Urban environment solutions to GPS signal near-far effect

Our aim at improving GPS receivers' availability in an urban environment, weak GPS signal acquisition becomes one key issue in satellite navigation signal processing. In special signal propagation environments, such as indoors, urban crayons, and woods, various factors such as signal propagation power loss, amplitude attenuation, and phase, time, and frequency delay distortions produce at the signal receiving end, what is now known in the literature as, the GPS signal near-far effect, which results in severe degradation of the GPS signal acquisition performance. To mitigate the near-far effect, we focus on four main factors, which are the signal strength attenuation; the Doppler frequency distortion; carrier phase uncertainty; and multi-path distribution because a proper optimization of these factors appears to improve the acquisition performance effectively.