Weak GPS Signal Acquisition Using Antenna Diversity

Abstract

GPS signal acquisition is challenging in attenuating and multipath fading environments. Standard methods, such as extending the coherent integration time to achieve more processing gain, are not always feasible for acquiring weak signals using unaided receivers. Spatial antenna diversity is used for indoor applications to mitigate the multipath fading effect in the acquisition process. Equal gain combining of two received signals is considered in a standalone processing strategy. The main novelty of this paper is to investigate improvement in acquisition time by utilizing antenna diversity for indoor scenarios. A detection threshold for which mean acquisition time is minimized is numerically shown to exist. The importance of acquisition time variance is discussed and diversity gain is evaluated. Theoretical analysis is compared with Monte Carlo simulations and real GPS data. Results show that antenna diversity improves detection probability, reduces false alarms and mean and variance of acquisition time in fading environments. Copyright © 2015 Institute of Navigation