What do you do if you have a poor or no GNSS signal, such has being indoors, inside a parking garage or in urban canyons? You could try CellLocate.
In a nutshell
CellLocate provides an estimated location based on visible network cell information reported by the cellular module. When CellLocate is activated, a data connection to the CellLocate server is established and the network cell information is passed to the server which provides an estimation of the device position based on the cell information.
CellLocate is fully integrated into the SARA-R5 which is on the OzzMaker SARA-R5 LTE-M GPS 10DOF board. The technology enables stand-alone location data based on surrounding mobile network information as well as hybrid technology that works in conjunction with GNSS. Through the single AT command interface, it is possible to define all the location settings for optimized performance.
When using CellLocate, the position accuracy is not predictable and is determined by the availability in the database of previous observations within the same area. CellLocate does not require a GNSS receiver to be present or active.
CellLocate requires a data connection (PDP) from the SARA-R5 module to the carrier.
Connect to the SARA-R5 cellular module
Setup the Packet Data Protocol (PDP) context.
First task is to setup the connection parameters for the PDP context using AT+CGDCONT. Any setting applied with this commend is persistent over power cycles. This means it only needs to be done once. You will however need to enter it again if you do a factory reset.
First, turn off the radio
Then set up a connection profile with the APN for your network operator, using the AT+CGDCONT command (Packet Switch Data configuration). In this example we are using a Hologram SIM, so the APN would be hologram.
Now turn the radio back on;
Once your SARA-R5 connects to the carrier, you can use AT+CGDCONT? to get your current IP address
Now active the PDP context
Set the PDP type to IPv4
Profile #0 is mapped on CID=1
Activate the PSD profile
Your SARA-R5 should now have internet access. If you want to test the data connection, you can use AT+UPING
When using CellLocate, There are two modes to choose from:
normal scan: the cellular module reports the serving cell and the neighboring visible cells designated by the network operator, which are normally collected by the module during its “network” activity. This configuration is suggested for a quick update of location
deep scan: the cellular module scans and reports all visible cells providing in addition to serving and neighboring cells by the serving network operator, also the cells of all other available (visible) network operators, thus increasing the probability of obtaining a successful position estimation. Although this takes a bit longer (approximately 30 sec to 2 minutes is needed to perform a deep scan), uses more data (each reported cell requires a few bytes), and more power, coverage and reliability are potentially better in corner cases.