Hewlett-Packard Company

Other

Steven Nicholas Bennett

Jan Schiefer

David Bonner

David Arthur Stephenson

David Andrew Clarke

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.

Method and apparatus for tracking identity-code changes in a

A method is provided of following a communication transaction during which a communicating mobile station (12) is handed-over from one radio cell to another in a mobile radio system. The transaction is followed across the handover by monitoring signaling messages on the signaling paths in the mobile radio system to detect the occurrence of common parameters related to communication transactions subject to handover. By correlating these parameters it is possible to associate fragments of the same transaction that give rise to signaling messages on different signaling paths. Thus in the case of a GSM mobile radio system with monitoring of the A interfaces, the parts of a communication transaction split by a handover from one BSC (17A) to another (17Z), can be associated by correlating the RR3 Handover Command signaling units appearing on the signaling links (68,69) to the old and new BSCs (17A,17Z). This correlation can conveniently be done at a central station (42) to which the signalling path monitors (40A,40Z) send report messages when they detect handovers occurring. A similar correlation can also be done when monitoring the Abis interfaces.

Handover following in a mobile radio system

A method is disclosed for determining delays in a network (10) carrying messages, such as an SS7 signalling network or a TCP/IP network. The method involves monitoring the network (10) at a predetermined location to detect first messages (REQ) and second messages (ACK) of respective predetermined categories (X, Y), the first and second messages each producing a respective time-dependent loading of the network and the second messages being caused by the first messages whereby the loadings vary in a similar manner with time but with the loading produced by the second messages being offset from that produced by the first messages. Load measures (L.sub.X,L.sub.Y) are then derived for the first and second messages (REQ, ACK), each load measure being derived by counting the number of messages of the category concerned that are detected in a predetermined time interval. These load measures (L.sub.X,L.sub.Y) are thereafter used to determine the offset between the network loadings produced by the first and second messages, this offset providing a network-delay measurement.

Method and apparatus for determining network delays

A message interceptor is interposed in a link of a communications signalling network such as an SS7 network. The interceptor separately maintains the link level protocols on the two portions of the link with which it interfaces. Message data is transferred across between the link portions by a transfer circuit of the interceptor. In the course of this transfer, the nature of the data is checked by a selective action control circuit against selection criteria held in a store. If a selection criteria is met, the control circuit acts to suppress or modify the data.

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Charlton Kings, United Kingdom

Steven Nicholas Bennett