Abstract:
In stationary or generally stationary devices that utilize the cellular network as a wireless front-end to another data network and that are involved strictly in machine-to-machine communication activities, a system is provided that supports the re-use of MINs between cellular markets. The system may also be used in other types of networks. A remote device, such as, for example, a cellemetry modem, communicates a commissioning request to a host system that has an associated system identifier (SID). The commissioning request includes a unique serial number (S/N) assigned to the remote device and an initial mobile identification number (MIN). If the remote device has not previously been commissioned, a temporary MIN from a list of predetermined temporary MINs is transmitted; otherwise, a previously assigned permanent MIN is transmitted. If necessary, the host system transmits a permanent MIN (or a new permanent MIN) selected from a list of available MINs associated with the host system&#39;s SID to the remote device. The transmitted MIN is thereafter used by the remote device to access the host system, until the remote device is moved from that host system or removed from service. The host system is also in communication with a remote device database, which maintains a table of S/Ns and associated SIDs and MINs. The effective use of S/Ns in the commissioning process allows MINs to be reused in different host systems. Furthermore, the use of a remote device database allows MINs assigned to remote devices that have moved or taken out of service to be reclaimed for reuse.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/088,890, filed Jun. 11, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to the allocation of mobile identification numbers (MIN) and, more particularly, to a system in which MINs are re-used efficiently in a cellular or wireless application environment. 
     The North American Cellular Network provides a ubiquitous wireless communication network designed to serve the needs of wireless voice communications. ANSI/EIA/TIA-552-1989, the Electronic Industries Association&#39;s specification “Mobile Station-Land Station Compatibility Specification” describes the technical requirements for a mobile station to ensure compatibility and the ability to obtain service in any Advanced Mobile Telephone System (AMPS) cellular system. This specification formalizes basic radio requirements (modulation-type, frequency range and stability, output power) call processing procedures, and the format of messages transferred between land and mobile stations for the system currently deployed throughout North America. 
     Each AMPS mobile telephone has two values associated with it: a MIN and an Electronic Serial Number (ESN). The ESN is a 32-bit value programmed into the telephones&#39;s internal software at the factory and is not adjustable. The MIN is a standard 10-digit telephone number assigned by the cellular carrier associated with a specific ESN when the telephone is sold or activated. The AMPS specification provides for a globally unique, 10-digit MIN to be associated with every mobile communication device using the system. The MIN global identifiers are managed according to the Numbering Plan Area (NPA) and individually administered by the various cellular carriers. The number space of nearly 1,000,000,000 numbers is allocated by the NPA governing body in blocks to the interested parties, such as telephone companies and cellular providers. When a mobile call is made, the cellular telephone transmits its MIN and ESN to identify itself to the cellular system for billing purposes. The use of a 10-digit MIN to identify a mobile communication device has several key advantages for voice applications, such as: (1) there is no conflict with addresses used by traditional, switched circuit telephone services; (2) mobile communication devices are addressable from wired telephone services using standard dialing methods; and (3) global uniqueness permits mobile devices to “roam” and be identified outside their “home” coverage area, which roaming feature is an integral feature of the AMPS cellular telephone network. 
     In addition to telephone service, AMPS also provides another service for the communication of small packets of data. This service is typically used for communication of data from remote, wireless devices to a customer&#39;s facility. Also, several commercial services provide access to the cellular network infrastructure as a wireless front-end to another data network. Such access includes cellular digital packet data (CDPD), several forms of control channel messaging, and short messaging services. In many cases, these technologies are utilized in applications that are deployed only in fixed, stationary locations. These devices typically are infrequently moved, and thereby do not require temporary roaming capability. Also, these devices are commonly involved in strictly machine-to-machine communication activities, thus eliminating the requirement that the communication device be addressed directly from switched circuit telephone services. Therefore, in many cases, such devices are assigned MINs that cannot be addressed directly from standard telephone devices. 
     With increasing numbers of cellular telephones, pagers, machine-to-machine communication devices, and even the increasing number of families having more than one telephone line, MIN space is becoming a scarce commodity. For communication devices that do not roam and do not need to be generally addressable by each device in the public network, there is at least a possibility that the MINs assigned to them could be reused in different cellular systems. Therefore, the practice of assigning globally unique identifiers to stationary or generally stationary communication devices is an inefficient use of MIN space. 
     In view of the wastefulness of providing unique MINs for stationary or generally stationary devices generally operating within a single system, a method for assigning MINs to such devices that permits efficient reuse of the assigned MINs between different systems would be advantageous and desirable. Because of restrictions imposed by carriers on amounts of data that may be communicated to and from devices such as cellemetry modems, it would also be desirable if such a method provided efficient and error-resistant assignment of MINs to remote units. It would also be desirable to provide a method for reclaiming of previously assigned MINs as the assigned device is taken out of service, or out of the service area of a particular system. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention, in one aspect, is a system and corresponding method supporting the re-use, between cellular systems, of MINs assigned to stationary or generally stationary devices. Such devices, for example, utilize a cellular network as a wireless front-end to another data network and are involved in machine-to-machine communication activities. The system and method are also applicable to other types of networks. A stationary or generally stationary device, e.g., a remote device such as a cellemetry modem, communicates a commissioning request to a host system that has an associated system identifier (SID). The commissioning request includes a unique serial number (S/N) assigned to the remote device and an initial mobile identification number (MIN). If the remote device has not previously been commissioned, a temporary MIN from a list of predetermined temporary MINs is transmitted; otherwise, a previously assigned permanent MIN is transmitted. If necessary, the host system transmits a permanent MIN (or a new permanent MIN) selected from a list of available MINs associated with the host system&#39;s SID to the remote device. The transmitted MIN is thereafter used by the remote device to access the host system, until the remote device is moved from that host system or removed from service. The host system is also in communication with a remote device database, which maintains a table of S/Ns and associated SIDs and MINs. 
     In another aspect of the invention, the invention comprises a remote device for communicating with a host system and a corresponding method of operating the remote device. The remote device communicates a commissioning request to a host system identified by a SID. The remote device then receives a permanent MIN from the host system, stores it in a memory of the remote device, and thereafter uses the permanent MIN to identify the remote device in communications with the host system. Use of the permanent MIN may continue until the remote device is decommissioned or moved to a different area. 
     In another aspect of the invention, the invention comprises a method of operating a host system associated with a SID to communicate a permanent MIN to a remote device. The host system receives a commissioning request from a remote device, selects a permanent MIN from a database of available MINs associated with the host system&#39;s SID, and communicates the permanent MIN to the remote device. 
     In another aspect of the invention, the invention comprises a method for re-allocating previously allocated MINs by storing a tabulation of MINs by SIDs in an available MIN database table managed with a host system. Information on at least one individual remote device is stored in a remote device database table managed by a host system. This information includes at least a currently assigned MIN, a last registered SID, an equipment serial number (ESN) and a last known switching center. Information on a MIN an ESN and a SID are received by the host system and compared with information in the remote device database table. Stored MIN and SID entries in the remote device database table are erased, and the erased information is added to the available MIN database table when the received SID information is different from the stored SID information. If the stored SID information is identical to the received SID information, the existing MIN information is preserved. 
     In another aspect of the invention, the invention comprises a method of establishing contact with a host system from a remote cellular device. A fixed block of temporary MINs is stored in non-volatile memory in a remote cellular device. In addition, a MIN is randomly selected and used to contact a system host. 
     In another aspect of the invention, the invention comprises a method of compressing data representing an assigned MIN. The method comprises establishing a base MIN, assigning a MIN, and encoding a difference between the assigned MIN and the base MIN on a digit-by-digit basis using a tuple, with one position of the tuple representing a digit difference and another position of the tuple representing a position difference. 
     The above described system provides for efficient reuse of MINs in conjunction with different host systems. In addition, MINs assigned to remote devices that have moved or taken out of service are efficiently reclaimed for reuse. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified block diagram of a remote device communicating with a host system and an equipment database in the system of the present invention. 
     FIG. 2 illustrates a flowchart detailing the operation of a remote device in the system of the present invention. 
     FIG. 3 illustrates a flowchart detailing the operation of a host system in the system of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The simplified block diagram of FIG. 1 represents one embodiment of a communication system  10  in an AMPS cellular environment. The present invention, with appropriate modifications, is also applicable to other types of environments, including other wireless communication environments and even, in appropriate instances, wired networks. 
     A remote device is represented as  100  in FIG.  1 . Typically, other remote devices are also present and operating in system  10 , but these other remote devices are not shown in FIG.  1 . In one embodiment, remote device  100  includes a processor  102  and a memory  104 , for example, a nonvolatile memory. Interconnections that may be necessary for routine operation of the remote device other than those used in the practice of this invention are not shown. Processor  102 , via a cellular transceiver  106  and an antenna  108 , communicates to a host system  110 . Communication is bidirectional, via a radio link  111  in the illustrated embodiment. In one embodiment, remote device  100  is stationary, or at least generally stationary, in contrast to standard portable or mobile cellular telephones. Memory  104  in remote device  100  includes a predetermined list of temporary MINs. In addition, memory  104  has the capability of storing a permanently assigned MIN, and may also store the SID associated with host system  110  and an identification of a switching station  124  that services host system  110 . A unique serial number (S/N) is also stored in remote device  100 , for example, in memory  104 . The unique serial number may be an ESN assigned by a regulatory agency. However, it will be understood that a set of unique serial numbers assigned by a manufacturer or licensee may be used consistently in place of an ESN in an embodiment of the invention. The set of serial numbers assigned by the manufacturer or licensee may be smaller than the set of ESNs assigned by the regulatory agency. 
     In one embodiment, host system  110  includes an antenna  112  and a transceiver  116  configured to transmit and receive signals via radio link  111 . Host system  110  further includes a processor  118  coupled to a memory  120 . Memory  120  contains a database of assignable MINs associated with the SID of host system  110 . Alternately, the database of assignable MINs associated with the SID may be maintained elsewhere and be made accessible to host system  110 , particularly if the SID is shared by other host systems (not shown). For example, the database of assignable MINs associated with the SID could be maintained at a central computer that is accessible by host system  110 . Processor  118  communicates to remote devices including remote device  110  via transceiver  116 , and also communicates, via a network interface  122  and a switch  124 , with a network  126 . Network  126  may be a public data network or a public switched network or another suitable network. System  10  also includes a computing system  128  including a processor  130  and a memory  132  including an equipment, or remote device database  134 . Computing system  128  communicates with processor  118  of host system  110  and with other processors of other host systems (not shown). A predefined reference MIN and a table of signaling MINs representing possible digit-by-digit differences between a specified MIN and the predefined reference MIN are also stored, both in a location accessible by host system  110 , for example, in memory  120 , and also in memory  104  of remote device  108 . 
     For this description, it will be assumed that the predefined reference MIN is the lowest-numbered MIN in a block of MINs including the assignable MINs, because assignable MINs may be allocated in contiguous blocks. However, the predefined reference MIN could be an arbitrarily selected MIN known throughout system  10 . 
     Remote device  100  may be of the class discussed in the &#39;371 patent and is remotely located equipment which accesses wireless communication services provided by host system  110 . Host system  110  is centrally located equipment with access to remote devices such as remote device  100  over the wireless communication services. 
     Host system  10  also includes a cellular market database table (not shown). This table is a database table managed by host system  110  that contains information relevant to cellular markets for which control channel messaging services are available. This information includes a SID associated with host system  110 , a network access method, a market description, and an available MIN block assignment. The cellular market database table may be stored in memory  120  of host system  110 . 
     The available MIN database is a database table managed by the host system that contains a tabulation of MINs by SID which have not yet been assigned or which have been reclaimed by relocating or removing of a communication device from service. 
     In one embodiment, the remote device database  134  is a database that is. managed by host system  110  and which is in communication with several host systems including host system  110  and separately managed, such as by an equipment manufacturer. Remote database  134  contains information relevant to the individual remote devices  100  using a given communication medium. This information includes a currently assigned MIN, if any, the last registered SID, if any, and ESN (or other uniquely assigned serial number, as described above). 
     In one embodiment and referring to FIG. 2, illustrating a flowchart  200  of the installation of a new remote device  100  in system  10 . Remote device  100 , upon activation or power up  212 , monitors  214  and determines  216  whether the SID of the cellular carrier providing local service is different from the SID stored in non-volatile memory  104 . Because remote device  100  has been newly installed, it is highly likely that remote device  100  will determine  216  that there is a difference between the received SID and the stored SID. 
     If there is a difference between the received SID and stored SID, remote device  100  randomly selects a temporary MIN from the reserved block of MINs stored in memory  104 . The random selection may be based upon the ESN or other unique serial number associated with remote device  100 . Remote device  100  then transmits  218  its unique ESN or other unique serial number through the wireless carrier using this temporary MIN as its address. This transmission may be understood by host system  110  as a new MIN request. The random selection feature is employed to reduce the possibility that two or more remote devices in a given market may simultaneous request a new MIN association. 
     Remote device  100  then waits  220  for a response from system host  110 . In one embodiment, after a selected period of time has elapsed  222 , for example, five minutes, remote device  100  determines whether a maximum number of attempts have been exhausted  224 . If so, remote device  100  goes into a sleep mode  226 . Sleep mode represents an error condition that, in one embodiment, requires, in order to exit, a manual reset of remote device  100 . The manner in which the error condition is corrected is a design choice that is not considered part of the invention. If the maximum number of attempts has not been exhausted, an alternative side  228 , i.e., in the case of AMPS, an alternate carrier, is selected, and the process of monitoring  14  is restarted. 
     In one embodiment, an assigned MIN is prepared for transmission by encoding the difference between the assigned MIN and a reference MIN on a digit-by-digit basis. In this embodiment, the reference MIN is the lowest possible MIN assignment recorded in the cellular market database table. The result is broadcast as a series of packets, each representing a unique tuple (digit 0-9, position 1-10). For example, 
     Assigned MIN: 0041001307 
     Reference MIN: 0041000000 
     Tuples Communicated: (7,1) (3,3) (1,4) 
     The tuples communicated indicate that the assigned MIN differs from the reference MIN in digit positions 1, 3, and 4 (as counted from the right), and that digits in the assigned MIN are 7, 3, and 1 in those positions, respectively. Host system  110  echoes the temporary MIN, followed by the packets prepared for transmission above. In this embodiment, the packets used for transmission are themselves MINs from a reserved group of signaling MINs. Each of the signaling MINs has a preassigned correspondence to a tuple in the matrix of possible tuples. In the example above, MINs corresponding to the tuples (7,1), (3,3), and (1,4) are transmitted by host system  110  to remote device  100 . A pause longer than a predetermined period without transmission of a signaling MIN indicates the end of the tuple broadcast. Remote device  100  decodes the signaling MIN broadcast to reconstruct the assigned MIN. 
     Blocks  220 ,  230 ,  232 ,  234 ,  236 ,  238 , and  240  in FIG. 2 are directed to receiving and decoding the signaling MINs broadcast from host system  110 . Upon receipt of the MIN corresponding to the temporary MIN transmitted  218  by remote device  100  earlier, remote device  100  switches  230  to a mode in which it is prepared to receive the signaling MINs. Specifically, remote device  100  receives and decodes the tuple-encoded packets containing its new MIN association. This value, along with the current SID is stored in non-volatile memory  104 . As seen in FIG. 2, the receipt and decoding of the tuple-encoded packets occurs digit-by-digit in blocks  232 ,  234 ,  236  and  238 . When a signaling MIN is received  232 , the received signaling MIN is decoded and the digit and digit position indicated are stored  234 . More digits and digit positions, represented by additional signaling MINs, may be received  232 , and if so, these digits and digit positions are also stored  234 . Eventually, all of the digit and digit position tuples will have been transmitted by host station  110 , and a lapse  236 , for example, one minute, will occur in the reception of signaling MINs. Lapse  236  is taken by remote device  100  as a termination of the transmission of differences between the reference MIN and the permanent MIN by host system  110 . After termination of transmission  236  is determined, remote device  100  determines  238  whether a sufficient number of digits and digit positions have been received. Typically, the reference MIN is not assigned as a permanent MIN, so if at least one digit and digit position has not been received, an error is indicated. In this case, remote device  100  switches to an alternate side  228 , i.e., switches to another cellular carrier, in a cellular market, and starts again as though a power up  212  had occurred. Otherwise, the assigned permanent MIN is decoded from the received digits and digit positions and the reference MIN, and the permanent MIN, as well as the SID associated with host system  10 , are stored  240  in non-volatile memory. 
     Using the newly assigned, permanent MIN, the ESN is again transmitted at  242  to system host  110  as verification of the assignment. This process will be repeated periodically as a routine confirmation of the association. 
     Corresponding actions are taken by host system  10  when a new MIN request is received. Referring to FIG. 3, host system  110  receives a new MIN request  256 . Host system  110  differentiates  246  between a new MIN request  248  and a received serial number and MIN registration  250  depending upon whether one of the reserved, temporary MINs was used or a permanent MIN was used. When a temporary MIN is used, the transmission from remote device is considered a new MIN request  248 . If the new SID and the existing SID entries are different  252 , then the existing MIN and SID entries are erased  254  from the remote device database table and added to the available MIN database table, if applicable. Next, a determination  256  is made as to whether an old MIN is available for the received SID. If available, the old MIN is reassigned  258  from the available MIN table and this MIN is transmitted  260 . If an old MIN is not available  256 , it is determined  262  whether a new MIN is available for the received SID. If so, a new MIN is assigned based upon the received SID  264  and the result is transmitted. If the new MIN is not available  262 , then an exception is posted  266 . 
     When a new MIN is assigned  264  based on the new SID, a number of operations occur in this embodiment. First, the available MIN database table is checked for any entries containing the new SID and a MIN with the same sense as the ESN. If available, the MIN is reclaimed and removed from the available MIN database table. If not, another MIN, for example, the next higher MIN, is determined from all entries in the remote device database table operating in the new SID. This determination may be based upon the ESN. The result is compared to the maximum available MIN stored in the cellular market database table. If no assignments are currently in use in the new SID, the minimum available MIN stored in the cellular market database table is used. The assigned MIN is recorded in the remote device database table. 
     Upon receipt  250  of a permanent MIN and ESN from remote device  100 , system host  110  verifies  270  the association between the SID, MIN and ESN at equipment database  134 . If a discrepancy is found, a command packet is transmitted  272  to remote device  100 , directing remote device  100  to re-commission itself This will have the effect of repeating the above process, as if remote device  100  had been first installed. 
     In one embodiment, after installation of remote device  100  as described above, remote device  100  is considered pre-existing. In this embodiment, when remote device  100  transmits  242  its ESN and MIN to host system  110 , the transmission is received  250 . System host  110 , via equipment database  134 , verifies  270  the association between the SID, MIN and ESN. If no discrepancy is found, the re-use and MIN assignment algorithms are not triggered. At this point, remote device  100  operates to provide the required information. In one application, remote device  100  may transmit information such as that disclosed in the &#39;371 patent. 
     If remote device  100  is moved from one location to another, the SID of the cellular carrier providing local service may change. In this embodiment, remote device  100  determines  16  from transmission by host system  110  that the SID of the cellular carrier providing local service has changed from the SID which has been stored in non-volatile memory  104 . At this point, the operation and the interaction between remote device  100  and host system  110  is essentially the same as that. described above. 
     Where remote device  100  is moved from one location to another, switch  124  that services host system  110  may change even if the SID of the cellular carrier does not. In some systems, host system  110  may not respond to a remote device  100  or a remote device may not respond to a host system unless each recognizes an identification number associated with switch  124 . Remote device  100  may thus also be receptive to broadcasts of the identification number of switch  124  by host system  110  for storing this number in memory  104 . This number may be used for transmission to host system  110  if required. 
     In view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. 
     As various modifications could be made in the construction and methods herein described and illustrated without departing from the scope of the invention, the matter contained in the foregoing description or shown in the accompanying drawings are to be interpreted as illustrative rather than limiting. Also, in the claims that follow, it will be understood that recitation of the communication of any item of information is intended to include communication of a signal indicative of such information, irrespective of how the information is encoded, encrypted, or modulated. Similarly, where storing, comparing, analyzing, or other operations are recited as being performed with any item of information, operations performed using representations of such information and having the same effect are also intended to be included. Those skilled in the art would also recognize the applicability of the invention to networks other than cellular networks. For example, such networks include other types of wireless networks, such as, specialized mobile radio systems (SMRs) and personal communication services networks (PCSs), and various types of wired networks. Thus, the terms “transceiver,” “transmitter,” and “receiver” should not be construed as being limited only to wireless transceivers, transmitters, and receivers unless otherwise specified, or unless required by the context in which the term appears. 
     In addition, the MINs, SIDs, and unique serial number (S/N) specified in the claims are not necessarily required to be the MINs of the specified in the AMPS specification, the SIDs assigned to wireless carriers, or the ESNs assigned by regulatory agencies to communication devices. Particularly in networks other than the AMPS network, MINs, SIDs and S/Ns referred to in the claims may be assumed to encompass other numbers or symbols that are used for corresponding identification purposes in communication networks, except where otherwise specified or in cases in which the context would be inconsistent with such inclusion. 
     From the preceding description of various embodiments of the present invention, it is evident that the invention provides a method for efficient reuse of the assigned MINs between different systems. Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is intended by way of illustration and example only and is not to be taken by way of limitation. Accordingly the spirit and scope of the invention are to be limited only by the terms of the appended claims and their equivalents.