Cross Correlation Mitigation by Adaptive Orthogonalization Using Constraints - New Results
Éamonn P. Glennon, Andrew Graham Dempster · UNSWorks (University of New South Wales, Sydney, Australia) · 2024
Many spread spectrum systems that employ Direct Sequence/Code Division Multiple Access (DS/CDMA) techniques suffer from cross correlation or ‘Near-Far’ problems if the spreading codes have a relatively short length, as is the case for CDMA cellular communications and C/A code GPS receivers. One class of methods available for cross correlation mitigation (CCM) includes Subspace Projection, although such methods have typically not been employed due to computational complexity. This paper describes a sub-optimal subspace projection approach to CCM that uses constraints to construct despreading codes that are exactly orthogonal to signals being received by the GPS receiver. Application of the technique using a software GPS correlator written in C and run within a Matlab environment are described and results presented based on realistic datasets acquired using hardware GPS simulators. The effectiveness of the method compared to other more traditional CCM methods is also discussed.