Parameter Estimation Using SAGE in a GNSS-Receiver

Abstract

The potential of the SAGE (Space-Alternating Generalised Expectation Maximisation) algorithm for navigation systems in order to distinguish the line-of-sight signal (LOSS) is to be considered. The SAGE algorithm is a low-complexity generalisation of the EM (Expectation-Maximisation) algorithm, which iteratively approximates the maximum likelihood estimator (MLE) and has been successfully applied for parameter estimation (relative delay, incident azimuth, incident elevation, Doppler frequency, and complex amplitude of impinging waves) in mobile radio environments. This study discusses receivers using a single antenna, and also points out the capabilities of this technique using multiple antennas (array processing), for the application in a GNSS (Global Navigation Satellite Systems) environment. Whereas for the single antenna case we estimate the complex amplitudes and relative delays of the impinging waves, in the latter additionally the spatial signature of the impinging waves (incident azimuth) is estimated. The results of the performed computer simulations and discussion indicate that the SAGE algorithm has the potential to be a very powerful high-resolution method to successfully estimate parameters of impinging waves for navigation systems. SAGE has proven to be a promising method to efficiently combat multipath for navigation applications due to its good performance, fast convergence, and low complexity.