A METHOD AND A SYSTEM FOR MONITORING OF ALARM APPLICATIONS IN CELLULAR NETS

Abstract: A method and a system for monitoring a communications possibility between a monitoring unit in a cellular radio network, such as a GSM-network, and a number of mobile units in the network, said mobile units being coupled to respective monitoring objects from which it shall be possible to send information to the monitoring unit via the network, wherein there is established in the monitoring unit a first list of those mobile units to be monitored, wherein the monitored mobile units choose an identity that corresponds to the identity of the net cell serving respective mobile units, wherein a monitored mobile unit that detects the net cells to which it is related chooses a new serving cell and therewith a new serving cell identity in the event of its preceding serving cell no longer being in function, and wherein the network maintains a second list which is continually updated with respect to status for the whole of the network. The first list is updated continually by virtue of each mobile unit that obtains a new serving cell identity automatically informing at least the monitoring unit in this respect, and therewith keep the first list updated. The first list is compared with the second list. A mobile unit that is included in the first list and its ability to communicate with the monitoring unit is identified by virtue of its serving cell identity referring to a net cell which, according to the second list, is out of function. The monitoring object can then be given other supervision.

Description: A METHOD AND A SYSTEM FOR MONITORING OF ALARM APPLICATIONS IN CELLULAR NETS The present invention relates to a method and to a system for monitoring a communications possibility between a monitoring unit in a cellular radio network, for instance a GSM-network, and a number of mobile units in the network, said mobile units being coupled to respective objects from which it shall be possible to send information to the monitoring unit via the network, in accordance with the preamble of the independent method Claim and in accordance with the preamble of the independent system Claim. It is well known that a cellular radio network can be used to monitor or watch over an object from a monitoring unit (an alarm centre) included in the network. The object may include an alarm sensor that is activated when the object changes state Alternatively, the object may have the form of report means that functions to deliver information to the monitoring unit via the network at chosen time points. However, a net cell of a cellular radio network, such as the GSM-network, will sometimes be non-functional, either unintentionally or as planned. It has hitherto been difficult to anticipate which mobile units will be affected by a planned interruption of a net cell, or a net cell that malfunctions or is replaced. Consequently, it is therefore desirable that a prediction can be made with respect to associated operational disturbances that concern mobile units, particularly when an operational disturbance means that a mobile unit is unable to perform a monitoring duty. A list of the monitored objects is established in a monitoring unit/alarm centre on the basis of the mobile units associated with said objects. The mobile units in the list are identified by an identity that corresponds to the identity of a net cell through which said mobile unit is served. The mobile unit detects its related cells from which it hunts a cell which, when found, then becomes its serving cell. One problem is that when a mobile unit serving cell is not in function and the mobile unit is unable to detect another cell in the network that can be reached by the mobile unit (or which can reach the mobile unit), the mobile unit is no longer able to deliver a message to the monitoring unit and the object is therefore no longer monitored. The object of the present invention is to provide a solution to this problem. This object is achieved in accordance with the invention by the method set forth in the accompanying independent method Claim. The object is also achieved with the system according to the accompanying independent system Claim. Further embodiments of the invention will be apparent from the accompanying dependent Claims. The invention will now be described schematically and by way of example with reference to the accompanying drawing. Fig. 1 is a schematic reproduction of an inventive system. A cellular radio network, for instance a GSM-network, includes a plurality of net cells C1-C4 and a plurality of mobile units, of which one, Ml, is shown. A monitoring object 01, for instance a building, a freezer or some other object is provided with a sensor, for instance an alarm, which can be activated, for instance, when detecting that the building has been broken into, or when the temperature of the freezer rises above a set threshold value. The sensor then activates the associated mobile unit Ml and said unit sends to a network-located monitoring unit 24 a message that corresponds to the event in question, via the radio network. The illustrated network includes a plurality of net cells C1-C4, whose covering ranges may overlap in the manner illustrated. A mobile unit Ml in the network senses or detects the cells C2, C4 with which it is related. The mobile unit chooses one (C2) of the cells as its serving cell in a conventional manner, and also establishes a list of neighbouring cells that it can detect. The transmitted information contains, inter alia, the list of neighbouring cells and data relating to serving cells. The mobile units are given addresses through the identity SCID of their respective serving cells. The monitoring unit sets up a list 11 of those mobile units to be monitored. The monitoring unit is in communication with net operator supervising centres. The address to these monitored mobile units is given by their respective SCIDs. The remaining net cells (scan cells) scanned or sensed by the mobile unit may also be adjusted or controlled in the list 11, suitably for each monitored mobile unit. The supervising or monitoring centre of the net operator may also include a list 10 that is continually updated with respect to the status of the entire network, including information concerning those net cells that are active, thereby also enabling information to be gained as to which cells may be inoperative at that moment in time. A mobile unit Ml that selects another serving cell C4 because its old serving cell C2 no longer functions for some reason or other is also given another SCID in the list 11 in the monitoring unit. The mobile units are suitably adapted to send information concerning a new cell ID voluntarily in the event of a change, and possibly also information relating to detected responses, or at least to the monitoring unit so as to keep the first list 11 in said unit updated. To be on the safe side, the monitoring unit 24 may be caused to ask a mobile unit Ml that has been given a new SCID about its status, as there is a risk that the mobile unit may have a problem in contacting its new serving cell C4, for instance when the mobile unit Ml is situated in the border region of the area covered by the new serving cell C4. The monitoring unit 24 may ask a mobile unit Ml about its status at any time whatsoever, in order to be updated with respect to status. However, if a monitored mobile unit whose serving cell is no longer in function is not allocated a new SCID for some reason or other, for instance because said mobile unit Ml is not related to any other net cell, i.e. lies outside the area covered by C4 in Fig. 1 and is not related to any other net cell, the monitoring unit SCID for mobile Ml will become invalid or erroneous. Furthermore, the mobile unit Ml will be unable to contact the monitoring unit 24, for instance should an alarm be triggered at the object 01. The two lists 11 and 10 are compared by a comparator 12, which may be included in the monitoring unit 24, each time a change occurs in the net list 10, and possibly also each time a monitored mobile unit Ml is given a new SCID. Should the list 11 in the monitoring unit include a mobile unit that has an SCID which indicates a cell C2 that according to the net list 10 is out of function, this mobile unit Ml is identified by the comparator 12. Because this mobile unit is unable to reach the monitoring unit via the network at that moment in time, the object concerned cannot be monitored correctly by the monitoring unit 24 via the network. The monitoring unit 24 is then able to arrange for the object 01 concerned to be monitored in some other way for the time being, for instance through the medium of some other communications equipment 14. For instance, supervising personnel in the area in which the object 01 is situated can be given instructions to go to the site of the object for the purpose of checking said object and possibly report the status to the monitoring unit (or to its personnel). Alternatively, the owner of the object concerned can be told that the object cannot be monitored correctly from the monitoring unit via the network, so that the owner of the object will be able to supervise the object personally. If the object 01 emits an alarm which is received by the monitoring unit 24, the monitoring unit, or possibly its personnel, can arrange for relevant service personnel, such as police, guards, repairmen or similar personnel, to be sent to the object and there deal with the cause of the alarm. When the object is of the kind that delivers information that shall be received by the monitoring unit, the monitoring unit may include means for recording information and/or forwarding information to a relevant receiver. The mobile unit associated with an object may be adapted to record information from its object, particularly if or when the mobile unit loses contact with the network, so that said information can be delivered later and, for instance, sent to the monitoring unit via the network when said communications possibility has been re-established.

Claims: CLAIMS 1. A method of monitoring a communications possibility between a monitoring unit in a cellular radio network, such as a GSM-network, and a number of mobile units included in said network, said mobile units being coupled to respective monitoring objects from which it shall be possible to deliver information to the monitoring unit via the network, wherein each of the mobile units is adapted to select a serving net cell from among the net cells that can be detected by said unit, and wherein the network contains a list that is updated with respect to the status of all net cells in the whole of the network, characterised by - setting up in the monitoring unit a first list (11) of the monitored mobile units and their respective serving cell identity; - causing a monitored mobile unit that detects at least one net cell in addition to the net cell serving said mobile unit to select a new serving cell and therewith a new serving cell identity in the event of its preceding serving cell being non-functional; - updating the first list (11) with respect to the serving cell identity of the monitored mobile units; - coupling the second list (10) set up by the network to the monitoring unit; - comparing the first list (11) with the second list (10); and - identifying a mobile unit in the first list that has lost the ability to communicate with the monitoring unit by virtue of its serving cell identity identifying a net cell that is out of function according to the second list. 2. A method according to Claim 1, characterised by causing the monitoring unit to voluntarily ask a monitored mobile unit about its status with respect to the identity of serving cells and of the neighbouring cells detected by the mobile unit. 3. A method according to Claim 1 or 2, characterised by making said comparison each time the second list is changed. 4. A method according to any one of Claims 1-3, characterised by causing the mobile unit to send to an inquiring unit its serving cell identity and a list of the identities of sensed neighbouring cells. 5. A method according to any one of Claims 1-4, characterised by making said comparison each time a monitored mobile unit chooses a new serving cell identity. 6. A method according to any one of Claims 1-5, characterised by causing a mobile unit that has chosen a new serving cell identity to voluntarily inform at least the monitoring unit of the identity of its new serving cell and of the identity of respective detected neighbouring cells. 7. A method according to any one of claims 1-5, characterised by also including the identity of the neighbouring cells of the monitored mobile unit in said first list. 8. A system for monitoring a communications possibility between a monitoring unit in a cellular radio network, such as a GSM-network, and a number of mobile units in said network, wherein the mobile units are coupled to respective monitoring objects from which it shall be possible to send information to the monitoring unit via the network, wherein each of the mobile units is adapted to choose a serving net cell from among the detected net cells, and wherein the net is adapted to maintain a list (10) which is kept updated with respect to the status of all net cells in the whole of the network, characterised in that - the monitoring unit contains a first list (11) of the monitored mobile units and their respective serving cells; - in that a monitored mobile unit that detects at least one net cell in addition to the net cell serving said mobile unit functions to choose a new serving cell and therewith a new serving cell identity in the event of its preceding serving cell being non-functional; - in that the first list (11) is intended to be updated with respect to the serving cell identity of the monitored mobile unit; - in that the second list (10) maintained by the network is connected with the monitoring unit; and - in that the system includes comparator means (12) for comparing the first list (11) with the second list (10), wherein said comparator means ( 12 ) is adapted to identify in the first list (11) a mobile unit that has lost its ability to communicate with the monitoring unit in said comparison, by establishing that its serving cell identity relates to a net cell that is no longer functional according to said second list. 9. A system according to Claim 8, characterised in that the monitoring unit is adapted to selectively ask a monitored mobile unit about its status with respect to the identity of respective serving cells and of respective detected neighbouring cells. 10. A system according to Claim 8 or 9, characterised in that the comparator means (12) is adapted to make said comparison each time the second list (10) is changed. 11. A system according to any one of Claims 8-10, characterised in that the mobile unit is adapted to send the identity of its serving cell and of detected neighbouring cells to an inquiring unit. 12. A system according to any one of Claims 8-11, characterised in that the comparator means (12) is adapted to make said comparison each time a monitored mobile unit has chosen a new serving cell. 13. A system according to any one of Claims 8-12, characterised in that each mobile unit is adapted to voluntarily inform at least the monitoring unit of the identity of a new serving cell and of the identity of detected neighbouring cells, for updating the first list. 14. A system according to any one of Claims 8-13, characterised in that the first list also includes the identity of cells that neighbour on the serving cell of the monitored mobile unit.

Inventors: EKBERG GUSTAF, WALLON MICHAEL, EKBERG, GUSTAF, WALLON, MICHAEL
Applicants: EKBERG GUSTAF, EUROPOLITAN AB, UNWIRE AB, WALLON MICHAEL, EKBERG, GUSTAF, WALLON, MICHAEL
Application year: 2000
Main classification: H04Q7
IPC codes: G08B25, H04M1, H04M11, H04W24, H04W36