Low-complexity code tracking loop with multipath diversity for GNSS over multipath fading channels

Abstract

A low-complexity noncoherent code tracking loop is proposed for global navigation satellite systems (GNSS) over multipath fading channels. Instead of trying to remove the multipath interference from the received signal or utilizing complex signal processing techniques such as maximum-likelihood estimation of the delay parameters, the proposed scheme collects useful component from the multipath signal by introducing assistant signals into the local reference signals. Cross-correlation from neighboring paths is combined constructively and forms an enhanced effective discriminator characteristic. Multipath diversity is thereby achieved with low computational complexity. The S-curve of the new loop is shown to be bias-free and odd-symmetric. Mean square tracking errors obtained by both linear and nonlinear analyses are used to assess the loop׳s tracking performance in terms of accuracy and robustness.