METHOD OF CHANGING THE TELECOMMUNICATION OF A SUBSCRIBER STATION IN A RADIO SYSTEM

Abstract: The present invention relates to a method of changing the telecommunication settings of a subscriber station (1) in a radio system providing a wireless subscriber interface. For easy and swift changing of the telecommunication settings the subscriber station (1) is equipped with means (13) for changing its telecommunication settings as a response to a message received by the subscriber station over the radio path, a message (S1) is transmitted to the subscriber station including new telecommunication settings, and an acknowledgement (S2) of the implementation of the new telecommunication settings is awaited from the subscriber station (1).

Description: Method of changing the telecommunication of a subscriber station in a radio system The present invention relates to a method of changing the tele¬ communication settings of a subscriber station in a radio system providing a wireless subscriber interface. The invention further relates to a radio system providing a wireless subscriber interface and comprising a subscriber network element in a data transmission connection with a local exchange of a public telephone network, base stations and subscriber stations, the subscriber net¬ work element and said base stations comprising means for transferring tele¬ communication signals between the local exchange and the subscriber sta- tions. The invention further relates to a subscriber station of a radio system providing a wireless subscriber interface and consisting of terminal equipment having a radio part, and of a user interface linked to the terminal equipment by means of a two-wire line. In this connection, the concept telecommunication setting refers to the parameters in a subscriber station affecting the telecommunication con¬ nection between the subscriber station and the system subscriber network element. That is, said telecommunications settings include e.g. the radio cell identity and the frequency of the calling channel the subscriber station should utilize, the maximum transmission output level used by the subscriber station, and information indicative of the subscriber station call set-up procedure (transparent vs. non-transparent). The invention relates to the operation of a subscriber station used in a WLL system (Wireless Local Loop), that is, a radio system providing a wire¬ less subscriber interface. In the WLL system, a usual two-wire telephone set is linked by means of special terminal equipment via a radio connection to a local exchange in a telephone network, the exchange in turn being linked to the public telephone network via network cabling. In this connection, a subscriber station refers to the equipment available to a subscriber for transmitting and receiving telecommunication signals, that is, in the case of a special WLL sub- scriber station, it comprises terminal equipment consisting of a radio part and a teleadapter (to which a user interface, such as a telephone set, is connected), and a user interface, such as a telephone, a telefax terminal, a computer/mo¬ dem combination or the like, connected to the terminal equipment. In WLL systems, the terminal equipment of a subscriber station is also located on subscriber premises where the operator maintenance person¬ nel often have no easy entry. In practice, this has caused problems, e.g. when the system has to be reconfigured and the telecommunications settings have to be modified. A typical situation is when a new radio cell is set up near a ra¬ dio cell that has been congested, the geographical areas covered by the cells being at least partially overlapping. In this case it is usually desirable to move part of the subscriber stations covered by the old radio cell to be covered by the new cell to equalize cell load. In known WLL systems such network recon¬ figuration has always called for manual changes by the operator maintenance personnel in all subscriber stations to be moved to the new cell. It is evident that this operation is slow and extremely laborious. It is an object of the present invention to solve the above problem and to provide an easier and faster method of changing the telecommunication settings of a subscriber station. This object is achieved with the method of the invention, characterized in that the subscriber station is equipped with means for changing its telecommunication settings as a response to a message re- ceived by the subscriber station over the radio path, a message containing new telecommunication settings is transmitted to the subscriber station, and an acknowledgement of the implementation of the new telecommunication settings is awaited from the subscriber station. The invention is based on the idea that controlling subscriber sta- tions in the WLL system becomes significantly easier if the subscriber stations are equipped with means by which the telecommunications settings can be changed over the radio path. Consequently, e.g. moving a subscriber station from one cell to another in connection with network reconfiguration becomes significantly easier as the operator can control the subscriber station as de- sired by a message transmitted directly from the network management centre. This facilitates system management considerably, as each modification in connection with system configuration is no longer subject to operator mainte¬ nance personnel visiting all the subscribers whose subscriber stations are af¬ fected by the reconfiguration. The invention further relates to a radio system to which the method of the invention can be applied. The radio system of the invention is charac¬ terized in that the subscriber network element comprises means for transmit¬ ting a predetermined message via a base station over the radio path to a given subscriber station in order to change its telecommunication settings, and that the subscriber station comprises means for changing its telecommunication settings as a response to information contained in the message, and means for transmitting an acknowledgement over the radio path via the base station to the subscriber network element in order to confirm the implementation of the new telecommunication settings. In a preferred embodiment of the system of the invention, signalling between the subscriber station and the subscriber network element is essen¬ tially similar to that defined in NMT-900 specifications, the subscriber network element being arranged to use frame 1a, 1a', 1a" or 1 b defined in NMT-900 specifications point 4.3.2.1 as said predetermined message, and the sub¬ scriber station is arranged to acknowledge the implementation of the new tele- communication settings to the subscriber network element by frame 10a or 10d defined in NMT-900 specifications point 4.3.2.2. This embodiment of the invention provides a chance to apply the method of the invention to the WLL system based on the N T-900 mobile communication system, the signalling of the subscriber station and the subscriber network element associated with changing the telecommunication settings being formed such that subscriber stations of the NMT-900 system can also be utilized in the system. This means that although all aspects of the signalling of the subscriber network element are not similar to the signalling defined in the NMT-900 specifications, the dif¬ ferences are, however, insignificant as regards the operation of a conventional NMT-900 mobile station, and consequently do not cause disturbance. Thus, the solution of the invention also allows the signalling associated with chang¬ ing the telecommunication settings of a subscriber station to be completely implemented on a system calling channel, which speeds up the operation and reserves less resources than if a traffic channel had to be assigned to the sub- scriber station before its telecommunications settings could be changed. The invention further relates to a subscriber station for applying the method of the invention, and suited for use in the system of the invention. The subscriber station of the invention is characterized in that the terminal equip¬ ment comprises means for changing the telecommunication settings of the subscriber station as a response to a predetermined message received over the radio path. The subscriber station of the invention allows the telecommuni¬ cations settings of the terminal equipment on subscriber premises to be changed without a visit from operator maintenance personnel, and without the subscriber being aware of the change in the telecommunications settings of his/her subscriber station. In a preferred embodiment of the subscriber station of the invention the subscriber station comprises means for changing the telecommunication settings associated with the radio cell it uses as a response to a message re¬ ceived from the radio path. This embodiment of the invention allows the sub¬ scriber station to be transferred from a radio cell to another, or e.g. communi- eating of a new calling channel to be taken into use to the subscriber station by a very simple procedure. The preferred embodiments of the method, system and subscriber station of the invention are disclosed in the attached dependent claims 2, 4 to 5, and 8 to10. In the following the invention will be described in greater detail by means of a preferred embodiment of the invention with reference to the ac¬ companying drawings, in which Figure 1 shows a block diagram of a first preferred embodiment of the system of the invention, Figure 2 illustrates the mutual location of the radio cells in the sys¬ tem of Figure 1 , and Figure 3A and 3B illustrate signalling frames utilized in the system of Figure 1. Figure 1 shows a block diagram of a first preferred embodiment of the system of the invention. Figure 1 shows the part of the WLL system to which the method of the invention can be applied. The WLL system shown in Figure 1 is based on the N T-900 system (Nordisk Mobil Telefon), simplified by irrelevant properties having been omitted. Base stations 5, 5', 5" are similar to parts of the NMT-900 cellular radio system. This means that signalling be- tween a subscriber station 1 and the base stations is quite similar to the sig¬ nalling between a subscriber station and a base station in the NMT-900 mobile communication system. Consequently, calls to a conventional NMT-900 sys¬ tem mobile station 9 can also be forwarded via the base stations 5, 5' and 5" and a subscriber network element 6, provided that the operator has pro- grammed the subscriber network element 6 for forwarding calls regarding said telephone. The subscriber station 1 shown in Figure 1 consists of a user inter¬ face, i.e. a telephone set 2, and terminal equipment 3. The telephone set 2 shown in Figure 1 can be a conventional voice-frequency telephone set con- nectable to a fixed telephone network. A two-wire line 4, via which signals can be transferred between the terminal equipment and the telephone set con- nects the telephone set 2 and the terminal equipment 3 in Figure 1. The termi¬ nal equipment 3 comprises signal processing means for adapting a speech path to a radio channel. Such signal processing means include e.g. a radio part 11 comprising an antenna 8, a radio transmitter and a radio receiver, and a teleadapter 10 for fitting the radio part to a conventional telephone set 2. The subscriber station 1 uses radio frequency signals to communi¬ cate via the antenna 8 with the base station 5' via which calls are forwarded to the subscriber network element 6 and further to an exchange 7 in a PSTN network (Public Switched Telephone Network), i.e. a fixed telephone network. In the case of Figure 1 , the subscriber network element 6 can be linked to the local exchange of a fixed telephone network via e.g. an open multiplexer in¬ terface of type CCITT Q.512 V2 or V5.1 or V5.2 using a 2 Mbit/s PCM system (Pulse Code Modulation). The subscriber network element 6 shown in Figure 1 is quite similar to the MTX exchange in the NMT-900 system except that properties irrelevant to the WLL system have been omitted, such as procedures associated with handover. Thus, the mobility of the subscriber stations of the system is limited to their home cells. In the system of Figure 1 this has been implemented so that the home cell identity has been stored in the subscriber station 1. This means that the subscriber station monitors the calling channel of a given radio cell only if the cell identities of calls transmitted on that calling channel corre¬ spond to the cell identity stored in the subscriber station. When the subscriber station 1 of Figure 1 is used for the first time to establish a connection with the base station 5' of its home cell, the radio part 11 of the subscriber station utilizes the highest possible transmission output level. If at that moment the subscriber station is located very near the base station 5', this can cause disturbance in other subscriber stations also utilizing the base station 5'. In accordance with the invention, to prevent such distur¬ bance, the operator can from e.g. the network management centre activate the subscriber network element 6 so that it transmits message S1 , by which it changes the telecommunication settings of the subscriber station by defining the maximum transmission output of its transmitter. At this point, a control unit 13 in the subscriber station adjusts the transmission output level of the trans¬ mitter 11 on the basis of the maximum transmission output level included in message S1 , and in addition it stores the value indicative of the maximum transmission output level in a memory 14 and transmits acknowledgement S2 to the base station 5' over the radio path in order to confirm the implementa¬ tion of the new maximum transmission output level. The memory 14 for storing the value indicative of the maximum transmission output level is of a type that keeps the information stored even if the operating voltage is switched off in the subscriber station 1. This way the control unit 13 can retrieve the maximum transmission output level (and other stored telecommunication settings) from the memory 14 after the subscriber station has been turned off and turned on again and the terminal equipment is reset, and adjust the transmitter 11 on the basis of this information. It is known that WLL systems allow the utilization of two optional call set-up procedures when a call is made from a WLL subscriber station, i.e. transparent call set-up or non-transparent call set-up. In non-transparent call set-up the subscriber station generates the sound signals to be input into the user interface 2 before the call is connected, and buffers the dialling input by the user until the dialling is complete. The whole dialling is then transmitted via the subscriber network element to a local exchange of the telephone network, after which a speech path is connected between the user interface 2 and the telephone exchange, i.e. the user hears the voice-frequency signals forwarded from the telephone exchange 7. In contrast, in transparent call set-up, the speech path is connected as soon as possible (immediately) between the telephone exchange 7 and the user interface 2 of the subscriber station, and the subscriber hears all the audible tones fed by the telephone exchange, and the dialling input by the subscriber is forwarded directly to the telephone exchange as the subscriber inputs it. In the case of Figure 1 , the subscriber station 1 is capable of utiliz¬ ing both above call set-up procedures. Thus the operator can define to the subscriber station via the network what call set-up procedure to use by send¬ ing to it relevant information by message S1. The control unit 13 then sees to it that the terminal equipment 3 uses the call set-up procedure assigned to it, and in addition stores information thereon in the memory 14 from which it can be read when the subscriber station is reset. Finally, the control unit 13 ac¬ knowledges the change in telecommunications settings by transmitting ac¬ knowledgement S2 to the subscriber network element 6 via the radio unit 11. Figure 2 illustrates the mutual location of the radio cells in the sys¬ tem of Figure 1. As can be seen from Figure 2, the geographical areas cov- ered by the radio cells 5, 5' and 5" are partially overlapping. In this way the subscriber station 1 can alternatively utilize either the radio cell 5 or the radio cell 5' depending on its telecommunication settings. In accordance with the invention, when a subscriber station 1 is manufactured, the cell identity is defined as TA=00H (Traffic Area code) in the telecommunication settings, i.e. the subscriber station observes all audible calling channels irrespective of the cell identity found on the calling channels. That is, the subscriber station 1 operates as a conventional subscriber station in the NMT mobile telephone system. To lock the subscriber station 1 to a given radio cell, e.g. cell 5', the operator transmits message S1 including the cell identity TA=40 of the radio cell 5' from the network management centre to the subscriber station 1 via the subscriber network element 6 of Figure 1. The control unit 13 of the subscriber station then makes the receiver of the subscriber station go through the calling channels available to the system until it finds the calling channel using the cell identity TA=40. The control unit then locks the radio part 11 of the terminal equipment 3 to said channel, stores the new cell identity in the memory 14, and transmits acknowledgement S2 to the subscriber network element 6 con¬ firming the change in telecommunication settings. Having received the ac- knowledgement, the subscriber network element updates the location of the subscriber station 1. However, if the subscriber station does not find a calling channel using the cell identity TA=40 included in message S1 within a predetermined time, e.g. two minutes from receipt of message S1 , it returns to the original cell, and the cell identity remains TA=00H in the telecommunication settings. The above can also be applied to the transfer and locking of a sub¬ scriber station, previously locked to a given radio cell, to another radio cell by transmitting to it message S1 including the identity of the new radio cell. Figures 3A and 3B illustrate signalling frames utilized in the systems of the invention and of Figures 1 and 2. To transfer the subscriber station 1 of Figures 1 and 2 to a given radio cell, the subscriber network element 6 transmits message S1 to the sub¬ scriber station 1 via a base station on a calling channel. A frame 1a, 1 a', 1a" or 1 b defined in the NMT-900 specifications point 4.3.2.1 (NMT Doc 900-1 , January 29, 1985) is preferably used as the message. Figure 3A illustrates frame 1 a (Calling Channel Indication, General). In accordance with this em- bodiment, variable Z is always assigned the value 0 and variable A1 the value 3. The new cell identity TA is communicated to the subscriber station by means of variables A2 and A3. Having found a calling channel using the cell identity assigned to it, the subscriber station acknowledges the change in telecommunication settings by transmitting to the subscriber network element acknowledgement S2, pref¬ erably frame 10a or 10d defined in the NMT-900 specifications point 4.3.2.2. Figure 3B illustrates frame 10a (Call acknowledgement from MS on calling channel, and access on access channel). In said frame variables A1 , A2 and A3 are assigned the same values as in message S1 , whereas the value of variable A4 is set to 0. To set the maximum transmission output of the subscriber station 1 to a desired level, the subscriber network element transfers to the subscriber station, via a base station, message S1 , i.e. in this embodiment the frame shown in Figure 3A, where variable A1 is assigned the value 4, and where the maximum allowed transmission output level is given by variable A2, e.g. as follows: A2 = 1 = output level class 1 A2 = 2 => output level class 2 A2 = 9 = output level class 9 The subscriber station acknowledges the change in the maximum transmission output level by acknowledgement S2, i.e. in this embodiment by the frame of Figure 3B, where the values of variables A1 , A2 and A3 are the same as in message S1 , and the value of variable A4 is 0. To communicate the call set-up procedure, message S1 is trans¬ mitted to the subscriber station, i.e. in this embodiment the frame shown in Figure 3A, where variable A1 is assigned the value 5, and where the maxi¬ mum allowed transmission output level is given by variable A2, e.g. as follows: A2 = 1 => non-transparent state A2 = 2 => transparent state The subscriber station acknowledges the change in the call set-up procedure by acknowledgement S2, i.e. in this embodiment by the frame of Figure 3B, where the values of variables A1 , A2 and A3 are the same as in message S1 , and the value of variable A4 is 0. It will be appreciated that the above description and the accompa¬ nying drawings are presented by way of illustration only. Thus the invention can also be applied to WLL systems not based on the NMT mobile telephone system. In addition, the changes in telecommunication settings performed on the subscriber station are not limited to the above, but any telecommunication setting of a subscriber station can be changed by applying the invention. It will be understood by those skilled in the art that various other modifications and changes may also be made without departing from the spirit and scope of the invention disclosed in the appended claims.

Claims: CLAIMS 1. A method of changing the telecommunication settings of a sub¬ scriber station (1) in a radio system providing a wireless subscriber interface, characterized in that the subscriber station (1) is equipped with means (13) for changing its telecommunication settings as a response to a message received by the subscriber station over the radio path, a message (S1) containing new telecommunication settings is transmitted to the subscriber station, and an acknowledgement (S2) of the implementation of the new tele¬ communication settings is awaited from the subscriber station (1). 2. A method as claimed in claim 1, characterized in that said means for changing the telecommunication settings comprise at least means for changing the telecommunication settings associated with the radio cell used in order to transfer the subscriber station to a given radio cell. 3. A radio system providing a wireless subscriber interface and comprising a subscriber network element (6) in a data transmission connection with a local exchange (7) of a public telephone network, base stations (5, 5', 5") and subscriber stations (1, 9), the subscriber network element (6) and said base stations (5, 5', 5") comprising means for transferring telecommunication signals between the local exchange and the subscriber stations, charac¬ terized in that the subscriber network element (6) comprises means for transmitting a predetermined message (S1) via a base station over the radio path to a given subscriber station (1) in order to change its telecommunication settings, and that the subscriber station (1) comprises means (13, 14) for chang¬ ing its telecommunication settings as a response to information contained in the message (S1), and means for transmitting an acknowledgement (S2) over the radio path via the base station to the subscriber network element (6) in order to confirm the implementation of the new telecommunication settings. 4. A radio system as claimed in claim 3, characterized in that when said message (S1) contains a new cell identity (TA), the subscriber station (1) comprises means for going through the calling channels used by the system until it finds a calling channel using said new cell identity (TA), and the subscriber station transmits said acknowledgement (S2) to the subscriber network element (6) and moves to said new calling channel, and if the sub¬ scriber station does not find a calling channel using said new cell identity (TA), it returns to the original calling channel without changing its telecommunication settings. 5. A radio system as claimed in claim 3, characterized in that signalling between the subscriber station (1) and the subscriber network element (6) is essentially similar to that defined in NMT-900 specifications, the subscriber network element being arranged to use frame 1a, 1a', 1a" or 1b defined in NMT-900 specifications point 4.3.2.1 as said predetermined mes¬ sage, and the subscriber station (1) is arranged to acknowledge the imple¬ mentation of the new telecommunication settings to the subscriber network element by frame 10a or 10d defined in NMT-900 specifications point 4.3.2.2. 6. A subscriber station (1) of a radio system providing a wireless subscriber interface and consisting of terminal equipment (3) having a radio part (11), and of a user interface (2) linked to the terminal equipment by means of a two-wire line (4), characterized in that the terminal equip¬ ment comprises means (13, 14) for changing the telecommunication settings of the subscriber station as a response to a predetermined message (S1) re- ceived over the radio path. 7. A subscriber station as claimed in claim 6, characterized in that the terminal equipment (3) comprises means (11, 13) for transmitting a predetermined acknowledgement (S2) over the radio path as a response to the implementation of the new telecommunication settings. 8. A subscriber station as claimed in claim 6, characterized in that the terminal equipment (3) comprises means for changing the telecom¬ munication settings (TA) associated with the radio cell used as a response to the message (S1) received by the subscriber station (1), whereby the sub¬ scriber station (1) is arranged to switch to utilize the new radio cell assigned to it by said message (S1). 9. A subscriber station as claimed in claim 6, characterized in that the terminal equipment (3) comprises means for limiting the maximum transmission output level used by the subscribe station (1) on the basis of in¬ formation included in said message (S1). 10. A subscriber station as claimed in claim 6, character¬ ized in that the terminal equipment (3) comprises means for changing the telecommunication settings associated with the call set-up of the subscriber station (1 ) in order for a transparent or a non-transparent call set-up procedure to be chosen as a response to the information contained in the message (S1) received by the subscriber station.

Inventors: LAEHDEMAEKI HEIMO, LAEHDEMAEKI, HEIMO
Applicants: LAEHDEMAEKI HEIMO, NOKIA TELECOMMUNICATIONS OY, LAEHDEMAEKI, HEIMO
Application year: 1997
Main classification: H04Q7
IPC codes: H04W8, H04W84