Abstract:
A method for controlling the overflow of roaming users in a public or private mobile communication system. When the number of roaming users is greater than the number of the roaming numbers in a specific region, a newly arriving roaming user is assigned the roaming number of an inactive roaming user already registered in the network, who becomes then an overflow roaming user. Should an overflow roaming user require the use of the mobile communication functions, for example to make or receive a call, the overflow roaming user is in turn assigned the roaming number of another inactive user, who then becomes an overflow user. By this method, a number of roaming numbers can be shuffled between a larger number of roaming users and roaming users arriving into a network with an overflow of roaming users are still able to access the mobile communication functions.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a roaming user overflow control system for application in a mobile communications network, and more particularly relates to a roaming user overflow control system in which a roaming user can register in a roaming area when the number of the roaming users in that roaming area is greater than the number of roaming numbers available.  
           [0003]    2. Description of the Prior Art  
           [0004]    When the user of a mobile communications system moves out of the region of his or her home location register (HLR), the user is in a “roaming state.” At this time, the roaming user must be allocated a roaming number to access the mobile communication service in the roaming area. In conventional mobile communication systems which allocate roaming numbers on registration (e.g. TACS system), the user must register in the roaming area to obtain a roaming number. The allocation of roaming number in such conventional public and private mobile communication systems will now be described.  
           [0005]    Public Mobile Communication System Which Allocates the Roaming Number On Registration  
           [0006]    [0006]FIG. 1 shows a diagram of a conventional public mobile communication system (take TACS system for example). As shown in FIG. 1, when a roaming user  18  moves, the public mobile communication system traces the roaming user  18  by means of the home location register  10 ,  14  (HLR) and visitor location register  12 ,  16  (VLR). The main function of HLR  10 ,  14  is to track the HLR user, while the main function of VLR  12 ,  16  is to track the roaming users who enter the control area of VLR  12 ,  16 . Therefore, HLR records the information, or profile, of a roaming user, while VLR records the location of the roaming user. When the roaming users wants to access the functions of the mobile communication system, for example dialing and call delivery, a mobile switching center  11 , 13  (MSC) is used. In FIG. 1, global location register  15 ,  17  (denoted as GLR) controls the MSC in the control area of the GLR.  
           [0007]    When roaming user  18  goes out of the control area of HLR  10 , the roaming user  18  is in a “roaming state.” At this time, the roaming user has to register to use the mobile communication system out of the control area of HLR  10 . The process of registering and call delivery of a conventional public mobile communication system will now be described.  
           [0008]    Refer to FIG. 2, which shows the flow chart of the registration process of the conventional public mobile communication system.  
           [0009]    Step  101 : roaming user  18  roams from home network A to network B.  
           [0010]    Step  102 : roaming user  15  delivers the register request to MSC  13 .  
           [0011]    Step  103 : MSC  13  delivers the register request to VLR  16 .  
           [0012]    Step  104 : VLR  16  provides a roaming number to the roaming user  18 .  
           [0013]    Step  105 : VLR  16  notifies HLR  10  that the roaming number of the roaming user  18  in network B.  
           [0014]    Step  106 : HLR  10  stores the roaming number of the roaming user.  
           [0015]    Refer to FIG. 3, which shows the flow chart of the call delivery process of the conventional public mobile communication system.  
           [0016]    Step  201 : when another user dials the telephone number of the roaming user  18 , the call request is connected to GMSC  15  of the home network A.  
           [0017]    Step  202 : GMSC  15  asks HLR  10  to provide the routing information of the roaming user  18 .  
           [0018]    Step  203 : HLR  10  delivers the roaming number, which is stored in advance, to GMSC  15 .  
           [0019]    Step  204 : GMSC  15  connects to GMSC  17  that controls roaming user  18 .  
           [0020]    Step  205 : GMSC  17  asks VLR  16  to provide more detailed routing information of the roaming user  18 .  
           [0021]    Step  206 : VLR  16  provides GMSC  17  the routing information of the roaming user  18 .  
           [0022]    Step  207 : GMSC  17  finishes the operation of connecting to the roaming user  18 .  
           [0023]    Accordingly, the conventional public mobile communication system must provide a roaming number to the roaming user who requests to register. Even if the roaming user doesn&#39;t use the communication functions, the roaming user still has to keep the roaming number. Therefore, the conventional public mobile communication system must provide roaming numbers corresponding to all the roaming users. If there are not enough roaming numbers, subsequently arriving roaming users cannot register to use the communication functions. However, in practical application, most roaming users are not using the communication functions at any given moment. Thus, assigning each roaming user a roaming number at all times is a waste of roaming numbers. Furthermore, a large number of roaming numbers are necessary to maintain the operability of the system, thus increasing cost.  
           [0024]    Private Mobile Communication System Which Allocates the Roaming Number When the User Register  
           [0025]    Refer to the FIG. 4, which shows a diagram of the conventional private mobile communication system. While a private mobile communication system may have more than two zones, two zones are used in this example.  
           [0026]    As shown in FIG. 4, PBX is a switching center in a firm. Different firms can be connected by a Public Switched Telephone Network (PSTN hereinafter) or a special telephone line. A mobility manager (MM hereinafter), a base station (BS hereinafter), and a mobile telephone enable wireless mobile communication. MM provides the connections between the mobile telephones, and provides the connections between the mobile telephone and the wire network and PSTN by PBX. There are two interfaces between MM and PBX, such as line interface (like T/R) and trunk interface (like R 2 /E 1 ) . When the MM and the PBX are connected by the line interface, the mobile telephone is considered an extension of PBX, so the supplementary service is controlled by the PBX. When the MM and PBX are connected by a trunk interface, the mobile telephone is considered an extension of the MM, so the supplementary service (like unconditional can forward) is controlled by the MM. Moreover, the MMs in the different zones can be connected by a digital network for transmitting the information.  
           [0027]    When a roaming user moves from home network C to zone D or zone E, the roaming user is considered in a “roaming” state. In the private mobile communication system, PBX provides the roaming numbers, which are controlled by the MM. MM comprises the home location register, visitor location register, and a part of the mobile switching center, etc.  
           [0028]    Refer to FIG. 5, which shows the flow chart of the registration process of the conventional private mobile communication system.  
           [0029]    Step  301 : roaming user  20  delivers a register request to MM  23  when roaming from home zone C to zone E.  
           [0030]    Step  302 : MM  23  stores the register information of roaming user  20  and provides a roaming number RN 1  for roaming user  20 .  
           [0031]    Step  303 : MM  23  delivers the register information to notify MM  21  that the roaming user  20  has roamed to zone E and roaming user&#39;s roaming number is RN 1 .  
           [0032]    Step  304 : when MM  21  receives the register information, M 21  implements the information of the user  20  according to the interface of the home zone C.  
           [0033]    a. if the roaming user uses the trunk interface, MM  21  stores the routing information of the roaming user  20 , wherein the routing information at least comprises the roaming number RN 1  and the zone E.  
           [0034]    b. if the roaming user uses the line interface, MM  21  stores the routing information of the roaming user  20  and changes the unconditional can forward number of PBX  25  to RN 1 , wherein the routing information at least comprises the roaming number RN 1  and the zone E.  
           [0035]    Step  305 : MM  21  delivers the register acknowledge message to inform MM  23  that it has received the information that the roaming user  20  has moved to zone E, wherein the register message further comprises the profile of the user.  
           [0036]    Step  306 : when MM  23  receives the register acknowledge message, MM  23  responds that the roaming user  23  is done with the register request.  
           [0037]    Refer to FIG. 6, which shows the flow chart of the registration cancellation process of the conventional private mobile communication system.  
           [0038]    Step  401 : if the roaming user  20  roams to zone D, MM  21  has to notify MM  23  to cancel the roaming number and the profile of the roaming user  20 . So MM  21  delivers the registration cancellation message to notify MM  23  the roaming user has left zone D.  
           [0039]    Step  402 : MM  23  delivers the cancel acknowledge to MM  21 .  
           [0040]    Refer to FIG. 7, which shows the flow chart of the call delivery process of the conventional private mobile communication system.  
           [0041]    Step  501 : a telephone user dials the telephone number of the roaming user  20 .  
           [0042]    Step  502 :  
           [0043]    a. if the roaming user uses the line interface, because the unconditional can forward number is set to RN 1 , PBX  25  connects to PBX  27  by RN 1 .  
           [0044]    b. if the roaming user uses the trunk interface, MM  21  checks the profile of the roaming user  20 , and asks PBX  25  to connect to PBX  27  by RN 1 .  
           [0045]    Step  503 : PBX  27  receives the call request of the PBX  25 .  
           [0046]    a. if the interface is line, PBX  27  rings the line, and the ring will be detected by MM  23 .  
           [0047]    b. If the interface is trunk, PBX  27  performs the call request with M 23  by signaling.  
           [0048]    STEP  504 : when MM  23  detects the ring or receives the signaling request, the roaming user  20  and the dialing user are connected.  
           [0049]    Like the conventional public mobile communication system, the conventional private mobile communication system must provide roaming numbers corresponding to all the roaming users. Because the roaming numbers of PBX are limited, an accumulation of users in a specific zone can lead to the situation where late coming roaming users in the specific zone cannot register because there are not enough roaming numbers, and thus cannot use the mobile communication functions. This might occur, for example, when an activity causes a large number of users to gather at one location.  
         SUMMARY OF THE INVENTION  
         [0050]    The object of the present invention is to provide a method for controlling the overflow of roaming users in a public or private mobile communication system. The method of this invention provides that when the number of roaming users is greater than the number of the roaming numbers in a specific region, a new roaming user arriving in the region is still able to register and use the mobile communication functions.  
           [0051]    In the case of an overflow of roaming users in a specific network of a public or private mobile communication system, there are not enough roaming numbers for every roaming user. However, at any given time, most roaming users are not utilizing the mobile communication functions. Thus, at any given time, a large number of the registered roaming numbers are inactive. The present invention takes advantage of this situation by providing a method of registering users in which a newly arriving roaming user is assigned the roaming number of an inactive roaming user already registered in the network, who becomes then an overflow roaming user. Should an overflow roaming user require the use of the mobile communication functions, for example to make or receive a call, the overflow roaming user is in turn assigned the roaming number of another inactive user, who then becomes an overflow user. By this method, a number of roaming numbers can be shuffled between a larger number of roaming users. Thereby, roaming users arriving into a network with an overflow of roaming users are still able to access the mobile communication functions. Furthermore, the cost of the system can be decreased because fewer roaming numbers are needed to serve the same number of roaming users. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0052]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, given by way of illustration only and thus not intended to be limitative of the present invention.  
         [0053]    [0053]FIG. 1 shows a diagram of the conventional public mobile communication system.  
         [0054]    [0054]FIG. 2 shows the flow chart of the registration process of the conventional public mobile communication system.  
         [0055]    [0055]FIG. 3 shows the flow chart of the call delivery process of the conventional public mobile communication system.  
         [0056]    [0056]FIG. 4 shows a diagram of the conventional private mobile communication system.  
         [0057]    [0057]FIG. 5 shows the flow chart of the registration process of the conventional private mobile communication system.  
         [0058]    [0058]FIG. 6 shows the flow chart of the registration cancellation process of the conventional private mobile communication system.  
         [0059]    [0059]FIG. 7 shows the flow chart of the call delivery process of the conventional private mobile communication system.  
         [0060]    [0060]FIG. 8 shows a diagram of the public mobile communication system according to the first embodiment of the present invention.  
         [0061]    [0061]FIG. 9 shows the flow chart of the overflow registration process of the public mobile communication system according to the first embodiment of the present invention.  
         [0062]    [0062]FIG. 10 shows a diagram of the public mobile communication system according to one example of the first embodiment of the present invention.  
         [0063]    [0063]FIG. 11 shows the flow chart of the overflow call delivery process of the public mobile communication system according to the first embodiment of the present invention.  
         [0064]    [0064]FIG. 12 shows a diagram of the private mobile communication system according to the second embodiment of the present invention.  
         [0065]    [0065]FIG. 13 shows the flow chart of the overflow registration process of the private mobile communication system according to the second embodiment of the present invention.  
         [0066]    [0066]FIG. 14 shows the flow chart of the overflow call delivery process of the private mobile communication system according to the second embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0067]    The present invention provides a method for controlling the overflow of roaming users in a mobile communication system. The method can be applied to any mobile communication system in which roaming numbers are allocated to roaming users before the users access mobile communication functions such as call delivery (e.g., the TACS system). The first embodiment applies the method of the invention to a public mobile communication system, while the second embodiment applies the method of the invention to a private mobile communication system. However, it is understood that this is not intended to limit the scope of the present invention.  
         [0068]    First Embodiment  
         [0069]    [0069]FIG. 8 shows a diagram of the public mobile communication system according to the first embodiment of the present invention.  
         [0070]    Moreover, FIG. 9 shows the flow chart of the overflow registration process of the public mobile communication system according to the first embodiment of the present invention.  
         [0071]    Step  601 : roaming user  38  roams from home network F to network G.  
         [0072]    Step  602 : roaming user  38  delivers the register request to MSC  33 .  
         [0073]    Step  603 : MSC  33  delivers the register request to VLR  36 .  
         [0074]    Step  604 : VLR  36  determines whether a roaming number is available. If a roaming number is available, go to the Step  605 , wherein VLR  36  allocates the roaming number to roaming user  38 . If there are no roaming numbers available, go to the Step  606 , wherein VLR  36  assigns a roaming number RN 2  of an inactive roaming user  39  to roaming user  38 . Inactive roaming user  39  becomes an overflow roaming user, and the inactive roaming user&#39;s profile is canceled from VLR  36 . The selection of the inactive roaming user  39  can be based on the longest period of inactivity, the earliest registration, random selection, or any other appropriate method.  
         [0075]    Step  607 : VLR  36  notifies HLR  30  that the roaming user  39  is an overflow user and the roaming number RN 2  is allocated to the roaming user  38 .  
         [0076]    Step  608 : HLR  30  registers the roaming number RN 2  of the roaming user  38  and sets up the roaming number overflow column of the roaming user  39 .  
         [0077]    It is possible that roaming user  38  and roaming user  39  do not come from the same home network. FIG. 10 shows a diagram of the public mobile communication system according where roaming user  38  comes from home network F while roaming user  39  comes from home network K. In this case, in Step  607 , VLR  36  notifies HLR  30  that the roaming number RN 2  is allocated to the roaming user  38  and notifies HLR  32  in network K that the roaming user  39  is an overflow user. In Step  608 , HLR  32  sets up the roaming number overflow column of the roaming user  39 .  
         [0078]    As described above, the method of this invention assigns the roaming number of an inactive roaming user to a newly arriving roaming user. The inactive roaming user then becomes an overflow roaming user. Should the overflow roaming user require the use of the mobile communication functions, for example to make or receive a call, the overflow roaming user must be re-registered. The following describes the situation where overflow roaming user  39  receives a telephone call, wherein FIG. 11 shows the flow chart of the overflow user call delivery process of the public mobile communication system according to the first embodiment of the present invention. In this example, network F is the home network of roaming user  39  and roaming user  40 .  
         [0079]    Step  701 : when a telephone user dials the telephone number of the overflow roaming user  39 , the call request is connected to GMSC  35  in the home network of the roaming user  39 .  
         [0080]    Step  702 : GMSC  35  asks HLR  30  to provide the routing information of the roaming user  39 .  
         [0081]    Step  703 : HLR  30  asks VLR  36  to provide a roaming number for the roaming user  39 .  
         [0082]    Step  704 : VLR  36  determines whether a roaming number is available. If a roaming number is available, go to the Step  705 , wherein VLR  36  allocates the roaming number to roaming user  39 . If there are not roaming number available, go to the Step  706 , VLR  36  assigns a roaming number RN 3  of an inactive roaming user  40  to roaming user  39 . Inactive user  40  becomes an overflow roaming user, and the inactive roaming user&#39;s profile is canceled from VLR  36 . The selection of the inactive roaming user  40  can be based on the longest period of inactivity, the earliest registration, random selection, or any other appropriate method. As can be seen, inactive roaming user  40  takes the place of roaming user  39  as an overflow roaming user.  
         [0083]    Step  707 : VLR  36  notifies HLR  30  that the roaming user  40  is an overflow user and the roaming number RN 3  is allocated to the roaming user  39 .  
         [0084]    Step  708 : HLR  30  registers the roaming number RN 3  of the roaming user  39  and sets up the roaming number overflow column of the roaming user  40 .  
         [0085]    As described above, if the roaming user  39  and the roaming user  40  belong to different networks (for example, if roaming  39  belongs to home network F while roaming user  40  belongs to home network K), in Step  607 , VLR  36  notifies HLR  30  that the roaming number RN 3  is allocated to the roaming user  39  and notifies HLR  32  in network K that the roaming user  40  is an overflow user. In Step  608 , HLR  32  sets up the roaming number overflow column of the roaming user  40 .  
         [0086]    Step  709 : HLR  30  delivers the roaming number RN 3  to GMSC  35 .  
         [0087]    Step  710 : GMSC  35  connects GMSC  37  with roaming number RN 3 .  
         [0088]    Step  711 : GMSC  37  asks VLR  36  provides more detail routing information of the roaming user  39 .  
         [0089]    Step  712 : VLR  36  notifies GMSC  37  the routing information of the roaming user  39 .  
         [0090]    Step  713 : GMSC  37  finishes the operation of connecting to the roaming user  39 .  
         [0091]    As long as the number of the roaming users being called at the same time does not exceed the number of roaming users of the VLR  36 , the system can handle all of the roaming users with a smaller number of roaming numbers. Thus, the efficiency of the present invention is better than the prior art. By the method according to the present invention, the performance of a conventional system can be improved with without upgrading the hardware.  
         [0092]    Second Embodiment  
         [0093]    [0093]FIG. 8 shows a diagram of the private mobile communication system according to the second embodiment of the present invention.  
         [0094]    The roaming numbers available in a specific zone of a PBX are limited. If there are some activity causing users to gather to in a specific zone, the specific zone will not have enough roaming numbers. Thus, roaming users in the specific zone cannot register, and cannot use the mobile communication functions. The second embodiment of the present invention provides a method to control the overflow roaming numbers to higher the performance of the private mobile communication system.  
         [0095]    [0095]FIG. 9 shows the flow chart of the overflow registration process of the private mobile communication system according to the second embodiment of the present invention.  
         [0096]    Step  801 : roaming user  48  roams from home zone H to zone J and registers to MM  42 .  
         [0097]    Step  802 : MM  42  determines whether a roaming number is available. If a roaming number is available, go to the Step  803 , wherein MM  42  allocates the roaming number RN 4  to roaming user  48 . If there are no roaming numbers available, go to the Step  804 , wherein MM  42  assigns a roaming number of an inactive roaming user  49  to roaming user  48 , wherein the inactive roaming user  49  becomes an overflow roaming user and the inactive roaming user&#39;s profile is canceled from MM  42 . The selection of the inactive roaming user  49  can be based on the longest period of inactivity, the earliest registration, random selection, or any other appropriate method.  
         [0098]    Step  805 : MM  42  notifies MM  41  that the inactive roaming user  49  is an overflow user and the roaming number RN 4  is allocated to the roaming user  48  whom is in zone J.  
         [0099]    Step  806 : MM  41  updates the routing information and the roaming number of the roaming user  48 , sets up roaming number overflow column of the roaming user  49 , stores the routing information of the roaming user  48  and changes the unconditional diverted number to RN 4  as in Step  304 , and cancels the set of the unconditional diverted number of user  49 .  
         [0100]    Step  807 : MM  41  delivers the registration acknowledged message to MM  42  indicating the MM  41  has received the information that the roaming user  20  has moved to zone J, wherein the message further comprises the profile of the user.  
         [0101]    Step  808 : when MM  42  receives the registration acknowledged message, MM  42  responds that the roaming user  48  has completed the registration request.  
         [0102]    In Step  802 , if the user  48  and the user  49  are from different zone (e.g., the home zone of the user  49  is zone I), MM  42  notifies MM  41  that the roaming number RN 4  is allocated to the roaming user  48  whom is in zone J and notifies MM  43  that the inactive roaming user  49  is an overflow user. Moreover, in Step  806 , MM  41  updates the routing information and the roaming number of the roaming user  48 , stores the routing information of the roaming user  48  and changes the unconditional diverted number to RN 4 , while MM  43  sets up roaming number overflow column of the roaming user  49 , and cancels the set of the unconditional diverted number of user  49  as in Step  304 .  
         [0103]    The following described the situation wherein the telephone number of the roaming user  48 , who is an overflow user, is dialed.  
         [0104]    Refer to FIG. 14, which shows the flow chart of the overflow call delivery process of the private mobile communication system according to the second embodiment of the present invention.  
         [0105]    Step  901 : the telephone number of the overflow roaming user  48  is dialed, wherein the telephone number is the extension number of the roaming user  48  in zone H.  
         [0106]    Step  902 : MM  41  delivers the routing information request message to ask MM  42  to provide a roaming number, wherein the routing information request message further comprises the user profile of the overflow roaming user  48 .  
         [0107]    Step  903 : MM  42  allocates a roaming number of an inactive roaming user  49  to overflow roaming user  48 , wherein the inactive roaming user becomes an overflow user and the inactive roaming user&#39;s profile is canceled from MM  42 . The selection of the inactive roaming user  49  can be based on the longest period of inactivity, the earliest registration, random selection, or any other appropriate method.  
         [0108]    Step  904 : MM  42  responds to MM  41  that the roaming number of the user  48  is RN 5  and the user  49  is an overflow user. MM  42  further updates the user information and sets up the divert information.  
         [0109]    Step  905 : MM  41  asks PBX  45  connecting to PBX  44  with RN 5 .  
         [0110]    Step  906 : PBX  44  receives the call request of the PBX  45 .  
         [0111]    a. if the interface is line, PBX  44  rings the line, and the ring will be detected by MM  42 .  
         [0112]    b. If the interface is trunk, PBX  44  performs the call request with M 42  by signaling.  
         [0113]    Step  907 : when MM  42  detects the ring or receives the signaling request, connects the roaming user  48  and the  5  dialing user to establish the calling.  
         [0114]    The foregoing description of the preferred embodiments of this invention has been presented for purposes of illustration and description. Obvious modifications or variations are possible in light of the above teaching. The embodiments were chosen and described to provide the best illustration of the principles of this invention and its practical application to thereby enable those skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.