GMLC - Gateway Mobile Location Centre
The Mobile Arts Gateway Mobile Location Centre (GMLC) is compliant with 3GPP specifications for GSM and UMTS.
Upon reception of a proprietary Erlang MLP location request from the Proxy Mobile Location Centre (XMLC) the GMLC will select which positioning method to use (“Location Method Selection”). Some location methods are completely implemented by the GMLC, other requires the interaction with a Serving Mobile Location Centre (SMLC).
3GPP GSM/UMTS Camel PSI/ATI location and OMA SUPL A-GPS location are completely handled by the GMLC, without the need for a SMLC. 3GPP GSM/UMTS LCS Location requires a SMLC to interact with the GMLC. All positioning methods result in the GMLC interacting with the network over MAP or SUPL/IP protocols as follows:
The GMLC interfaces the UMTS and GSM MSC/VLR using MAP for:
- 3GPP CAMEL Circuit-based PSI Location (CGI)
- 3GPP LCS Standard & Emergency Circuit-based MO Location
- 3GPP LCS Standard & Emergency Circuit-based MT Location
The GMLC interfaces the UMTS and GSM SGSN using MAP for:
- 3GPP CAMEL Packed-based PSI Location (CGI)
- 3GPP LCS Standard Packet-based MO Location
- 3GPP LCS Standard Packet-based MT Location
- 3GPP CAMEL Packet-based and Circuit-switched PSI/ATI Location (CGI); and
- 3GPP LCS Standard & Emergency Circuit-based MT Location
The GMLC interfaces the SUPL-compliant mobile terminal via the mobile packet data network using SUPL/IP.
Positioning a subscriber requires the GMLC to translate radio network data into a location estimate. The GMLC fetches radio network data from Cell Planning System or other external database using FTP.
GPS based positioning methods require obtaining A-GPS reference information from a local or external GPS reference station. The RINEX/IP protocol is used for retrieval of A-GPS reference data.
The GMLC stores positions received for each subscriber (“location caching”).
All newly calculated or received location data is stored in a Location Cache within the GMLC. If a location request is made for the same subscriber within a time period (expiration time), instead of making new queries to the network the location can be retrieved from the cache. This provides fast retrieval of the last known location, as required by the OMA MLP protocols and the 3GPP LCS standard. It also reduces the core and access network load resulting from mobile location and facilitates the efficient and timely operation of emergency service location.
As for the XMLC, SMLC server synchronisation is obtained from a NTP server and Network Management System is interfaced using SNMP. An Administration PC can interface the GMLC using a Command Line Interface (CLI), FTP, SCP and SFTP or a Graphical User Interface (GUI) accessed from a standard web-browser. For support reasons the GMLC can be accessed over VPN/IP by a Remote Access Gateway.