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AssigneeHewlett-Packard Company
InventorsDavid Arthur Stephenson, David Bonner, Jan Schiefer, Steven Nicholas Bennett
Estimating the term…
In a mobile radio network such a GSM network, an operative identity code is passed by a mobile station to the fixed network part at the start of each communication transaction. This operative identity code will either be the unique identity code (IMSI) assigned to the mobile-station user or, more usually, a temporary, substitute, identity code (TMSI) allocated by the fixed network part with a view to obscuring the identity of the user to anyone monitoring the network radio traffic. Whilst the fixed network infrastructure knows the association between a temporary identity code (TMSI) and the corresponding unique identity code (IMSI) of a user, this information is generally not readily accessible. To enable the current temporary identity code (TMSI) of a user to be readily tracked without burdening the network infrastructure, a monitoring arrangement is provided which monitors network signalling messages to link the different messages associated with a particular user mobile station that separately give the current operative identity code (line "c") and assign a successor operative identity code to that user (line "h"). In one embodiment applicable to a GSM network, messages on the A interface that carry identity code information for a particular user during a communication transaction are linked through the local references of the SCCP connection established for the transaction. In a second embodiment, also applicable to GSM, messages on the Abis interface are monitored and linked through the channel numbers contained in these messages.
A method of tracking identity-code changes in a communications system in which a plurality of user stations can simultaneously conduct respective communication transactions during which signalling messages are exchanged with operational elements of the remainder of the communication system over at least one signalling path of a signalling subsystem of said communications system, said signalling messages including first messages sent by said user stations and each including an identity code associated with the user station sending that message, and second messages specifying corresponding identity codes for particular user stations;
Apparatus for tracking identity-code changes in a communications system in which a plurality of user stations can simultaneously conduct respective communication transactions during which signalling messages are exchanged with operational elements of the remainder of the communication system over at least one signalling path of a signalling subsystem of said communications system, said signalling messages including first messages sent by said user stations and each including an identity code associated with the user station sending that message, and second messages specifying corresponding identity codes for particular user stations;
Dependencies are inferred from the claim text.