ML estimator and hybrid beamformer for multipath and interference mitigation in GNSS receivers

Abstract

Abstract-This paper addresses the estimation of the code-phase (pseudorange) and the carrier-phase of the direct signal received from a direct-sequence spread-spectrum satellite transmitter. The signal is received by an antenna array in a scenario with interference and multipath propagation. These two effects are generally the limiting error sources in most high-precision positioning applications. A new estimator of the code-and carrier-phases is derived by using a simplified signal model and the maximum likelihood (ML) principle. The simplified model consists essentially of gathering all signals, except for the direct one, in a component with unknown spatial correlation. The estimator exploits the knowledge of the direction-of-arrival of the direct signal and is much simpler than other estimators derived under more detailed signal models. Moreover, we present an iterative algorithm, that is adequate for a practical implementation and explores an interesting link between the ML estimator and a hybrid beamformer. The mean squared error and bias of the new estimator are computed for a number of scenarios and compared with those of other methods. The presented estimator and the hybrid beamforming outperform the existing techniques of comparable complexity and attains, in many situations, the Cramér-Rao lower bound of the problem at hand.

Multipath Mitigation Techniques for Satellite-Based Positioning Applications

“…Several advanced multipath mitigation techniques were also proposed in Bhuiyan (2011), Granados et al (2005), Granados & Rubio (2000), Lohan et al (2006). These techniques, in general, offer better tracking performance than the traditional DLL at a cost of increased complexity.…”

GLRT-based array receivers for the detection of a known signal with unknown parameters corrupted by noncircular interferences

“…This detection scheme is commonly referred to as the GLRT [5]. Extensions of the Kelly's GLRT approach assuming that no signal free data vectors are available are presented in [6] and [7] for radar and GPS applications respectively. In [8], Brennan and Reed propose a minimum mean square error detector for time acquisition purposes in the context of multiusers DS-CDMA radio communications networks.…”

A New Parameter Estimation Algorithm for Actual COSPAS-SARSAT Beacons

“…For TOA estimation, Reference [7] points out that we can get accurate estimation by using the time-delay correlation algorithm based on Maximum Likelihood criterion. TP (Tone and Preamble) based algorithm and TPD (Tone, Preamble and Data) based algorithms are researched respectively in [8] and [9], and the conclusion is that the performance of TPD based algorithm is better.…”