Patent Publication Number: US-10313999-B2

Title: Method for detachment of MS moving between communication systems

Description:
PRIORITY 
     This application is a Continuation Application of U.S. patent application Ser. No. 12/527,328, filed on Dec. 28, 2009, which is a National Phase Entry of PCT International Application No. PCT/KR2008/000843, filed on Feb. 13, 2008, and claims priority to Chinese Patent Application No. 200710080147.6, filed on Feb. 14, 2007, the contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a field of communication, especially to a method for a mobile set detaching from two or more communication systems that share the same equivalent route area (hereinafter referred to as ERA). 
     2. Description of the Related Art 
     In general, for the convenience of management, a service area of a mobile communication system can be divided into several different route areas (hereinafter referred to as RA) with each managed by a service node. After a mobile set is registered with a mobile communication system, it learns about the RA it locates. If a subscriber moves within the mobile communication system, when the mobile set finds out that it enters a new RA or it needs to initiate a periodical RA update process, it is necessary for this mobile set to carry out a RA update process. During the RA update process, if the service node changes, information on the mobile set will be eliminated from the original service node after it has been transferred to the new service node. 
     Generally, a detachment process may be performed so that: the mobile set informs the network that the mobile set no longer needs any service, or the network informs the mobile set that the network no longer offer any service for the mobile set. The mobile set may be detached either explicitly or implicitly. The explicit detachment means that either the network or the mobile set carries out the detachment process explicitly, while the implicit detachment means that the network detaches the mobile set without any notification. For instance, the system receives no message from the mobile set in a preset period of time, or an error (which can not be settled) happens to the physical link between the system and the mobile set. The process that the network detaches a mobile set may be initiated by either the service node (within the network) that offers service to the mobile set, or a home network register (hereinafter referred to as HSS) corresponding to the mobile set. After the detachment process completes, it is necessary to inform the HSS that the mobile set in state of detachment. 
     In general, when a mobile set moves from a service area of one mobile communication system to a service area in another new mobile communication system, the RAs of the two communication systems are different. In this case, it is necessary to perform a RA update process between the mobile set and the service node in the new mobile communication system. In addition, during this process, a series of processes may be implemented between the service node in the new mobile communication system and the original one to exchange relevant information to support the mobility of the mobile set. The two processes are necessary to be implemented once the mobile set returns the original communication system. 
     Now, an ERA method is adopted to effectively reduce the implementations of the process mentioned above during the mobile set switches between mobile communication systems. With this method, a RA of a mobile communication system and a RA of another mobile communication system are considered as one ERA. For the first time when a mobile set moves from a RA of a mobile communication system to a RA of another mobile communication system, the two service nodes of the two mobile communication systems exchange the relevant information on the mobile set so that the relevant information on the mobile set are saved in the service nodes of the two mobile communication systems. In this way, the fact that the mobile set moves within the ERA or enters a new mobile communication system is considered as that it moves within one RA of the same service node. Therefore, it is not necessary to perform any RA update process or corresponding information exchanging. 
     However, with the movement of the mobile set during the process that the mobile is detached from an equivalent route area (hereinafter referred to as ERA) shared by two or more communication systems, several available methods have no idea but support that the mobile set could be detached from only one of the communication systems. Therefore, in the case that the mobile is powered off, the service node of other communication system (but within the same ERA) learns about no relevant information yet. Thus, waste is caused to the system resource. 
     SUMMARY OF THE INVENTION 
     The object of this invention is to provide a method for detachment of a mobile set moving between two or more communication systems which share the same equivalent route area (hereinafter referred to as ERA), and all service nodes within the ERA of the communication systems may correctly manage relevant information on the mobile set correctly. 
     According to one aspect of present invention, a method for detachment of a mobile set within an ERA moving between communication systems, including receiving, by a service node of a communication system, a detachment request from the mobile set, transmitting, by the service node of the communication system, a delete context request message for the mobile set to a first service node of another communication system, and transmitting, by the service node, a detachment indicator to a second service node of the another communication system, wherein the service node of the communication system is different from the service node of the another communication, wherein both the service node of the communication system and the first service node of the another communication system store context information related to the mobile set, and wherein the mobile set moves between the service node of the communication system and the first service node of the another communication system without an area updating. 
     With the method disclosed in present invention, when a mobile set is detached from two or more communication systems which share the same ERA, the service nodes in all communication systems within the ERA may still correctly manage this mobile set&#39;s relevant information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of the present disclosure will be more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  shows a block diagram of a radio communication system in accordance with a preferred embodiment of present invention; 
         FIG. 2  shows a block diagram of another radio communication system in accordance with a preferred embodiment of present invention; 
         FIG. 3  illustrates an ERA in accordance with a preferred embodiment of present invention; 
         FIG. 4  illustrates a process of a first preferred embodiment of present invention; 
         FIG. 5  illustrates a process of a second preferred embodiment of present invention; 
         FIG. 6  illustrates a process of a third preferred embodiment of present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Present invention relates to a method for detachment of a mobile set between two or more communication systems which share the same equivalent route area (hereinafter referred to as ERA). With this method, when a mobile set is detached from two or more communication systems which share the same ERA, the service nodes in all communication systems within the ERA can still correctly manage the relevant information on this mobile set. During the detachment process is implemented between a mobile set and a service node in one communication system, the service node generates one message (or several different ones) and transmits it (or them) to the service nodes in one or more communication systems within the ERA. If the message is transmitted to the service node (within the ERA) in only one communication system, then this service node transmits this message (or the one(s) generated according to the message) to the service nodes (within the ERA) of the other(s) communication system(s). The service nodes within the ERA disable relevant information on the mobile set. The detachment process may be implemented between the service nodes within the ERA and the HSS in the mobile set. 
     Referring to drawings, the following description shows three preferred embodiments of communication system according to present invention. Especially, the communication system is a wireless communication system that follows at least one of the following communication standards. The standards may include but not be limited to an analogous, digital, or analogous/digital dual-mode communication system protocols. For instance (but not confined to), an advanced mobile phone system (referred to as AMPS), a narrow-band advanced mobile phone system (referred to as NAMPS), a global system for mobile communication (referred to as GSM), an enhanced data rate GSM evolvement (referred to as EDGE), a general packet radio service (referred to as GPRS), a universal mobile telecommunication system (referred to as UMTS), a frequency-division multiple access (referred to as FDMA), an IS-55 time-division multiple access (referred to as TDMA) digital cell, an IS-136 TDMA digital cell, an IS-95 code-division multiple access (referred to as CDMA) digital cell, an on-demand allocation modes (DA/TDMA, DA/CDMA, DA/FDMA), a wideband code-division multiple access (referred to as WCDMA), CDMA 2000, IMT-2000, a personal radio communication system (referred to as PCS/PHS), 3GPP, 3GPP2 and these protocols&#39; varieties and evolvements. The communication system of present invention could further refer to all kinds of communication network system in the following description. A node in these communication systems needs to differentiate different subscribers. For example, the communication network system determines whether the subscriber that needs to access to it is a local subscriber or a roaming subscriber that roams into it; or different networks, for example, when a subscriber is accessing a communication network system, it should tell whether the network to be accessed is the signed home network or visit network. It could include but not be limited to a local area network (hereinafter referred to as LAN hereinafter), a wireless local area network (hereinafter referred to as WLAN), etc. To avoid making the description ambiguous, detailed descriptions for functions or equipment that well known for those skilled in the art are omitted. 
     Referring to  FIG. 1 , a radio communication system  100  includes a backbone network  110 , a group of radio network controllers (hereinafter referred to as RNC)  140  and  141 , which jointly offer service within the route area  180 . Generally, RNC handles signal coding/decoding, handover decision and access decision. Wireless communication system  100  could be, but not limited to a FDMA-based communication system, a TDMA-based communication system or a CDMA-based communication system. It is well known that the communication backbone network  110  includes GPRS support node GGSN  120 , service GPRS support node SGSN  130 . With the help one or more relevant base stations (hereinafter referred to as Node B)  150 ,  151  and  152 , each of the RNCs  140  and  141  provides service in the communication cells  160 ,  161  and  162  within the entire route area  180 . For sake of description convenience, RNC and Node B are described from the point of the invention. Whereas this doesn&#39;t mean the invention is only limited to RNC and Node B because base station controller (BTC), base station (BTS) and other similar techniques could be used to realize present invention, which is very obvious to technician of the art. Following practical standards, GGSN  120 , SGSN  130 , RNC  140  and Node B 150  offer radio communication service to mobile sets (hereinafter referred to MS)  170  within the communication cell  160 . Every system part mentioned above could be obtained commercially, such as purchasing from Motorola Company. 
     Referring to  FIG. 2 , a wireless communication system  200  comprises a communication trunk network  210 , a group of enhanced base stations E-Node B  230  and  231 , and they jointly provide services within the route area RA 260 . Wireless communication system  200  could be, but not limited to FDMA-based communication system, TDMA-based communication system or CDMA-based communication system. It is well known that the communication backbone network  110  includes the mobile management/user plane entity  220 , which takes charge of signal encryption/decryption, handover decision and access decision. Each enhanced base station  230  and  231  provides services for all communication cell  240  and  241  in the whole route area. Following practical standards, MME/UPE  220  and E-Node B  230  offer radio communication service to mobile sets (hereinafter referred to as MS)  250  within the communication cell  240 . Each system part mentioned above is expected to be obtainable commercially. 
     Referring to  FIG. 3 , the route area RA  180  of radio communication system  100  and the route area RA  260  of radio communication system  220  are jointly defined as an equivalent route area ERA 1 . 
     A First Embodiment 
     In this embodiment, the detachment decision is made for a mobile set in the ERA shared by both the service node SGSN 130  of the radio communication system  100  and the service node MME/UPE  220  of radio communication system  200 . In practical, according to the current choice of the MS between radio communication system  100  and radio communication system  200 , MS may transmit a detachment request to either service node SGSN  130  of radio communication system  100  or service node MME/UPE  200  of radio communication system  200 . The implementations are similar in the two cases. To avoid making the description too tedious, detailed descriptions on the latter are omitted.  FIG. 4  illustrates a process of the first preferred embodiment of present invention. 
     Step  400 , the MS determines to be detached from the system. 
     Step  401 , the MS sends the detachment request to the service node SGSN  130  of radio communication system  100 . 
     Step  402 , service node SGSN 130  sends a context (corresponding to the MS) request message for deleting the MS to service node MME/UPE 220  of radio communication system  200 . 
     Service node SGSN 130  obtains the location of service node MME/UPE 220  through several optional methods. 
     One method is that, before step  400 , through the processes like the configuration operations by the operator, SGSN 130  has obtained that it shares the same ERA with node MME/UPE 220 . Therefore, after receiving the detachment request mentioned in step  401 , the SGSN  130  transmits the delete context request message to the node MME/UPE 220 . 
     Another possible method is that, the MS includes information such as an address of the node MME/UPE 220 , an identifier of the node MME/UPE 220 , an identifier that node MME/UPE 220  assigned to the MS, and (or) an identifier of a route area of the node MME/UPE 220  of communication system  200  and so on into the detachment request in step  401 . With the message(s), the service node SGSN 130  may obtain the location of node ME/UPE 220 . 
     Step  403 , service node MME/UPE 220  sends a Delete Context Response to service node SGSN 130 . 
     Step  404 , service node SGSN 130  sends a Detachment Accept to the MS. 
     Step  405 , service node SGSN 130  sends the Detachment Indicator to HSS. In this embodiment, the information that HSS saves is about that MS is attached to node SGSN 130 . Actually, if the information that HSS saves is about that MS is attached to node MME/UPE 220 , then node MME/UPE 220  can be adopted to send the Detachment Indicator to HSS. 
     Alternatively, in this embodiment, no time sequence exists between step  404  and steps  402  through  403 . 
     Alternatively, in this embodiment, no time sequence exists between step  405  and steps  402  through  404 . 
     Alternatively, service node SGSN 130  disables and/or deletes the relevant context information on the MS after step  401 . 
     Alternatively, service node MME/UPE 220  disables and/or deletes the relevant context information on the MS after step  402 . 
     A Second Embodiment 
     In this embodiment, within the ERA shared by both the service node SGSN 130  of the radio communication system  100  and the service node MME/UPE  220  of radio communication system  200 , the service node MME/UPE 220  determines to detach the UE. Similarly, the service node SGSN 130  can also determine to detach UE. The implementations are similar in the two cases. To avoid making the description too tedious, detailed descriptions on the latter are omitted.  FIG. 5  illustrates a process of the second preferred embodiment of present invention. 
     Step  500 , MME/UPE 220  determines to detach the UE. 
     Step  501 , the service node MME/UPE 220  sends the Detachment request to UE. 
     Step  502 , service node MME/UPE 220  sends the delete context request message to service node SGSN 130  of radio communication system  100 . Service node MME/UPE 220  obtains the location of service node SGSN 130  through several optional methods. 
     One method is that, before step  500 , through the processes like the configuration operations by the operator, MME/UPE 220  has obtain that it shares the same ERA with node SGSN 130 . Therefore, after receiving the detachment request mentioned in step  501 , SGSN 130  determines to transmit the delete context request message to node SGSN 130 . 
     Step  503 , service node SGSN 130  sends the Delete Context Response to service node MME/UPE 220 . 
     Step  504 , the MS sends the detachment accept message to the service node MME/UPE 220 . 
     Step  505 , the service node MME/UPE 220  sends the Detachment Indicator to HSS. In this embodiment, the information that HSS saves is about that MS is attached to node MME/UPE 220 . Actually, if the information that HSS saves is about that MS is attached to node SGSN 130 , then node SGSN 130  can be adopted to send the Detachment Indicator to HSS. 
     Alternatively, in this embodiment, no time sequence exists between step  504  and steps  502  through  503 . 
     Alternatively, in this embodiment, no time sequence exists between step  505  and steps  502  through  504 . 
     Alternatively, service node MME/UPE 220  disables and/or deletes the MS&#39;s relevant context information after step  501 . 
     Alternatively, service node SGSN 130  disables and/or deletes the relevant context information on the MS after step  502 . 
     The Third Embodiment 
     In this embodiment, the MS locates in the ERA shared by both the service node SGSN 130  of radio communication system  100  and the service node MME/UPE  220  of radio communication system. The HSS determines to detach UE. In fact, the information saved in HSS indicates which radio communication system MS locates: the radio communication system  100  or the radio communication system  200 . The implementations are similar in the two cases. To avoid making the description too tedious, detailed descriptions on the latter are omitted.  FIG. 6  illustrates a process of the third preferred embodiment of present invention. 
     Step  600 , HSS sends a Cancel Location message to the service node SGSN  130  of radio communication system  100 . 
     Step  601 , the service node SGSN 130  sends the Detachment request to UE. 
     Step  601 , service node SGSN 130  sends the delete context request message to service node MME/UPE 220  of radio communication system  200 . Service node SGSN 130  obtains the location of service node MME/UPE 220  through several optional methods. One method is that, before step  600 , through the processes like the configuration operations by the operator, SGSN 130  has learnt about that it shares the same ERA with node MME/UPE 220 . Therefore, after receiving the detachment request mentioned in step  601 , the SGSN  130  may transmit the delete context request message to node MME/UPE 220 . 
     Step  603 , service node MME/UPE 220  sends the Delete Context Response to service node SGSN 130 . 
     Step  604 , MS sends the detachment accept message to the service node SGSN 130 . 
     Step  605 , the service node SGSN 130  sends the Detachment Indicator to HSS. 
     Alternatively, in this embodiment, no order exists between steps  602  through  603  and step  601 ,  604  and  605 . 
     Alternatively, service node SGSN 130  disables and/or deletes the relevant context information on the MS after step  600 . 
     Alternatively, service node MME/UPE 220  disables and/or deletes the relevant context information on the MS after step  602 . 
     Although a few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.