Side peak cancellation method for sine-BOC(m,n)-modulated GNSS signals

Abstract

In this paper, we propose an efficient scheme for side peak cancelation in binary offset carrier (m,n) (BOC(m,n)) with integer modulation order. The proposed scheme reduces significantly the width of the main peak of the auto-correlation function (ACF) and thus the range of influence of the multipath (MP) in BOC-modulated signals. It is based on the use of reference ACFs like that of ideal pseudo random noise (PRN) code generated by linear feedback shift register (LFSR) and used in global positioning system (GPS) and the Russian Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS). In MP environment, the proposed method is used in combination with fast iterative maximum likelihood algorithm (FIMLA) that is adapted to future modernized GPS and Galileo signals. As a result, the obtained ACF of the proposed scheme does not contain any side peaks, and thus, the discriminator function (DF) has no ambiguity in the delay-locked loop (DLL) code tracking operation. The simulation results show that the proposed technique has superior performances in MP mitigation and permits the same resistance to noise compared to the traditional techniques.

Unambiguous method for DLL BOC signals tracking

“…In Global Navigation Satellite System (GNSS) applications, the subcarrier introduced in binary offset carrier (BOC) modulations and used as a part of the signal code permits to use efficiently the allocated frequency bands and to improve, at the same time, the acquisition and tracking performances in presence of noise, multipath (MP), and narrowband interferences . However, these modulations are limited by the ambiguity problem in the acquisition and tracking processes caused by the presence of multiple zero‐crossing points in the discriminator function (DF) at the output of the delay‐locked loop (DLL) especially in unfavorable environment . As a result, the subcarrier has become a major source of performance degradation in the GNSS receivers .…”

“…This reference locally generated ideal CF is then subtracted from the resulting CF between the received BOC signal and the locally generated one. In contrast to the ICF of the ASPeCT method, the reference CF is calculated just once for a given BOC signal and stored at the receiver end, permitting a reduction of the correlators number and thus a less complex solution . Even though the SCM method is completely nonambiguous, it may present errors in the estimation of the code delay in presence of MP .…”

“…In Attia et al, another efficient approach, called no‐central peak ACF (NCPACF), intended for BOCs(m,n) signals, is based on the combination of several reference PRN ACFs to generate an ACF without central peak. The latter ACF is then combined with the received signal ACF along with the fast‐iterative maximum likelihood algorithm (FIMLA) to get an ACF that is completely unambiguous and having a sharper central peak.…”

GNSS Signals Acquisition and Tracking in Unfavorable Environment

“…As examples, we can cite Autocorrelation Side-Peak Cancellation Technique (ASPeCT) [22], Sidelobes Cancellation Method (SCM) [23], and General Removing Ambiguity via Side Peak Suppression (GRASS) method for only BOCsin signals [24]. We can mention also Simultaneous Perturbation Stochastic Approximation (SPSA) for BOCcos signals [25], No Central Peak ACF for BOCsin signals [26], Pseudo Correlation Function method for MBOC signals [24], Combined Correlation Functions method for BOCsin/cos, CBOC and Alternate BOC signals [27] and BOC-PRN (Pseudo Random Noise) method for BOCsin/cos signals [28].…”

GNSS Multipath Reduction Using GPS and DGPS in the Real Case

“…Several methods have been proposed for side peaks cancelation and true Delay Locked Loop (DLL) zerocrossing detection [10] [11] [12] [13] [14]. Nonetheless, the majority of them still have the problem of the existence of some secondary peaks or the invalidity in the presence of MPs [15] [16] [17] [18].…”