Integration Manual

LISA-U2 series - System Integration Manual
UBX-13001118 - R25 Features description Page 150 of 182
4. The visibility of multiple cells provides increased accuracy based on the intersection of areas of
visibility.
CellLocate
®
is implemented using a set of two AT commands that allow configuration of the
CellLocate
®
service (AT+ULOCCELL) and requesting position according to the user configuration
(AT+ULOC). The answer is provided in the form of an unsolicited AT command including latitude,
longitude and estimated accuracy.
☞ The accuracy of the position estimated by CellLocate
®
depends on the availability of historical
observations in the specific area.
3.10.2 Hybrid positioning
With u-blox Hybrid positioning technology, u-blox cellular devices can be triggered to provide their
current position using either a u-blox GNSS receiver or the position estimated from CellLocate
®
. The
choice depends on which positioning method provides the best and fastest solution according to the
user configuration, exploiting the benefit of having multiple and complementary positioning methods.
Hybrid positioning is implemented through a set of three AT commands that allow configuration of
the GNSS receiver (AT+ULOCGNSS), configuration of the CellLocate
®
service (AT+ULOCCELL), and
requesting the position according to the user configuration (AT+ULOC). The answer is provided in the
form of an unsolicited AT command including latitude, longitude and estimated accuracy (if the
position has been estimated by CellLocate
®
), and additional parameters if the position has been
computed by the GNSS receiver.
The configuration of mobile network cells does not remain static (e.g. new cells are continuously
added or existing cells are reconfigured by the network operators). For this reason, when a Hybrid
positioning method has been triggered and the GNSS receiver calculates the position, a database self-
learning mechanism has been implemented so that these positions are sent to the server to update
the database and maintain its accuracy.
The use of hybrid positioning requires a connection via the DDC (I
2
C) bus between the LISA-U2 cellular
module and the u-blox GNSS receiver (see section 1.10).
See the GNSS Implementation Application Note [15] for the complete description of the feature.
☞ u-blox is extremely mindful of user privacy. When a position is sent to the CellLocate
®
server u-blox
is unable to track the SIM used or the specific device.