  A Global Navigation Satellite System (GNSS) receiver usually needs a
sufficient number of full pseudorange measurements to obtain a position
solution. However, it is time-consuming to acquire full pseudorange information
from only the satellite broadcast signals due to the navigation data features
of GNSS. In order to realize fast positioning during a cold or warm start in a
GNSS receiver, the existing approaches require an initial estimation of
position and time or require a number of computational steps to recover the
full pseudorange information from fractional pseudoranges and then compute the
position solution. The BeiDou Navigation Satellite System (BDS) has a unique
constellation distribution and a fast navigation data rate for geostationary
earth orbit (GEO) satellites. Taking advantage of these features, we propose a
fast positioning technique for BDS receivers. It simultaneously processes the
full and fractional pseudorange measurements from the BDS GEOs and non-GEOs,
respectively, which is faster than processing all full measurements. This
method resolves the position solution and recovers the full pseudoranges for
non-GEOs simultaneously within 1 s theoretically and does not need an estimate
of the initial position. Simulation and real data experiments confirm that the
proposed technique completes fast positioning without a priori position and
time estimation, and the positioning accuracy is identical with the
conventional single-point positioning approach using full pseudorange
measurements from all available satellites.
