CA2265685A1

CA2265685A1 - Radio system forming a wireless subscriber interface

Info

Publication number: CA2265685A1
Application number: CA002265685A
Authority: CA
Inventors: Anu Virtanen
Original assignee: Individual
Current assignee: Nokia Oyj
Priority date: 1996-09-17
Filing date: 1997-09-16
Publication date: 1998-03-26
Also published as: FI963676A0; JP2001500702A; EP0976279A1; FI963676A; AU4304597A; WO1998012892A1; CN1231109A; FI105066B

Abstract

A radio system providing a wireless subscriber interface comprising subscriber stations (1, 2, MS) and a network element (4) comprising means for transmitting telecommunication signals between the subscriber stations and a fixed telephone network exchange (3), whereby the system comprises a subscriber station (1, 2) consisting of a radio unit (6) and a fixed telephone network telecommunication terminal (5) connected to the radio unit. In order to route a local call correctly even when the subscriber does not dial an area code, the network element (4) comprises a register (10) including the fixed telephone network area code corresponding to the location (A, B) of the subscriber station (1, 2). In addition, the network element (4) comprises means for retrieving an area code from the register (10) and for adding it as a prefix to the number dial transmitted from the subscriber station (1, 2) in connection with call set-up if the number dial transmitted from the subscriber station (1, 2) does not include an area code.

Description

ï»¿101520253035W0 98/ 12892CA 02265685 l999-03- l5PCTlFI97l0055lRADIO SYSTEM FORMING A WIRELESS SUBSCRIBER INTERFACEThe invention relates to a method of transmitting a number dial froma subscriber station of a radio system providing a wireless subscriber interfaceto an exchange in a fixed telephone network, in which method a number dialtransmitted from a subscriber station is received. The invention also relates toa radio system providing a wireless subscriber interface and comprising sub-scriber stations and a network element comprising means for transmitting tele-communication signals between subscriber stations and an exchange in afixed telephone network, the system comprising at least one subscriber stationconsisting of a radio unit and a telecommunication terminal connected to afixed telephone network radio unit. The invention further relates to a networkelement of a radio system providing a wireless subscriber interface, the ele-ment comprising means for transmitting telecommunication signals betweensubscriber stations and an exchange in a fixed telephone network.The present invention relates to a radio system providing a wirelesssubscriber interface. i.e. a WLL system (Wireless Local Loop), wherein tele-phone sets are connected by a radio connection through base stations and aWLL network element to the exchange of a public switched telephone network(PSTN). Any kind a conventional telecommunication terminal of a fixed tele-phone network can be connected to the WLL system through a special termi-nal, the radio path being transparent to the user.A problem with known WLL systems is that in systems where thenetwork element is connected to the fixed public switched telephone network(PSTN) via a trunk network, an upper layer trunk exchange cannot route a lo-cal call correctly if the number dial transmitted from a subscriber station doesnot include an area code. This means that if an attempt is made to make alocal call (to e.g. the next building) from a WLL subscriber station locatedphysically within the area code area of a fixed network, the call is incorrectlyconnected if the number dial does not include the area code of that specificarea.The object of the present invention is to solve the above problemand provide a method wherein a local call made from a WLL subscriber stationis connected correctly also when the user does not key in an area code inconnection with the number dial. This goal is achieved with the method of theinvention, characterized in that the received number dial is tested for an areacode; if an area code is not included, a predetermined area code is prefixed toï»¿101520253035W0 98ll2892CA 02265685 l999-03- l5PCT/F197/005512the number dial, and the number dial is fon/varded to the exchange of the fixednetwork.The invention also relates to a system to which the method of theinvention can be applied. The system of the invention is characterized in thatthe network element comprises a register including a fixed telephone networkarea code corresponding to the location of the subscriber station comprisingsaid fixed network telecommunication terminal, and that the network elementcomprises means for retrieving said area code from the register, and for pre-fixing it to the number dial transmitted from the subscriber station in connec-tion with the set-up of a call originating from the subscriber station if the num-ber dial transmitted from the subscriber station does not include an area code.The invention further relates to a network element for implementingthe method of the invention, and which can be utilized in the system of the in-vention. The network element according to the invention is characterized inthat it comprises a register including a fixed telephone network area code cor-responding to the location of predetermined subscribers stations, and that thenetwork element comprises means for retrieving said area code from the reg-ister, and for preï¬xing it to the number dial transmitted from a predeterminedsubscriber station in connection with the set-up of a call originating from thesubscriber station if the number dial transmitted from the subscriber stationdoes not include an area code.The invention is based on the idea that when a WLL system con-nected to a fixed telephone network via a PSTN exchange uses a subscriberstation register in which the parameters of each WLL subscriber include, be-sides other parameters, information on the PSTN area code corresponding tothe physical location of a subscribe station, the network element can retrievethe necessary area code from said data base and add it as a prefix to the localnumber dialled. information on the local area code of a WLL subscriber maybe input into the register from the system network management centre. Themost significant advantage of the solution according to the invention is that alocal call is routed correctly without the subscriber having to add an area codeto the number dial, the WLL system even in this aspect functionally corre-sponding better to the operation of a conventional fixed telephone network,and the radio path is more effectively made transparent to the user.In a preferred embodiment of the invention, the radio system con-sists of a mobile telephone system, such as a GSM system, connected to theï»¿WO 98/12892101520253035CA 02265685 l999-03- l5PCT/FI97/005513trunk exchange of a fixed telephone network, and the network element con-sists of a mobile telephone exchange. In this case both the mobile stations ofthe mobile telephone system and the WLL subscriber stations may utilize themobile telephone system. In this case, information stating which subscriberstations are WLL subscriber stations and information on the area codes of thePSTN local directory area may be stored in the VLR register (Visitor LocationRegister) of the mobile telephone exchange. This embodiment of the inventionallows efficient utilization of the mobile telephone system, because in this casethere is no need to construct a separate WLL system in the geographic areacovered by the mobile telephone system, but instead the calls of WLL sub-scriber stations, too, may be switched through the mobile telephone system. Inaddition, one can be certain that local calls made by WLL subscribers are cor-rectly connected even if the number dial does not include an area code.The preferred embodiments of the method, system, and networkelement according to the invention are disclosed in the attached dependentclaims 2, 4 to 6, and 8 to 9.The invention will be described in more detail below by means of apreferred embodiment with reference to the attached Figure 1 showing a blockdiagram of a first preferred embodiment of the system according to the inven-tion.In the case of Figure 1, the WLL system has been implemented asa part of a GSM mobile telephone system (Groupe SpÃ©ciale Mobile), wherebythe same radio system can be used to switch both mobile station MS calls andWLL subscriber station 1 and 2 calls. In addition to the case in Figure 1, thesolution according to the invention may naturally be applied to some othermobile telephone system, e.g. an NMT or DCS system (Nordisk Mobil Telefon,Digital Cellular System), or alternatively in a WLL system exclusively designedfor switching WLL subscriber station calls.In the case of Figure 1, a mobile telephone exchange 4 of a mobiletelephone system serves as the network element of the WLL system, the ex-change being connected to a PSTN network trunk exchange 3. The mobiletelephone exchange is in connection with the subscriber stations MS, 1, and 2of the radio system via base station controllers BSC and base stations BTS.The mobile telephone exchange 4 comprises a VLR register formaintaining information on mobile stations âtemporarilyâ roaming the geo-graphical area covered by the system in accordance with GSM specifications.ï»¿W0 98/12892101520253035CA 02265685 l999-03- l5PCT/FI97/005514In accordance with the invention, the VLR register also serves as the sub-scriber station register 10 of the WLL system, i.e. information on the WLL sub-scriber stations 1 and 2 utilizing the mobile telephone system of Figure 1 isstored in said register. In the case of Figure 1, the WLL subscriber stations arephysically located in the areas A and B of the different directory areas of theï¬xed telephone network.Both of the WLL subscriber stations 1 and 2 consist of a conven-tional telecommunication terminal 5 of a type used in fixed telephone net-works, such as a telephone, a telefax terminal or a computer/modem combi-nation linked to a WLL terminal 6 by means of a twoâwire line. The terminal 6comprises signal processing means for adapting the speech path to the radiochannel. Such signal processing means include e.g. a radio part comprisingan antenna, a radio transmitter and a radio receiver, and a teleadapter foradapting the radio part to a conventional telecommunication terminal 5 of afixed telephone network.In the case of Figure 1, the subscriber station 1 uses radio signalsto communicate with a base station 7 via which calls are switched through thebase station controller BSC to the mobile telephone exchange and further tothe trunk exchange 3 of the PSTN network (Public Switched Telephone Net-work), ie. a fixed telephone network. In accordance with the invention the pa-rameters of the WLL subscriber stations are stored in the VLR register 10 ofthe mobile telephone exchange 4. Said parameters also include information onthe area code of the fixed PSTN local directory area corresponding to the lo-cation of a subscriber. The locations of the WLL subscriber stations are knownbecause the WLL subscriber stations are installed permanently at specific lo-cations, similarly as is a telephone 8 of the PSTN network.When a call is made from a WLL subscriber station 2 located in thearea of the local directory area A to the telephone 8 of the PSTN network, themobile telephone exchange 4 identiï¬es it as a WLL subscriber station on thebasis of the information in the VLR register. The mobile telephone exchange 4then tests the number dial received from the subscriber station 2 for an areacode. If the dialled number does not include an area code, i.e. in Finland, forexample, this may be concluded by the first number of the dialled number se-ries being between 2 and 8, the mobile telephone exchange retrieves from theVLR register 10 the area code stored therein for subscriber station 2; the areacode corresponding to the area code of area A in the case of Figure 1. Theï»¿101520WO 98/12892CA 02265685 l999-03- l5PCT/F197/005515mobile telephone exchange then adds the area code retrieved as a prefix tothe number dial transmitted from the subscriber station before routing the callfurther. Thus, the call is switched from the trunk exchange 3 of the fixed tele-phone network via the PSTN network to the telephone 8.The mobile telephone exchange may retrieve the local number fromthe VLR register immediately having received a SETUP message from sub-scriber A, i.e. the subscriber station 2, this being the time when the mobiletelephone exchange retrieves the other parameters of subscriber A from theVLR register. Call set-up from the GSM system to a fixed telephone networkhas been described in more detail in e.g. GSM specification part 09.09 (GSM09.09 â Version 3Ø0. â point 3.2.2.1.1) and is hence not described in anymore detail here.It is possible for the operator to key in manually the local area codeof a WLL subscriber to the VLR register from an operation and maintenancecentre 9 (O & M, Operations & Maintenance). Simultaneously a restrictionshould be made in the VLR register to the effect that the WLL subscriber sta-tion 2 must not register in the network in other parts than the area of said di-rectory area.It is obvious that the above description and the related figures areonly intended to illustrate the present invention. A variety of modifications andvariations will be apparent to those skilled in the art without deviating from thescope and spirit of the invention disclosed in the appended claims.

Claims

1. A method of transmitting a number dial from a subscriber station of a radio system providing a wireless subscriber interface to an exchange in a fixed telephone network, in which method a number dial is received from a subscriber station, characterized in that said method comprises testing the received number dial for an area code, adding a predetermined area code as a prefix to the number dial if an area code is not included, and forwarding the number dial to the exchange of the fixed network.

2. A method as claimed in claim 1, characterized in that a fixed telephone network area code corresponding to the location of the subscriber station which transmitted the dial is added as a prefix to the received number dial if the received number dial does not include an area code.

3. A radio system providing a wireless subscriber interface and comprising subscriber stations (1, 2, MS) and a network element (4) comprising means for transmitting telecommunication signals between subscriber stations (1, 2) and an exchange (3) in a fixed telephone network, the system comprising at least one subscriber station (1, 2) consisting of a radio unit (6)and a telecommunication terminal (5) of a type used in fixed telephone net-works connected to said radio unit, characterized in that the network element (4) comprises a register (10) including a fixed telephone network area code for said subscriber station (1, 2) with a fixed network telecommunication terminal (5), said area code corresponding to the location (A, B) of the subscriber station (1, 2), and that the network element (4) comprises means for retrieving said area code from the register (10), and for adding it as a prefix to a number dialreceived from the subscriber station (1, 2) in connection with the set-up of a call originating from the subscriber station if the number dial received from the subscriber station (1, 2) does not include an area code.

4. A system as claimed in claim 3, characterized in that said fixed network telephone exchange is a trunk exchange (3) of the PSTN network.

5. A system as claimed in claim 3 or 4, characterized in that said radio system consists of a mobile telephone system, and that said net-work element (4) consists of a mobile telephone exchange, at least one of the system subscriber stations consists of a mobile station (MS).

6. A system as claimed in claim 5, characterized in that said mobile communication system is a GSM or DCS system, whereby said register (10) consists of the VLR register of the mobile telephone exchange (4), the register comprising the fixed telephone area code corresponding to the location of the station (1, 2) for each subscriber station (1, 2) comprising a telecommunication terminal (5) of a type used in fixed telephone networks.

7. A network element (4) of a radio system providing a wireless subscriber interface, the element comprising means for transmitting telecommunication signals between subscriber stations (1, 2) and an exchange (3) in a fixed telephone network, characterized in that the network element comprises a register (10) including fixed telephone network area codes corresponding to the location (A, B) of predetermined subscribers stations (1, 2), and that the network element (4) comprises means for retrieving said area code from the register (10), and for adding it as a prefix to a number dialreceived from a predetermined subscriber station (1, 2) in connection with the set-up of a call originating from the subscriber station if the number dial received from the subscriber station (1, 2) does not include an area code.

8. A network element as claimed in claim 7, characterized in that said radio system consists of a mobile telephone system connected to a trunk exchange (3) of a fixed telephone network, the network element consisting of a mobile telephone exchange (4) of the mobile telephone system.

9. A network element as claimed in claim 8, characterized in that said mobile telephone system is a GSM or DCS system, and that said register (10) consists of the VLR register of the mobile telephone exchange.