Delayed PIC for Postcorrelation Mitigation of Continuous Wave and Multiple Access Interference in GPS Receivers

Several techniques are available to mitigate the problem of multiple access interference (MAI) caused by the limited dynamic range of the 1023-chip global positioning system (GPS) coarse acquisition Gold codes. MAI causes difficulties in several high-sensitivity applications, including indoor GPS and the use of pseudolites for GPS augmentation. This paper provides details on a variation on the existing techniques of successive interference cancellation (SIC) and parallel interference cancellation (PIC), but with the advantage of being more readily applied. This postcorrelation method is suitable for use in both hardware and software GPS receivers and is able to use commercially available GPS front-end chips employing 2-bit quantization of the received radio signal. The method can also be used to cancel some forms of continuous wave (CW) interference. Simulation results providing statistics on the effectiveness of the technique are provided, as well as results obtained when the technique was implemented in hardware on a GPS receiver based on a field programmable gate array correlator. The proposed method is also compared to some other MAI-mitigating techniques.