Low-complexity synchronization in a navigation receiver under multipath interference

The time-of-arrival estimation error produced by multipath interference in a navigation receiver causes a strong degradation of the positioning accuracy. We present a synchronisation technique, operative in a navigation receiver under multipath interference, that takes into account its special conditions: low signal-to-noise ratio, DS-CDMA signals with long spreading codes, and very low data rates. The paper begins by introducing the signal model of a deterministic antenna array. In this context, the system-specific features translate into the assumption that all times of arrival must be inside a delay interval in which a truncated series approximation of the reference signal is valid. The introduction of this series in the signal model leads to an implementation based on a bank of correlators. Finally, the associated minimization problem is solved using three minimization algorithms: ESPRIT, IQML and a modification of Newton´s method. The latter calculates the maximum likelihood estimator with a low computational burden