Direct Position Estimation approach outperforms conventional two-steps positioning

GNSS receivers compute its position by a two-steps procedure. First, synchronization parameters are estimated and, then, a geometrical problem is solved to obtain receiver's position. This is the approach typically taken due to its simplicity and modularity. However, recent results pointed out the potential pitfalls of such approach. In that vein, Direct Position Estimation arise as a potential alternative, computing receiver's position directly from the digitized GNSS signal. The latter is performed as a single-step procedure, obtaining the Maximum Likelihood estimate of position. We base on a recent result to show that the variance of the single-step estimator is lower than the variance of the conventional two-steps estimation of position. The result is validated by computer simulations, comparing the performances of both alternatives.