System and device for accessing services of a mobile communication network directly or via an ip network

ES 2 264 255 T3

DESCRIPTION

System and device for accessing the services of a mobile communication network, directly or through an IP network.

The present invention relates to mobile communication systems, and more especially, to a system for transferring information between a mobile station and a mobile communication network.

Modern office work requires flexible information transfer connections for employees, which can transfer voice, fax messages, email and other data, usually in digital format. The transfer of information is necessary inside an office or in a similar work environment, to allow communication between employees, to transfer information between branches of a company, whose offices may be located in other cities or even in other countries , and to establish communications between the company and “the outside world”. In this paragraph, as well as in the paragraphs that follow, "office" means an environment with several users, to which said users "jointly belong", said office encompassing a reasonably limited area. In the telecommunications sector there is a trend towards integrated systems, through which various types of telecommunications can be controlled as a single entity.

A conventional implementation of an office communication system of the type mentioned above includes a company telephone switchboard to facilitate telephony services, as well as telephones connected to it via twisted pair connections, in addition to a separate local area network (LAN). in which applications for advanced telecommunications services have been implemented, and which has the necessary information for its execution. The local network is connected to the telephone exchange using a telecommunications server (Telephony Server) that supports the traditional client / subscriber architecture, in which the subscribers and subscribers' computers are connected to the local network. For example, call, data, fax, email, and voicemail services are connected inside an office using the telecommunications server. In an integrated system users can also, for example, control telephone services using their computer terminals connected to the local network. The complete integrated communication system of the office is connected to the public telephone network through the telephone switchboard.

Figure 1 shows an example of an office communication system known in the prior art, in which the telephones of the TP users (TelePhone) are connected by cable connections, having connected a local area network (LAN ) through a telecommunications server TS (Tele Server) to a PBX (Private Branch Exchange) that is connected to the public telephone network PSTN / ISDN PSTN, Public Switched Telephone Network, ISDN, Integrated Services Digital Network). Servers running various services, such as the DBS database server (Data Base Server), the voice server (Voice Server) and the mail server, have been connected to the local area network (LAN). electronic EMS (Electronic Mail Server), and on the other, the computers of the users PC (Personal Computer). With this type of embodiment, it can be considered a problem that even if a user's TP phone and his PC are normally on the same table, next to each other, separate cable connections must be run to the utility room. User work, on the one hand from the PBX telephone exchange and on the other hand from the telecommunications server TS of the LAN. Naturally, the construction and maintenance of two overlapping telecommunications networks entail a number of costs.

The problem of overlapping telecommunications networks is exacerbated by portable mobile stations, which use radio connections and are rapidly increasing in popularity. Many people who work in an office need a mobile station, due to the mobility of their work, and often also require a portable fax machine and / or a combination of mobile station and laptop. In order to also be able to use the devices via radio connection inside buildings, the construction of which attenuates radio signals, it has been suggested that mobile radio networks should be supplemented by small individual base stations for offices, and even for offices, said base stations being connected, either directly or through a cable telephone network, to the central systems of the mobile communication network. The network of small base stations would already constitute a third overlapping telecommunications network within the same office, and therefore, it is evident that in a preferred solution, which constitutes the object of the present invention, the configuration that supports the communication stations Radio should be implemented using essentially the same telecommunications networks and media as all other information transfer in the office.

One of the unique challenges that telecommunications systems face stems from the fact that work is carried out more and more frequently in home or small office environments, which is described by the SOHO concept (Small Office , Home Office). Even in this case, advanced communication services are often needed for the office, and it is especially preferable if you have such a flexible system that can be used both in the office and at home. Current systems that require overlapping connections for the use of mobile communication services, conventional telephone services and fast data transfer services are very inflexible for work in a small or home office. In addition to the foregoing, the following types of solutions connected to integrated telecommunications systems are known in the prior art.

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If an integrated communication system for the office is carried out using the traditional technique, separate cable connections must be laid at a user's workplace, on the one hand from the PBX telephone exchange (figure 1) and on the other from the telecommunications server TS of the local area network (LAN). To contact a subscriber through various switchboards and servers, various numbers and addresses must be used. Managing multiple addresses for each user complicates things both for the subscribers themselves and for those who try to contact them. In previous applications according to the prior art no real attempt has been made to obtain a solution to this problem.

Document D1: EP 766490 describes an integrated data transfer system that includes a cellular network (GSM) and a wireless LAN (Hiperlan). The connection between both networks is controlled by a GATEWAY computer located in each wireless LAN. For the cellular network, the GATEWAY computer operates as a base station controller (BSC). The PASARELA computer performs the protocol conversions between the cellular network protocol and the LAN protocol.

Today an improved integrated office communication system has been invented. As different aspects of the invention, a system, a mobile station emulator, a mobile station and a method are presented, which are characterized by what is described in the independent claims. Some embodiments of the invention are described in the dependent claims.

Various embodiments of the present invention will now be described, by way of example, with reference to the attached figures, in which:

Figure 1 presents an example of a previously known office communication system.

Figure 2 is a block diagram showing the basic elements of the GSM system;

Figure 3 is a block diagram showing in greater detail the transmission and reception functions of a GSM mobile station;

Figure 4 is a block diagram showing a system according to the invention;

Figure 5 is a block diagram showing the structure of an interconnection unit;

Figure 6 is a block diagram showing the functionality of a mobile station in relation to the implementation of a virtual terminal;

Figure 7 is a flow chart showing the operation of the virtual terminal based on a message received from a mobile communication system;

Figure 8 is a block diagram showing the architecture of a system in accordance with an embodiment of the present invention;

Figure 9 shows the basic elements of a communication system according to an embodiment of the present invention;

Figure 10 shows the modules of a mobile station;

Figure 11 shows the protocol stack of a mobile station MS;

Figure 12 shows the concept of Wireless Internet Office (WIO);

Figure 13 shows an example of a general WIO network architecture;

Figure 14 shows the architecture of a personal base unit in accordance with one embodiment of the present invention;

Figure 15 shows a way of connecting the mobile station MS according to the invention to the terminal equipment TE incorporating a personal base unit (PBU);

Figure 16 shows the protocol stack of a vMS virtual terminal in the PBU; Y

Figure 17 shows the configuration of a preferred embodiment of the invention.

Embodiments of the invention will be described using the terms and elements of a GSM (Global System for Mobile Communications) digital mobile communication network. It should be noted that the invention can be used in connection with any mobile communication network with equivalent functionalities, such as NMT (Nordic Mobile Telephone), AMPS (Advanced Mobile Phone Service), DECT (Digital European Cordless Telecommuni3

ES 2 264 255 T3 cations [digital European wireless telecommunications]), the DCS1800 (Digital Cellular System for 1800 MHz), and so on. The selection of the access network is also not essential as far as the present invention is concerned. Therefore, the solution can be applied in relation to other fixed and wireless access techniques such as WLAN (Wireless Local Area Network), Ethernet, ATM (Synchronous Transfer Mode), WATM (Wireless Asynchronous Transfer Mode), HIPERLAN, LPRF (Low Power RF), etc.

Figures 2 to 8 show a first embodiment, in which a virtual mobile station is established on the operator equipment, and from Figure 9 onwards a second embodiment is shown, in which the virtual mobile station is located on the equipment. of the user.

The block diagram in figure 2 shows the basic elements of the GSM system. The mobile stations MS are connected to the base stations BTS using radio communications. The base stations BTS are additionally connected, through the so-called Abis interface, to a base station controller BSC, which controls and manages various base stations. The entity made up of several base stations BST and a single base station controller BSC controlling them is called a base station system BSS. Specifically, the base station controller BSC manages the radio communication channels, as well as the handoffs. On the other hand, the base station controller BSC is, through the so-called interface A, connected to a mobile services switching center (MSC), which coordinates the establishment of connections with and from the mobile stations. Via the mobile services switching center MSC, a connection can also be established with a subscriber not operating in the mobile communication network.

The block diagram of figure 3 shows in greater detail the transmission and reception functions of a mobile station according to the GSM system. The first stage of a transmission sequence is digitization 201 and encoding 202 of the analog voice. An A / D converter 201 takes a sample at a frequency of 8 kHz and a speech coding algorithm assumes that the input signal is of the 13-bit linear PCM type. The samples provided by the A / D converter are segmented into 160 sample speech frames, making the duration of each speech frame 20 ms. Speech coder 202 processes the 20 ms speech frames, or in other words, 20 ms of speech are put into a buffer before encoding begins. The encoding operations are carried out specifically by frames, or as its sub-frames (as blocks of 40 samples). As a result of the encoding of the speech coder 202, a frame generates 260 bits.

After the voice coding 202, the channel coding 203 is carried out in two stages, whereby, first, a part (the most important 50) of the bits (260 bits) is protected by a block code 203a (= CRC, 3 bits) and then these and next bits in order of importance (132) are further protected by a convolution code 203b (encoding ratio of /) ((50 + 3 + 132 + 4) * 2 = 378), and a part of the bits is taken unprotected (78). As shown in figure 3, the signaling and logic messages come directly from a control unit 219, which controls the blocks of the mobile station, going to the block coding block 203a, and of course, none is carried out. voice coding for these data messages. Correspondingly, the signaling and logic messages received on reception are carried from a channel decoding block 215 to the control unit 219. In block coding 203a, a sequence of bits is connected to the end of a frame by which transport errors can be detected on reception. In 203b convolution coding, the redundancy of the speech frame increases. Thus, a total of 456 bits is transmitted per 20 ms frame.

These 456 bits are interleaved 204, and interleaved 204 also has two stages. First, the frame bit order is shuffled 204th, and the shuffled bits are divided into eight blocks of the same size. These blocks are further divided 204b into eight successive TDMA frames, whereby the 456 interleaved bits are transmitted in eight time slots over the radio path (57 bits each). The purpose of interleaving is to distribute the transfer errors, which normally occur as bursts of errors, evenly over the entire transmitted data, thereby making channel decoding more effective. After deinterleaving, the error burst is converted into separate error bits, which can be corrected in channel decoding. The next stage in the transmission sequence is data encryption 205. Encryption 205 is implemented by an algorithm, which is one of GSM's most closely guarded secrets. Encryption prevents unauthorized listening in on calls, which is possible in analog networks.

From the encrypted data, the burst to be transmitted is generated 206 by adding to it a training period, a tail bits, and a protection period. The burst to be transmitted is carried to a GMSK 207 modulator, which modulates the bursts for transmission. The GMSK (Gaussian Minimum Shift Keying) modulation method is a digital modulation method, of standard amplitude, in which information on phase changes is included. A transmitter 226 mixes the modulated burst through one or more intermediate sequences for 900 MHz, and transmits it through an antenna to a radio interface. Transmitter 226 is one of three radio frequency blocks 30. A receiver 228 is the first block on the receive side that reverses the operations of transmitter 226. The third RF block is a synthesizer 227, which deals with the generation of frequencies. The GSM system incorporates frequency hopping in its use, with which the transmission and reception frequencies vary in each TDMA frame. Frequency hopping improves the quality of the connection, but sets strict requirements for the synthesizer 227. The synthesizer 227 must be able to switch from one frequency to another very quickly; in less than a millisecond.

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At reception the transmission operations are reversed. After an RF receiver 28 and a demodulator 211 a linear detection 212 is carried out, for example, by means of a channel equalizer of the received samples, its purpose being to find the transmitted bit sequence. After detection, decryption 213 and deinterleaving 214 are carried out, implementing channel decoding 215 for the detected bits, and checking the sum of errors by means of a cyclic redundancy check (CRC). In channel 215 decoding, the intention is to correct bit errors caused by the transfer of the burst. The 260-bit long speech frame, after channel 215 decoding, contains the transmitted parameters that describe the speech by which a speech decoder 216 generates digital samples of the speech signal. Samples undergo D / A conversion 217 for playback on speaker 32. In the transmitter / receiver, the main unit that controls the mobile station is the control unit 219, which essentially controls the blocks described above, coordinates their functions, and controls the timing.

The block diagram of figure 4 shows a configuration, according to an embodiment of the present invention, for the use of the services of a mobile communication network through an IP access protocol. An interconnection unit 40 (IWU) has been connected to the mobile services switching center 31 of a mobile communication system, the interface of which with the mobile services switching center corresponds to an ordinary interface of a base station controller BSC, that is, interface A, and towards the IP network, corresponds to an ordinary interface between the IP network and an IP terminal. The IWU is a new element of the network according to the present invention, which includes the necessary means to interconnect the functionalities of the mobile communication system and the IP network. The AP element presents the connection point of the IP network.

The structure of the interconnection unit 40 is shown by means of the block diagram of Figure 5. The interconnection unit 40 includes a first functional block 41, comprising means for emulation of the base station controller of the communication system to the mobile services switching center. The IWU also includes a second functional block 42, which includes means to operate as an IP host towards the Internet or the corresponding telecommunications network, such as ISDN, AMT, etc. There is a third functional block 43 between the first and the second functional blocks, including means for establishing one or more virtual terminals. Later we will discuss the generation and operation of virtual terminals in greater detail.

Referring to Figure 4, the company's local area network LAN 32 is connected to a public IP network through an IP router 33. In a system according to the invention, a mobile station includes means for switching to an access network; The mobile station, shown in Figure 4, is coupled to the LAN 32, for example, by connecting the mobile station to a personal computer coupled to a subscriber's LAN using a cable, an infrared connection, or a transceiver pair via radio. How the mobile station is coupled to the point of the network is not essential as far as the invention is concerned. Subsequently, mobile stations may be equipped with sufficient IP functionality, whereby a separate terminal will not be required. In the example presented in Figure 4, the mobile station switches to a fixed access point of a local area network. The access point can also be another access point, for example that of a wireless local area network, as will be demonstrated later.

By means of its control unit, the mobile station can make a decision about switching to the access network after checking, for example, that it is in the subscriber area of ​​a wireless access network. When the mobile station is connected to the network through a terminal, the mobile station will detect the switching or de-switching, for example, from an indicator 37B of a signal indicating the selected core of a multi-core cable or of an information access service (IAS) that is mandatory in equipment that conforms to the IrDA standard.

In connection with switching to the local area network, the mobile station transfers the dynamic data relating to the status of the mobile station and ongoing calls to the interconnection unit via the IP network. Subsequently, the traditional radio frequency components of the mobile station are disconnected and the mobile station goes on to communicate with the interconnection unit 40 via the IP network. Referring to Figure 3, this configuration means that, for example, blocks 233, 201,202, 216,217, 219 and 232 are kept, and the rest of the blocks are disconnected, whereby the mobile station transmits and receives coded voice from in accordance with the 13 Kbps GSM specification. When operating in the GSM system, a mobile station 34 exchanges signals with a mobile services switching center 31 through a base station controller. When mobile station 34 switches to network mode, it no longer continues with such signaling and the signaling is transported to be carried elsewhere in order to maintain connections. Therefore, the interconnection unit 40 is not an element that performs only protocol conversions; it also contains a functional unit 43 for the maintenance of virtual terminals.

When entering the IP mode, the mobile station 34 transfers the dynamic data related to the status of the mobile station and the calls in progress to a virtual terminal vMS 35 to be established in the interconnection unit 40. This data is maintained in a machine status, found in the virtual terminal. In this context, the state machine means a functional entity that describes the allowed state changes in relation to the operation of the mobile station and related messages according to the protocol. The functionality component described by the state machine maintains data on possible state changes related to said protocol layer, the instantaneous state, data structures related to state changes, etc. Thus, a state machine in relation to GSM means that the functionality component of the station, which controls the functionalities related to the GSM layer 3 protocol of the mobile station (NULL, current connected, connected to a base station,

ES 2 264 255 T3 etc.). Furthermore, this top-level state machine maintains a partial state machine corresponding to each connection of the mobile station, whereby the state of the connection can be, for example, NULL, call initiated, call procedure, active, etc. .

The simplified block diagram presented in Figure 6 shows an implementation of the functionality of the mobile station, and the division of its hierarchy in relation to the establishment of a virtual terminal. The interconnection unit 40 has been connected to the mobile services switching center 31 through a fixed network of the GSM system, whereby the lower layer of the protocol stack of the mobile services switching center 31 and the interconnection unit 40 is a transport protocol 315, 411, of a fixed network 50 of the GSM system. In addition to the transport protocol 411 mentioned above, block 41 of the interconnection unit includes layers 412 necessary to emulate a network subsystem. A block 42 of the interconnection unit includes the MAC 421, IP 422 and UDP 423 protocols related to IP communications. Corresponding protocols 341, 342, 343 are found in the protocol stack of mobile station 34 operating in network mode. The protocol stack of the virtual terminal 43 includes the GSM functionality entity described by a state machine 431, which includes at least one resource for radio (RR), mobility management (MM) and call management (CM). Above is a protocol 432 (GSM over IP) relating to communication between the interconnection unit and the mobile station operating in network mode. This will be discussed in more detail later. In the mobile station there is the corresponding protocol 344, operating in network mode, which also includes the necessary applications for the processing of basic services (voice, short messages, telefax) of a mobile communication system.

Normally, the maintenance of the state machine in the virtual terminal 35 is an application-specific solution, since the virtual terminal must maintain the data on the state of the connection both in the direction of the mobile communication system and in that of mobile station 34. From the state data held in the virtual terminal, the virtual terminal signaling can be controlled both in the direction of the mobile communication system and in the direction of the mobile station. It should be noted that because of the state machine maintained by the virtual terminal, the signaling to be implemented in the various directions is independent of the protocol, or in other words, changing the protocol in any direction does not interrupt the operation of the virtual terminal.

To allow the operation of the virtual terminal, in addition to the status data of the mobile station, the interconnection unit needs the data stored in a subscriber identity module: the SIM card. The SIM card is a smart card, in which the identification information of the subscriber and the terminal have been stored, as well as an information field containing various types of data defined by the GSM standard and provided by the subscriber. For a more detailed description of the SIM card, we will refer to pages 67-71, 444-492 and 561 of the aforementioned Mouly-Pautet GSM guide. As regards the present invention, the most important part of the data contained in the SIM card can be kept as static information, whereby the corresponding information can be kept stored in the memory of the interconnect unit.

When the interconnection unit has the use of the data from the state machine and the SIM card, the IWU 40 initiates the virtual terminal 35, which emulates the operation of the real mobile station 34 towards the mobile communication system. This receives signals from the mobile communication system through the first functional block 41 of the interconnection unit and, depending on the status data it maintains, carries out a signaling directed to the mobile communication system. It receives, through the second functional block 42 of the interconnection unit, the data according to the IP transmitted by the real terminal, compares the message with the status data it maintains and, based on the same, generates a required signal at the time in question for transmission by the mobile communication system.

The flow chart presented in figure 7 shows the operation of a virtual terminal as a function of the message from a mobile communication system. At point 610, the virtual terminal 35 receives a message through the first functional block 41 of the interconnection unit. At point 615, the virtual terminal compares the message checked with the state machine that it maintains, and based on this comparison, defines the message necessary to move to the next state. At point 620, the virtual terminal defines whether a connection with the mobile station 34 operating in network mode is necessary to generate the next signal, or whether the necessary data is included in the subscriber information stored in the interconnection unit. . If a connection with the mobile station is necessary, the virtual terminal generates the message relating to said function (point 630) and sends it through the IP network to the mobile station (point 635). At the same time, it updates the state of the process in question to the signaling state that it maintains (point 640). If a connection with the mobile station 34 is not necessary and the virtual terminal concludes that the necessary signal can be managed by itself, the virtual terminal checks whether the subscriber information stored in the interconnection unit is necessary for the response or if the response message can be directly generated based on the status data (point 625). If additional information is necessary, the virtual terminal retrieves it from the database of the interconnection unit (point 650) and, based on this, generates a message to be transmitted to the mobile communication system (point 655) . If no additional information is required, the virtual terminal generates a message according to the protocol of the mobile communication system defined based on the status data (point 655). At point 660, the message generated by the virtual terminal is transmitted to the mobile services switching center through the first functional block 41 of the interconnection unit. Simultaneously, the virtual terminal updates the state of the process in question in the state machine maintained by it.

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One way of managing a connection between the interconnection unit and the mobile station is to convert the GSM signaling into packets according to the IP protocol and transfer the signaling to the mobile station in the GSM format. As can be concluded from figure 3, the signaling between the mobile station and the mobile services switching center includes a large amount of signaling relating to the use of a radio resource whose transfer in the configuration according to the invention is not necessary. Therefore, a connection through an IP link should preferably be managed by simplifying said protocol during network operation. This type of protocol can be established, for example, by selecting a group of AT commands, which are transported through a UDP / TCP protocol layer or using methods according to the H.323 family of protocols standardized by the ITU-T . A simple, manufacturer-specific protocol can also be defined to establish a connection. The implementation of such a protocol can be illustrated by providing an example of the functions, which are separated from each other between a mobile station operating in the network mode and an interconnection unit. These include, for example, the functions 1.1-1.7 indicated in the first column of Table 1. The second column of Table 1 contains a functional description of the messages, which are separated from each other by a protocol according to the invention.

TABLE 1

<td>Reference</td><td>Function</td><td>Messages</td>

<td> 1.1</td><td>Call forwarding</td><td>Call request MS -&gt; IWU New IWU call request initialization -&gt; MS</td>

<td> 1.2</td><td>Call reception</td><td>Call indication IWU -&gt; MS New initialization of call indication MS -&gt; IWU</td>

<td> 1.3</td><td>Voice</td><td>Encrypted voice transport over UDP</td>

<td> 1.4</td><td>Doorbell</td><td>Disconnection / identification request</td>

<td> 1.5</td><td>SMS</td><td>SMS transmission / reception via UDP or TCP</td>

<td> 1.6</td><td>Fax</td><td>Fax transmission / reception via UDP or TCP</td>

<td> 1.7</td><td>Transfer</td><td>Transfer Message Transmission / Reception (State Machine)</td>

When a subscriber wishes to make a call through a mobile communication network (1.1), a mobile station makes a call request and receives the call setup message provided by an interconnection unit, before the data transfer begins relative to the call. When the subscriber receives a call (1.2), the mobile station receives the message of the incoming call from the interconnection unit and informs the interconnection unit about the reception of the call, before the transfer of the related data begins to the call. When the subscriber or the other party wishes to cut the call (1.3) the mobile station facilitates or receives a request to cut the call. From the protocol, both the mobile station and the interconnection unit should be able to distinguish whether it is a voice transfer (1.4), a short message (1.5) or a fax data (1.6). Message 1.7 contains the status data relating to calls in progress, which are conveyed when the virtual terminal is started to be used or when the use of the virtual terminal ends, as described above. The command group mentioned above is one possible way of implementation. For example, making a call can be configured in such a way that the mobile station identifies, based on the first voice packets, that it is a call, in which case not even a separate calling step is necessary. Similarly, the virtual mobile station unit can automatically adapt to cut off the call when the reception of the call packet from the mobile station stops. With a simple group of commands, it is possible to implement suitable functions by which the mobile station operating in the network mode can use the services of the mobile communication network through a connection to an IP network.

The simplified configuration described above shows the functionality of an interconnection unit according to the invention and a virtual terminal established therein, as well as its connection to a mobile station operating in network mode. By connecting the mobile IP to the configuration presented above to use the functions of a mobile communication network through the interconnection unit that operates as an IP terminal, according to figure 8, we can present a system that provides the user the opportunity to use the services of the mobile communications system itself anywhere, when an Internet connection is possible, regardless of the access technique available.

The Mobile IP protocol is a protocol that is currently in the standardization phase. For a more detailed description, we will refer to the document “Engineering Task Force (ETF) instructions Request for

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Comments (RFC) 2002 ". The Mobile IP protocol describes the home agent (HA) of a network element that is to connect to the home network of a mobile subscriber. When the subscriber moves away from the home network, the HA maintains the data regarding the subscriber's address and routes the data packets assigned to the mobile subscriber to the address where the subscriber is registered at that specific time. As a result, the data packets are routed to the subscriber's new address without a significant number of them being lost due to the handover. The connection between the mobile station operating in the IP mode and the interconnection unit can be maintained due to the Mobile IP protocol, whereby a mobile virtual station operating within the interconnection unit appears to remain in the same cell for the network of mobile communications, when operating through the same home agent on the home network.

The block diagram of figure 8 shows a configuration according to the invention presented above. The mobile communication system containing an interconnection unit, according to the present invention, has been connected through the interconnection unit to an IP network. The different access networks 71, 72 and 73, reached through the routing devices 710, 711, 721 and 731 of the IP network provide the mobile station of the mobile communication system with IP access points 712, 722, 732 The IP network is made up of a large number of access networks at the MAC level, many of which support the mobility of the subscriber in the access network in question (for example, 802.11 and WATM). The Mobile IP protocol enables mobility between IP access protocols, for example between two independent WLANS or between an Ethernet network and a WLAN. A mobile communication system, eg GSM, enables mobility via the IP Mobile protocol between mobile communication networks. Thus, a configuration in accordance with the present invention produces extended functionality that supports mobility between a mobile communication network and an IP network, and provides the subscriber with the opportunity to preferably maintain a flexible and uninterrupted connection within an area. enormously extensive service.

Figure 9 shows an architecture for a system according to an embodiment of the invention. The system includes a mobile station MS, a mobile communication network MOB, eg, the public land mobile network (PLMN), and an IP communication network, all connected by virtue of an interconnection unit IWU. The interface of the IWU and the MS is a BTSE base sender / receiver emulator. These items will be explained in more detail below.

The mobile station MS is a generic portfolio of terminal products consisting of a complete cellular telephone, which supports the services of the mobile communication network. When access to the IP communications network is not available, the MS transfers information (such as voice and data) through the MOB in the ordinary way, as explained in Figure 2.

Fig. 10 is a block diagram showing the modules of a mobile station MS. A central processing unit 401 controls the blocks responsible for the different functions of the mobile station: a memory (MEM) 402, a radio frequency (RF) block 403, a user interface (404) and an interface unit (IU) 405. The operating instructions of the microprocessor, that is, the basic menus of the program and the mobile station, have been previously stored in the mobile station, for example, during the manufacturing process, in memory 402. According to its program, the The microprocessor uses the RF block 403 to transmit and receive messages on the radio path and communicates with the user via the UI 404. The interface unit 405 is the link to a data processing entity, and is controlled by the CPU 401. The data processing entity may be an integrated data processor or external data processing equipment.

Figure 11 shows the functionalities of a mobile station MS according to the invention, represented by layers 1 to 3 of the reference model 7 OSI. Layers are data communication protocols whose purpose is to provide a link between two communication devices, and are well known to anyone skilled in the art. The layers shown are the physical layer (layer 1) 51, the data link layer (layer 2) 52 and the network layer (layer 3) 53. The network layer 53 of the mobile station MS facilitates the management of the call 531 (including supplementary services 532 and short message services 533). This layer also provides mobile management 534 and radio resource management 535. Additionally, it includes a multiplexer 536 that "switches" to a second branch of layer 2 to request the services of the data link (FBUS Ctrl. 523) and of the physical layer (FBUS 522) when the mobile station MS connects to the communications network through the IWU. In any case, the network requests the services of the data link layer 52 (data link 521 and control 522) and the physical layer 51 of the first branch, in order to allow the mobile station MS to perform and communicate its relative measurements to the adjacent GSM network (adjacent BTSs) and thus meet the GSM requirements.

For example, with a serial cable, any RF interface or infrared link, which has adequate software, connected to the PC, the MS allows through the second branch the connection to a mobile communications network and other telephony entities within the IP communications network. The IP communication system can belong to various classes, such as a data communication network, Internet, intranet, LAN, WAN or an ATM packet network.

As mentioned above, the IWU acts as a gateway between the entities of the system. In Fig. 12, which shows the Wireless Internet Office (WIO) concept, an embodiment of the IWU is shown. WIO allows a subscriber MS 63 to use communication networks 62, such as private intranets, to carry cellular network services 61 when within the coverage area. In the WIO, the IWU includes various elements

ES 2 264 255 T3 network, including a mobile intranet cluster GSM / IP gateway 601, an intranet location register (ILR) 602, a WIO gatekeeper or gatekeeper 63 and a WIO A gateway 604.

Information, such as data and / or voice, can be transferred from mobile station 63 to IP local area network 62 via two routes, each of which includes a BTS BTSE emulator. In a first mode, mobile station 63 connects to local area network 62 through a personal base unit 64 (PBU), which in turn includes a BTS BTSE emulator.

In a second mode, mobile station 63 is part of a mobile cluster. In this case, the information is transmitted to the local area network through a GSM BTS 65 dedicated to said cluster, and an IMC GSM / IP gateway 601. The BTS transmits the signal through the A bis interface, and the IMC 601 gateway performs a protocol transformation from GSM to H.23, so that the signal can be transmitted through the IP local area network (as can seen in this figure, the wireless intranet office architecture uses the H.323 protocol for signaling and data connections inside the interconnection unit).

The basic access interfaces to the cellular network are the Hertzian interface, the A-interface, the MAP protocol, the ISUP / TUP interface and the DSS.1 interface.

Interface A is an interface to the mobile switching center, and interface MAP is an interface to HLR / VLR. The ISUP / TUP interface connects the switching centers, while the DSS.1 interface resides between the BSX and the switching center. The Hertzian interface connecting the mobile terminals to the network can be any RF interface or infrared link. Candidate RF interfaces include low power RF (LPRF), 802.11, WATM wireless LAN (WLAN), and HIPERLAN. The Hertzian interface can also be replaced by a physical connection (for example, an RS-232 serial cable or a universal serial bus (USB). The GSM network considers this new access network as a BSS entity. New network entities are added to the access network to modify or undo the modification of cellular signaling The principle of the design of the system consists in complying with the H.323 recommendation of the ITUT, improving it with mobility extensions.

The WIO-A gateway 604 appears to the MSC 611 as a base station controller.

An example of a general WIO network architecture is shown in Figure 13. A local area network 71 is provided with an IMC mobile Internet cluster 72, an LPRF cell 74 and a land line connection 75. The IMC includes a plurality of mobile stations, a BTS (private GSM BTS) and a server, in the form of a GSM / IP IMC gateway. The BTS interface between the BTS and the IMC GSM / IP gateway is a GSM A-bis interface. The IMC GSM / IP gateway is responsible for the signaling conversions between the GSM and H.323 protocols. The low power RF cell 74 includes a personal base unit having a virtual BTS and a low power transmitter / receiver, and the mobile stations associated with their corresponding low power RF transmitters / receivers. The PBU is directly connected to the WIO network. To facilitate mobile stations 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 capabilities and H.323, which supports mobility and WIO location management capabilities. The land line connection includes a land line terminal 751, connected by cable to a personal base unit 752, which in turn is connected by cable to the local area network.

A WIO 76 gatekeeper is also connected to the local area network, which is responsible for connecting the mobile stations to points inside and outside the network. For example, it could route a call from the server to an external system, such as a PSTN, or it could provide a connection to the IP network 87. The local area network additionally has an intranet gateway A 791 and a location register of Intranet 792.

In this embodiment, the main function of the Intranet Location Register is to store the mobility management information and call statistics of the subscribers configured in the Wireless Intranet Office system. The itinerant nature of the visitors is controlled by the mobile switching center. In the case of visitors, only temporary information will be stored in the intranet location register. The ILR has a MAP interface to the home location network of the cellular system network (not shown here).

The intranet-A gateway 791 of this embodiment performs protocol conversion to and from the IP protocol of interface A, and performs intranet and cell site area associations. It has an operation and management software entity that functions as an administrative server gateway for the corresponding agents of the mobile intranet clusters. Intranet A gateway functions as a firewall between the public telecommunications network and private Intranet solutions.

The Mobile Intranet cluster simulates a BSC in a local environment. It consists of a minimal set of BTS functionalities with a reduced physical construction. The Mobile Intranet cluster is a BTS, and a BTS driver software package for Windows NT, including rate adaptation, an O&amp;M agent software package, and a GSM / IP telephony gateway entity. The Mobile Intranet cluster allows interconnection with data and fax services as a direct access to the IP network, and can provide local call routing capabilities within its coverage area.

ES 2 264 255 T3

The purpose of the GSM / IP telephony gateway is to reflect the characteristics of an Internet telephony terminal point for a mobile intranet station, and conversely, transparently. The GSM / IP telephony gateway provides adequate voice and signaling format translation, that is, audio format translations between GSM 06.10, 06.20, 06.60, J-STD-007 and G.711, G.723, and the transformation of communications procedures. The gateway performs call setup and release, both at the Internet telephony end and at the Wireless Intranet Office end.

The MS-IP (WIO) gatekeeper 76,603 provides call and mobility management services, as well as certain radio resource management functions.

The MS-IP gatekeeper provides the following services:

Registry control. The MS-IP gatekeeper authenticates all entities on the network, i.e. mobile intranet stations, mobile intranet clusters, intranet gateways, IP telephony gateways, intranet location records, H.323 terminals, that have access to system. In the case of the Mobile Intranet Station, authentication and registration are based on the automatic gateway discovery procedure. In other cases, it is based on a manual gatekeeper registration procedure.

Connection encryption - A part of the gatekeeper authentication procedure is the connection encryption service. It provides key distribution, identification, and encryption / decryption services to the gatekeeper and other entities on the system. The service has an independent selection option for encryption, hash, key distribution, and signature algorithms. Key distribution is based on public key cryptography, and message encryption is based on secret key cryptography.

Address translation - The MS-IP gatekeeper executes E.164 to transport address translation and association. This is done using the Intranet location register directory service, which is updated during mobility management procedures, i.e. during TMSI reassignment, authentication, identification, IMSI separation, cancellation and update of locations. .

Call control signaling - The MS-IP gatekeeper can be configured to route call control signaling to the cellular system network or to the gatekeeper's local call management entity.

Call management - The MS-IP gatekeeper also maintains a list of calls in progress and collects call statistics. The gatekeeper stores this information in the intranet location register and can be used, for example, for billing purposes.

Cellular procedures - The MS-IP gatekeeper must be able to manage the signaling and resource management procedures (BSSMAP resources) specified in the GSM 08.08 recommendation.

Status control - In order for the MS-IP gatekeeper to determine if the registered entity has been disconnected or if on the contrary it has entered a failure situation, the MS-IP gatekeeper uses a status query to poll the entity at specified intervals .

The MS-IP gatekeeper entity of this embodiment may be a software package for an operating system that meets, for example, the requirements of the ITUT H.323 gatekeeper specifications, extended with certain mobility management capabilities in accordance with GSM 04.08.

A preferred embodiment of a Personal Base Unit (PBU) 74 is a "PC Card" radio card for a desktop PC, with a piece of software that enables wireless access to the IP network. It provides dual LPRF access for wireless networks in the 2.4 GHz band, exploiting unlicensed radio spectrum. In wireless mode, the lower layers of the “unlicensed” mode will be replaced by new ones, but the signaling above them is still cellular. It also allows the intelligent roaming of terminals between the different radio frequency bands, that is, between cellular and unlicensed bands, as will be explained later.

Referring again to Figure 9, the BTSE is the interface element between the MS and the IWU. In this embodiment of the invention, the BTSE is a PBU. The PBU and the MS are connected to a radio frequency (preferably LPRF) or via an infrared connection. Likewise, they can also be connected indirectly, for example, through a connecting device, such as a mobile station base, a tabletop stand or a charger.

Figure 14 shows the architecture of a personal base unit in accordance with one embodiment of the present invention. The PBU includes a phone controller that implements the physical layer and the data link layer 81 and 82 (FBUS 811 and FBUS Ctrl 821). The PBU network layer 83 includes an IMC basic control / PBU control 832 and an H.323 protocol entity 833 that facilitates protocol conversion between GSM and H.323. The conversions are necessary for the signaling messages of the GSM layer 3, when the voice is transported as encoded GSM as a whole in this intranet office network. The PBU further includes a TCP / IP entity 821 and a local area network adapter driver for interface 823 to the local area network. PBU 832 control includes a BTS

ES 2 264 255 T3 virtual 834, that is, a BTSE base station emulator for communicating with the network layer 53 (ref. Fig. 5) of a mobile station MS.

When the mobile station MS is outside the wireless intranet office environment, it operates like an ordinary GSM phone. The multiplexer 536 does not couple the radio resource management entity 533 with the second branch 523, 512. Voice and signaling are transmitted through the data link layer 52 and the physical layer 51 through the first branch ( GSM) to the cellular Hertz interface. Likewise, if the mobile station MS is located within the wireless intranet office, but is part of a mobile intranet cluster, this same path is taken to the cellular Hertzian interface, and the information and signaling are transmitted to the GSM BTS of said cluster. However, when the mobile station MS is connected to a PBU (eg via RF 232 serial cable or RF interface), the information, such as voice, data, fax, SMS, etc. it is transmitted over the local area network.

Figure 15 shows a way of connecting the mobile station MS, according to the invention, to a terminal equipment TE incorporating the PBU. In this embodiment, the connection is carried out by a connection device 100. It can be seen that any connection method mentioned above is also possible. In this example, the connection device 90 can be a base, such as a desktop stand or desktop charger. In this case, by way of example, the connection device is described by a charger called a smart charger 90. The smart charger 90 is non-permanently connected to a terminal device TE with a physical lead wire 91 and an interface unit. 92. Using the same interface unit 92 and the same lead wire 93, the smart charger 90 is also non-permanently connected to the mobile station MS when the mobile station MS has been installed in the smart charger 90. The lead wires 91 and 93 they form a bus for communication between the terminal device T and the mobile station MS through an intelligent charger 90. The connection illustrated by lead wires 91 and 93 can also be implemented in other ways, for example, by infrared connection or by electrical connectors, or connection device 90 can be integrated into terminal device TE. The terminal device TE can be for example a PC previously known in the office environment, or a workstation, including, among other things, a processor 95, a memory 96 and a network interface unit 97 (NI, network interface) for connection of the terminal device TE to the local area network (LAN).

The processor 95 manages the control in the terminal device TE to establish a connection with the mobile station MS and subsequent to the establishment of the connection. Said control operations can be implemented as application software 98, which is executed by the processor. The interface 92 of the smart charger 90 also includes means for configuring the charging voltage from the power supply PWR to the battery 413 of the mobile station MS through the lead wire 100. If the connection device 90 lacks a power source self-powered, it can obtain and transfer power to the mobile station from the terminal device TE.

When the mobile station MS is connected to a terminal device TE in a way characteristic of the invention, for example, using an interconnection cable or any infrared or RF connection, the MS operates in a different way. The switching between both modes is detected by both the terminal device TE and the mobile station MS and, depending on the switching method used, the switching can be detected by various methods. When, for example, multi-core interconnection cable is used, one of the cores can be assigned to the indication signal. If, for example, in the terminal device TE said indication signal is connected to the operating voltage (for example, +5 V), the mobile station MS detects the activation of the mobile station MS by monitoring the voltage level of the signal indication, for example, using a level detector. The level detector transfers the information to the processor 401 that controls the system, with the mobile station MS and the terminal device TE passing to that control using the information transfer connection over the wire. In a similar way, the terminal device TE can detect the connection to the mobile station MS by controlling an indicator signal of the same type, the signal level of which asks a program installed in the terminal device TE in the interface unit 99 at certain predetermined intervals. . Because such a computer program executed in the processor 95 and in the memory 96 can be executed in the background, it lacks an essential effect on the other operation of the terminal device TE. When the cable between the mobile station MS and the terminal device TE is disconnected, the processor of the terminal device TE detects the disconnection of the interface unit 99 and the processor 401 of the mobile station MS from the interface units 411 using the detector. The connection can also be manually disconnected from the user interface of the terminal device TE or the user interface of the mobile station MS.

If the connection between the mobile station MS and the terminal device SE TE is carried out using a wireless connection, there are also various ways of detecting the connection. When using the common IrDA (Infrared Data Association) protocol, the connection is detected, for example, based on the IAS (Information Access Service) service, which is mandatory for devices. conforming to the IrDa standard, using a detector. IAS service means a handshake operation between a device (in this application, the mobile station MS) and a server (in this application, the terminal device TE) in which a device can query a server for available services. The most important information transferred in the handshake is the LSAP ID (Link Service Access Point), which defines the connection point at which the requested service is available. This is the information that is necessary for the successful establishment of a contact. When using the infrared connection, disconnection of the connection is detected using infrared transmitters / receivers. If the connection is established using low power transmitter / receiver units operating on radio frequencies, the establishment and disconnection of a connection takes place according to the same kind of principle.

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If the connection between the mobile terminal MS and the terminal device SE TE is established using an intelligent charger 90, the processor 95 (running the application software 98) of the terminal device TE monitors the establishment of the connection. The processor 95 periodically checks whether the mobile station MS has been installed in the smart charger 90 or not. Alternatively, the detection of the connection establishment can be performed by the mobile station MS. In both cases, this can be easily accomplished, for example, by monitoring the voltage of a pin of a connector, as described above in connection with the embodiment without a separate connection device 90. Once the connection is established, the Mobile station MS sends an information message to the terminal device TE, in which it informs about the connection to the smart charger 90. The terminal device TE can acknowledge receipt of this message.

In these cases, the multiplexer 536 requests the service of the layers 1 and 2 of the second branch (LAN) and the layer 3 of the mobile station MS is seen communicating with the BTS emulator BTSE 834 of the PBU. That is, information (eg voice) and signaling messages from GSM layer 3 are redirected to the second leg interface. Since the mobile station MS and the PBU are connected, the field strength of the BTSE 914 will be greater than that of the other BTSs in the GSM network. Consequently, the handover is made to the BTSE 834. Thereafter, handover signaling related to this BTSE 834 is handled from the MUX via the second leg. When the transfer is done, the MUX handles all the messages and forwards them to the new host cell through the RS 232 interface, etc. and "talks" to the other BTSs (as in conventional GSM) through the first leg. The general broadcast traffic is also seen by the mobile station MS, for example, from layers 1 and 2 to the MUX and from there, through the mobile station / PBU interface to the BTSE 834.

The parameters of the BTSE 834 within the IMC core are set in such a way that the terminals are forced to stay connected to this virtual GSM cell. This avoids possible handovers to any other GSM cells that the mobile station might listen on.

The operation of the multiplexer can also be explained as follows. When the mobile station switches to network mode, the MUX communicates with the new BTS in a similar way as it does with other BTSs to which it is not connected. At this stage, the mobile station perceives that the field strength of the new BTS in relation to this new interface is more powerful than the field strength of other BTSs, and therefore, it performs the handover to this BTS. After handover, the signaling relative to the new BTS is handled by the MUX through the new interface, and "talks" over the GSM radio link with the other BTSs. The general transmission 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.

As explained above, when the mobile station MS switches to the network mode, it is no longer necessary to perform, for example, all the RR-specific signaling, and the signaling operations to maintain the connections can be carried out anywhere. In order to accommodate this, when entering IP mode, the mobile station transfers the dynamic data relating to the status of the mobile station and ongoing calls to a virtual terminal vMS, which is established in the PBU.

The data is kept in a state machine, which is located in the virtual terminal. In this context, the state machine means a functional entity that describes the authorized state changes in relation to the operation of the mobile station and related messages, according to the protocol. The functionality described in the state machine maintains the data related to the possible state changes related to said protocol layer, the instantaneous state, the data structures related to the state change, etc. Thus, a state machine in relation to GSM means the functionality of the mobile station in relation to the GSM layer 3 protocol of the mobile station (NULL, currently connected, connected to a base station, etc.). Furthermore, said state machine at the top level maintains a partial state machine for all connections of the mobile station, whereby the state of the connection can be, for example, NULL, call started, call procedure, active, etc.

The protocol stack of the virtual terminal vMS in the PBU shown in Figure 16 includes the GSM functionality described by a state machine 105, which includes at least one radio resource (RR), mobility management (MM) and management. Calls (CM), that is, functions related to protocol layer 3 (ref. 53) in the figure

eleven. Above that, there is an additional protocol 106 relating to communication between the PBU and the mobile station operating in network mode. This will be discussed in greater detail later.

When the PBU has the use of the state machine data, the PBU starts the virtual terminal vMS, which emulates the operation of the real mobile station MS towards the mobile communication system. It receives signals from the mobile communication network and, based on the state data it maintains, carries out signaling to the mobile communication system, either independently or in accordance with the information it requests from the mobile station in signal mode. net. It should be noted that since the state machine, during network mode, is maintained by the virtual terminal, the signaling to be implemented in different directions is independent, which means that the protocol change in any direction does not interrupt the operation of the device. virtual terminal.

The virtual terminal can operate as shown in the flow chart in figure 7.

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When the connection with the IP is configured and the virtual terminal is established, the use of the mobile station in the network differs greatly from the original. A good solution is the multi-mode terminal device capable of adjusting its operations according to the operating mode. Another preferred solution consists of using the simplest configuration necessary for operation in network mode, facilitating the routing of information to another terminal device, which is more convenient for the conditions in which the subscriber is. A preferred option is to incorporate into the PBU a low power radio frequency transmitter / receiver, according to the current technique (See Figure 11) to transmit and receive information to and from an external user terminal (UT) 103 with the simplified commands, as described above. Such a user terminal could be selected to suit current user needs, and could include, for example, a combination of a virtual terminal, a cordless telephone and a wrist user interface, as shown in FIG. figure 17.

In Figure 17, the services of the mobile communication network MOB are used through an IP communication network accessed with a PC as a terminal device. Said terminal device acts as a PBU, and therefore has a built-in LPRF server. The user has a WH cordless telephone connected through a Hertzian interface using the LPRF remote audio protocol, and a WUI user interface, consisting of a wristwatch, connected through the Hertzian interface using the user interface protocol. LPRF remote. When a user enters an office carrying their traditional mobile phone, the phone indicates that they have access to an LPRF LAN. When the subscriber so desires, they can, for example, connect the phone to a smart charger as described above, and thus activate "phone-free operation", using merely the wrist UI and a wireless headset. In this operation, the traditional terminal is idle and the virtual terminal acts as a mobile station towards the mobile communication network. The traffic between the thin terminal and the virtual terminal is carried out through the LPRF connection using the specific protocol layer, as described above. When in the office, the user can roam the LPRF coverage area and use GSM services without the headset. When leaving the office, you can switch to ordinary cellular operation, taking your mobile phone with you, and even continue the ongoing call. Thus, the invention provides a fully usable communication device in the office environment, with the user identified as the same mobile subscriber as outside the office, with the mobile phone. Phone numbers, user settings, custom features, etc. they will be preserved in both modes of operation.

The implementation and embodiments of the present invention have been presented with the aid of examples. It will be apparent to a person skilled in the art that the present invention is not limited to the details of the embodiments presented above, and that the invention can also be implemented in another way without departing from the characteristics of the invention. The embodiments presented above should be considered illustrative, but not limiting. Thus, the possibilities of implementation and use of the invention are limited only by the appended claims. Consequently, the various implementation options of the invention, as specified in the claims, including equivalent implementations, also fall within the scope of the invention.