Patent Publication Number: US-2015071128-A1

Title: Mobile communication system, gateway device, charging policy control method, and non-transitory computer readable medium storing program

Description:
TECHNICAL FIELD 
     The present invention relates to a mobile communication system, and more particularly, to a mobile communication system that provides services to communication terminals by using a service providing server. 
     BACKGROUND ART 
     In recent years, various services have been provided to mobile communication terminals such as portable telephone terminals. For example, not only a voice call or e-mail communication between mobile communication terminals, but also services associated with a server device or the like located in an external communication network different from a mobile communication network are provided. In this way, when services have been provided to mobile communication terminals by the server device or the like located in an external communication network, communication charges are charged to the mobile communication terminals based on charging policies determined in the mobile communication network. 
     Patent Literature 1 discloses a charging control method for changing a charging rule based on a trigger event sent from a UE (User Equipment) or the like, and for applying the changed charging rule. Specifically, Patent Literature 1 discloses that when QoS or the like is changed, a charging rule function unit selects a new charging rule and applies the selected charging rule. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2010-213302 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     According to the charging control method disclosed in Patent Literature 1, a charging rule defined by a mobile communication carrier or the like is selected, and the selected charging rule is applied to mobile communication terminals and the like. However, it is considered that M2M communications will become widespread in the future and thus there will be more opportunities for mobile communication terminals to be provided with services in cooperation with the server device or the like located in an external communication network. It is also considered that there are a variety of service contents that can be provided in cooperation with the server device or the like located in the external communication network, and there are also a variety of charge forms depending on the services. Accordingly, there is a problem that when only the charging rule defined by the mobile communication carrier is applied to mobile communication terminals, it is difficult to set a flexible charging rule depending on the service contents. 
     To solve the above-mentioned problem, it is an object of the present invention to provide a mobile communication system, a gateway device, a charging policy control method, and a program, which are capable of setting a flexible charging rule depending on service contents. 
     Solution to Problem 
     A mobile communication system according to a first exemplary aspect of the present invention is a mobile communication system including: a node device located in a mobile communication network; a service providing server located in an external communication network different from the mobile communication network; and a gateway device that relays a data communication between the node device and the service providing server. The gateway device includes: a signal reception unit that receives a charging policy change request signal from the service providing server, the charging policy change request signal including: identification information about a first communication terminal that performs communication via the mobile communication network; and a charging policy change request for requesting to change a first charging policy applied to the first communication terminal to a second charging policy determined in the service providing server; a charging policy extraction unit that identifies, based on the identification information about the first communication terminal, charging policy information about the first communication terminal from a charging server that manages charging policy information about a plurality of communication terminals; and a charging policy control unit that changes a charging policy applied to the first communication terminal from the first charging policy to the second charging policy. 
     A gateway device according to a second exemplary aspect of the present invention is a gateway device that relays a data communication between a node device located in a mobile communication network and a service providing server located in an external communication network different from the mobile communication network. The gateway device includes: a signal reception unit that receives a charging policy change request signal from the service providing server, the charging policy change request signal including: identification information about a first communication terminal that performs communication via the mobile communication network; and a charging policy change request for requesting to change a first charging policy applied to the first communication terminal to a second charging policy determined in the service providing server; a charging policy extraction unit that identifies, based on the identification information about the first communication terminal, charging policy information about the first communication terminal from a charging server that manages charging policy information about a plurality of communication terminals; and a charging policy control unit that changes a charging policy applied to the first communication terminal from the first charging policy to the second charging policy. 
     A charging control method according to a third exemplary aspect of the present invention is a charging policy control method in a gateway device that relays a data communication between a node device located in a mobile communication network and a service providing server located in an external communication network different from the mobile communication network. The charging policy control method includes: receiving, from the service providing server, a charging policy change request signal including: identification information about a first communication terminal that performs communication via the mobile communication network; and a charging policy change request for requesting to change a first charging policy applied to the first communication terminal to a second charging policy determined in the service providing server; identifying, based on the identification information about the first communication terminal, charging policy information about the first communication terminal from a charging server that manages charging policy information about a plurality of communication terminals; and changing a charging policy applied to the first communication terminal from the first charging policy to the second charging policy. 
     A program according to a fourth exemplary aspect of the present invention is a program causing a computer in a gateway device that relays a data communication between a node device located in a mobile communication network and a service providing server located in an external communication network different from the mobile communication network, to execute the steps of: receiving, from the service providing server, a charging policy change request signal including: identification information about a first communication terminal that performs communication via the mobile communication network; and a charging policy change request for requesting to change a first charging policy applied to the first communication terminal to a second charging policy determined in the service providing server; identifying, based on the identification information about the first communication terminal, charging policy information about the first communication terminal from a charging server that manages charging policy information about a plurality of communication terminals; and changing a charging policy applied to the first communication terminal from the first charging policy to the second charging policy. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to provide a mobile communication system, a gateway device, a charging policy control method, and a program, which are capable of setting a flexible charging rule depending on service contents. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram showing a mobile communication system according to a first exemplary embodiment; 
         FIG. 2  is a block diagram showing the mobile communication system according to the first exemplary embodiment; 
         FIG. 3  is a diagram showing an MTC-IWF according to the first exemplary embodiment; 
         FIG. 4  is a diagram illustrating a flow of a process for transmitting a charging policy change request signal according to the first exemplary embodiment; 
         FIG. 5  is a diagram illustrating a flow of a charging policy change control process according to the first exemplary embodiment; 
         FIG. 6  is a diagram illustrating a flow of a charging policy change control process according to a second exemplary embodiment; and 
         FIG. 7  is a block diagram showing a case where an MTC-IWF according to the second exemplary embodiment is applied to a network specified in 3GPP technical specifications. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Exemplary Embodiment 
     Exemplary embodiments of the present invention will be described below with reference to the drawings. Referring first to  FIG. 1 , a configuration example of a gateway device according to a first exemplary embodiment of the present invention and a configuration example of a mobile communication system including peripheral devices of the gateway device will be described. 
     The mobile communication system includes a gateway device  1 , a charging server  40 , a node device  50 , and a service providing server  60 . The gateway device  1  includes a signal reception unit  10 , a charging policy extraction unit  20 , and a charging policy control unit  30 . The gateway device  1 , the charging server  40 , and the node device  50  are located in a mobile communication network, and the service providing server  60  is located in an external communication network. 
     The gateway device  1  relays a data communication between the node device  50  and the service providing server  60 . The components of the gateway device  1  will be described below. 
     The signal reception unit  10  receives a charging policy change request signal from the service providing server  60 . The charging policy change request signal includes identification information about a communication terminal, and a charging policy change request for requesting to change a charging policy applied to the communication terminal to a charging policy determined in the service providing server  60 . 
     The communication terminal is a terminal that communicates with another communication terminal, a server device, or the like via the mobile communication network. Specifically, the communication terminal is a terminal that is used by a user who subscribes to a mobile communication carrier that manages the mobile communication network. Examples of the identification information about the communication terminal may include a MAC address, an IP address, and a telephone number, which are allocated to the communication terminal, and also include the machine number of the communication terminal. 
     The term “charging policy” refers to a charging rule that defines a person who is to be charged, a charge rate, and the like. The person who is to be charged is a person who pays communication charges incurred by data communication. The person who is to be charged may be, for example, a person who owns the communication terminal, or a person who manages the service providing server  60 . The charge rate may be determined depending on, for example, a period of time in which a bearer that is set for the communication terminal to establish a communication is maintained, or the amount of data communication by the communication terminal. 
     The charging policy defined by the mobile communication carrier that manages the mobile communication network is generally applied to the communication terminal. In this case, the service providing server  60  transmits the charging policy change request signal to the gateway device  1  so that the charging policy determined by the mobile communication carrier is changed to a charging policy determined by a service provider that provides services by using the service providing server  60 . 
     The charging policy extraction unit  20  identifies, based on the identification information about the communication terminal, charging policy information about the communication terminal from the charging server  40  that manages the charging policy information about a plurality of communication terminals. The charging server  40  manages each communication terminal and applied charging policy information in such a manner that they are associated with each other. Accordingly, the charging policy extraction unit  20  can identify the charging policy set to the communication terminal, by using the identification information about the communication terminal. 
     The charging policy control unit  30  updates the charging policy applied to the communication terminal so that the charging policy currently applied is changed to a charging policy sent from the service providing server  60 . 
     As described above, the gateway device  1  shown in  FIG. 1  is a device that relays a communication between the mobile communication network and the service providing server  60  located in the external communication network. Accordingly, the gateway device  1  receives the charging policy change request signal from the service providing server  60 , and accesses the charging server  40  located in the mobile communication network, thereby making it possible to change the charging policy managed by the charging server  40 . 
     Next, a detailed configuration example of the mobile communication system according to the first exemplary embodiment of the present invention will be described with reference to  FIG. 2 . The mobile communication system shown in  FIG. 2  is configured using devices specified in 3GPP technical specifications. The mobile communication system shown in  FIG. 2  includes a UE (User Equipment)  101 , a CDF/CGF  111 , an MTC (Machine Type Communication)-IWF (Inter Working Function)  113 , an SCS (Service Capability Server)  121 , and an M2M service PF  131 . 
     The UE  101  described herein refers to equipment used in 3GPP technical specifications, the UE being a general term for mobile communication terminals. The CDF (Charging Data Function)/CGF (Charging Gateway Function)  111  corresponds to the charging server  40  shown in  FIG. 1 . The MTC-IWF  113  and SCS  121  correspond to the gateway device  1  shown in  FIG. 1 . The M2M service PF  131  corresponds to the service providing server  60  shown in  FIG. 1 . 
     The UE  101  may be, for example, a portable telephone terminal, a smartphone terminal, a laptop personal computer, or mobile means having a communication function installed in an automobile, a train, or the like, or a device having a communication function installed in a machine, such as a watch, which is worn by the user. Alternatively, the UE  101  may be a device, which is rarely moved and controlled via a wireless communication line, such as a vending machine having a communication function installed therein. The UE  101  communicates with the M2M service PF  131  via the mobile communication network. In the case where the services provided by the M2M service PF  131  are used, the UE  101  transmits an event notification to the M2M service PF  131 . 
     The CDF/CGF  111  manages charging policies for each UE. For example, when a session between the UE  101  and the M2M service PF  131  is started, a charging process is started using the charging policy corresponding to the UE  101 . When the session between the UE  101  and the M2M service PF  131  is terminated, the CDF/CGF  111  generates charge information and transmits the generated charge information to another device that processes the charge information to, for example, create a charge bill. 
     The M2M service PF  131  is located in an external communication network different from the mobile communication network. The M2M service PF  131  may be composed of one server device, or may be composed of a plurality of server devices which operate in cooperation with each other. The M2M service PF  131  notifies the SCS  121  of the charging policy change request signal. The charging policy change request signal includes identification information about the UE  101  which has transmitted the event notification, and information about the charging policy to be applied to the UE  101 . 
     Examples of the services provided by the M2M service PF  131  include provision of online games and provision of advertisement information. Alternatively, the M2M service PF  131  may provide the service of collecting sensor information detected by a sensor function installed in the UE  101  and releasing the result of an analysis of the sensor information to the public. 
     The SCS  121  is located between the MTC-IWF  113  and the M2M service PF  131 , and, for example, converts control data, user information, and the like into a form that can be read by each device. For example, upon receiving the charging policy change request signal from the M2M service PF  131 , the SCS  121  may notify the MTC-IWF  113  of the IMSI of the UE, to which a charging policy change is applied, or an identifier, such as MSISDN.  FIG. 2  illustrates the configuration in which the SCS  121  is located in the external communication network, but the SCS  121  may instead be located in the mobile communication network. In other words, the SCS  121  is configured to communicate with devices located in the external communication network and devices located in the mobile communication network. 
     The MTC-IWF  113  relays a communication between the SCS  121  and the CDF/CGF  111 . That is, the MTC-IWF  113  and the SCS  121  operate in cooperation with each other, so that the MTC-IWF  113  and the SCS  121  serve as a gateway to the M2M service PF  131  located in the external communication network. The MTC-IWF  113  receives, from the SCS  121 , a Device Trigger Request which indicates a request for changing the charging policy. Further, upon receiving the Device Trigger Request, the MTC-IWF  113  designates a target UE and notifies the CDF/CGF  111  of the change of the charging policy. 
     In this case, the MTC-IWF  113  may execute an authentication process as to whether or not the M2M service PF  131  is the M2M service PF that is allowed in advance to change the charging policy in the CDF/CGF  111 . The MTC-IWF  113  may manage information about a list of M2M service PFs which are allowed in advance to execute a process for changing the charging policy. The MTC-IWF  113  may execute the authentication process for the M2M service PF  131  by determining whether or not the identification information about the M2M service PF  131 , which is transmitted together with the Device Trigger Request, is included in the list of managed transmission destinations. 
     The CDF/CGF  111  changes the charging policy of the target UE according to a charging policy change instruction sent from the MTC-IWF  113 . 
     Next, a configuration example of the MTC-IWF  113  according to the first exemplary embodiment of the present invention will be described with reference to  FIG. 3 . The MTC-IWF  113  includes a mobile communication network interface  12 , an authentication control unit  13 , an authentication unit  14 , the charging policy extraction unit  20 , and the charging policy control unit  30 . 
     The authentication control unit  13  uses the authentication unit  14  to determine whether or not to execute the process associated with the charging policy change request signal transmitted from the M2M service PF  131 . The authentication unit  14  stores a list of identification information pieces about the M2M service PFs which are allowed in advance to execute the charging policy change process. The authentication control unit  13  determines whether or not the identification information about the M2M service PF  131  is stored in the authentication unit  14 . When the authentication control unit  13  determines that the M2M service PF  131  is allowed in advance to execute the charging policy change process, the authentication control unit  13  notifies the charging policy extraction unit  20  that the M2M service PF  131  is the M2M service PF which is allowed in advance to execute this process. 
     The charging policy extraction unit  20  extracts the charging policy of the UE, for which the charging policy is to be changed, from the CDF/CGF  111  via the mobile communication network interface  12 . Further, the charging policy extraction unit  20  outputs the extracted charging policy and the changed charging policy sent from the M2M service PF  131  to the charging policy control unit  30  via the SCS  121 . 
     The charging policy control unit  30  transmits an instruction signal, which indicates an instruction to change the charging policy of the target UE to the charging policy sent from the M2M service PF  131 , to the CDF/CGF  111  via the mobile communication network interface  12 . Further, when the charging policy extracted by the charging policy extraction unit  20  is different from the charging policy sent from the M2M service PF  131 , the charging policy control unit  30  may transmit the instruction signal to change the charging policy. 
     The mobile communication network interface  12  is used to communicate with node devices in the mobile communication network, such as SGW (Serving GW), PGW (PDN GW), and the CDF/CGF  111 . 
     Next, a flow of a process for transmitting the charging policy change request signal according to the first exemplary embodiment of the present invention will be described with reference to  FIG. 4 . First, to receive the services provided by the M2M service PF  131 , the UE  101  transmits an event notification to the M2M service PF  131  (S 11 ). For example, to participate in an online game provided by the M2M service PF  131 , the UE  101  may transmit an event notification to the M2M service PF  131 . 
     Next, the M2M service PF  131  determines the charging policy of the UE  101  (S 12 ). The M2M service PF  131  determines the charging policy to the effect that when the UE  101  participates in an online game, for example, communication charges to be incurred in the mobile communication network are charged to the M2M service PF  131 . 
     Next, the M2M service PF  131  transmits, to the SCS  121 , a charging policy change request for the UE  101  (S 13 ). Next, the SCS  121  transmits, to the MTC-IWF  113 , a Device Trigger Request signal including identification information about the M2M service PF  131 , identification information about the UE  101 , for which the charging policy is to be changed, and charging policy information determined by the M2M service PF  131  (S 14 ). 
     Next, the MTC-IWF  113  determines whether the M2M service PF  131  is the M2M service PF allowed in advance as the M2M service PF that changes the charging policy in the CDF/CGF  111  (S 15 ). 
     Referring next to  FIG. 5 , a flow of a process performed after the M2M service PF  131  is authenticated as the M2M service PF that can change the charging policy will be described. The MTC-IWF  113  transmits a Subscriber Information Request to an HSS so as to identify the CDF/CGF  111  that manages the charging policy of the UE  101  for which the charging policy is to be changed (S 21 ). The HSS is a node device specified in 3GPP technical specifications, and holds subscriber information about the UE, information about an MME that manages the UE, and the like. The Subscriber Information Request includes MSISDN, SCS ID, or the like as identification information about the UE  101 . 
     Next, the HSS transmits a Subscriber Information Response to the MTC-IWF  113  (S 22 ). The Subscriber Information Response is a response signal corresponding to the Subscriber Information Request, and is used to notify the MTC-IWF  113  of the identification information about the CDF/CGF  111  that manages the charging policy of the UE  101 . 
     Next, the MTC-IWF  113  performs a control to change the charging policy of the UE  101  that is managed by the CDF/CGF  111  sent from the HSS (S 23 ). Specifically, the MTC-IWF  113  controls the charging policy of the UE  101 , which is set by the mobile communication carrier, to be changed to the charging policy sent from the M2M service PF  131 . 
     Next, the MTC-IWF  113  notifies the SGW and PGW, which are located in the mobile communication network, about counting of the number of packets, for example, after the charging policy is changed (S 24 ). The SGW and the PGW relay user data between the UE  101  and the M2M service PF  131 . In steps S 21  and S 22 , the MTC-IWF  113  may acquire information about the SGW and PGW which send and receive user packets to and from the UE  101 . Alternatively, in steps S 21  and S 22 , the MTC-IWF  113  may identify the MME that manages the movement of the UE  101 , and may acquire, from the MME, information about the SGW and PGW which send and receive user packets to and from the UE  101 . 
     Next, the SGW and PGW count the number of packets, which are transmitted by their own devices, set the counting results in a Delivery Report, and notify the MTC-IWF  113  of the Delivery Report (S 25 ). The SGW and PGW may count the number of packets separately before and after the change of the charging policy. In this case, the SGW and PGW may count the number of packets for each bearer set in the UE  101 , or may count the number of packets for each APN associated with the M2M service PF  131 . Alternatively, the SGW and PGW may count the number of packets for each IP address of the M2M service PF  131  or the UE  101 . Instead of counting the number of packets, the SGW and PGW may count the period of time during which the UE  101  is connected to the mobile communication network, that is, the period of time during which resources are allocated to the UE  101 . 
     Next, the MTC-IWF  113  generates information (CDR Information) about the charge bill based on such information as the number of packets transmitted from the SGW and PGW to the SCS  121 , and transmits the CDR Information to the SCS  121  by using the Delivery Report (S 26 ). 
     Next, the SCS  121  notifies the M2M service PF  131  of the charge information on the session between the UE  101  and the M2M service PF  131  (S 27 ). 
     As described above, the use of the mobile communication system according to the first exemplary embodiment of the present invention enables the SCS  121  to receive the request for changing the charging policy sent from the M2M service PF  131  managed by a third party. Furthermore, the use of the SCS  121  and the MTC-IWF  113  makes it possible to change the charging policy of the CDF/CGF  111  located in the mobile communication network. 
     Second Exemplary Embodiment 
     Referring next to  FIG. 6 , a flow of a process performed after the M2M service PF  131  according to a second exemplary embodiment of the present invention is authenticated as the M2M service PF that can change the charging policy will be described.  FIG. 6  illustrates a case where the M2M service PF  131  collects sensor information in a plurality of UEs. 
     Steps S 31  to S 34  shown in  FIG. 6  are the same as steps S 21  to S 24  shown in  FIG. 5 , and thus the detailed description thereof is omitted. However, since the M2M service PF  131  communicates with a plurality of UEs, in step S 33 , the control is performed so as to change the charging policy for each UE with which the M2M service PF  131  communicates. 
     In step S 35 , the SGW and PGW count the number of packets, which are transmitted by their own devices, set the counting results in the Delivery Report, and notify the MTC-IWF  113  of the Delivery Report (S 35 ). In this case, the M2M service PF  131  communicates with a plurality of UEs so as to collect sensor information from the plurality of UEs. Accordingly, the MTC-IWF  113  receives the Delivery Report from a plurality of SGWs and PGWs. 
     Next, the MTC-IWF  113  generates one Delivery Report by combining a plurality of Delivery Reports, and transmits the generated Delivery Report to the SCS  121 . In other words, instead of transmitting a plurality of Delivery Reports, one of which is generated for each UE, to the SCS  121 , the MTC-IWF  113  generates one Delivery Report by adding the numbers of packets counted in each Delivery Report. The SCS  121  then notifies the M2M service PF  131  of the charge information based on the generated one Delivery Report. 
     As described above, the use of the mobile communication system according to the second exemplary embodiment of the present invention enables the MTC-IWF  113  to generate one Delivery Report by combining a plurality of Delivery Reports. Accordingly, it is not necessary for the SCS  121  to notify the M2M service PF  131  of a plurality of pieces of charge information. This leads to a simplification of the charging process and a reduction in the amount of communication between the SCS  121  and the M2M service PF  131 . 
     In general, communication charges incurred during transmission of packets in the mobile communication network are charged to each UE subscribing to the mobile communication carrier. On the other hand, the use of the mobile communication system according to the second exemplary embodiment of the present invention makes it possible to change the charging policy by using the MTC-IWF  113  and SCS  121  so that communication charges are charged to the M2M service PF  131  which has used the UEs each serving as a sensor terminal. 
     Another Exemplary Embodiment 
     Referring to  FIG. 7 , a network system in which the MTC-IWF  113  and the SCS  121  according to the first to third exemplary embodiments described above are applied to the network specified in 3GPP technical specifications will be described. 
     The network system shown in  FIG. 7  includes a UE (User Equipment)  201 , a RAN (Radio Access Network)  206 , an MSC (Mobile Switching Center)  202 , an MME  203 , an SGSN (Serving GPRS Support Node)  204 , an S-GW  205 , a GGSN (Gateway GPRS Support Node)/P-GW  211 , an MTC-IWF  212 , an SCS  213 , ASs (Application Servers)  214  and  215 , an HSS  216 , an SMS-SC (Short Message Service-Service Center)/GSM® SC/IWMSC  217 , a CDF (Charging Data Function)/CGF (Charging Gateway Function)  218 , an SME (Short Message Entity)  219 , and an IP-SM-GW  220 . 
     The MTC-IWF  212  and SCS  213  are located so as to relay a communication between the MSC  202 , MME  203 , and SGSN  204 , and the AS  214 . In this case, the AS  214  is located in an external communication network different from the mobile communication network. The MTC-IWF  212  is located in the mobile communication network. The SCS  213  may be located in either the mobile communication network or the external communication network. In other words, the position where the SCS  213  is located depends on the network design policies of the communication carrier, the AS carrier, and the like. 
     The present invention is described as a hardware configuration in the exemplary embodiments described above, but the present invention is not limited thereto. According to the present invention, the processes in the MTC-IWF  113  can also be implemented by causing a CPU (Central Processing Unit) to execute a computer program. 
     In the above-mentioned example, the program can be stored and provided to a computer using any type of non-transitory computer readable media. Non-transitory computer readable media include any type of tangible storage media. Examples of non-transitory computer readable media include magnetic storage media (such as floppy disks, magnetic tapes, hard disk drives, etc.), optical magnetic storage media (e.g., magneto-optical disks), CD-ROM (Read Only Memory), CD-R, CD-R/W, and semiconductor memories (such as mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory), etc.). The program may be provided to a computer using any type of transitory computer readable media. Examples of transitory computer readable media include electric signals, optical signals, and electromagnetic waves. Transitory computer readable media can provide the program to a computer via a wired communication line, such as electric wires and optical fibers, or a wireless communication line. 
     Note that the present invention is not limited to the exemplary embodiments described above, and can be modified in various manners without departing from the scope of the invention. For example, the charging policy may be determined in such a manner that communication charges for service contents provided by the M2M service PF  131  are reduced, for example, when a relatively long transmission delay is allowed, or when the allocated communication bandwidth is narrow. 
     While the present invention has been described above with reference to exemplary embodiments, the present invention is not limited to the above exemplary embodiments. The configuration and details of the present invention can be modified in various manners which can be understood by those skilled in the art within the scope of the invention. 
     This application is based upon and claims the benefit of priority from Japanese patent application No. 2012-101828, filed on Apr. 26, 2012, the disclosure of which is incorporated herein in its entirety by reference. 
     REFERENCE SIGNS LIST 
     
         
           1  GATEWAY DEVICE 
           10  SIGNAL RECEPTION UNIT 
           12  MOBILE COMMUNICATION NETWORK INTERFACE 
           13  AUTHENTICATION CONTROL UNIT 
           14  AUTHENTICATION UNIT 
           20  CHARGING POLICY EXTRACTION UNIT 
           30  CHARGING POLICY CONTROL UNIT 
           40  CHARGING SERVER 
           50  NODE DEVICE 
           60  SERVICE PROVIDING SERVER 
           101  UE 
           111  CDF/CGF 
           113  MTC-IWF 
           121  SCS 
           131  M2M SERVICE PF