Method, mobile exchange, and subscriber station in a mobile radio system for establishing a high-priority call

A method, a radiotelephone exchange, and a subscriber station of a radiotelephone system for establishing a high priority call or a high priority group call.

The invention relates to a method for establishing a high priority call or group call to at least one subscriber of a radiotelephone system participating in a first group call on a certain channel.

The method according to the invention is intended to be used in particular in so-called trunking networks, which are typically corporate networks or government networks in which all channels are used by one or more companies or government organizations. In these networks, subscribers have, in addition to their own subscriber numbers, group numbers indicating to which group call group or group the subscriber belongs, so that the subscribers of that group can be forwarded the calls intended for the subscribers of that group.

The invention is suitable for use in both radio path digital and radio path analog radiotelephone systems. Analog radiotelephone systems are described, for example, in the UK Department of Trade and Industry's publications MPT 1327, January 1988, Revised and reprinted November 1991, A Signaling Standard for Trunked

Private Land Mobile Radio Systems, Radiocommunications Agency and MPT 1343, January 1988, Revised and reprinted September 1991, Performance Specification, Radiocommunications Agency.

In public radiotelephone networks such as

In the NMT system (NMT = Nordic Mobile Telephone), all calls have the same priority, ie no user has rights over any other user.

In private radio networks, some of which have been implemented with trunking technology, the situation is different. In these PMR95428 networks (PMR = Private Mobile Radio), it is possible to control the operation of the network so that users performing certain types of maintenance, such as alarm-related maintenance or other urgent tasks, have a higher priority, i.e. their high-priority call is connected first in a congestion situation. It is even possible to set such a high priority that the old call is dropped from under it if the new call cannot be connected in any other way. In most cases, switching can be prevented by the fact that all radio channels are in use or that the subscriber being called is already on the call. However, resources other than radio channels may be reserved and prevent the call from being connected.

When calls are established in the radio system between two subscribers, the radio system, for example its exchange or the exchange's database, knows which telephones are in the call. Based on this, when it is desired to make a high-priority call to a subscriber in a call, the exchange can disconnect the old call to release the subscriber to whom it is desired to make a new call.

In a group call, the situation is more difficult because the radio system center may not know which group calls certain subscribers belong to and thus the center does not know which radio channel those subscribers are listening to.

A group call is a call to which the system commands several, at least three, subscribers to join the same call with a single command. Groups are formed from members of a company or other user organization, and often the groups are programmed into the radio, and the center may not know which mobiles belong to which group. Typically, one phone can belong to more than one group. Some of the group numbers may even be such that they can be changed very often if necessary, even every morning, and information on these changes may not be communicated to the center in any way. For example, the MPT 1327 and MPT 1343 standards do not provide ways to transmit group numbers from a mobile, i.e. subscriber station, to a exchange. This makes it particularly difficult to involve a subscriber who is already participating in a previously initiated group call in a high priority call. This situation is very common in radiotelephone5 networks, as very often those subscribers who want to join high-priority calls are already involved in previous group calls, as those subscribers are important in their own organizations.

The above problem has been solved in the prior art solutions by disconnecting all group calls in the area of ​​operation of the radiotelephone system. By discharging group calls, the desired subscriber is found to be included in the high-priority call, but at the same time the original, i.e. the first, group call is discharged and has to be re-established without the member included in the high-priority call. This procedure causes considerable inconvenience to other subscribers of the radiotelephone system, as those subscribers have to interrupt their group calls unnecessarily. When interrupted group calls are further re-established, the radiotelephone system is overloaded with unnecessary connection steps. Furthermore, if there is a lot of traffic in the radiotelephone system, the original group call group may lose the radio channel they are using, as another group call or call may gain access to the channel while the group call is disconnected and one of its subscribers is called for a high priority call or group call.

Another disadvantage of the prior art solution is that if it is not desired to disconnect an existing group call, the desired subscriber for the high-priority call will not be included in the new call to be established at all. In this case, the reachability of the subscriber is poor.

It is an object of the present invention to provide a method for establishing a high priority call or group call to a subscriber participating in a first group call on a particular channel, which method avoids the problems of prior art solutions. The purpose is to be able to free the subscriber involved in the group call to participate in the high priority call without the problems posed by the prior art solution. A further object of the invention is to enable the connection of a desired subscriber to a desired high priority call.

This new type of method for establishing a high priority call or group call to at least one subscriber of a radiotelephone system participating in a first group call on a given channel is achieved by a method according to the invention characterized by transmitting a high priority group call to a subscriber participating in the first group call on said channel. and / or a cancellation message with the identifier identifying the high priority call or high priority group call to be established to all subscribers participating in the first group call, the subscribers participating in the first group call receive said unloading message, said state25 and, for which it is desired to form, that the unloading message is for said subscriber, said subscriber terminates his participation in the group call, said subscriber joins said high-priority call based on the received high-priority call ID.

The present invention further includes a radiotelephone exchange comprising: a switching field for connecting calls to desired subscribers and subscriber groups; The radiotelephone exchange according to the invention is characterized in that said controller comprises means for identifying a subscriber participating in the first group call to which a high priority call or a high priority group call is to be established and / or a high priority group call or a high priority group call identified.

The invention further relates to a subscriber station of a radiotelephone system comprising: memory means for storing group call IDs allowed to the subscriber station, adapting the transceiver to each radio channel used, transmitting information between the user and the cellular radio system, including the acoustic transducer means and the control panel, controlling the operation of the subscriber station The subscriber station of the radiotelephone system according to the invention is characterized in that the subscriber station further comprises: means for receiving the unloading message and comparing the high priority call or high priority group call ID to be established contained in the unload message with the subscriber station's own ID and / or the group call ID as an allowed group call ID in the subscriber station's storage medium, means responsive to said comparison for disconnecting the subscriber station from the first group call and connecting the subscriber station to the established high priority call or group call.

The invention is based on the idea that a subscriber involved in a group call 95428 can be released for a high priority call by sending a cancellation message on the channel of all group calls, either to that subscriber in the case of establishing an individual call or to the group in the case of establishing a group call. The radiotelephone must be able to handle the incoming discharge message so that it leaves the group call. Other subscribers can still remain in the group call if the channel does not need to be activated. In this case, the desired subscriber or subscribers are freed from the ongoing group calls. This is, of course, only the case if they are within range of the radiotelephone system, but if they are not within range, receiving a disconnection message is irrelevant, as outside the range15 subscribers would not hear a new call. If the current traffic channel needs to be released for telephone use, then the unloading message is sent using the ID of the same group call to be established with which the call was established, because all subscribers have to leave the group call in question.

An advantage of such a method, a radiotelephone exchange and a radiotelephone system subscriber station for establishing a high priority call or a high priority group call is that the method, exchange and subscriber station according to the invention improve the reachability of a subscriber participating in a group call when said subscriber is want to disconnect the group call in which said subscriber is involved30.

A further advantage of the invention is that the necessary disconnection of the entire group call in the prior art solution, when it is desired to establish a high priority call to one subscriber participating in the group call, can be omitted. In this case, the other subscribers belonging to said group call are not unnecessarily excluded from the group call, but can continue the group call without interruption, even if one or more subscribers participating in the group call join the high5 priority group call.

As a result, it is a further advantage of the invention, as it avoids the creation of a new group call to those subscribers who participated in the group call and were not invited to participate in the new high-priority call.

Furthermore, the fact that the old group call does not have to be disconnected has the advantage that the radiotelephone system does not have to send the connection establishment messages required to establish a new group call, which would load the radiotelephone system.

A further advantage of the invention is that since the old group call is not disconnected, the risk of the old group call radio channel being allocated to the needs of another call while the group call is disconnected is avoided.

The invention will be explained in more detail below with reference to the accompanying drawings, in which Fig. 1 shows a schematic diagram of a group call subscriber station, Fig. 2 shows a block diagram of a radiotelephone system exchange according to the invention, Fig. 3 shows a block diagram of a radiotelephone system subscriber station according to the invention; 5 shows a flow chart of the operation of a subscriber station according to the invention, Figure 6 shows a block diagram of an embodiment of a subscriber station according to the invention.

Figure 1 shows a schematic diagram of subscriber stations in a group call. The diagram shows a radio telephone exchange MX, to which base stations BS1 to BS4 have been connected by means of telecommunication connections. The figure also shows the subscribers MSI to MS6 in the service area of ​​this exchange, which are connected to the base stations BS1 to BS4 via radio paths. The subscriber stations MSI - MS4, i.e. radiotelephones, participate in the first (old) group call by listening to the channel of this group call. The exchange now receives information that the subscriber station MS4 would like to join another, high-priority call, which may be an ordinary call between two subscribers MS4, MS5 or a group call between several subscribers MS4, MS5, MS6. In this case, the exchange MX sends a release message on all group call channels to the subscriber stations MSI to MS4. The unloading message can be, for example, in trunking systems, the normal unloading message MAINT (clear) sent on the traffic channel. This message is described in more detail in the MPT 1327 and MPT 1343 specifications. However, the invention differs from MPT 1327 and MPT 1343 and what is new is that during group calls, disconnection messages are sent which are in no way related to this particular call but to new calls to be established. The transmission of the discharge message is decided by the call control processor of the exchange, which is also responsible for the new call to be established. The subscriber station MS4 which is to be included in the high priority call instead of the group call detects from the decryption message that the subscriber MS4 is to be included in said new high priority call. In this case, said subscriber MS4 stops participating in the old group call and starts listening to the channel of the new group call or starts a new call with the second subscriber station MS5.

It should be noted that multiple group calls may be established simultaneously in the radiotelephone system, and a demultiplexing word 95428 mat may be sent to all participating subscriber stations on the respective group call channels urging the desired subscribers to stop participating in said group calls and to participate in new, high or higher priority calls. or new calls between two subscribers.

The cancellation message must be sent to the subscribers of all currently established group calls because it is not known in which group call the subscriber in question is participating or whether the desired (retrieved) subscriber is participating in any currently existing group call. The transmitted decoding message causes a slight deterioration in speech quality, which can be almost completely compensated by current technology.

Figure 2 shows a block diagram of a radiotelephone system exchange 300 according to the invention. The function of the interface part 304 is to provide interfaces 305 to the base stations BS1, BS2, BS3, BS4 for both speech and signaling. There may also be connections elsewhere, such as to the telephone network, telephone exchanges and other exchanges 307. A switch field 301 and a control section 302 are connected to the connection part 304, for example by means of a data bus.

The function of the switch field 301 is to switch voice paths between the subscriptions of different subscribers on a call-by-call basis. In a two-way call, the voice paths of the two subscriptions are connected to each other. In a group call, for example, all subscriber stations MSI, MS2, MS3, MS4, MS5, MS6 belonging to the call are connected together in a conference type.

The function of the control part 302 is e.g. take care of making and ending calls. To this end, the controller connects to an interface 304 through which it can send and receive signaling messages. The control section 302 is also associated with a switch field 301, which it controls on a call-by-call basis. In the exchange 300 according to the invention, means 306 are arranged in the control part 302 for sending a discharge message to all subscribers participating in the first group call.

MSI, MS2, MS3, MS4. Said means 306 may also send a cancellation message to other subscribers participating in group calls. The unloading message may be provided with an identifier identifying the subscriber MS4 participating in the first group call, for which it is desired to establish a high-priority call or a high-priority group call. Furthermore, the unloading message may be provided with an identifier identifying the high-priority call or high-priority group call to be established. The subscriber station compares the identifier in the unloading message to its own identifier and if the unloading message identifier and the subscriber station's own identifier are the same, the subscriber station terminates its participation in the group call and returns to the paging channel, after which the subscriber station joins the desired high priority call.

The subscriber station performs a similar comparison, and if the unloading message contains one of the subscriber's group numbers, then the subscriber station terminates its participation in the previous group call and joins the high priority group call.

The controller 302 is also associated with a memory means 303. This memory means 303 may be implemented either together with the controller part 302, or together with the entire control panel, or as a separate memory means. The storage medium 303 stores all the information necessary for the operation of the radiotelephone system. These may include information related to subscriber stations MSI, MS2, MS3, MS4, MS5, MS6. For example, information on the subscriber stations authorized to operate in the system, information on the functions allowed for each subscriber station MSI, MS2, MS3, MS4, MS5, MS6, information on the location of the subscriber stations, for example with base station or location area accuracy, and information related to ongoing calls .

Figure 3 shows a typical subscriber station, i.e. the structure of the radiotelephone used by the subscriber. The function of the transmitter (TX / RX) 501 is to match the radio channel used in each case. An antenna 502 is connected to the transceiver 501 and communicates with the radio path RP. Radio frequencies between 60 and 1000 MHz (VHF and UHF bands) are generally used, although other frequencies may be used. In the radio path RP, analog modulation can be used, in which case the modulation method is usually phase modulation. Other types of modulation can also be used. For example, an audio frequency subcarrier (FFSK) can be used to transmit signaling, i.e. signaling. Radio transmission can also be digital.

The actuator 505 includes electroacoustic transducer means, typically a headset 506 and a microphone 507, and possibly buttons for initiating and ending a call and selecting a user interface 507.

Since in a trunking system the call on the radio path RP is preferably alternating, the drive usually also has a speech button that must be pressed during the speech.

The function of the controller 503 is to control the operation of the subscriber station. The controller 503 is connected to the drive device 505, from which it receives e.g. prompts to start and end a call. The controller 503 may also provide the user, via the drive 505, or the user interface 507, with audio or visual signals related to the operation of the radiotelephone and / or radiotelephone system.

Controller 503 is connected to a transceiver TX / RX

501. The channel used by the transceiver is determined by the controller 503, i.e. the transceiver 501 tunes to the channel determined by the controller 503, i.e. the radio frequency. The transceiver 501 is also turned on by the controller 503 controlled30 Mana. The controller 503 receives and transmits signaling messages via the transceiver 501. The controller can also obtain information about the field strength of the received signal.

Associated with the controller 503 is a memory medium 504 with permanent data and variable data. Permanent information includes, for example, the subscriber station's own subscriber number, the numbers of the group call groups to which the subscriber station can join, i.e. the identifiers of permitted group calls, and the radio channels belonging to the system. Variable information includes status5 and the current status of the station, such as sleep mode, call set-up mode, call status, etc., as well as information on which channel the station is tuned to.

The subscriber station 500 according to the invention further comprises: means 508 for receiving a decryption message sent by the exchange 300 and comparing the ID contained in the decryption message with the subscriber station's own ID and / or the group call ID as an allowed group call ID in the subscriber station memory 504. The decryption message sent by the exchange contains the high-priority call or high-priority group call ID to be established, which the subscriber station compares to its own ID in the memory or to the allowed group call ID. When that comparison is performed, the means 509 responsive to said comparison disconnects the subscriber20 from the first group call and connects the subscriber station to a high priority call or group call if the result of the comparison is such that the ID contained in the decryption message is the same as in the subscriber station's memory. is thus posi25 tight.

Figure 4 shows a flow chart of the operation of the exchange according to the invention. The figure shows the command of a subscriber in a group call to an emergency call, i.e. a very high priority call. Figure 4 shows a description for the radiotelephone 30 system exchange 300 or system controller. At the beginning, the exchange, or its controller, waits 401 for a call to be connected. The exchange checks 402 whether the call is an emergency call, or some other high priority call. If the incoming call is of high priority, then the exchange 405 sends a cancellation message to the desired subscribers for said call on the traffic channels of all currently valid group calls. Thereafter, and also if the call to be connected is not a 404 high-priority, emergency call, the exchange sends a call on the paging channel 406 to the desired subscriber of the new call, after which the exchange returns to waiting for the new call to be connected to step 401.

Figure 5 shows a flow chart of the operation of a subscriber station 500 according to the invention. The figure shows the command of a subscriber in a group call to an emergency call, i.e. a high priority call. The description here is for the radiotelephone of the subscriber station, i.e. the subscriber unit. The subscriber station waits 701 for the mobile (subscriber station) to be commanded on the call. When a subscriber station is assigned to a call, typically a group call, the subscriber station 702 waits for a decryption message from the exchange. Upon receipt of the unloading message by the subscriber station, the subscriber station checks 703 whether the unloading message is for the subscriber or individual number of that subscriber station. If the unloading message contains 704 the subscriber number of that subscriber station, then the subscriber station exits the group call in which it has participated and returns to the paging channel. If, on the other hand, the decryption message did not contain 705 the subscriber number of that subscriber station, then the subscriber station checks whether the decryption message is intended for one of that subscriber's group numbers, i.e. the subscriber station compares If so, operation proceeds from step 706 as described above. If, on the other hand, the unloading message 708 does not contain the group number identifiers of the subscriber station, the subscriber station moves to wait for a new unloading message 702.

Figure 6 shows a block diagram of an embodiment of a subscriber station according to the invention. The signaling controller 604 of the subscriber station interprets the incoming radio messages and generates the outgoing messages and the necessary acknowledgment messages, respectively. Signal control

604 also receives incoming unloading messages and checks whether they are addressed to that subscriber, either to its own individual number or to one of its group numbers. The network supervisor 603 maintains a connection to the radiotelephone system. The FFSK modem 602 generates an audio level signal from the signaling controller to the radio 601, which modulates the radio's RF (80 MHz, 160 MHz, or 450 MHz) carrier. The user interface 605 is the interface between the terminal and the user.

The drawings and the related explanation are only intended to illustrate the idea of ​​the invention. The details of the method according to the invention, the radiotelephone exchange and the subscriber station of the radiotelephone system for establishing a high-priority call or a high-priority group call may vary within the scope of the claims. Although the invention has been described above mainly in connection with trunking systems, the invention can be implemented in other types of radiotelephone and mobile telephone systems.

The invention further comprises a method for speeding up call set-up. In the method, the unloading message by which the subscriber is unloaded from the previous call may contain information in response to which the subscriber immediately begins listening to the new channel. The unloading message is a message that immediately causes the subscriber to listen to a new radio channel.