazar, M. Zeitzew, R. Wong, J. Michaelson, A. Doran and M. Bottjer

Abstract:	In order to assess the impact of a potential interferer to GPS C/A-code service, a baseline must be established for the inherent interference environment. A recent development in understanding this interference environment, and therefore the problem of sharing the GPS band by other systems, is the Code Division Multiple Access (CDMA) Limited Interference Model and Analysis Tool (CLIMAT). CLIMAT recognized the finite capacity of the GPS C/A-codes due to the short length of the Gold codes. The analysis of GPS using CLIMAT reveals that for short duration and over limited areas on the Earth, GPS has only a minimal margin for external sources of interference. As a result, a GPS user in a safety-of-life (high availability required) application may have difficulty meeting requirements in an interference scenario that those more traditional analyses based on random codes may not find problematic. Accurate modeling of the C/A-code CDMA interference forms the backbone of CLIMAT. In this paper, such an analytical model is described along with simulation and laboratory test results to validate the analytical model.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	569 - 580
Cite this article:	Raghavan, S., Kumar, R., Lazar, S., Zeitzew, M., Wong, R., Michaelson, J., Doran, A., Bottjer, M., "The CDMA Limits of C/A Codes in GPSApplications - Analysis and Laboratory Test Results," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 569-580.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In