GB2336069A

GB2336069A - Base station emulator

Info

Publication number: GB2336069A
Application number: GB9805843A
Authority: GB
Inventors: Jussi Lemilaeinen; Markku Niemi; Markku Rautiola
Original assignee: Nokia Mobile Phones Ltd
Current assignee: Nokia Oyj
Priority date: 1998-03-18
Filing date: 1998-03-19
Publication date: 1999-10-06
Also published as: GB9805843D0

Abstract

A wireless intranet office has a base station which emulates a cellular mobile network base station. Information is transferred over the office network via the base station emulator when a mobile station is within the cell of the base station emulator and via the cellular mobile network when the mobile station is outside the cell of the base station emulator. A further personal device such as a computer may be connected to the mobile station. The emulated base station may be a virtual base station. Access may be provided through the intranet to the GSM MSC 26 by a WIO (Wireless Intranet Office) interworking unit 24 which may comprise several network entities for example intranet mobile cluster 241, intranet location register 242, WIO gatekeeper 243, WIO gateway 244, and H.323 gateway.

Description

A system for transferring a call and a mobile station 2336069 The present

invention relates to a mobile station operating in a mobile communication network, which mobile station comprises connecting means for establishing a telecommunication connection and transferring information between a mobile station and a subscriber device connected to the telecommunication network over said telecommunication network.

In modem office work it is necessary to provide the employees with versatile information transfer connections which can transfer speech, facsimile messages, electronic mail and other data - usually in digital form. Transfer of information is needed inside an office or corresponding working environment for communication between employees, for transfer of information between branch offices of an enterphse, which offices can be in other towns or even in other countries, and for communication between the office and "outside world". In this text and all of the following text "office" stands for an environment with several users, which users "belong togetheC, and which office physically covers a reasonably limited area. There has been a trend in the telecommunication branch toward integrated systems in which various forms of telecommunication can be controlled as one entity.

A conventional realization of an above mentioned type of office communication system comprises a company telephone exchange for providing telephone services and telephones connected to R over twisted-pair connections and a separate local area network (LAN) in which applications for advanced telecommunication services have been implemented and which has the intelligence to run them. The local network is connected to the telephone exchange using a telecommunication server (Telephony Server) which supports the traditional subscriber server architecture in which subscribers are subscribers' computers connected to the local network. For example call-, data-, facsimile-, electronic mail- and speech mail services are connected within an office utilizing the telecommunication server. In an integrated 2 system users can also e.g. control telephone services using their computer terminals connected to the local network. The whole integrated office communication system is connected to public telephone network through the telephone exchange.

Figure 1 presents an example of a prior known office communication system in which users' telephones TP (TelePhone) have been connected by wire connections and a local area network (LAN) has been connected over a telecommunication server TS (Tele Server) into a telephone exchange PBX (Private Branch Exchange) which is connected to a public telephone network PSTNIISDN (PSTN, Public Switched Telephone Network, ISDN, Integrated Services Digital Network). To the local area network (LAN) have been connected on one hand servers executing various services such as data base server DBS (Data Base Server), voice server VS (Voice Server) and electrical mail server EMS (Electrical Mail Server) and on the other hand the users' computers PC (Personal Computer). It can be regarded as a problem with this kind of realization that even if a user's telephone TP and computer PC usually are on the same table next to each other separate wire connections must be laid to the user's working room for them, on one hand from the telephone exchange PBX and on the other hand from the telecommunication server TS of the LAN. Building and maintenance of two overlapping telecommunication networks naturally causes cost.

The problem of overlapping telecommunication networks is increased by portable mobile stations utilizing radio connection coming rapidly more popular. Many persons working in an office need, because of their mobile work, a mobile station and often also a portable facsimile device andlor a combined portable computer/mobile station. In order to be able to use the devices based on radio connection also inside buildings, the constructions of which attenuate radio signals, it has been suggested that mobile radio networks should be supplemented with small base stations individual for offices or even for rooms, which base stations would be connected either directly or over wired telephone network to the central systems of mobile communication network. The network of small base stations would be already a third overlapping telecommunication network within the same 3 office, and accordingly it is clear that in a preferable solution, which the present invention is aiming at, also the arrangement supporting radio communication stations should be realized using essentially the same means and telecommunication networks than the rest of the transfer of information in the office.

A challenge of its own to telecommunication systems is issued by the fact that work is done more and more in small-office or domestic environment, which is described by the concept SOHO (Small Office, Home Office). Even here advanced office communication services are often needed and it is particularly preferable if such a flexible system is available which can be utilized even both in the office and at home. The present systems which require overlapping connections for the utilization of mobile communication services, conventional telephone services and fast data transfer services are very inflexible for working in a small- or home office. In addition to above, the following kinds of solutions connected with integrated telecommunication systems are known from prior art.

EP publication 599 632 presents a wireless local network designed to replace the present kind of wired local networks (e.g. registered trade marks Ethemet and Token Ring) by a radio transfer network which forms inside an enterprise a private cellular system designed for data transfer. A network utilizing radio connection is, however, relatively expensive to realize and R is more sensitive to interference than a local network based upon wired connections. In addition to that it requires establishing of an extra radio network in addition to previous networks.

EP publication 462 728 presents an intelligent base station controller, subordinated to which at least one radio communication system base station is operating and which is capable of connecting calls from a certain mobile station coming through the base station directly to the wired telephone network. This system, however, requires said additional base stations, which increases the cost. The system is also, alike the system presented in publication 599 632, sensitive for external (radio)interference.

4 If an integrated office communication system is realized utilizing traditional technique, separate wired connections must be laid into a user's working room on one hand from telephone exchange PBX (Figure 1) and on the other hand from telecommunication server TS of local area network (LAN). Constructing and maintaining two overlapping networks naturally brings extra cost. In said solutions according to prior art a solution to this problem has not actually been striven for.

A target of the present invention is to present a system which reduces the problems caused by overlapping networks. Additionally, the purpose of the invention is to reduce problems caused by wireless information transfer inside an office and extra cost. A further target of the invention is to present an arrangement, in which said system, integrating information transfer, can also serve home office- and small office users. A further target of the invention is to present an arrangement of said kind, in which the same devices can be used as terminal devices (e.g. mobile stations) in the telecommunication system both in the office and outside it.

According to one aspect of the present invention, there is provided a system for transferring information between a mobile station and a further communication device, the system comprising he mobile station, a communication network to which the further communication device is coupled, and a base transceiver station emulator for interfacing the mobile station and the communication network, wherein the system transfers information over the communication network when the mobile station is within the cell of the base transceiver station emulator, and transfers information over a mobile communication network when the mobile station is outside the cell of the base transceiver station emulator.

A base transceiver station emulator and mobile station are also provided for such a system.

Such a system allows users to utilise communication networks, such as private intranets to carry cellular services (eg speech, data, SMS, facsimile etc) when within a coverage area. In addition, the W10 concept provides a good platform for local multi-media extensions because it potentially offers higher bandwidth to the user. Access to the public cellular network (eg GSM) is offered by introducing a transparent location management method, which allows mobile stations connected to the communication network, such as the intranet, to be reached from the public cellular network in the normal way. Hence, the concept can be utilised to provide extra capacity in hot-spot areas, such as airports and malls.

The base transceiver station (BTS) emulator may be an actual base transceiver station or a virtual base transceiver station. In any event, it is an interface between the mobile station and the communication network over which the information (eg, speech, data) is to be transmitted.

The BTS emulator may be the BTS of a mobile cluster. In this event, it is an actual base transceiver station. Whilst a mobile station is within this BTS cell, the information to/from the mobile station is transmitted over the communication network, even if there is an overlap with the cell of another public GSM BTS.

Alternatively, the BTS emulator may form part of a personal base unit for a mobile station, in which case it is a virtual BTS. That is, it looks like a BTS to the mobile communication network, but does not handover to another BTS. In one embodiment, where the communication network is an P network, the virtual BTS takes care of the binding of GSM and IP numbers, so that only one number is required.

The communication system may be one of several kinds, such as. a data communication network, internet, intranet, LAN, WAN, ATM packet network, Ethernet (TM), or Token Ring (TM). AJso, the further communication device may be one of several kinds, including a PBU, another mobile station, an MSC or an FSC.

The mobile station and PBU may be connected by RS232 cable. Alternatively, they may have an RF (preferably LPRF) or infrared connection. Also, they may be 6 indirectly connected, for example via a connection device such as a mobile station cradle, deskstand or charger.

According to another aspect of the present invention, there is provided a dual mode mobile station comprising control means for controlling transfer of information such that in a first mode transfer of information is between the mobile station and a mobile communication network, and in a second mode transfer of information is between the mobile station and a second communication network, and means for providing radio contact between the mobile station and the mobile communication network in both the first and second modes.

The first mode is, for example, when the mobile station is outside the office environment and the second, when it is within it.

In a preferred embodiment, the control means and means for providing radio contact are realised by virtue of a software enhancement to conventional mobile terminals. Hence, the terminals are much simpler than existing dual mode terminals, which, for example, require switches to change between the modes. Also, the terminal of the present invention remains connected to the mobile network while the actual data (datalspeech etc.) is carried over another interface. Thus it provides the mobile network with what seems to be the same operation specified for the standard mobile communication network entities.

Now a system has been invented for transfer of information, e.g. speech or data, in which the trunk of information transfer is inside the office a local network (e.g. local area network, LAN), and between office units e.g. a traditional telephone network utilizing wired connections or a fast data packet network utilizing ATM (Asynchronous Transfer Mode) technique, for example According to one embodiment of the invention the mobile station may be connected to the terminal device by means of a connection device, having a functional connection to the terminal device, and having means for connecting functionally to 7 the mobile station. In response to connecting a mobile station to the connection device, the system will be informed to direct calls to the mobile station via the data communication network. The connection device can be a desktop stand or desktop charger and may be a separate device or integrated into the terminal device.

The system for transferring information according to the invention, comprises a mobile station operating in a mobile communication network, which mobile station comprises first connecting means for establishing a telecommunication connection and transferring information between the mobile station and a subscriber terminal connected to telecommunication network through said mobile communication network, and means for directing calls to the mobile station on basis of a first identifier via the mobile communication network, the system being characterized in that it further comprises a data communication network connected to the telecommunication network, a terminal device comprising a base station transceiver emulator connected to the data communication network, second connecting means for connecting said mobile station into a functional connection with said terminal device, means for establishing a telecommunication connection and transferring information between said mobile station and said subscriber terminal through said terminal device and said data communication network, and means for directing calls to the mobile station on basis of a second identifier via said data communication network and said terminal device.

The mobile station according to the invention comprises first connecting means for establishing a telecommunication connection and transferring information between a mobile station and a subscriber terminal connected to a telecommunication network through a mobile communication network, means for receiving calls on basis of a first identifier via the a mobile communication network, characterized in that the mobile station further comprises second connecting means for connecting the mobile station into a functional connection with a terminal device, which terminal device has a connection to telecommunication network and for establishing a telecommunication connection and for transferring information between said mobile 8 station and said subscriber terminal through said terminal device, and means for receiving calls on basis of a second identifier via said terminal device.

A subscriber device means a terminal device connected to a telecommunication network, such as a telephone connected to a fixed telephone network, and a mobile station connected to a mobile communication network. A subscriber device also means servers and telephone exchanges connected to telecommunication networks, providing telecommunication services to the users of the telecommunication networks. In other words, a subscriber device means all the parts of a telecommunication network with which a telecommunication terminal device (e.g. a telephone) can communicate over a telecommunication network.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, of which:

figure 1 presents traditional communication networks and terminal devices used in an office environment; figure 2 illustrates a wireless intranet office architecture according to an embodiment of the present invention; figure 3 illustrates a wireless intranet office architecture according to an embodiment of the present invention; figure 4 illustrates the architecture of a mobile station and personal base unit of a wireless intranet office, according to an embodiment of the present invention; figure 5 illustrates a general GSM intranet office concept; figure 6 to 11 show information flow from terminals of a GSM intranet office according to an embodiment of the present invention; 9 figure 12 presents in more detail the structure of the various parts of the information transfer system according to an embodiment of the invention as a block diagram; figure 13 presents connection of the mobile terminal to the terminal device using an intelligent charger; figure 14A presents the functional blocks of a traditional mobile station as a block diagram; figure 14B presents information transfer routes in a mobile station and a information transfer system according to an embodiment of the invention; Figure 2 illustrates a wireless intranet office architecture according to an embodiment of the present invention.

As can be seen, the wireless intranet office integrates an IP based private intranet environment with a public cellular network, in this case the GSM network. This allows cellular users to utilise private intranets to carry the cellular services (ie speech data SMS facsimile etc.) wfthin the intranet coverage area. In addition, the wireless intranet office architecture provides a good platform for local multimedia extensions because it potentially offers higher bandwidth to the user. Access to public GSM network is offered by introducing a transparent location management method, which allows terminals connected to the intranet to be reached from the public GSM network in the normal manner. Thus, the wireless intranet office arrangement can be utilised to provide extra capacity in hot spot areas, such as airports, malls etc., where this might be needed.

In this wireless intranet office arrangement, the intranet forms a new kind of access network to the GSM network. The communication between the GSM backbone network and the end user access node takes place via internet protocol based networks instead of the GSM air interface, as will be seen below.

Figure 2 shows a mobile station 21 which, in one mode connects to a personal base unit 22 (eg either with a inter-connection cable, a infrared connection, or with low power RF transmitter and receiver), and in another mode connects to a GSM base transceiver station (BTS) 23. The mobile station 21 is connected to an IP local area network (LAN) and a home location register (HLR) and visitor location register (VI---R) 25 and a mobile station controller (MSC) 26 by virtue of an inter-working unit (IWU) 24. This IWU comprises several network entities, including an intranet mobile cluster (IMC) GSIVI11P Gateway 241, an intranet location register (ILR) 242, a W10 gatekeeper 243 and a W10 A-gateway 244.

Information such as data andlor speech may be transferred from the mobile station to the IP local area network by 2 routes, each of which includes a BTS emulator. In a first mode, the mobile station 21 is connected to the local area network via a personal base unit 22 (PBU), which itself comprises a virtual BTS. This is further explained with reference to figure 4 below.

In a second mode, the mobile station 21 forms part of a mobile cluster (for example see reference 32 in figure 3). In this case, the information is transmitted to the local area network via a GSM BTS 23 dedicated to that cluster, and an IMC GSIVI11P Gateway 241. The BTS transmits the signal over the A bis interface, and the IMC Gateway 241 performs a protocol transform from GSM to H.323, so that the signal can be transmitted over the IP local area network. (As can be seen from this figure, the wireless intranet office architecture uses the H.323 protocol for the signalling and data connections inside the inter-working unit).

The basic access interfaces to the cellular network are the air interface, the Ainterface, the MAP protocol, the ISUPITUP interface and the DSS.1 interface. The A-interface is an interface to mobile switching centre and the MAP interface is an interface to HLR/VLR.]SUP/TUP interface connects switching centres, while the DSS.1 interface resides in between of the BSX and switching center. The air 11 interface connecting mobile terminals to the network can be any RF interface or infrared link. Candidate RF interfaces include e.g. Low Power RF (LPRF), 802.11, wireless LAN (WLAN) WATM and HIPERLAN. The air interface can also be replaced with a physical connection (e.g. RS-232 serial cable or Universal Serial Bus (USB). The GSM network sees this new access network as a BSS entity. New network entities are added to the access network to modify/de-modify cellular signalling. System design principle is to fulfil ITU-T's recommendation H.323 and enhances it with mobility extensions.

The W10 A-gateway 244 looks like a base station controller to the MSC 26.

A general W10 network architecture is shown in figure 3. A local area network 31 is provided with an internet mobile cluster IMC 32, an LPRF cell 34 and a land)ine connection 35. The IMC comprises a plurality of mobile stations, a BTS (private GSM BTS) and a server in the form of an IMC GSIVII1P gateway. The BTS interface between the BTS and IMC GSIVI11P gateway is a GSM A-bis interface. The IMC GSWIP gateway is responsible for signalling conversions between the GSM and H.323 protocols. The low power RF cell 34 comprises a personal base unit which has a virtual BTS and a low power transceiver, and associated mobile stations with corresponding low power RF transceivers. The PBU is directly connected to the W10 network. To provide the mobile stations with access to the GSM network, the PBU provides conversions between the GSM and H.323 protocols. These conversions can be seen as a bridge between cellular phone and H. 323 features which support W10 location management and mobility features. The landline connection comprises a landline terminal 351 hardwired to a personal base unit 352, which in turn is hardwired to the local area network.

Also connected to the local area network are a W10 gatekeeper 36, which is responsible for the connection of mobile stations to within and outside the network. For example it might transfer a call from the server to an external system such as PSTN (via gateway 38) or it could provide connection to the IP network 37. The IP network, in turn, is connected to the operators local area network 39. This local area 12 network is provided with an A-intranet gateway 391, an intranet location register 392 and IP telephony gateway 393.

In this embodiment the main function of the intranet Location Register is to store mobility management information and call statistics of the subschbers configured into the Wireless Intranet Office system. Roaming of visitors are controlled by the mobile switching center. For visitors only temporary information will be stored into the Intranet Location Register.

The ILR has a MAP interface to cellular system network HLR 25.

The IP Telephony Gateway 393 in this embodiment supports interworking between Internet telephony endpoints and mobile stations in the public cellular network. The interworking is based on the H.323 specifications.

The A-Intranet Gateway 391 in this embodiment makes protocol conversion between SCCP11VITP and IP protocols at the A-interface, and makes the cellular and Intranet location area associations. It has an O&M software entity which operates as an administrative server gateway for corresponding agents in intranet Mobile Clusters. The A-Intranet Gateway operates as a firewall between public telecommunication network and private Intranet solutions.

Further explanation of the network entities in Figures 2 and 3 are outlined below.

The Intranet Mobile Station is a generic terminal product portfolio consisting of fullfeatured cellular phone which support services of GSM and GSM derivatives. It may have specific features such as extended office/home cell selection criterias, and support of office and home area priority. With a sehal cable and with a piece of software to a PC, Intranet Mobile Station - so called LANdline version - enables seamless landline communication to cellular system network and between other Internet telephony entities within IP network. It may be a GSIVI1PRF dualmode device enabling high value services within certain service areas.

The Personal Base Unit (PBU) may be a PC Card type of radio card for a desktop PC with a piece of software enabling wireless access to]P network. It provides LPRF cordless and wireless LAN - on 2.4 GHz band - dual-mode access exploiting an unlicensed radio spectrum. In cordless, "unlicensed" mode lower layers will be replaced with new ones, but signalling above them remains the cellular one. It also enables intelligent roaming of terminals between different radio frequency bands, i.e. between cellular and unlicensed bands.

The Intranet Mobile Cluster is simulating BSC in a local environment. It consists of minimum set of BTS functionality with reduced physical construction. Intranet Mobile Cluster is a BTS and a BTS driver software package for Windows NT 5.0 including rate adaptation, an O&M agent software package and a GSIVI11P Telephony Gateway entity. Intranet Mobile Cluster provides interworking with data services and facsimile as a direct access to [P network, and. it may provide local call routing capability within its radio coverage.

The purpose of the GSM/IP Telephony Gateway is to reflect the characteristics of an Internet telephony endpoint to an Intranet Mobile Station, and the reverse, in a transparent fashion. The GSIVI11P Telephony Gateway provides appropriate format translation of signalling and speech, i.e., audio format translations between GSM 06.10, 06.20, 06. 60, J-STD-007 and G.71 1, G.723 and transformation of communications procedures. The Gateway performs call setup and clearing on both the Internet telephony side and the Wireless Intranet Office side.

The MS-IP (WIO) Gatekeeper 36,243 provides mobility and call management services, and certain radio resource management functions.

The MS-IP Gatekeeper provides the following services:

Registration control - The MS-IP Gatekeeper authenticates all the network entities, i.e., Intranet Mobile Stations, Intranet Mobile Clusters, 14 A-Intranet Gateways, IP Telephony Gateways, Intranet Location Registers, H.323 terminals, which have access to the system. In case of Intranet Mobile Station, authentication and registration is based on automatic Gatekeeper discovery procedure. In other cases, it's based on manual Gatekeeper registration procedure.

Connection ciphering - Part of the Gatekeeper's authentication procedure is connection ciphering service. It provides key distribution, identification and encryption/decryption services to the Gatekeeper and other entities in the system. Service has an option to select ciphering, hashing, key distribution and signature algorithms independently. Key distribution is based on public key cryptography and message ciphering is based on secret key cryptography.

Address translation - The MS-IP Gatekeeper performs E.164 to transport address association and translation. This is done using directory service in the Intranet Location Register which is updated during mobility management procedures, ie., during TMSI reallocation, authentication, identification, IMSI detach, abort, and location updating.

Call control signalling - The MS-IP Gatekeeper can be configured to route call control signalling to the cellular system network or to the local call management entity within the Gatekeeper.

Call management - The MS-IP Gatekeeper maintains also list of ongoing calls and collects call statistics. This information is stored into the Intranet Location Register by the Gatekeeper.

Cellular procedures - The MS-IP Gatekeeper must be able to handle signalling and resource management procedures (13SSMAP resources) specified in GSM recommendation 08.08.

Status control - In order for the MS-IP Gatekeeper to determine if theregistered intity is turned off, or has otherwise entered a failure mode, the MS-IP Gatekeeper uses status inquiry to poll the entity at a certain interval.

The IVISAP Gatekeeper entity is a sofeware package for Windows NT 5.0 and fulfils the ITUT's H.323 Gatekeeper specifications, extended with certain mobility management capabilities according to GSM 04.08.

Figure 4 shows the architecture of a mobile station 41 and a personal base unit, personal computer 42, according to a preferred embodiment of the present invention.

The mobile station 41 and personal base unit 42 are represented showing layers 1 to 3 of the 7 layer OSI reference model, namely physical layer (layer 1), data link layer (layer 2) and network layer (layer 3). (These are data communication protocols whose purpose is to provide a link between 2 communicating devices).

Network layer 43 of the mobile station 41 provides call control management 431 (including supplementary services 435 and short message services 436). This layer also provides mobile management 432 and radio resource management 433. Further, it comprises a MUX which switches" to a second branch of layer 2 to demand services of the data link (FBUS Ctd 443) and physical layer (FBUS 452) when the mobile station 41 and the personal base unit 42 are "connected". In any event, the network laser demands the services of the data link layer 44 (data link 441 and control 442) and the physical layer 45 of the first branch, to allow the mobile station 41 to perform and report its measurements about the surrounding GSM network (neighbouring BTSs) and thus comply with GSM requirements.

Turning now to the personal base unit 42, this PBU comprises a phone driver implementing the physical and data link layers 48 and 47 (FBUS 481 and FBUS Ctri 471). The network layer 46 of the PBU comprises a PBU control/IMC core control 16 462 and an H.323 protocol entity 463 which provide protocol conversion between GSM and H.323. The conversions are needed for GSM layer 3 signalling messages while the speech is carried as GSM coded in the whole while this intranet office network. The PBU further comprises TCP/IP entity 422 and a local area network adapter driver for the 23 for interfacing with the local area network. The PBU control 462 comprises a virtual BTS 49 for communicating with the network layer 43 of a mobile station 421.

This figure shows layers 1 and 2 of the second branch of the mobile station and the PBU as FBUS. This is because, in this embodiment an RS 323 serial connection is used. However, it is evident to a person skilled in the art that these layers would be implemented using different technologies if, for example, connection is via I R or RF.

The mobile phone also has a user interface 461.

In the network, the mobile station interfaces the intranet mobile cluster and personal base unit entities. The interface to the personal base unit, as can be seen from figure 4, uses a modified GSM layer 3 (04.08) signalling. Part of the virtual terminal can be implemented also inside the mobile station control software, so that RR specific 04.08 signalling is not delivered to the PBU.

The mobile station 41 and PBU 42 operate as follows.

When the mobile station 41 is outside the wireless intranet office environment, it operates as a normal GSM phone. The MUX 434 does not couple the radio resource management entity 433 with the second branch 443, 452. Voice and signalling is transmitted via the data link layer 44 and physical layer 45 over the first (GSM)branch to the cellular air interface.

Also, if the mobile station 41 is within the wireless intranet office, but forms part of an intranet mobile cluster, this same path is taken to the cellular air interface and the information and signalling is transmitted to the GSM BTS of that cluster.

17 However, when the mobile station 41 is connected to a PBU 42 (for example by an RF 232 serial cable or RF interface) information such as voice, data, fax, SMS etc., is transmitted over the local area network. in this case, the MUX 434 demands the service of the second (LAN) branch layers 1 and 2, and layer 3 of the mobile station 41 is seen to communicate with the virtual BTS 49 of the PBU 42. That is, the information (eg. speech) and GSM layer 3 signalling messages are redirected to the second branch interface. As the mobile station 41 and the PBU 42 are linked, the field strength of the virtual BTS 49 will be greater than that of other BTSs in the GSM network. Consequently handover is made to the virtual BTS 49. After this, the handover signalling relating to this virtual BTS is handled from the MUX through the second branch. When handover has been made, the MUX handles all messages and forwards them to the new host cell through the RS 232 interface etc and "talks" to the other BTSs (as is conventional in GSM) over the first branch. General broadcast traffic is also seen by the mobile station 41, for example from layers 1 and 2 to the MUX and from there through the mobile station/PBU interface to the virtual BTS 49.

While in this mode, the speech and layer 3 signalling are routed to the personal base unit, and the radio resource management entity at layer 3 remains connected to the GSM layer 2 (441), that is branch 1. As mentioned above, this is so that the mobile station can act as required by GSM (for example by measuring the RSSI for neighbouring BTSs etc.).

The parameters in the virtual BTS 49 within the IMC core are set in such a manner that the terminal is forced to remain clamped to this virtual GSM cell. This avoids possible handovers to any other GSM cells the mobile station might hear.

The operation of the MUX can also be explained as follows. When the mobile station changes to "LANdline" mode (for example when the other interface is connected), the MUX communicates with the new BTS in a similar way to as it does to other BTSs to which it is not connected. In this phase, the mobile station notices 18 that the field strength of the new BTS relating to this new interface is more powerful than the field strength of other BTSs, and hence makes the handover to this BTS. After the handover, signalling relating to the new BTS are handled by the MUX through the new interface, and "talks" over the GSM radio link with the other BTSs. General broadcast traffic is also sent to the new mobile station, for example from the lower stage to the MUX and from there through the new interface to the virtual BTS.

Figure 5 shows a general GSM intranet office concept, and figures 6 to 11 show information flow between terminals - figures 6 to 9 being within the office environment and figures 10 and 11 extending to outside the environment.

Figure 5 shows the GSM intranet office 57 comprising different terminal arrangements 51 to 54. The intranet office interfaces with an, internet protocol network 58, which is partially situated within the office and partially at the operators location. The operator 59 controls transfer of information between the IP network 58 and network switching centres, such as mobile switching centres 55 and fixed line switching centres 56.

Terminal arrangements 51 and 52 comprise a mobile station 51a, 52a and a BTS Emulator 51 b, 52b. These mobile stations can be within an intranet mobile cluster or can be coupled to a personal base unit comprising a virtual BTS.

Figure 6 illustrates a call between mobile stations of the same office. In this case, the call might be sent by mobile station 51 a to mobile station 52a. The information is transmitted from mobile station 51 a to BTS emulator 51b and on to the LAN via the inter-working unit. The local area network then transfers the information to BTS emulator 52b which in turn forwards it to mobile station 52a.

Figure 7 shows a call between a mobile station 51 a and an H.323 terminal 54 within the same office. Information transferred from mobile station 51 a will be forwarded to the LAN in the same manner as in figure 6 (ie via BTS Emulator 51b and the W10 inter-working unit). The LAN then transfers the information to the terminal 54.

19 Figure 8 shows a call between a mobile station 52a and a fixed line extension 53a of a private branch exchange 53b of the same office. Again, information is transferred from mobile station 52a to a local area network via BTS Emulator 52b and the office 1M. The information is then transferred over the local area network via a PSTN gateway to PBX 53b. This PBX then switches the information to the requisite extension 53a.

Figure 9 shows a call between a H.323 terminal and a PBX extension of the same office. In this case, there is no GSM connection. Information is forwarded to the local area network from the terminal 54 where it is transferred to PBX 53b via the local area network on a PSTN gateway. The PBX 53b then switches the information to the requisite extension 53a.

Figure 10 shows a call between a mobile station 51a of the W10 to the mobile network. In this case, information is transferred from mobile station 51 a to the local area network via the BTS Emulator 51b and the inter-working unit. It is then transferred across the local area network and to a mobile switching centre 55 via an A-gateway.

Figure 11 shows a call between a mobile station 52a of the W10 and a fixed line network. In this case, information is transferred from mobile station 52a to the local area network via BTS Emulator 52b and the inter- working unit. The information is then transferred over the]an to a fixed line switching centre 56 via a PSTN gateway.

In the information transfer system according to the invention, information transfer connections based upon ATM and GSM technologies may been utilized. Furthermore, it is fully possible to utilize instead of these techniques other kind of information transfer connections. For example it is possible to arrange, instead of the ATM system, the information transfer connections between terminal devices 40 to 43, teleservers 60, 61 and network server 90 entirely e.g. using systems based upon Ethernet and Token Ring or future wide band networks. Correspondingly it is possible to realize, instead of GSM-system, an information transfer system according to the invention even in connection with other mobile communication systems, such as e.g. TDMA (Time Division Multiple Access), CDMA, W-CDMA AMPS (Advanced Mobile Phone Service) and NIVIT (Nordic Mobile Telephone) systems.

Moreover, it can be transferred over WATM, 802.11 and mobile]P, which allows the network entities (PBU, IMC, etc.) being mobile. This enables, for example, forming a W10 cluster/IMC into a train or airplane.

Figure 12 presents modules of mobile station 10, terminal device (including virtual BTS) 40, telecommunication server 60, node 70 and network server 90. The structure of mobile station resembles that of a traditional mobile station, such as e.g. a GSM-mobile station. It comprises among other things processor 20 controlling the function of mobile station 10, signal processor 21 executing mainly time-critical operations, ASIC (Application Specific Integrated Circuit) -block 22, memory 23, DIA-converter 24, A/D-converter 25 and radio frequency part 30.

Mobile station 10 operates independently, that is when not connected to terminal device 40, exactly like ordinary mobile station 14. The functions performed by mobile station 10 have then been shared between processor 20 and signal processor 21 for example in such a way that processor 20 carries out mainly operations essential for communication between the mobile station and a base station requiring versatile processing, such as mobility management (e.g. change of base station), management of radio frequencies (transmission and reception frequencies) control of calls (handling of outgoing and incoming calls). Correspondingly, signal processor 21 executes shares requiring real time processing of incoming and outgoing signals, such as channel encoding and channel decoding, interleaving and de-interleaving, and ciphering and deciphering. Mobility Management, management of radio frequencies (Radio Resource Management), control of calls (Call Control), channel encoding (Channel Coding), interleaving and de-interleaving, ciphering and de- ciphering are functional blocks prior known to a 21 person skilled in the art, the functional connection of which will be presented in following chapters in connection with the explanation of Figure 14A.

The presence of speech encoding and decoding in the operation of a mobile station is illustrated in the following, where, in order to make the invention understood, the operation of the transceiver of a cellular mobile communication system is explained. As an example, the transmitter and receiver functions of the European GSIVI-systern based upon time division multi-use are explained referring to Figure 14A, which presents the block diagram of a mobile station transceiver according to GSM system. The transceiver of a base station differs from that of a mobile station usually by being a multi-channel one and having no microphone and loudspeaker, in other respects it is in principle similar to the transceiver of a mobile station.

The first stage of a transmission sequence is digitizing 1 of analogue speech and encoding 2. Sampling with AID-converter 1 is carded out at 8 kHz frequency and a speech encoding algorithm assumes an input signal to be of 13 bit linear PCM. The samples obtained from the A/D-converter are segmented into 160-sample speech frames of 20 ms duration each. Speech encoder 2 processes the 20 ms speech frames, meaning that before the beginning of encoding, 20 ms of speech is taken in a buffer. The encoding operations are carried out individually for each frame or for subframes of theirs (in 40 sample blocks). As a result of the encoding by speech encoder 2, 260 bits are obtained out of one frame.

After speech encoding 2, channel encoding 3 is carried out in two stages, when to begin with (260 bits) part of the bits (50 most significant) are protected using block code 3a (= CRC, 3 bits) and after this these and the next most important bits (132) are further protected with convolution code 3b (encoding ratio 1/2) (50+3+132+4)2 = 378, and some of the bits are taken unprotected (78). As shown in Figure 14, signaling- and logic messages come from control unit 19 controlling the blocks of the telephone, directly to block encoding block 3a, and naturally no speech encoding is done to these data messages. Correspondingly, at reception, the received signaling- and logic messages are taken from channel decoding block 115 to control 22 unit 19. At block encoding 3a a queue of bits is joined at the end of a speech frame, with the help of which transfer errors can be detected at reception. At convolution encoding 3b the redundancy of a speech frame is enhanced. In all 456 bits are transmitted per each 20 ms frame.

These 456 bits are interleaved in block 4 and even interleaving 4 has two stages. At first, in block 4a, the order of the bits of a frame is shuffled and the shuffled bits are organized into eight blocks of equal size. The blocks are divided in block 4b further into eight subsequent TDMA frames, in which case the interleaved 456 bits are transmitted in eight time slots of the radio way (57 bits in each). The purpose of the interleaving is to spread transfers errors, which normally occur in error bursts, evenly over the whole transmitted data, in which way the channel encoding works most effectively. After de-interleaving an error burst is transformed into individual error bits which can be corrected at channel decoding. The next stage in a transmission sequence is data encryption 5. Encryption 5 is carried out using an algorithm which is one of the most guarded secrets of GSM. Encryption prevents unauthorized listening of calls, which is possible in analogue networks.

Encrypted data is formed 6 into a burst to be transmitted by adding into it a teaching sequence, tail bits and protection time. A burst to be transmitted is taken into GMSK-modulator 7 which modulates the burst for transmission. GMSK-modulation method (Gaussian Minimum Shift Key) is a constant-amplitude digital modulation method in which information is contained in changes of phase. Transmitter 26 mixes the modulated burst through one or more intermediate frequencies into 900 megahertz and transmits it through an antenna to radio way. Transmitter 26 is one of three radio frequency blocks 30. Receiver 28 is the first block of the receiving side and carries out functions inverse to transmitter 26. The third RF-block in synthesizer 27 which performs the generating of frequencies. GSM-system utilizes frequency jumping, in which transmission and reception frequencies are altered in each TDMA-frame. Frequency jumping improves the quality of a connection but sets strict requirements to synthesizer 27. Synthesizer 27 must be capable of moving from one frequency to another very quickly, in less than one millisecond.

23 At reception operations inverse to transmission are executed. After RFreceiver 28 and demodulator 111, bit detection 112 is carried out with e. g. a channel corrector, in which bits in received samples are detected, or in other words the transmitted bit sequence is tried to be found out. After the detection de-encryption 113 and deinterleaving 114 are carried out, and channel decoding 115 is performed on the detected bits and the error sums are checked using cyclic redundancy check (CRC, Cyclic Redundancy Check). At channel decoding 115 bit errors occurred in the transfer of the burst are attempted to be corrected. The 260 bit-long speech frame contains after channel decoding 115 the transmitted parameters describing speech, based upon which speech decoder 116 forms the digital samples of speech signal. The samples are D/A-converted 117 for reproduction with loudspeaker 32.

In the transceiver there is as the central controlling unit of the mobile station control unit 19 which essentially controls the above described blocks, coordinates their functions and controls timing. Control unit 19 comprises usually e.g. microprocessor 20 and ASIC-block 22. ASIC-block 22 takes care of the digital connection of the transmitted signal and the received signal. It comprises among other things buffer memories for transferring digital data to both directions (transmission/reception) and takes care of the digital modulation of data. ASIC (Application Specific Integrated Circuit) means an application specific integrated circuit which is manufactured in an integrated circuit factory to a customer's specification. In a mobile station ASICblock 22 typically controls synthesizer 27, required clock signals 38, and controls power supply 39 together with processor 20. ASIC-block 22 is connected with DIA (Digital to Analog) -converter 24 and AID (Analog to Digital) -converter 25 to radio frequency section 30.

Mobile station 10 communicates with the user utilizing user interface unit 31 (Figure 12, UI, User Interface) which comprises among other things loudspeaker 32, microphone 33 and a display (not shown in the figure). User interface unit 31 comprises also A/D-converter 1 for transforming a microphone signal into a digital form and D/A converter 117 for forming a loudspeaker signal, and required 24 amplifiers. Mobile station 10 also comprises SIM (Subscriber Identification Module)intelligence card 34 prior known to a person skilled in the art, which card contains among other things the user's telephone number.

In this embodiment of the information transfer system according to the invention it is possible to connect mobile station 10 and terminal device 40 to each other in a number of methods. One of the methods is to interconnect the devices using a mechanical wire connection using interface units IU (Interface Unit, Figure 12, references 35 and 49). The interconnection interface can be e.g. a serial port. The advantage of a physical wire connection is among other things safe operation and the logical use, because a user directly sees whether mobile station 10 is connected to terminal device 40 or not. Another method of connecting mobile station 10 to terminal device 40 is to use e.g. wireless transfer 52 carried out in infrared wavelength range. A very common, and suitable for the purpose, data transfer protocol is IrDA (Infrared Data Association) -protocol prior known to a person skilled in the art. In this case data transfer 52 taking place in the infrared wavelength range is realized between infrared transceivers 36 and 48. It is also possible to realize the connection using low-power radio frequency transceiver units (not shown in the figure).

In figure 13 there is shown an alternative way of connecting mobile station 10 according to the invention to terminal device 40. The connection is carded out by means of a connection device 140. This connection device 140 can be a cradle such as a desktop stand or desktop charger. Here, by way of example, the connection device is described by means of a charger called intelligent charger 140. The intelligent charger 140 is connected releaseably to terminal device 40 with physical conducting wire 141 and interface unit 142. Using same interface unit 142 and conducting wire 143 the intelligent charger 140 is also connected releaseably to mobile station 10 when mobile station 10 has been installed to intelligent charger 140. Conducting wires 141 and 143 form a bus for communication between terminal device 40 and mobile station 10 via intelligent charger 140. The connections illustrated by conducting wires 141 and 143 may as well implemented in other ways, e.g. by infrared connection or by electrical connectors or the connection device 140 may be integrated into the terminal device 40. Possible signaling between terminal device 40 and mobile station 10 in establishing the connection therebetween can be carried out using Hayes AT-commands (a de facto standard) under control of the processors 20, 45 of each of the devices. The control in the terminal device 40 for establishing a connection to the mobile station 10 and after an established connection is handled by the processor 45. Such control operations can be implemented as an application software 144, which is executed by the processor. Interface 142 of intelligent charger 140 also includes means for arranging the charging voltage from power supply 145 to battery 147 of mobile station 10 via conducting wire 146. If the connection device 140 has no own power source, it can get and transfer power to the mobile station from the terminal device 40.

Terminal device 40 may be e.g. a PC prior known from office environment or a workstation, which comprises among other things processor 45, memory 46 and network interface unit 50 (NI, Network Interface) for connecting terminal device 40 to local area network (LAN)(references 53 and 65).

When mobile station 10 is connected to terminal device 40 in a way characteristic of the invention, e.g. using interconnecting cable 51 or infrared connection 52, it operates in a different mode. As mentioned with regard to figure 14, the radio frequency section 30 is used for certain GSM BTS information requirements etc. However layer 3 GSM signalling and the information is forwarded to the terminal device for transmission over wire connections. Switching is detected by both terminal device 40 and mobile station 10 and, depending on the switching method used, switching can be detected in a number of methods. When e.g. multi-core interconnecting cable 51 is used, one of the cores can be allocated for the indication signal. If e.g. in terminal device 40 said indication signal is connected to operating voltage (e.g. + 5 V), mobile station 10 detects the switching in of mobile station 10 by monitoring the voltage level of the indication signal e.g. using a level detector. Level detector transfers the information to processor 20 controlling the 26 system, controlled by which mobile station 10 and terminal device 40 go over to using wired information transfer connection over cable 51. A physical connection within mobile station 10 is established when processor 20 orders switch K3 to close. For example in order to save power, processor 20 can in this case switch off infrared transceiver 36 by opening switch K4 (if it was closed). In a corresponding way terminal device 40 can detect connecting to mobile station 10 by monitoring an indication signal of same type, the signal level of which a program installed in terminal device 40 polls in interface unit 49 at certain, predetermined intervals. Because said computer program executed in processor 45 and memory 46 can be run in the background, it does not have an essential effect in the other operation of terminal device 40. When the cable between mobile station 10 and terminal device 40 is disconnected, the processor of terminal device 40 detects the disconnection from interface unit 48 and processor 20 of mobile station 10 from interface units 35 using the detector. The connection can also be switched off manually from the user interface of terminal device 40 or from the user interface of mobile station 10.

If the connection between mobile station 10 and terminal device 40 is realized using an infrared connection, there also is a number of ways for detecting the connection. When the common IrDA (infrared Data Association) protocol is used, connecting is detected e.g. based upon IAS (information Access Service) -service, obligatory for devices according to IrDA standard, using a detector. IAS-service means a handshake operation between a device (in this application mobile station 10) and a server (in this application terminal device 40) in which a device can ask a server about services available. The most important information transferred at handshake is LSAP ID (Link Service Access Point), which defines the connection point at which the required service is available. It is this information that is required for a successful establishing of a contact. Processor 20 selects IrDA-connection 52 by closing switch K4. The wire connection is disconnected if required with switch K3. When infrared connection 52 is used, disconnection of connection 52 is detected correspondingly using infrared transceivers 36 and 48. If the connection is established using low-power transceiver units operating on radio frequency, the 27 establishing and disconnection of a connection takes place according to same type of principle.

If the connection between mobile terminal 10 and terminal device 40 is established using intelligent charger 140, the processor 45 (executing the application software 144) of terminal device 40 is monitoring the establishment of the connection. The processor 45 checks periodically whether mobile station 10 has been installed to intelligent charger 140 or not. Alternatively the detecting of the establishment of the connection can be carried out by mobile station 10. In both alternatives this can easily be done e.g. by monitoring the voltage of a pin of a connector as was described above in relation to the embodiment without a separate connection device 140. After the connection has been established, mobile station 10 sends an information message to terminal device 40, in which it informs about the connection to intelligent charger 140. The terminal device 40 may acknowledge receipt of this message. Once connection is established call transfer is performed according to the invention. For example, when the terminal device is ready it sends via the intelligent charger 140 a call transferring order to mobile station 10, and the mobile station 10 performs the call transfer via the mobile network and sends a confirmation message to terminal device 40 on completion.

If no virtual BTS is used in a W10, 2 separate numbers are required - a GSM number and a LAN number and the server needs to keep a register to take care of the binding of these 2 numbers. However, in a preferred embodiment of the present invention, the virtual BTS takes care of this binding, and the MUX of the mobile of the mobile station changes between GSM and LAN modes. This provides greater flexibility because the bindings are not determined inside the IP network, but are instead made between the virtual base station and the base station controller. The above is a description of the realization of the invention and its

embodiments utilizing examples. It is self evident to a person skilled in the art that the invention is not limited to the details of the above presented embodiments and that the invention can be realized also in other embodiments without deviating from the characteristics

28 of the invention. The presented embodiments should be regarded as illustrating but not limiting. Thus the possibilities to realize and use the invention are limited only by the enclosed claims. Thus different embodiments of the invention specified by the claims, also equivalent embodiments, are included in the scope of the invention.

For example, whilst the embodiments refer to intranet offices, it is not restricted to the intranet, but is also applicable to the internet.

Annex 1 comprises a technical overview of wireless internet telephony according to the present invention.

Annex 2 comprises a technical overview of wireless intranet telephony according to the present invention.

29

Claims

Claims

A system for transferring information between a mobile station and a further communication device, the system comprising: the mobile station; a communication network to which the further communication device is coupled; and a base transceiver station emulator for interfacing the mobile station and the communication network; wherein the system transfers information over the communication network when the mobile station is within the cell of the base transceiver station emulator, and transfers information over a mobile communication network when the mobile station is outside the cell of the base transceiver station emulator.

2. emulator communicates with the mobile station by RF A system as claimed in claim 1, wherein the base transceiver station 3. A system as claimed in claim 2, wherein the base transceiver station emulator and the mobile station form part of a mobile cluster.

4. A system as claimed in claim 1, wherein the base transceiver station emulator is a virtual base transceiver station.

5. A system as claimed in claim 4, wherein the base transceiver station dedicated to the mobile station.

6. A base transceiver station emulator for a system as claimed in any of claims 1 to 5.

7. A personal device for a mobile station, the device comprising a base transceiver station emulator as claimed in claim 6.

is 8. A device as claimed in claim 7, further comprising means for connecting the mobile station and base transceiver station emulator by means of infrared connection, wire connection or low power RF connection.

9. A device as claimed in claim 8, wherein the connecting means further comprises a cradle for the mobile station.

10. A mobile station for a system as claimed in any of claims 1 to 5.

11. A dual mode mobile station comprising: control means for controlling transfer of information such that in a first mode transfer of information is between the mobile station and a mobile communication network, and in a second mode transfer of information is between the mobile station and a second communication network; and means for providing radio contact between the mobile station and the mobile communication network in both the first and second modes.

12. A system for transferring information between a mobile station and a further communication device, substantially as hereinbefore described, with reference to, andlor as illustrated in any one or any combination of Figures 2 to 14B of the accompanying drawings.

13. A mobile station, substantially as hereinbefore described, with reference to, andlor as illustrated in any one or any combination of Figures 2 to 14B of the accompanying drawings.

14. A personal device for a mobile station, substantially as hereinbefore described, with reference to, and/or as illustrated in any one or any combination of Figures 2 to 14B of the accompanying drawings.

31 Amendments to the claims have been filed as follows 1. A dual mode mobile station comprising: means for managing network information independently of the mode of operation of the mobile station; first linking means for linking to the interface of a mobile communication network so as to transfer control and mobility information between the mobile station and the mobile communication network; second linking means for providing a link to the interface of a further communication network so as to transfer control and mobility information between the mobile station and the further communication network: and means for coupling the managing means to the first linking means when the mobile station is in a first mode and to the second linking means when the mobile station is in the second mode.

2. A mobile station as claimed in claim 1, wherein the managing means manages call control and mobility information independently of the mode of operation of the mobile station.

3. A mobile station as claimed in claim 1 or 2, wherein the managing means further manages radio resources information independently of the mode of operation of the mobile station.

4. A mobile station as claimed in claim 1 or 2, wherein the first linking means comprises a radio resource manager for the mobile communication network, and the second linking means comprises a radio resource manager for the further communication network.

5. A mobile station as claimed in claim 4, wherein the second linking means comprises a low power RF radio resource.

4 32- 6.

Bluetooth.

A mobile station as claimed in claim 5, wherein the low power RF is 7. A mobile station as claimed in claim 3, wherein the radio resource management is that of the mobile communication network.

8. A mobile station as claimed in any of claims 2 to 8, wherein the call control and mobility management is that of the mobile communication network.

9. A mobile station as claimed in any preceding claim, wherein the mobile communication network is GSM.

10. A mobile station as claimed in any preceding claim, further comprising a radio resource manager for a user terminal, and linking means for linking to the interface of the terminal device so as to transfer radio resource information between the mobile station and the user terminal.

11. A mobile station as claimed in any preceding claim, further comprising a browser, such as a WAP browser.

12. A base station transceiver emulator for interfacing a mobile station of a mobile communication network and a further communication network, the base station transceiver emulator comprising:

means for determining the presence of a mobile station within its cell; transceiving means for receiving call transfer information from the mobile station when the mobile station is within the cell and for transmitting call transfer information to the mobile station as it prepares to leave the cell.

13. A mobile station emulator for interfacing a mobile station of a mobile communication network and a base transceiver station emulator of a further communication network, the mobile station emulator comprising:

: 1" 1.. 1 z 1 -315' means for receiving call transfer information from the mobile station and for forwarding it to the base transceiver station emulator, when the mobile station enters the cell of the base transceiver station emulator; means for maintaining the call transfer information while the mobile station is within the cell; and means for transmitting the call transfer information to the mobile station as it prepares to leave the cell.

14. A mobile station emulator as claimed in claim 13, further comprising means for communicating with a user terminal.

15. A device for coupling a mobile station of a mobile communication network to a further communication network, the device comprising a base transceiver emulator as claimed in claim 12 andlor a mobile station emulator as claimed in claim 13 or 14.

16.

17.

A device as claimed in claim 15, which is a personal base unit.

A personal computer comprising a device as claimed in claim 16.

18. A system for transferring information between a mobile station and a further communication device, the system comprising: the mobile station; a communication network to which the further communication device is coupled; and a base transceiver station emulator for interfacing the mobile station and the communication network; wherein the system transfers information over the communication network when the mobile station is within the cell of the base transceiver station emulator, and transfers information over a mobile communication network when the mobile station is outside the cell of the base transceiver station emulator.

1 ( 19. A system as claimed in claim 18, wherein the base transceiver station emulator communicates with the mobile station by RF.

20. A system as claimed in claim 19, wherein the base transceiver station emulator and the mobile station form part of a mobile cluster.

21. A system as claimed in claim 18, wherein the base transceiver station emulator is a virtual base transceiver station.

22. A system as claimed in claim 21, wherein the base transceiver station is dedicated to the mobile station.

claims 18 to 22.

A base transceiver station emulator for a system as claimed in any of 24. A personal device for a mobile station, the device comprising a base transceiver station emulator as claimed in claim 23.

25. A device as claimed in claim 24, further comprising means for connecting the mobile station and base transceiver station emulator by means of infrared connection, wire connection or low power RF connection.

26. A device as claimed in claim 25, wherein the connecting means further comprises a cradle for the mobile station.

27. A mobile station for a system as claimed in any of claims 18 to 22.

28. A dual mode mobile station comprising: control means for controlling transfer of information such that in a first mode transfer of information is between the mobile station and a mobile communication network, and in a second mode transfer of information is between the mobile station and a second communication network., and means for providing radio contact between the mobile station and the mobile communication network in both the first and second modes.

29. A system for transferring information between a mobile station and a further communication device, substantially as hereinbefore described, with reference to, and/or as illustrated in any one or any combination of Figures 2 to 16 of the accompanying drawings.

30. A mobile station, substantially as hereinbefore described, with reference to, andlor as illustrated in any one or any combination of Figures 2 to 16 of the accompanying drawings.

31. A personal device for a mobile station, substantially as hereinbefore described, with reference. to, andlor as illustrated in any one or any combination of Figures 2 to 16 of the accompanying drawings.

32. A base transceiver station emulator for interfacing a mobile station of a mobile communication network and a further communication network, substantially as hereinbefore described, with reference to, andlor as illustrated in any one or any combination of Figures 2 to 16 of the accompanying drawings.

33. A mobile station emulator for interfacing a mobile station of a mobile communication network and a further communication network, substantially as hereinbefore described, with reference to, andlor as illustrated in any one or any combination of Figures 2 to 16 of the accompanying drawings.

1