Characterization of Tracking and Position Errors in GNSS Receivers with Intermittent Tracking

In traditional GNSS receiver architectures, the receiver normally acquires the visible satellite signals and keeps tracking them throughout their availability. Although this approach is perfectly viable for reliable and accurate positioning in most applications, tracking all satellites in view throughout the receiver power-on duration results in a significant penalty on power consumption in battery-operated portable devices. Modern GNSS receivers employ cyclic tracking or intermittent tracking to conserve power. The receiver temporarily halts signal tracking during a “sleep period”, and continues tracking in the remaining “active period”. The ratio of active period duration to the total duration within a position update interval expressed as a percentage is known as the duty cycle. The duty cycles employed in portable receiver design are generally heuristic in order satisfy a given set of requirements on power conservation and position accuracy. A thorough analysis of possible duty cycles as a function of targeted user position and velocity accuracy for various user dynamics is therefore necessary. This paper investigates various aspects of intermittent Global Navigation Satellite System (GNSS) signal tracking and analyzes positioning and tracking performance with various duty cycles for three different user motion cases.