Dual-Polarized Synthetic Antenna Array for GNSS Handheld Applications

V Dehghanian,J Nielsen,M Zaheri,A Broumandan

doi:10.1155/2013/985401

Abstract

Small portable Global Navigation Satellite System (GNSS) receivers have revolutionized personal navigation through providing real-time location information for mobile users. Nonetheless, signal fading due to multipath remains a formidable limitation and compromises the performance of GNSS receivers. Antenna diversity techniques, including spatial and polarization diversity, can be used to mitigate multipath fading; however, the relatively large size of the spatially distributed antenna system required is incompatible with the small physical size constraints of a GNSS handheld receiver. User mobility inevitably results in motion of the handset that can be exploited to achieve diversity gain through forming a spatially distributed synthetic array. Traditionally, such motion has been construed as detrimental as it decorrelates the received signal undermining the coherent integration processing gain generally necessary for acquiring weak faded GNSS signals. In this paper the processing gain enhancement resulting from a dual-polarized synthetic array antenna, compatible with size constraints of a small handset that takes advantage of any user imposed motion, is explored. Theoretical analysis and experimental verifications attest the effectiveness of the proposed dual-polarized synthetic array technique by demonstrating an improvement in the processing gain of the GNSS signal acquisition operation.

Highlights

E initial Global Navigation Satellite System (GNSS) signal acquisition is a necessary step in the process of obtaining a set of pseudorange estimates sufficient for location estimation. e underlying multihypothesis detection problem is typically exasperated by a large search space which limits the processing resources and time that can be appropriated for testing individual hypotheses [1, 2]
An innate property of the mobile receiver is that it is generally undergoing some form of motion as part of the typical usage mode. While such motion is typically regarded as being detrimental as it results in signal decorrelation limiting the processing gain achievable by coherent signal integration, it can be exploited to achieve usable diversity gain. e resulting diversity gain can enhance the performance of GNSS signal acquisition in multipath faded environments
To utilize shorter trajectories it is necessary to incorporate another form of diversity system in addition to the spatial diversity available. is paper proposes a combination technique based on merging polarization and spatial diversities through utilizing a dual-polarized RHCPLHCP antenna in a GNSS handheld receiver and exploiting user movements to form a dual-polarized synthetic array, called DPSA

Summary

Introduction

E initial GNSS signal acquisition is a necessary step in the process of obtaining a set of pseudorange estimates sufficient for location estimation. e underlying multihypothesis detection problem is typically exasperated by a large search space which limits the processing resources and time that can be appropriated for testing individual hypotheses [1, 2]. Assume a linearly polarized antenna is translated along a smooth MMMMMM-long trajectory during the signal snapshot interval of duration TT such that MM spatially uncorrelated samples can be collected (UPSA scenario). Since a half-wavelength antenna spacing is enough to provide uncorrelated samples and to achieve full diversity gain, a longer trajectory, DD D MMMMMM, does not improve the detection performance

Measurements and Analysis

Conclusions