%0 Journal Article
%T Dual-Polarized Synthetic Antenna Array for GNSS Handheld Applications
%A V. Dehghanian
%A A. Broumandan
%A M. Zaheri
%A J. Nielsen
%J ISRN Communications and Networking
%D 2013
%R 10.1155/2013/985401
%X 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. 1. Introduction The initial GNSS signal acquisition is a necessary step in the process of obtaining a set of pseudorange estimates sufficient for location estimation. The 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]. Multipath fading, in the form of spatial signal power fluctuations £¿[3], poses a formidable challenge to GNSS signal acquisition, a problem which has recently attracted significant interest £¿[4, 5]. Utilizing a higher processing gain through a longer integration time is not an attractive solution as the mean acquisition time is significantly increased £¿[6]. In addition, signal decorrelation due to oscillator instability and user mobility effectively limits the coherent integration time £¿[7]. Recently multiple receive antennas have been utilized to enhance signal detection performance in the form of beamforming and diversity systems £¿[8, 9]. Antenna diversity based on employing multiple antennas with different radiation characteristics has long been in use in diversity systems £¿[10, 11]. It
%U http://www.hindawi.com/journals/isrn.communications.networking/2013/985401/