Method for acquiring business operator network identification number of visited network

Abstract

An embodiment of the present specification provides a method for acquiring an identifier of a visited public land mobile network (V-PLMN), in which a user equipment is roaming, by a proxy-call session control function (P-CSCF) of a home public land mobile network (H-PLMN). The method may comprise the steps of: receiving a register message from the user equipment; generating a first V-PLMN identifier on the basis of the register message; and transferring the first V-PLMN identifier to a home subscriber server (HSS), wherein whether the first V-PLMN identifier corresponds to an identifier of the V-PLMN which is serving the user equipment is verified by the HSS through comparison with a second V-PLMN identifier acquired in an initial attach procedure for an evolved packet core (EPC) of the user equipment.

Claims

1. A method of acquiring an identifier of a visited public land mobile network (V-PLMN), in which a user equipment is roaming, the method performed by a proxy-call session control function (P-CSCF) of a home public land mobile network (H-PLMN) and comprising: receiving, by the P-CSCF, a register message from the user equipment; generating, by the P-CSCF, a first V-PLMN identifier on the basis of the register message; and transferring, by the P-CSCF, the first V-PLMN identifier to a home subscriber server (HSS), wherein whether the first V-PLMN identifier generated by the P-CSCF corresponds to an identifier for the V-PLMN which is serving the user equipment is verified by the HSS through comparison with a second V-PLMN identifier acquired in an initial attach procedure for an evolved packet core (EPC) of the user equipment.

2. The method of claim 1, wherein the generating of the identifier of the first V-PLMN comprises: extracting mobile country codes (MCC) and mobile network codes (MNC) from a P-Access-Network-info header of the register message; and generating the first V-PLMN identifier by combining the MCC and the MNC.

3. The method of claim 1, wherein the transferring of the first V-PLMN identifier comprises: adding the first V-PLMN identifier to a P-Visited-Network-ID header of the register message; and transmitting the register message, to which the first V-PLMN identifier is added, to the HSS through an interrogating-CSCF (I-CSCF).

4. The method of claim 1, wherein in the generating of the first V-PLMN identifier, the first V-PLMN identifier is generated only when the user equipment is roaming to the V-PLMN through a home routed (HR) scheme by using an S8 reference point for transmitting/receiving a signal between a serving-gateway (S-GW) of the V-PLMN and a PDN-gateway (P-GW) of the H-PLMN.

5. The method of claim 1, further comprising performing, by the P-CSCF, a registration procedure for an IP multimedia subsystem (IMS) of the user equipment by using the first V-PLMN identifier upon receiving from the HSS an identifier which informs that the first V-PLMN identifier is verified.

6. A proxy-call session control function (P-CSCF) in a home public land mobile network (H-PLMN) for acquiring an identifier of a visited public land mobile network (V-PLMN) in which a user equipment is roaming, the P-CSCF comprising: a transceiver; and a processor controlling the transceiver, wherein the processor is configured to: receive a register message from the user equipment by controlling the transceiver; generate a first V-PLMN identifier on the basis of the register message; and transfer the first V-PLMN identifier to a home subscriber server (HSS), wherein whether the first V-PLMN identifier corresponds to an identifier for the V-PLMN which is serving the user equipment is verified by the HSS through comparison with a second V-PLMN identifier acquired in an initial attach procedure for an evolved packet core (EPC) of the user equipment.

7. The P-CSCF of claim 6, wherein the generating of the first V-PLMN identifier comprises: extracting mobile country codes (MCC) and mobile network codes (MNC) from a P-Access-Network-info header of the register message; and generating the first V-PLMN identifier by combining the MCC and the MNC.

8. The P-CSCF of claim 6, wherein the transferring of the first V-PLMN identifier comprises: adding the first V-PLMN identifier to a P-Visited-Network-ID header of the register message; and transmitting the register message, to which the first V-PLMN identifier is added, to the HSS through an interrogating-CSCF (I-CSCF).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the configuration of an evolved mobile communication network.

(2) FIG. 2 is an exemplary diagram showing the architecture of a common E-UTRAN and a common EPC.

(3) FIG. 3 is an exemplary diagram showing the structure of a radio interface protocol in a control plane between UE and an eNodeB

(4) FIG. 4 is another exemplary diagram showing the structure of a radio interface protocol in a control plane between UE and an eNodeB.

(5) FIG. 5 illustrates a connection process in a radio resource control (RRC) layer.

(6) FIG. 6 shows a connection between an EPC and an IP multimedia subsystem (IMS).

(7) FIG. 7 is an exemplary signal flow diagram showing an initial access procedure of a UE.

(8) FIG. 8 is an exemplary signal flow diagram showing an IMS initial registration procedure.

(9) FIG. 9 is an exemplary diagram showing a roaming scheme of voice over LTE (VoLTE).

(10) FIG. 10 is an exemplary signal flow diagram showing an IMS registration procedure of a UE roaming in a visited network through an HR scheme.

(11) FIG. 11 is an exemplary view showing the concept of a PLMN-ID structure.

(12) FIG. 12 is a signal flow diagram for explaining a method of acquiring a PLMN-ID according to the present specification.

(13) FIG. 13 is a flowchart showing a method of acquiring a PLMN-ID according to a disclosure of the present specification.

(14) FIG. 14 is a flowchart showing a method of acquiring a PLMN-ID according to another disclosure of the present specification.

(15) FIG. 15 is a block diagram showing a structure of a UE and a P-CSCF according to a disclosure of the present specification.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(16) The present invention is described in light of UMTS (Universal Mobile Telecommunication System) and EPC (Evolved Packet Core), but not limited to such communication systems, and may be rather applicable to all communication systems and methods to which the technical spirit of the present invention may apply.

(17) The technical terms used herein are used to merely describe specific embodiments and should not be construed as limiting the present invention. Further, the technical terms used herein should be, unless defined otherwise, interpreted as having meanings generally understood by those skilled in the art but not too broadly or too narrowly. Further, the technical terms used herein, which are determined not to exactly represent the spirit of the invention, should be replaced by or understood by such technical terms as being able to be exactly understood by those skilled in the art. Further, the general terms used herein should be interpreted in the context as defined in the dictionary, but not in an excessively narrowed manner.

(18) The expression of the singular number in the specification includes the meaning of the plural number unless the meaning of the singular number is definitely different from that of the plural number in the context. In the following description, the term include or have may represent the existence of a feature, a number, a step, an operation, a component, a part or the combination thereof described in the specification, and may not exclude the existence or addition of another feature, another number, another step, another operation, another component, another part or the combination thereof.

(19) The terms first and second are used for the purpose of explanation about various components, and the components are not limited to the terms first and second. The terms first and second are only used to distinguish one component from another component. For example, a first component may be named as a second component without deviating from the scope of the present invention.

(20) It will be understood that when an element or layer is referred to as being connected to or coupled to another element or layer, it can be directly connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being directly connected to or directly coupled to another element or layer, there are no intervening elements or layers present.

(21) Hereinafter, exemplary embodiments of the present invention will be described in greater detail with reference to the accompanying drawings. In describing the present invention, for ease of understanding, the same reference numerals are used to denote the same components throughout the drawings, and repetitive description on the same components will be omitted. Detailed description on well-known arts which are determined to make the gist of the invention unclear will be omitted. The accompanying drawings are provided to merely make the spirit of the invention readily understood, but not should be intended to be limiting of the invention. It should be understood that the spirit of the invention may be expanded to its modifications, replacements or equivalents in addition to what is shown in the drawings.

(22) In the drawings, user equipments (UEs) are shown for example. The UE may also be denoted a terminal or mobile equipment (ME). The UE may be a laptop computer, a mobile phone, a PDA, a smartphone, a multimedia device, or other portable device, or may be a stationary device such as a PC or a car mounted device.

(23) Definition of Terms

(24) For a better understanding, the terms used herein are briefly defined before going to the detailed description of the invention with reference to the accompanying drawings.

(25) A GERAN is an abbreviation of a GSM EDGE Radio Access Network, and it refers to a radio access section that connects a core network and UE by GSM/EDGE.

(26) A UTRAN is an abbreviation of a Universal Terrestrial Radio Access Network, and it refers to a radio access section that connects the core network of the 3rd generation mobile communication and UE.

(27) An E-UTRAN is an abbreviation of an Evolved Universal Terrestrial Radio Access Network, and it refers to a radio access section that connects the core network of the 4th generation mobile communication, that is, LTE, and UE.

(28) An UMTS is an abbreviation of a Universal Mobile Telecommunication System, and it refers to the core network of the 3rd generation mobile communication.

(29) UE or an MS is an abbreviation of User Equipment or a Mobile Station, and it refers to a terminal device.

(30) An EPS is an abbreviation of an Evolved Packet System, and it refers to a core network supporting a Long Term Evolution (LTE) network and to a network evolved from an UMTS.

(31) A PDN is an abbreviation of a Public Data Network, and it refers to an independent network where a service for providing service is placed.

(32) A PDN connection refers to a connection from UE to a PDN, that is, an association (or connection) between UE represented by an IP address and a PDN represented by an APN.

(33) A PDN-GW is an abbreviation of a Packet Data Network Gateway, and it refers to a network node of an EPS network which performs functions, such as the allocation of a UE IP address, packet screening & filtering, and the collection of charging data.

(34) A Serving gateway (Serving GW) is a network node of an EPS network which performs functions, such as mobility anchor, packet routing, idle mode packet buffering, and triggering an MME to page UE.

(35) A Policy and Charging Rule Function (PCRF) is a node of an EPS network which performs different QoS for each service flow and a policy decision for dynamically applying a charging policy.

(36) An Access Point Name (APN) is the name of an access point that is managed in a network and provides to UE. That is, an APN is a character string that denotes or identifies a PDN. Requested service or a network (PDN) is accessed via a P-GW. An APN is a name (character string, e.g., internet.mnc012.mcc345.gprs) previously defined within a network so that the P-GW can be searched for.

(37) A Tunnel Endpoint Identifier (TEID) is an end point ID of a tunnel set up between nodes within a network and is set in each section as a bearer unit of each terminal.

(38) A NodeB is an eNodeB of a UMTS network and installed outdoors. The cell coverage of the NodeB corresponds to a macro cell.

(39) An eNodeB is an eNodeB of an Evolved Packet System (EPS) and is installed outdoors. The cell coverage of the eNodeB corresponds to a macro cell.

(40) An (e)NodeB is a term that denotes a NodeB and an eNodeB.

(41) An MME is an abbreviation of a Mobility Management Entity, and it functions to control each entity within an EPS in order to provide a session and mobility for UE.

(42) A session is a passage for data transmission, and a unit thereof may be a PDN, a bearer, or an IP flow unit. The units may be classified into a unit of the entire target network (i.e., an APN or PDN unit) as defined in 3GPP, a unit (i.e., a bearer unit) classified based on QoS within the entire target network, and a destination IP address unit.

(43) A PDN connection is a connection from UE to a PDN, that is, an association (or connection) between UE represented by an IP address and a PDN represented by an APN. It means a connection between entities (i.e., UE-PDN GW) within a core network so that a session can be formed.

(44) UE context is information about the situation of UE which is used to manage the UE in a network, that is, situation information including an UE ID, mobility (e.g., a current location), and the attributes of a session (e.g., QoS and priority)

(45) A Non-Access-Stratum (NAS) is a higher stratum of a control plane between UE and an MME. The NAS supports mobility management and session management between UE and a network, IP address maintenance, and so on.

(46) RAT is an abbreviation of Radio Access Technology, and it means a GERAN, a UTRAN, or an E-UTRAN.

(47) Meanwhile, an embodiment proposed hereinafter may be implemented alone, or may be implemented by combining several embodiments.

(48) <Disclosure of the Present Specification>

(49) The present specification proposes a method which allows IMS entities of a home network to effectively acquire a PLMN-ID of a visited network in a state where a UE is roaming based on an HR scheme. In particular, the present specification proposes a method in which the IMS entities of the home network can acquire the PLMN-ID of the visited network from the UE in an IMS registration procedure. Further, the present specification also proposes a method of performing comparison and verification on the basis of the PLMN-ID acquired at an EPC level to ensure reliability of the PLMN-ID of the visited network, acquired from the UE.

(50) 1. Acquiring of PLMN-ID at EPC Level

(51) In the aforementioned initial attach procedure, upon receiving an attach request message from the UE 10, the MME 51 transmits an update location request (ULR) message to the HSS 54 in order to perform a location registration procedure of the UE 10. In this case, an international mobile station identify (IMSI), an MME ID, and a visited-PLMN-ID may be included in the ULR message. Herein, the visited-PLMN-ID indicates a PLMN-ID of a visited network which is serving the UE 10.

(52) The HSS 54 extracts the PLMN-ID of the visited network from the received ULR message and stores it.

(53) As a result, the HSS 53 may acquire the PLMN-ID of the visited network which is serving the UE 10 in the initial attach procedure.

(54) 2. Acquiring of PLMN-ID at IMS Level

(55) In the aforementioned IMS registration procedure, the P-CSCF 61 receives a register message from the UE 10. In this case, mobile country codes (MCC) and mobile network codes (MNC) are included in a P-Access-Network-info header of the register message.

(56) FIG. 11 is an exemplary view showing the concept of a PLMN-ID structure.

(57) As shown in FIG. 11, a PLMN-ID consists of MCC and MNC.

(58) Therefore, the P-CSCF 61 may generate a PLMN-ID of a visited network which is serving the UE 10, by using the MCC and MNC included in the P-Access-Network-info header of the received register message.

(59) The P-CSCF 61 adds the generated PLMN-ID to the P-Visited-Network-ID header of the register message, and temporarily store the generated PLMN-ID. In addition, the P-CSCF 61 transfers to the I-CSCF 64 the register message to which the PLMN-ID is added.

(60) In particular, the P-CSCF 61 may be implemented to determine whether the roaming UE 10 is roaming through an HR scheme using an S8 reference point, and to generate the PLMN-ID only when it is determined that the UE 10 is roaming through the HR scheme.

(61) The I-CSCF 64 transfers to the HSS 54 the PLMN-ID received from the P-CSCF 61 in a process of transmitting a user authorization request (UAR) message. The I-CSCF 64 may transfer the PLMN-ID to the HSS 54 by including it to the UAR message, or may transfer the PLMN-ID to the HSS 54 through an additional message.

(62) As a result, the HSS 54 may acquire the PLMN-ID of the visited network which is serving the UE 10 in the IMS registration procedure.

(63) 3. PLMN-ID Verification Scheme

(64) A PLMN-ID acquired at an IMS level is generated based on a register message transmitted from the UE 10, and thus reliability may be low. That is, when the UE 10 transmits the register message by maliciously changing it, the PLMN-ID acquired at the IMS level may be different from the PLMN-ID of the visited network which is actually serving the UE 10. Therefore, the HSS 54 may verify the PLMN-ID acquired at the IMS level in comparison with a PLMN-ID acquired at an EPC level.

(65) Specifically, the HSS 54 determines whether the PLMN-ID acquired at the IMS level is identical to the PLMN-ID acquired at the EPC level. In particular, the HSS 54 may be implemented to determine whether the roaming UE 10 is roaming through an HR scheme using an S8 reference point, and to determine whether the PLMN-ID acquired at the IMS level is identical to the PLMN-ID acquired at the EPC level only when it is determined that the UE 10 is roaming through the HR scheme. The HSS 54 may determine whether the UE 10 is roaming through the HR scheme on the basis of a roaming agreement or subscriber information of the UE 10.

(66) If the PLMN-ID acquired at the IMS level is not identical to the PLMN-ID acquired at the EPC level, the HSS 54 may determine that the PLMN-ID acquired at the IMS level is unreliable, and may transmit to the P-CSCF 61 a reject message for preventing IMS registration of the UE 10. In addition, the P-CSCF 61 transmits an IMS registration failure message to the UE 10.

(67) Otherwise, if the PLMN-ID acquired at the IMS level is identical to the PLMN-ID acquired at the EPC level, the HSS 54 and IMS entities perform the IMS registration procedure by using the PLMN-ID acquired at the IMS level.

(68) Specifically, in the same manner as the existing IMS registration procedure, the HSS 54 may transmit a UAA message to the I-CSCF 64 in response to the UAR message. In addition, the P-CSCF 61, the I-CSCF 64, and the S-CSCF 63 may perform the IMS registration procedure by using the PLMN-ID acquired at the IMS level. That is, when the UAA message is transmitted from the HSS 54 instead of the reject message, the IMS entities may determine that the PLMN-ID acquired at the IMS level is verified implicitly or indirectly, and may perform the IMS registration procedure by using the PLMN-ID acquired at the IMS level.

(69) Unlike this, the HSS 54 may transmit to the I-CSCF 64 or the P-CSCF 61 an indicator for informing that the PLMN-ID acquired at the IMS level is verified in addition to the UAR. In addition, only when the indicator is received from the HSS 54, the P-CSCF 61, the I-CSCF 64, and the S-CSCF 63 may perform the IMS registration procedure by using the PLMN-ID acquired at the IMS level. That is, when the indicator is transmitted directly from the HSS 54, the IMS entities may determine that the PLMN-ID acquired at the IMS level is verified, and may perform the IMS registration procedure by using the PLMN-ID acquired at the IMS level.

(70) Therefore, according to the present specification, the IMS entities may perform the IMS registration procedure and subsequent procedures by using the PLMN-ID acquired at the IMS level, without having to perform a process of registering a notification for a PLMN-ID change for the EPS entity and receiving the PLMN-ID reported from the EPS entity.

(71) For example, the P-CSCF 61 may perform non UE detectable emergency call or charging processing by using the PLMN-ID acquired at the IMS level. In addition, a telephony application server (TAS) may acquire the PLMN-ID acquired at the IMS level from the HSS 54 through an Sh interface.

(72) FIG. 12 is a signal flow diagram for explaining a method of acquiring a PLMN-ID according to the present specification.

(73) Referring to FIG. 12, the HSS 54 receives a ULR message received in an initial attach procedure of the UE 10 (S401). The HSS 54 extracts a PLMN-ID of a visited network from the ULR message and stores it (S403).

(74) Upon receiving a register message from the UE 10 (S405), the P-CSCF 61 generates the PLMN-ID on the basis of MCC and MNC included in a P-Access-Network-info header of the register message (S407). The P-CSCF 61 transmits the generated PLMN-ID by adding it to a P-Visited-Network-ID header of the register message, and temporarily stores the generated PLMN-ID (S409).

(75) The I-CSCF 64 transfers to the HSS 54 the PLMN-ID received from the P-CSCF 61 in a process of transmitting a UAR message (S411).

(76) The HSS 54 verifies the PLMN-ID by determining whether the PLMN-ID stored in step S403 is identical to the PLMN-ID generated in step S407 (S413).

(77) If the PLMN-ID stored in step S403 is not identical to the PLMN-ID generated in step S407, the HSS 54 transmits a reject message to the P-CSCF 61, and the P-CSCF 61 transmits an IMS registration failure message to the UE 10. Otherwise, if the PLMN-ID stored in step S403 is identical to the PLMN-ID generated in step S407, the HSS 54, the P-CSCF 61, the I-CSCF 64, and the S-CSCF 63 perform an IMS registration procedure by using the PLMN-ID generated in step S407. Details of the IMS registration procedure are the same as described above, and thus descriptions thereof will be omitted.

(78) FIG. 13 is a flowchart showing a method of acquiring a PLMN-ID according to a disclosure of the present specification.

(79) Referring to FIG. 13, the P-CSCF 61 receives a register message from the UE 10 (S510).

(80) The P-CSCF 61 generates a first V-PLMN identifier on the basis of the register message (S520). Specifically, the P-CSCF 61 may extract MCC and MNC from a P-Access-Network-info header of the register message, and may generate the first V-PLMN identifier by combining the extracted MCC and MNC. In particular, the P-CSCF 61 may generate the first V-PLMN identifier only for a case where the UE 10 is roaming to a V-PLMN through an HR scheme by using an S8 reference point.

(81) The P-CSCF 61 transfers the generated first V-PLMN identifier to the HSS 54 (S530). Specifically, the P-CCF 61 may add the first V-PLMN identifier to a P-Visited-Network-ID header of the register message, and may transmit the register message, to which the first V-PLMN identifier is added, to the HSS 54 through the I-CSCF 64. In this case, whether the first V-PLMN identifier corresponds to an identifier for the V-PLMN which is actually serving the UE 10 is verified through comparison with a second V-PLMN identifier acquired in an initial attach procedure of the UE 10.

(82) Upon receiving from the HSS an indicator which informs that the first V-PLMN identifier is verified, the P-CSCF 61 performs the IMS registration procedure of the UE 10 by using the first V-PLMN identifier (S540).

(83) FIG. 14 is a flowchart showing a method of acquiring a PLMN-ID according to another disclosure of the present specification.

(84) Referring to FIG. 14, the HSS 54 receives a ULR message from the MME 51 in an initial attach procedure (S610).

(85) The HSS 54 extracts a second V-PLMN identifier from the ULR message (S620).

(86) The HSS 54 receives the first V-PLMN identifier generated by the P-CSCF 61 (S630). Herein, the first V-PLMN identifier is a value acquired in an IMS registration procedure of the UE 10.

(87) The HSS 54 verifies whether the first V-PLMN identifier corresponds to an identifier for the V-PLMN which is actually serving the UE 10 by comparing the first V-PLMN identifier and the second V-PLMN identifier (S640). Specifically, the HSS 54 may verify the first V-PLMN identifier only for a case where the UE 10 is roaming to the V-PLMN through an HR scheme by using an S8 reference point. The HSS 54 may determine whether the UE 10 is roaming through the HR scheme by using the S8 reference point on the basis of subscriber information for the UE 10 and a roaming agreement between the H-PLMN and the V-PLMN.

(88) If the first V-PLMN identifier is different from the second V-PLMN identifier, the HSS 54 transmits to the P-CSCF 61 a reject message for rejecting IMS registration of the UE 10 (S650). In this case, the P-CSCF 61 ends the IMS registration procedure by transmitting an IMS registration failure message to the UE 10.

(89) In addition, if the first V-PLMN identifier is identical to the second V-PLMN identifier, the HSS 54 transmits to the I-CSCF 64 a UAA message together with a direct or indirect indicator for informing that the first V-PLMN identifier is verified (S660). In this case, the indicator for informing that the first V-PLMN identifier is verified may be any one of additional information different from UAA and information included in the UAA. In this case, IMS entities perform the IMS registration procedure by using the first V-PLMN identifier.

(90) The aforementioned embodiments of the present invention can be implemented through various means. For example, the embodiments of the present invention can be implemented in hardware, firmware, software, combination of them, etc.

(91) FIG. 15 is a block diagram showing a structure of a UE and a P-CSCF according to a disclosure of the present specification.

(92) The UE 100 includes a processor 101, a memory 102, and an RF unit 103. The memory 102 is connected to the processor 101 to store various information for driving the processor 101. The RF unit 103 is connected to the processor 101 to transmit and/receive a wireless signal. The processor 101 implements a suggested function, procedure, and/or method.

(93) The P-CSCF 200 includes a processor 201, a memory 202, and a radio frequency RF unit 203. The memory 202 is connected to the processor 201 to store various information for driving the processor 201. The RF unit 203 is connected to the processor 201 to transmit and/receive a wireless signal. The processor 201 implements a suggested function, procedure, and/or method. An operation of the base station 200 according to the above embodiment may be implemented by the processor 201.

(94) The processor may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and/or a data processor. A memory may include read-only memory (ROM), random access memory (RAM), a flash memory, a memory card, a storage medium, and/or other storage devices. An RF unit may include a baseband circuit to process an RF signal. When the embodiment is implemented, the above scheme may be implemented by a module procedure, function, and the like to perform the above function. The module is stored in the memory and may be implemented by the processor. The memory may be located inside or outside the processor, and may be connected to the processor through various known means.

(95) In the above exemplary system, although methods are described based on a flowchart including a series of steps or blocks, the present invention is limited to an order of the steps. Some steps may be generated in the order different from or simultaneously with the above other steps. Further, it is well known to those skilled in the art that the steps included in the flowchart are not exclusive but include other steps or one or more steps in the flowchart may be eliminated without exerting an influence on a scope of the present invention.