MXPA98007289A - Method and system for supporting personal personnel communications using a mobile switching center for a global communications system movi - Google Patents

Abstract

A method to allow the integration of the Personal Access Communications System (PACS) (2) which supports low stacking radio communication wireless devices with a GSM (1) network used to support cellular devices, highly stacked to allow connection from the PACS system (2) to public switched telephone networks that do not have Intelligent Advanced Network capabilities. The functions of the conventional PACS Access Manager are distributed among the components of the PACS / GSM integrated system. The PACS protocol modifications that make it compatible with the G protocol are detailed

Description

• METHOD AND SYSTEM TO SUPPORT PERSONAL ACCESS COMMUNICATIONS # • USING ON MOBILE SWITCHING CENTER FOR A GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS FIELD OF THE INVENTION 5 This invention relates to personal wireless communication. More specifically, this invention relates to a method for supporting personal wireless communication services using a personal access communication system (PACS), which is interconnected through a mobile switching center in a Global Communications System. Mobile (GSM) to the public switched telephone network (PSTN).

BACKGROUND OF THE INVENTION 15 Current cellular services are provided around a frequency band of 800 MHz. These systems are known as "Highly stacked" systems. "Highly stacked" refers to a system that is characterized by higher base stations, a power of transmission and several miles or kilometers of coverage, and that can support wireless subscribers (e.g., cell phones), which are traveling at a relatively high speed, such as approximately 48 to 64 kilometers per hour or more (30 to 40 miles per hour). REF. 28200 One such highly stacked system is the Global System for Mobile Communication (GSM), which is deployed in many areas of the world including parts of North America, Europe and Asia. The GSM supports the subscriber units in a service area by handling the location and identification information of each subscriber unit, the information of the transmission system and incoming calls * to the subscriber units, and receiving transmissions from subscriber units. The GSM is also interconnected to the subscriber units with the public switched telephone network (PSTN). A cellular base station in a GSM system is typically a large and expensive structure. A highly stacked base station can be hundreds of meters (feet) high and serve a sixteen-kilometer (ten-mile) radius. In addition to their size and cost, traditional cellular communications are often of low voice quality (8 kilobytes / second to 13 kilobytes / second) compared to the voice quality of low stacking wireless access technologies (32 kilobytes / second). ) when the subscriber unit is used indoors. Traditionally highly stacked cellular systems are also limited in the amount of traffic they can support. When enough subscribers attempt to use the system at the same time, highly stacked systems become congested and calls from subscribers are blocked. "Cell division" is a known method for increasing the capacity of highly stacked systems, but when enough demand is experienced, cell division is no longer effective. In addition to these systems, "low stacking" radio standards have been developed for wireless communications. One such low stacking system is the Personal Access Communications System (PACS), a radio standard for wireless communication that operates in the frequency band of 1850-1990 Mhz. PACS has several advantages over known high-stacking systems, such as small and inexpensive base stations and a much lower transmission power requirement. The development of the PACS is described in the following articles, which are incorporated herein by reference: D. C. Cox, Universal Digital Portable Radio Communications, Proceedings of the IEEE, Vol. 75 April 1987, p. 436-477; D. C. Cox, A Radio System Proposal for idespread Low-Power Tetherless Communications, IEEE Trans. On Comm., 'February 1991, pp. 324-335; V. K. Varma et al., A Flexible Low-Delay TDMA Frame Structure, IEEE ICC 91, Denver, CO, June 23-26, 1991; American National Standars Institute J-STD-014, Personal Access Communication System Air Interface Standard, 1995 (here after "ANSÍ J-STD-014"). The advantages of PACS come from the small size of the base stations used. Known as radio doors (RP), these base stations serve a relatively small area (trajectory lengths up to a few kilometers). Being both small and relatively cheap, RPs can be widely deployed in utility poles, in buildings, in tunnels, interiors and so on, to provide more comprehensive support for wireless access services. Additionally, PRs have relatively small power requirements compared to highly stacked base stations. An RP can be powered by a power line or batteries. The PACS also has operational advantages. Its narrowband transmission format creates a relatively large number of frequency channels in the 10 MHz sub-bands from which an RP can be chosen. This allows the PACS to have high frequency reuse factors that allow a more efficient use of the available radio frequency band. Additionally, because most circuits are located in radio gate controller units (RPCU) that service a number of RPs, the system update can be achieved without visiting each RP. The PACS, however, is not exempt from limitations. As noted, the PACS is a low stacking system and can only support subscriber units that move at relatively low speeds. Due to the small service areas supported by each RP, subscriber units traveling at more than 48 to 64 kilometers per hour (30 to 40 miles per hour) will require frequent release or handover of a PR or coverage area of base station to another. This is one reason why PACS is cheaper in areas with high density of slow-moving subscribers (eg, pedestrians). The PACS was originally developed under the assumption that the radio door network could be interconnected with the public switched telephone network (PSTN), specifically, to an ISDN switch. To support PACS, a PSTN must perform mobility management or management functions that are similar to those performed by GSM '. Specifically, a PSTN supporting PACS must track the location within the service area of each subscriber unit and handle the routing of calls.

To support the wireless access mobility management or management functions mentioned above using the PACS? a PSTN will require advanced intelligent network (AIN) capabilities. However, PSTNs in many areas, especially in developing countries, are not equipped with AIN capabilities; an alternative architecture is desired, which could rapidly deploy the PACS to provide wireless services in such areas. As described in detail below, support PACS using GSM systems will provide this alternative architecture.

BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to satisfy the needs set forth above and others. More specifically, an object of the present invention is to provide a method by which a Personal Access Communications System (PACS) for wireless access can be interconnected with a Global Mobile Communications System (GSM) network through or via a mobile switching center (MSC) to provide management or mobility management functions. A further object of this invention is to provide alerting functions in a PACS / GSM integration and to modify the protocol of the PACS system to be compatible with the GSM. The additional objects, advantages and novel features of the invention will be set forth in part in the following description, and in part will be apparent to those skilled in the art after assimilating the following or can be learned by practice of the invention. The objects and advantages of the invention can be realized and achieved by means of the implementation and combinations particularly pointed out in the appended claims. To achieve the stated and other objectives of the invention, as incorporated and described below, the method of this invention may comprise the steps of: providing a number of PACS radio doors controlled by a number of radio door controller units to through a service area; connecting the radio door controller units to a mobile switching center of the GSM network; and provide PACS radio door controller units with protocols for the authentication and registration of a subscriber unit, and protocols for determining and encrypting which are compatible with the protocol GSM. This invention will allow a service provider to service subscribers compatible with the PACS whenever the GSM is deployed. Such a service provider will have to build the PACS infrastructure and then use the present invention to interconnect with the GSM and the local public switched telephone network (a PSTN without AIN).

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated and form part of the specification, illustrate the method of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: Figure 1 is a block diagram showing a PACS infrastructure system interconnected with a GSM infrastructure according to the method of the present invention. Figure 2 is a diagram ^ showing the content of a system information channel that broadcasts in an integrated GSM / PACS system according to the present invention. Figure 3 is a block diagram showing a GSM / PACS system illustrating the method of tracking the location of the subscriber unit of the present invention. Figure 4 is a schematic diagram showing the alert protocol procedure of the present invention required to support the authentication and delivery of calls in a GSM / PACS integrated system according to the present invention. Figure 5 is a schematic diagram showing the procedure of the protocol of the present invention required to support transfers in a GSM / PACS integrated system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODE Using the drawings, the preferred embodiment of the present invention will now be explained.

PHYSICAL INTEGRATION OF PACS AND GSM Figure 1 shows a GSM 1 network that has been integrated and supports a PACS 2 network. In this example, the basic components of the PACS 2 network are a radio gate (RP) 3 and a radio door controller unit (RPCU) 4.

The radio door 3 comprises a radio transmitter / receiver that communicates with the units 8 through the air. Although only one RP 3 and one RPCU 4 are shown, it should be understood that several may be provided. The PACS uses frequency division duplexing (FDD) to support two-way communication links. A related standard, the PACS-UB, uses time division duplexing (TDD). Additional details of the structure of the transmissions by PACS between the subscriber units and the RPS are described in the following articles incorporated herein by reference: L. F. Chang et al. , Combined Burst Synchronization and Error Detection Scheme for TDMA Portable Communications Systems, IEEE Trans. Comm., 1991; J. Chuang, Autonomous Adaptive Frequency Assign ents of TDMA Portable Radio Systems, IEEE Trans. Veh. Tech., Vol. 40, No. 3, pp. 627-635, August 1991; AR Noerpel et al., PACS-UB, A Protocol for the Unlicensed Spectrum, IEEE ICC? 95 Conf. Proceedings, Seattle, A, June 1995. RPCU 4 is connected to RP 3 through an interconnection P. The signal used by the RPCU to maintain the RP through the interconnection P is logically separated from the call traffic in an integrated operations channel (EOC). In this way, RPCU 4 controls RP 3 and interconnects RP 3 with the wired network. Typically, a single RPCU controls an RP number. In the PACS system, several RPs and RPCUs are provided as needed through a service area. This deployment may include RPs placed indoors where traditional cellular devices are difficult to operate. Conventionally, where a PSTN with AIN capability is available, and the RPCU is connected to the PSTN via an ISDN connection. However, in the example shown in Figure 1, the PACS 2 system is integrated with a GSM 1 system through the mobile switching center (MSC) 7, of the GSM. In the GSM 1 system, a network of base stations (BTS), represented by BTS 5, are connected through an interconnection known as Abis to a base station controller (BSC) 6. Although only one BSC is shown in Figure 1, it should be understood that several may be provided. A subscriber unit 8 is interconnected with a BTS 5 through an interconnection Um. The BTS 5 and the BSC ß are analogous to the RP 3 and the RPCU 4. Together, the BTS 5 and the BSC 6 form a base station system (BSS). The different BSSs of a GSM network are connected to a mobile switching center (MSC) 7 through an interconnection A. The MSC 7 is then interconnected to the BSS network with the public switched telephone network (PSTN). According to the present invention, such PSTN does not need to have AIN capabilities because the MSC performs intelligent switching functions. In the preferred embodiment of the invention, the RP 3 and the RPCU 4 are provided through an area served by the GSM. The RPCUs 4 are connected, via an interconnection A, to the MSC 7 and the GSM 1. This interconnection A is of the same type of interconnection that links the MSC 7 to the system of the GSM base station 6. The MSC 7 is also connected to a Visitor Location Register (VLR) 9 and a Home Location Register (HLR) 10. For each registration area where the service is available, there is a VLR 9. When a subscriber initially requests service ", an identification is created and a service profile for that subscriber and are maintained in the HLR of the subscriber's home area This identification is used to route the incoming calls to the subscriber Each HLR 10 is also connected to an authentication center (AuC) 11, which stores unique authentication information to verify the identity of each subscriber unit 8. If the subscriber unit travels to a different registration area, the subscriber unit may not be known to the system in the new area, and of this mode could not receive calls. As explained in more detail later, this problem is solved by a temporary registration of the subscriber unit with the local VLR. When the subscriber unit finds itself in a new registration area, it registers with the local system by sending a message to the local VLR. The local VLR then contacts the HLR 10 in the area of the subscriber's home and receives the identity information of the subscriber. The local VLR then assigns to the subscriber unit a temporary identification to be used while it is in the new registration area. Temporary identification is assigned for security, privacy and other purposes. When a call is made to the subscriber, the call is routed to the home area where the subscriber's HLR resides. If the subscriber is in the home registration area, the home system routes the call to the subscriber. If a remote VLR has made contact with the HLR 10 to temporarily register the subscriber in another area, the home HLR 10 has the routing information1 of the subscriber's current location and the call is routed accordingly to the registration area where the unit of subscriber is temporarily registered.

INTEGRATION OF THE PACS AND GSM PROTOCOL: Because the PACS and the GSM are very different systems, the present invention incorporates several modifications to the operation procedures used by the PACS to obtain compatibility with the GSM. By creating a PACS / GSM integration, the present invention avoids making changes to the GSM equipment. The modification of the GSM equipment could involve a great cost because the GSM is already deployed in many areas and could have to be modified where and when it is in use. Changing the PACS protocol to make it compatible with GSM before the PACS equipment is deployed eliminates the need to modify the GSM. A preferred example for implementing this method is described in detail below. 1) Authentication Algorithms A subscriber unit must verify its identity with the system when it receives / initiates a call. This procedure is known as authentication. During authentication, a random number is given to the subscriber unit by the support system. The subscriber unit performs a unique algorithm on the random number to generate a different number. If the new number generated by the subscriber unit is verified by the system, the subscriber unit is authenticated. In this example, the subscriber unit compatible with the GSM is programmed with particular authentication algorithms, the algorithms A3 and A8, which allow the unit to identify itself to the system. The subscriber units compatible with the PACS 'have lar algorithms, such as the CAVE algorithm. To facilitate a PACS / GSM integration, the algorithms A3 and A8 are used by the subscriber unit in this embodiment of the invention instead of the CAVE algorithms. The security menu of the subscriber unit compatible with the PACS is modified to include the coding for the authentication algorithms A3 and A8. In the PACS, the system information channel (SIC) is constantly transmitting a random number, called Rand, and Real Time. A subscriber unit compatible with the PACS can authenticate itself by taking the Rand and the Real Time of the SIC transmission, running the numbers through a CAVE algorithm and returning the result to the system for verification. With reference to Figure 1, when a subscriber unit compatible with the GSM is being authenticated, three numbers are sent (1) a random challenge of 128 bits, RAND, (2) a cession key, Kc, and (3) a signed response (SRES), by HLR 10 and AuC 11 in the home area of the subscriber to VLR 9 and MSC 7 where the unit is located. Those three numbers are unique for each subscriber unit. The GSM system then transmits the RAND to the subscriber unit 8. The subscriber unit 8 then executes the algorithm A3 / A8 to derive the SRES from the RAND. The subscriber unit then transmits the derived SRES to the local VLR 9. The local VLR 9 compares the derived SRES with the SRES sent from the HLR 10. If the numbers of the SRES are equal, the subscriber unit is authenticated.

Thus, in this example of an integration of the PACS and the GSM, the subscriber unit 8 is supplied with the algorithms A3 and A8. However, as can be noted, the subscriber unit in a PACS system performs the authentication algorithm on a random number taken from the system information channel. In this embodiment, because such a random number is not transmitted continuously in the GSM, an integrated PACS / GSM subscriber unit 8 is equipped with new messages to request a random number, RAND, of the local VLR 9. As shown in FIG. Table 1, in the preferred embodiment, the subscriber unit 8 is provided with an authentication request message (AUTH_REQ_C) to request the RAND. This message contains the following information elements; (1) Message Type, (2) Call Reference, (3) Security Menu Selection, (4) Type of Location Update, (5) Sequence Number of Code Cipher, (6) Identification of Location Area, (7) Class Mark of the Mobile Station, (8) SubID or TSubID = TMSI or IMSI, and (9) Type of Initial Message (The initial message types for this information element about the call request message (CALL_REQ ), the terminal registration request message (TERM_REG_REQ) and the alert recognition message (ALERT ACK).

Also in Table 1. are the types and lengths of each information element in the message. In all the tables herein, the values in the "reference" column refer to ANSÍ J-STD-014 and the "address" column indicates the communication direction between the subscriber unit ("SU") and an RPCU.

Table 1: Authentication Request Message (AUTH REQ C) Table 1: Authentication Request Message (AUTH REQ C) (continued) Table 2 shows an authentication challenge message (AUTH_CHALLENGE) which uses the RPCU 4 to transmit the RAND to the subscriber unit. This message contains the following information elements: (1) Message Type, (2) Call Reference, (3) Cipher Key Sequence Number, (4) Semi-Ectet available, and (5) GSM RAND.

Table 2: Authentication Challenge Message (AUTH CHALLENGE) Table 3 shows an authentication response message (AUTH_RESP) for transmitting the derived SRES to the RPCU and the VLR 9 for verification. This message contains the following information elements: (1) Message Type, (2) Call Reference, and (3) GSM SRES.

Table 3: 'Authentication Response Message (AUTH RESP) 2) Encryption The transmission between a subscriber unit 8 and an RP 3 is coded to protect the privacy of the subscriber. This coding process is called encryption. Although both GSM and PACS use methods of encryption of flow and private key to encrypt the information and signature of the user, there are differences in both in terms of the protocol / flow of messages of the information elements. In the preferred embodiment, the encryption algorithm A5 of the GSM is used for an integrated PACS / GSM system instead of the BRAID encryption developed1 with the PACS. Algorithm A5 can be used with PACS provided that: a) The public key encryption option developed for the PACS is not supported. b) Only 88 bits of the 114-bit number that are available with algorithm A5 are used to encrypt and decrypt PACS traffic and signaling channels. c) The GSM key, Kc (64 bits) is used in place of the PACS key (88 bits) with a defined bitmap. d) The message requesting the authentication of the subscriber unit (AUTH_REQ_C) does not contain any more encrypted information elements. e) Only the 22 least significant bits of the PACS block or frame account are used in algorithm A5 and derived from the PACS radio channel. The ALT_COUNT information is ignored. f) The speed of Algorithm A5 (figure of 228 bits / 4.615 ms, 449.4 kit / s) is adapted to the speed of the PACS (cleaning of 176 bits / 2.5 ms, 70.4 kit / s). 3) Subscriber Identity In the GSM, when a subscriber initially registers in the service, an international mobile subscriber identity (IMSI) is assigned to that subscriber. The same occurs in a PACS system, but the identification is structured differently and is called subscriber identity (SubID). To facilitate the integration of the PACS and GSM systems, the IMSI is included in the identity of the PACS subscriber (SubID). 4) Subscriber's Temporary Identity In GSM, a mobile subscriber's temporary identity (TMSI) is assigned to a subscriber each time the subscriber enters a new service area. Again, the same occurs in a PCAS system, but the identification is structured differently and is called temporary subscriber identifier (TSubID). To facilitate the integration of the PACS and GSM systems, the TMSI must be included in the temporary subscriber identity of the PACS (TSubID).

) Identity of the Equipment In the GSM, each subscriber unit also has an international mobile equipment identity (IMEI). In the PACS, an electronic serial number (ESN) is used. For PACS / GSM integration, the IMEI is included in the ESN. 6) Door Identity As described above, the subscriber unit compatible with the PACS finds the RP that provides the best signal and informs the network which RP will be used to access the system. To do this, the subscriber unit must be able to identify individual RPs and RPCUs for the system.In the GSM each base station is identified by a global cell identifier (CGI) .This way, to facilitate the integration of the GSM and the PACS to each RP and RPCU is given a CGI that should be used in place of the full door identification (CPID) developed for use with the PACS. 7) Location Identification In the PACS, an area comprising a group of RPCU served by the same VLR is identified by a complete record area identifier. The GSM uses a location area identifier (LAI). To integrate the two systems, the RPCU can translate the entire record area identifier into a valid LAI for the GSM. Alternatively, the preferred mode, the system information channel (SIC) used in the PACS between the RP and the subscriber unit is modified to use the GSM LAI and other GSM codes. Specifically, the modification of the present example comprises adding the GSM information fields to the mobile country code (MCC), the mobile network code (MNC), the location area code (LAC) and the cell identity (Cl). ); and remove the PACS information fields for the identification of the complete registration area and the identification of the PR. You can also remove the real time field. In this mode, these modifications are made to the RPCU, eliminating in this way the need to modify the existing GSM protocol. The modified SIC format is shown in Figure 2. The first octet is the identification of the SIC header. The second octet in the discriminator of the SIC protocol (= GSM). The third and fourth octets are the discriminators of the protocol of layer 2 and layer 3, respectively. The fifth octet indicates the number of messages in the SIC. The sixth octet is reserved. The seventh octet contains the revision number of the SIC and part of the mobile country code (MCC), the rest of which is in the eighth octet. The ninth octet contains the mobile network code (MNC). The tenth and eleventh octets contain the location area code (LAC) and the twelfth and thirteenth octets contain the identity of the cell (Cl). Together, the MCC, MNC, LAC and Cl constitute the cell's global identity (CGI). Octets 14 through 16 contain the service capabilities. Octets 17 through 20 contain the security menu. Octet .21 is largely reserved, but does not contain the mobility management package (MM). The octets 22 and 23 contain the identification of the RPCU. The remaining octets are reserved. 8) Management of the Location and Identity of the Subscriber Additionally, some of the functions necessary for the support of a PACS system as originally designed are carried out by a network element known as the access manager (AM) (not shown). ). The AM can receive at a service control point, an attached switch, or an intelligent peripheral device. This can also be combined with a RPCU or be autonomous. In general, a single AM supports multiple RPCUs and takes care of network control tasks such as remote database queries to visit user information, establishment and delivery of calls, and so on. More explicitly, the AM generates a temporary ALERT_ID for each subscriber unit within an area served by any RPCU 4 that is connected to the AM. When the user of a subscriber unit 8 receives a call or page, the AM equals the identifion of the requested user with the temporary ALERT_ID for that subscriber unit of the user 8. The AM then transmits an alert to the subscriber unit .8 and routes the call to the subscriber unit once the subscriber unit. subscriber has been authentid. When the PACS is interconnected with GSM, an AM will not necessarily be included in the integration since GSM does not include a separate access manager in its specifion. In accordance with the preferred embodiment of the present invention, the RPCU 4 took possession of most of the functions of the AM, including the assignment of ALERT_ID. By doing so, the following two aspects are discussed. First, the ALERT_ID within a service area should be unique to each subscriber unit 8. Otherwise, if each RPCU 4 within a service area independently assigns an ALERT_ID to the subscriber units 8, it is possible that two Subscriber units 8 are assigned the same ALERT_ID by two different RPCUS 4. Second, the ALERT_IDs of each subscriber unit must be made known to all RPCUs. 4 in the service area, so that the subscriber unit 8 does not have to remember multiple ALERT_IDs that can be paged. An additional problem is that which arises from the fact that the GSM 1 system does not use an ALERT_ID at all. When a subscriber unit 8 is pageed, the GSM 1 sends a paging signal over the interconnection A to the BSC 6. The paging signal may contain the international mobile subscriber identity. (IMSI) of the user being paged, the mobile subscriber temporary identity (TMSI), a list of cell identifiers and the fields required for the channel. The list of cell identifiers indis in which areas the user will be paged or lod.

After receiving the paging signal, the BSC 6 page or locates the user through the BTS, 5 connected to it. Therefore, in the PACS / GSM integrated system of the present invention, the RPCU 4 maintains a translation table that equals the TMSIs and the IMSIs. with the ALERT_ID that has. been generated for given subscriber unit 8. As noted above, an RPCU 4 will assign a new ALERT_ID to a registered subscriber unit. Identical identification may already have been 0 conceivably assigned to a different subscriber unit 8 by a different RPCU serving an overlay or close area. The unacceptable result is that a single ALERT_ID can page two different subscriber units. 5 On the other hand, although in the new ALERT_ID it can not conflict with another ALERT_ID, it is almost certain that a different ALERT_ID was used by the previous RPCU page of the subscriber unit in question. As a result, the subscriber unit must remember multiple ALERT_IDs for which it can be paged. In this example, this problem is solved by registering the subscriber unit 8 when it is moved to a new area served by a new RPCU 4. This process will now be described in more detail with reference to Figure 5 3.

Initially, subscriber unit 8 is in the location indicated by 12. The device is registered with the system through the radio gate, RPA. The RPCUi is interconnected with the GSM via the MSCí. In a GSM network, the TMSIs are assigned by the VLR 9 and are correlated with the IMSIs by the communication between the VLR and the HLR 10 in the area of the subscriber's home. During registration, the HLR 10 authenticates the identity of the subscriber unit and reports the VLR of the IMSI. The VLR 9 then assigns a TMSI and informs the RPCUi.

The RPCUi then assigns an ALERT_ID attached to that TMSI and informs the subscriber unit 8 of its ALERT_ID. When the subscriber unit 8 moves to the location indicated by 13, it recognizes the global cell identifier (CGI) in the system information channel (SIC) that the RPB is served by the same RPCU as the RPA. Therefore, the subscriber unit does not need to register again, but will continue to use the same ALERT_ID. When the subscriber unit 8 moves to the location indicated by 14, it is served by a new RPCU 4, the RPCU2. Transmissions over the SIC will tell the subscriber unit 8 that its current location is still being served by the same VLR 9. However, because a new RPCU is involved, the subscriber unit performs a quick registration by sending a message (FAST_REG) to the new RPCU. This message includes the following information elements: (1) Message Type, (2) TMSI (TSub_Id), (3) ALERT_ID, (4) Reserved, (5) Continuation Header, (6) CPID = CGI, and ( 7) Sum of Control. The type and length of the information elements of the FAST_REG message are detailed in Table 4 below.

Table 4: Quick Registration Message (FAST REG) 0 As can be seen from the Table, the subscriber unit registers with the RPCU 4 providing its TMSI and the ALERT_ID given to it by the last RPCU. This avoids the need for the subscriber unit to store two ALERT_IDs, allowing it to store only the ALERT_ID given to it by the present RPCU 4. As can be noted, if the subscriber unit now remains in the area served by the RPCU2, the RPCUi it will not necessarily maintain an ALERT_ID for the subscriber unit 8 that. is outside of your service area. This problem can be solved -by a registration procedure based on the timer integrated in the RPCU, 4 which cancels the ALERT_ID that has a stamped time of more than 24 hours. After receiving the quick registration message, the RPCU2 will assign the subscriber unit a new ALERT_ID or store the relationship between the TMSI, IMSI and the new ALERT__ID. The RPCU responds to the subscriber unit 8 with the fast registration recognition message (FAS _REG_ACK) detailed in Table 5. This message essentially informs the subscriber unit of its new ALERT__ID. The message (FAS _REG_ACK) contains the following information elements: (1) Message Type, (2) TMSI (TSub_Id), (3) ALERT ID, and (4) Sum of Control.

Table 5: Quick Registration Recognition Message (FAST REG ACK) Still with reference to Figure 3, when the subscriber unit moves to the location indicated by 15, the CGI message on the SIC will inform the subscriber unit that is in an area served by a different RPCU, the RPCU4, and for a different MSC 7 (MSC2) and the VLR 9. Consequently, the bonado unit will be registered again using the protocol described above as well as the normal GCM registration process. The only difference is that the new VLR 9 will consult the HLR 10 in the home area of the subscriber unit for the IMSI of the subscriber unit. The VLR 9 will then assign to the subscriber unit 8 a new TMSI, equated with the IMSI, for the area indicated by LA2 in Figure 3.

The flow of messages for alerting and delivery of calls is shown in Figure 4. In Figure 4, the solid lines indicate a three-layer message of the PACS. The dotted lines indicate a two-layer message from the PACS and the shaded lines indicate a message from the GSM Interconnection A. Bold and italic messages are modifications to the PACS protocol to facilitate PACS / GSM integration. Outgoing messages are shown in a concise text. As indicated, the different functions that must be performed are grouped conceptually in two layers. A layer is a functional plane of the communication system. The functions of a layer are carried out by a component or components of the particular system. For the preferred embodiment of the present invention, the message and recognition of fast registration are best placed in layer two, which comprises the functions of registration and authentication of the system. The message flow shown in Figure 4 is as follows. A GSM paging message (PAGE) is sent by the MSC to all RPCU served by that MSC. Any RPCU that has a registration of the subscriber unit that has been registered will send the appropriate ALERT_ID (SBC (Alert ID)). After receiving the alert, the subscriber unit begins the process of authentication and encryption. The authentication request message (AUTH_REQ_C) contains the alert recognition message (ALERT_ACK) as the initial message type to inform the RPCU that the subscriber unit is replying to the page. Then the authentication process proceeds. After completing the authentication and establishing the encryption of the link, the RPCU sends a message that assigns an identification for the call (RCID) to the subscriber unit. The GSM INSTALL message is then sent to the RPCU from the GSM network. The RPCU translates the message to an incoming PACS call message (INC0MING_CALL). The rest of the call flow then involves a direct mapping of the PACS message in the message of the GSM interconnection A that was developed by the RPCU. 9) Transfer As noted, when the subscriber unit is moving, the RP or base station that provides the best signal can change. Thus, in addition to the possible need to have to register again as described above, there must be a protocol for transferring a link established between the subscriber unit and an RP or base station to a different RP or base station when it is this, so that a service of higher quality is provided to the subscriber. The switching of a link is known as "handover". In the PACS, transfers are also called automatic link transfers (ALT). In a PACS / GSM integrated system, if the handover is between two RPs that are controlled by the same RPCU, the protocol before the PACS is sufficient. However, if the new RP is controlled by a different RPCU, the GSM MSC must perform the handover. Since there are significant differences between the PACS handover process and the GSM handover process, the PACS protocol must be modified again. Both in the PACS and in the GSM, the subscriber unit measures the strength of the signal of the existing link with the RP or base station that is being used and the strength of the signals transformed by other RP or nearby base stations that can be used. In the GSM, the network decides when to transfer the 'link to a different base station. The GSM subscriber unit transmits the results of signal measurements to the base station every 0.5 seconds, where they are processed and compared. The controller of the base station then decides when the handover is necessary and which new base station will receive the link. Thus, in the GSM, the handover request originates in the old controller of the base station that identifies the new controller of the base station. In the PACS, the subscriber unit decides when to transfer the link and which new RP to use. The PACS subscriber unit then signals the transfer to the new RP directly. The advantage of this method is that the signaling of the transfer takes place in the new link with the new RP and therefore is more reliable. In this way, to integrate PACS and GSM, the new link transfers the messages that must be introduced in the PACS protocol. The flow chart for the new transfer of the PACS between RPCU is described in Figure 5, in which the same style and text conversions were used as in Figure 4. As shown in Figure 5, when the subscriber unit decides that a handover must be made, suspends the current call with the old RP (LINK_SUSPEND) and uses a link with the new RP. The subscriber unit then sends an automatic link transfer request message (ALT_REQ) to the new RP. The type and lengths of the information elements in this message are detailed in Table 6 below. The message contains the following information elements: (1) Message Type, (2) Global Cell Identifier (CGI) for the new RP (RP), (3) Reserved, (4) Continuation of the Message (ALT REQ CONT) , (5) RCID, (6) Access Information, (7) Reserved, and (8 Control Sum.

Table 6: Request Automatic Link Transfer Request (ALT REQ) Referring still to Figure 5, if the new RPCU can accept the link transfer, it responds to the subscriber unit with the recognition message of the automatic link transfer (ALT_ACK). The ALT_ACK message contains a new information element called handover reference (HO reference). The HO reference information element is used in the GSM to identify the link during the handover. The ALT_ACK message is detailed in Table 7 below and contains the following information elements: (1) Message Type, (2) Time Interval, (3) RCID, (4) HO Reference, (5) Reserved, and (6) Sum of Control.

Table 7: Automatic Link Transfer Recognition Message (ALT ACK) The GSM is informed of where to transfer the link. In the preferred embodiment of the present invention, two new messages are added to the PACS two-layer protocol. In Figure 5, when the subscriber unit receives the automatic link transfer recognition of the new RP that will accept the new link, the subscriber unit then resumes the link to the old RPCU (LINK_RESUME) and sends a notification message. automatic link transfer (ALTJMO IFLCATIÓN) that gives the identity of the new RPCU to the old RPCU. This message is detailed in Table 8 and contains the following information elements: (1) Message Type, (2) CGI, and (3) Control Sum.

Table 8: Automatic Link Transfer Notification Message (ALT NOTIFICATION) The old RPCU then responds to the subscriber unit with an automatic link transfer notification acknowledgment message (AL _NOTIF_ACK), which is detailed in Table 9 below. The old RPCU then instructs the GSM to change the link with the subscriber unit to the new RPCU and identifies the new RPCU for the GSM. The message ALT_NOTIF_ACK contains the following information elements: (1) Message Type, (2) RCID, (3) Reserved, and (4) Sum of Control Table 9: Automatic Link Transfer Notification Recognition Message (ALT NOTIF ACK) In Figure 5, after the subscriber unit has begun the encryption process on the new link, it sends a standard link transfer message from the standard PACS (ALT__COMP) to the radio control gate. When the old radio control door receives this standard PACS message, it clears the old link from the subscriber unit. (CLEAR_COMMAND, CLEAR_COMPLETE).

) Temporary Identification Reassignment In the GSM, the TMSI assigned to the subscriber unit is temporarily changed to help preserve the confidentiality of the subscriber identification. This procedure for reallocating the TMSI can be effected either implicitly during a location update or registration, or can be initiated explicitly at any time during which the subscriber unit is communicating with the MSC and the VLR. There is no procedure in the PACS that corresponds to the explicit assignment process of the TMSI. There are several ways to resolve this incompatibility. The simplest way is to abandon the process of reassigning the TMSI for an area served by a particular MSC if PACS RPCUs are connected. The second and most complete alternative is to introduce a new pair of messages to the protocol of the PACS subscriber unit in layer 3 that performs the reassignment procedure of the GSM TMSI.

A third alternative is to use an existing message in the PACS that assigns an identification to an incoming radio call (RCID_ASSIGN) for the purpose of reallocating the TSubID of the PACS that could then be matched by the RPCU with the TMSI reassigned. The problem with this alternative is that there is no recognition for the RCID_ASSIGN message in the PACS protocol and the GSM MSC expects a recognition when a TMSI of the subscriber unit is changed. There are three possibilities to overcome this problem. First, the RPCU could send the acknowledgment message that the GSM is waiting without obtaining an acknowledgment from the subscriber unit. Second, it does not send acknowledgment and the MSC sends through the connection part of the failure of its protocol. Third, a message acknowledgment for temporarily marked identification could be written to the subscriber unit to recognize the change. 11. Deleting the Registry The GSM has a procedure called Union / Detachment of the IMSI that the subscriber units require to support, but this- is optional for GSM networks. This procedure allows the subscriber units to eliminate the network register when they are de-energized or turned off, so that the network does not have to page the de-energized subscriber units. The PACS supports a registration removal procedure that can be mapped simply in the GSM join / detach procedure by the RPCU.

Conclusion A detailed description of a preferred embodiment of the present invention satisfying the objectives set forth above has been concluded. The advantages provided by the invention will be readily appreciated by those skilled in the art, as will be the many modifications and alternative embodiments that fall within the scope and spirit of the present invention. For example, it is evident that a subscriber unit can be designed to operate exclusively with the PACS system. Alternatively, the ability to communicate using the PACS in a superior link system, such as GSM, can be easily constructed in standard subscriber units with little increase in size or cost. The details of such integration are best explored in the following article, which is incorporated herein by reference: R Malkemes et al., An Interoperable PACS and DCS 1900 Subscriber Unit Radio Architecture, The Sixth IEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'95), September 27-29, 1995, Toronto Canada. Thus, if a subscriber has a subscriber unit that can make use of high or low stacking support system, the subscriber can use any stacking that provides the highest quality of service under those circumstances. For example: 1) A subscriber who is indoors can use the improved signal quality of a nearby PACS RP instead of a high-stacking service that has poor quality indoors; 2) A subscriber can switch to a low stacking service if the high stacking service is saturated with other subscribers; 3) A subscriber can use the high stacking service if he is in a car or other vehicle that travels more than 64.4 kilometers per hour (40 miles per hour). The above description has been presented solely to illustrate and describe the invention. It is not intended to be exhaustive or to limit the invention to the precise described form. Many modifications and variations are possible in light of the above teachings. It is intended that the scope of the invention be defined by the following claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (23)

1. A method for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM) characterized in that it comprises the steps of: providing a number of PACS radio doors controlled by a number of radio door controller units through a service area; interconnect the door controller units , radio with a mobile switching center of a GSM network; provide PACS radio gate control units with communication protocols that are compatible with GSM protocols; and assigning alert identifications to the subscriber units within a service area with each radio gate controller unit.

The method according to claim 1, characterized in that it further comprises the steps of: communicating temporary mobile subscriber identifications to the subscriber units of the mobile switching center to the radio door controller units; and maintaining a translation table with the radio gate controller unit that matches the alert identifications with the mobile temporary subscribers.

The method according to claim 2, characterized in that each subscriber unit registers and receives a new alert identification when the subscriber unit moves from an area served by a radio door controller unit to an area served by a different radio door controller unit.

The method according to claim 3, characterized in that each subscriber unit registers and receives a new alert identification and a new mobile subscriber temporary identity when the subscriber unit moves from a served area to a visitor location register. to an area served by a different visitor location record.

5. The method of compliance with the claim 4, characterized in that it also comprises the steps of: recognizing a record of the subscriber unit; and informing the subscriber unit of its new identification with the radio door controller unit.

6. The method of compliance with the claim 5, characterized in that it further comprises the step of providing a message to start the registration and a message to recognize the record.

7. A method for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises the steps of: providing a number of PACS radio doors controlled by a number of radio door controller units through a service area; interconnect the radio gate control units with a mobile switching center of a GSM network; provide PACS radio gate control units with communication protocols that are compatible with GSM protocols; providing the subscriber unit with at least one GSM authentication algorithm to authenticate the identity of the subscriber unit; providing a message to the subscriber unit that allows the subscriber unit to request a random number of the GSM on which to perform at least one authentication algorithm; and providing the subscriber unit with a message to send the results of at least one authentication algorithm to the GSM for verification.

A method for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises the steps of: providing a number of PACS radio doors controlled by a number of radio door controller units through a service area; interconnect the radio gate control units with a mobile switching center of a GSM network; and provide PACS radio gate control units with communication protocols that are compatible with GSM protocols, including the insertion of an international mobile subscriber unit used by the GSM into a subscriber identity used by the PACS.

9. A method for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises the steps of: providing a number of PACS radio doors controlled by a number of radio door controller units through a service area; interconnect the radio gate control units with a mobile switching center of a GSM network; and providing PACS radio gate control units with communication protocols that are compatible with GSM protocols, including the insertion of an international mobile equipment identity used by the GSM into an electronic serial number used by the PACS.

A method for integrating a network of personal communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises the steps of: providing a number of PACS radio doors controlled by a number of radio door controller units through a service area; interconnect the radio gate control units with a mobile switching center of a GSM network; and provide the PACS radio control units with communication protocols that are compatible with the GSM protocols, including the assignment to each of the radio gates and the radio gate controller units to a global cell identifier to identify the radio door or radio door controller unit to GSM.

11. A method for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises the steps of: providing a number of PACS radio doors controlled by a number of radio door controller units through a service area; interconnect the radio gate control units with a mobile switching center of a GSM network; and provide PACS radio gate control units with communication protocols that are compatible with GSM protocols, including modifying a channel of system information used by the PACS by removing a radio gate identification and identification fields from the PACS area. registration, and add a mobile country code, a mobile network code, location area code and cell identification fields that are used by the GSM.

12. A method for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication system (GSM), characterized in that it comprises the steps of: providing a number of PACS radio doors controlled by a number of radio gate I control units through a service area; interconnect the radio gate control units with a mobile switching center of a GSM network; provide PACS radio gate control units with communication protocols that are compatible with GSM protocols; provide a message by which the subscriber unit requests that the GSM switch an existing link between the subscriber unit and the GSM to be routed through a radio door controller unit to another radio gate controller unit determined by the subscriber unit; and providing a message by which the subscriber unit indicates to the GSM which radio gate controller unit to switch to such a link.

A system for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises: a plurality of PACS radio doors distributed through an area service that supports subscriber units and are controlled by a plurality of radio door controller units; and a mobile switching center of a GSM network interconnected with the radio gate control units; wherein the radio gate control units of the PACS are provided with protocols compatible with the GSM protocols and wherein the radio gate control units assign alert identifications to the subscriber units within a service area.

The system according to claim 13, characterized in that the mobile switching center has a temporary mobile subscriber identity of the subscriber unit of a visitor location register, and communicates such temporary identity of the subscriber to the door controller unit of radio; and wherein the radio gate controller unit maintains a translation table that matches the alert identifications with the mobile temporary subscriber identities for the subscriber unit in a service area.

The system according to claim 14, characterized in that the subscriber units register and receive a new alert identification when the subscriber units move from an area served by a radio door controller unit to an area served by a different radio door controller unit.

The system according to claim 15, characterized in that the subscriber units register and receive a new alert identification and a new mobile subscriber temporary identity when the subscriber units move from an area served by the visitor location register. to an area served by a different visitor location record.

The system according to claim 16, characterized in that the radio door controller units recognize the registration of the subscriber units and inform the subscriber units of the new identifications.

18. A system for integrating a network of personal access communication systems (PACVS) with a global system for a mobile communication network (GSM), characterized in that it comprises: a plurality of PACS radio doors distributed through an area service that supports subscriber units and are controlled by a plurality of radio door controller units; and a mobile switching center of a GSM network interconnected with the radio gate control units; wherein the radio gate control units of the PACS are provided with protocols compatible with the GSM protocols; wherein the subscriber unit has at least one GSM authentication algorithm for authenticating the identity of the subscriber unit; and wherein, the subscriber unit has messages to request a random number from the GSM over which it performs at least one authentication algorithm and a message to send the results of at least one authentication algorithm to the GSM for verification.

19. A system for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises: a plurality of PACS radio doors distributed through an area service that supports subscriber units and are controlled by a plurality of radio door controller units; and a mobile switching center of a GSM network interconnected with the radio gate control units; wherein the radio gate control units of the PACS are provided with protocols compatible with the GSM protocols; and wherein the subscriber unit is identified by an international mobile subscriber identity used by the GSM included in a subscriber identity used by the PACS.

A system for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises: a plurality of PACS radio doors distributed through an area of service that support subscriber units and are controlled by a plurality of radio door controller units; and a mobile switching center of a GSM network interconnected with the radio gate control units; wherein the radio gate control units of the PACS are provided with protocols compatible with the GSM protocols; and wherein the subscriber unit is identified by an international mobile equipment identity used by the GSM included in an electronic serial number used by the PACS.

21. A system for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises: a plurality of PACS radio doors distributed through an area service that supports subscriber units and are controlled by a plurality of radio door controller units; and a mobile switching center of a GSM network interconnected with the radio door controller units; wherein the radio gate control units of the PACS are provided with protocols compatible with the GSM protocols; and wherein the radio doors and the radio gate controllers are each identified by a global cell identifier of the GSM.

22. A system for integrating a network of personal access communication systems (PACS) with a global system for a mobile communications network (GSM), characterized in that it comprises: a plurality of PACS radio doors distributed through an area of service that support subscriber units and are controlled by a plurality of radio door controller units; and a mobile switching center of a GSM network interconnected with the radio door controller units; wherein the radio gate control units of the PACS are provided with protocols compatible with the GSM protocols; and wherein a channel of system information used by the radio gate controllers is modified by removing a radio gate identification and registration area identification fields, and adding a mobile country code, mobile network code, code location area and cell identity field that are used by the GSM.

23. A system for integrating a network of personal access communication systems (PACS) with a global system for a mobile communication network (GSM), characterized in that it comprises: a plurality of radio doors of. PACS distributed through a service area that supports subscriber units and are controlled by a plurality of radio door controller units; and a mobile switching center of a GSM network interconnected with the radio gate control units; wherein the radio gate control units of the PACS are provided with protocols compatible with the GSM protocols; and wherein the subscriber unit requests the GSM to switch an existing link between the subscriber unit and the GSM to be routed through a radio door controller unit to another radio door controller unit determined by the subscriber; and wherein the subscriber unit tells the GSM to which radio gate controller unit to switch the link.