Method of processing downlink data notification message and server therefore

Abstract

The present invention provides a method for processing paging from a server managing mobility in a mobile communication network. The method comprises: receiving from a network node a notification with respect to downlink data to be relayed to user equipment; transmitting a paging signal with respect to the user equipment to one or more base stations; receiving a context request with respect to the user equipment from a different server; recognizing that the paging will fail if the context request with respect to the terminal is received before receiving a reply to the paging; relaying a context reply to the different server depending on the recognition; and transmitting a processing request message with respect to the downlink data to the network node.

Claims

1. A method of processing a downlink data notification (DDN) message in a mobile communication network, the method comprising: receiving, by a transceiver in a server, a DDN message from a serving gateway which buffers a downlink data to be delivered to a terminal; and transmitting, by the transceiver in the server, a message for requesting the serving gateway to keep buffering the downlink data and wait to receive a modify bearer request message from another server, if the terminal is under a tracking area update (TAU) procedure and if the server does not receive a response to a paging signal, but receives a context request message from the another server according to the TAU procedure.

2. The method of claim 1, further comprising: transmitting the paging signal to the terminal before completing the TAU procedure.

3. The method of claim 2, further comprising: not transmitting a reject message if the server does not receive the response to the paging signal from the terminal and if the server receives the context request message from the another server during the TAU procedure.

4. The method of claim 1, further comprising: receiving the context request message from the another server; and transmitting a context response message to the another server, wherein the context response message includes at least one of: information on a paging procedure; information required for allowing the another server to perform the paging procedure or information required to setup a user plane bearer; and information for requesting not to perform a reselection or relocation of the serving gateway.

5. The method of claim 4, wherein the information on the paging procedure includes: information for indicating that the DDN message has been received; information for indicating that the paging procedure for the terminal is being performed; and information for informing that the user plane bearer is needed to be set up in the another server.

6. The method of claim 3, wherein if the server does not receive the response to the paging signal from the terminal and if the server receives the context request message from the another server, the server is aware that a paging procedure will have failed.

7. The method of claim 1, wherein the transmitted message triggers a retransmission of the DDN message to the another server.

8. A server managing mobility for processing a downlink data notification (DDN) message in a mobile communication network, the server comprising: a transceiver configured to receive a DDN message from a serving gateway which buffers a downlink data to be delivered to a terminal; and a controller configured to control the transceiver to transmit a message for requesting the serving gateway to keep buffering the downlink data and wait to receive a modify bearer request message from another server, if the terminal is under a tracking area update (TAU) procedure and if the server does not receive a response to a paging signal, but receives a context request message from the another server according to the TAU procedure.

9. The server of claim 8, wherein the controller is further configured to transmit the paging signal to the terminal before completing the TAU procedure.

10. The server of claim 9, wherein the controller is further configured to not transmit a reject message if the server does not receive the response to the paging signal from the terminal and if the server receives the context request message from the another server during the TAU procedure.

11. The server of claim 8, wherein the controller is further configured to: receive the context request message from the another server, and transmit a context response message to the another server, wherein the context response message includes at least one of: information on a paging procedure; information required for allowing the another server to perform the paging procedure or information required to setup a user plane bearer; and information for requesting not to perform a reselection or relocation of the serving gateway.

12. The server of claim 11, wherein the information on the paging procedure includes: information for indicating that the DDN message has been received; information for indicating that the paging procedure for the terminal is being performed; and information for informing that the user plane bearer is needed to be set up in the another server.

13. The server of claim 10, wherein if the server does not receive the response to the paging signal from the terminal and if the server receives the context request message from the another server, the server is aware that a paging procedure will have failed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view illustrating the structure of an evolved mobile communication network.

(2) FIG. 2 is an exemplary view illustrating functions of main nodes of a common E-UTRAN and a common EPC.

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

(4) FIG. 4 is another exemplary view illustrating the structure of a radio interface protocol in a user plane between a UE and a base station.

(5) FIG. 5 is a flowchart illustrating a random access procedure in 3GPP LTE.

(6) FIG. 6 illustrates a connection process in a radio resource control (RRC) layer.

(7) FIG. 7 illustrates an example in which a UE geographically relocates.

(8) FIG. 8 illustrates a problem that may arise in the example shown in FIG. 7.

(9) FIG. 9 is an exemplary view illustrating a TAU (Tracking Area Update) procedure.

(10) FIG. 10 is an exemplary view illustrating a TAU (Tracking Area Update) procedure as proposed herein.

(11) FIG. 11 is an exemplary view illustrating a TAU (Tracking Area Update) according to a first embodiment of the present invention.

(12) FIG. 12 is an exemplary view illustrating a TAU (Tracking Area Update) according to a second embodiment of the present invention.

(13) FIG. 13 is an exemplary view illustrating a TAU (Tracking Area Update) according to a third embodiment of the present invention.

(14) FIG. 14 is an exemplary view illustrating a TAU (Tracking Area Update) according to a fourth embodiment of the present invention.

(15) FIG. 15 is an exemplary view illustrating a TAU (Tracking Area Update) according to a fifth embodiment of the present invention.

(16) FIG. 16 is an exemplary view illustrating a TAU (Tracking Area Update) according to a sixth embodiment of the present invention.

(17) FIG. 17 is an exemplary view illustrating a TAU (Tracking Area Update) according to a seventh embodiment of the present invention.

(18) FIG. 18 is a view illustrating an exemplary protocol and interfaces between a UE, an eNodeB, and an MME.

(19) FIG. 19 is a block diagram illustrating the configuration of an MTC device 100, an MME 510, and an SGSN 520 according to an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(20) 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.

(21) 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.

(22) 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.

(23) 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.

(24) 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.

(25) 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.

(26) 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.

Definition of Terms

(27) 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.

(28) UMTS: stands for Universal Mobile Telecommunication System and means a 3rd generation mobile communication network.

(29) UE/MS: User Equipment/Mobile Station. Means a terminal device.

(30) EPC: stands for Evolved Packet Core and means a core network supportive of a long term evolution (LTE) network. An evolved version of UMTS

(31) EPS: stands for Evolved Packet System and means a mobile communication system including a UE, an access network including LTE, and an EPC

(32) PDN (Public Data Network): an independent network in which a service providing server is located

(33) PDN connection: connection from UE to PDN, i.e., association (connection) between a UE represented with an IP address and a PDN represented with an APN (access point name)

(34) PDN-GW (Packet Data Network Gateway): a network node of an EPS network performing functions such as UE IP address allocation, packet screening & filtering, and charging data collection

(35) Serving GW (Serving Gateway): a network node of an EPS network performing functions such as mobility anchor, packet routing, idle mode packet buffering, and triggering MME to page UE

(36) PCRF (Policy and Charging Rule Function): an EPS network node performing policy decision for dynamically applying QoSs and billing policies differentiated per service flow

(37) APN (Access Point Name): name of an access point managed by a network, provided from a UE, i.e., a character string for denoting a PDN or distinguishing a PDN from another. Accessing a requested service or network (PDN) gets through a corresponding P-GW, and an APN is a name (e.g., internet.mnc012.mcc345.gprs) pre-defined in the network to be able to discover the P-GW.

(38) TEID (Tunnel Endpoint Identifier): End point ID of a tunnel configured between nodes in a network. A TEID is configured per section by the bearer of each UE.

(39) NodeB: a UMTS network base station. A NodeB is installed outdoors and corresponds in cell coverage size to a macro cell.

(40) eNodeB: an EPS (Evolved Packet System) base station and is installed outdoors. An eNodeB corresponds in cell coverage size to a macro cell.

(41) (e)NodeB: collectively denotes NodeB and eNodeB

(42) MME: stands for Mobility Management Entity and plays a role to control each entity in an EPS to provide mobility and session for a UE.

(43) Session: a pathway for data transmission. The unit of session may include PDN, bearer, and IP flow which respectively correspond the unit of the overall target network (unit of APN or PDN), the unit distinguished by QoS therein (unit of bearer), and unit of destination IP address.

(44) PDN connection: a connection from a UE to a PDN, i.e., an association (connection) between a UE represented with an IP address and a PDN represented with an APN. This means a connection (UE-PDN GW) between entities in a core network to form a session.

(45) UE Context: information on UE's context used to manage UE in network, i.e., context information consisting of UE id, mobility (e.g., current location), and session attribute (QoS, or priority)

(46) OMA DM (Open Mobile Alliance Device Management): a protocol designed for managing mobile devices such as mobile phones, PDAs, or portable computers and performs functions such as device configuration, firmware upgrade, and error reporting.

(47) OAM (Operation Administration and Maintenance): denotes a group of network management functions displaying network faults and providing capability information, diagnosis and data.

(48) NAS configuration MO (Management Object): MO (Management Object) used to configure in UE parameters associated with NAS functionality

(49) Hereinafter, the present disclosure is described with reference to the accompanying drawings.

(50) FIG. 9 shows an exemplary TAU (Tracking Area Update) procedure.

(51) 1) In idle mode, the UE 100 moves into the coverage of the target eNodeB 200b. Accordingly, a TAU (Tracking Area Update) procedure is determined to start.

(52) 2) Then, the UE 100 sends a TAU request message to the target eNodeB 200b.

(53) 3) Then, the target eNodeB 200b determines a responsible MME. In this case, assume, for example, that the target MME 510b is determined as a proper responsible MME. The target eNodeB 200b transfers the TAU request message to the target MME 510b. In this case, assume that the S-GW 520 is not changed.

(54) 4-5) Then, the target MME 510b sends the UE's context request (e.g., Context Request) to the source MME 510a, and in response, receives a context response (e.g., Context Response). This is a process to obtain PDN connection-related information and EPS bearer-related information from the source MME 510a.

(55) 6) The UE 100 conducts an authentication/security procedure with the target MME 510b, and the target MME 510b conducts a security procedure with the HSS 590.

(56) 7) Meanwhile, the target MME 510b transmits to the source MME 510a a context acknowledge (e.g., Context Acknowledge) message in response to obtaining the context.

(57) 8) Subsequently, the target MME 510b, since the S-GW 520 is not changed by the TAU, transmits to the S-GW 520 a bearer modification request message (e.g., Modify Bearer Request), not a session creation request message (e.g., Create Session Request).

(58) 9-11) Then, the S-GW 520 transmits a bearer modification request message to the PDN-GW 530 as necessary. The PDN-GW 530 performs an IP-CAN session modification procedure as necessary. The PDN-GW 530 transmits a bearer modification response message (e.g., Modify Bearer Response) to the S-GW 520.

(59) 12) Then, the S-GW 520 transmits a bearer modification response message to the target MME 510b.

(60) 13) Then, the target MME 510b transmits to the HSS 590 a location update request message (e.g., Update Location Request).

(61) 14-15) Then, the HSS 590 transmits a location cancel message (e.g., Cancel Location) to the source MME 510a, and the source MME 510a transmits a location cancel acknowledgement message (e.g., Cancel Location Ack) to the HSS 590.

(62) 16) Then, the HSS 590 transmits a location update acknowledgement message (e.g., Update Location Ack) to the target MME 510b.

(63) 17-18) Then, the target MME 510b transmits a TAU accept message (e.g., TAU accept) to the UE 100 through the target eNodeB 200b, and the UE 100 transmits a TAU complete message (e.g., TAU Complete) to the target MME 510b as necessary.

(64) Hereinafter, the following Table 2 to Table 9 show the messages used in each process.

(65) First, the TAU request message may contain one or more pieces of information as shown in Table 2.

(66) TABLE-US-00002 TABLE 2   Protocol discriminator Security header type Tracking area update request message identity EPS update type NAS key set identifier Old GUTI Non-current native NAS key set identifier GPRS ciphering key sequence number Old P-TMSI signature Additional GUTI NonceUE UE network capability Last visited registered TAI DRX parameter UE radio capability information update needed EPS bearer context status MS network capability Old location area identification TMSI status Mobile station classmark 2 Mobile station classmark 3 Supported Codecs Additional update type Voice domain preference and UE's usage setting Old GUTI type Device properties MS network feature support TMSI based NRI container

(67) The EPC Update type information element shown in Table 2 above may contain the following bits.

(68) TABLE-US-00003 TABLE 3   EPC Update Type Value 000: indicates TAU 001: indicates joint update of TAU/LA(Location Area) 010: indicates joint update of TAU/LA (Location Area) together with IMSI attach 011: indicates periodic update 100: unused (if used, interpreted as TAU) 101: unused (if used, interpreted as TAU) “Active” flag (octet 1, bit 4) 0: bearer creation not requested 1: bearer creation requested

(69) Meanwhile, the above-described context request message may contain the information elements shown in the following Table 4.

(70) TABLE-US-00004 TABLE 4 Information elements Conditions/descriptions IMSI should be included in case UE successfully authenticated GUTI A new target MME should include over S10 interface may be included if SRVCC procedure from UTRAN/GERN to E-UTRAN is available Complete a new target MME may include if previous TAU request source MME needs it for acknowledgement message of no decision RAT Type indicates what radio access technology is in use Target if available, may be included for previous PLMN ID MME to determine whether unused authentication vector is to be distributed MME node is transferred by a new target MME if the name new target MME and associated S-GW both support SR

(71) Meanwhile, the context response message may contain the information elements shown in the following Table 5.

(72) TABLE-US-00005 TABLE 5 Information element Conditions/descriptions IMSI IMSI necessarily included except emergency even when UE does not have UICC MME/SGSN UE Included in case at least one PDN connection EPS PDN is present for UE. Connections SGW node name Indicates the identifier that has been used to identify S-GW by previous source MME Trace Information may be included in case session tracking is activated Subscribed RFSP May be included during mobility procedure Index between MMEs UE Time Zone Included by source MME MME node name Transmitted by previous source MME in case previous MME and associated S-GW both support ISR

(73) The information on the PDN connection in the context response message may contain the information elements shown in the following Table 6.

(74) TABLE-US-00006 TABLE 6 APN Restriction Indicates limitations on combinations of APN types for APNs related to bearer context. Target MME or SGSN may determine the largest APN limitation using the APN limitations. Linked EPS Indicates basic bearer of PDN connection Bearer ID PGW node name may be included in case source MME has the overall name (e.g., FQDN) of PDN GW Bearer Contexts a number of pieces of information of such type may be included Charging May be included in case billing information is characteristics offered by HSS to MME Change Reporting May be included whenever available by source Action MME

(75) The bearer context information included in the PDN connection information in the context response may contain the information shown in the following Table 7.

(76) TABLE-US-00007 TABLE 7 Information elements Conditions/descriptions PGW S5/S8 IP May be included for GTP-based S5/S8 Address and TEID for user plane Bearer Level QoS BSS Container MME may include packet flow ID, radio priority, SAPI, PS handover XID parameter in TAU/RAU/handover procedure-related message Transaction may be transmitted over S3/S10/S16 in case UE Identifier supports A/Gb and/or Iu mode

(77) The TAU accept message may contain the information shown in the following Table 8.

(78) TABLE-US-00008 TABLE 8 Information Description TAU accept message message identifier identifier TAU result indicate result of update, e.g. success or fail T3412 value timer value for periodic TAU T3402 value timer starting upon TAU failure T3412 extended extended value of T3412 for further value lengthening periodic TAU

(79) In Table 8 above, the T3412 value is a value for allowing the UE 100 to conduct periodic TAU. In order to reduce network load by such periodic TAU, the T3412 extended value is present which allows TAU to be conducted at a longer period. The T3412 extended value may be set up in the MME or may be retained as subscriber information in the HSS 540.

(80) 19) Meanwhile, while the UE 100 performs a TAU procedure as above, as described in the Background section, the source MME 510a has data to transmit to the UE 10, it may transmit a paging signal to the source eNodeB 200a. The UE 100 has moved to the inside of the coverage of the target eNodeB 200b, and thus, it cannot receive a paging signal from the source eNodeB 200a.

(81) The source MME 510a, unless receiving from the source eNodeB 200a a response to the paging signal until before a paging-related time value, e.g., the T3413 timer expires, the source MME 510a re-transmits the paging signal. The paging-related time value, e.g., the T3413 timer, may be a timer for re-transmission of the paging signal.

(82) Resultantly, the paging signal is re-transmitted a predetermined number of times, and the caller is encountered with the situation where it keeps receiving the ring back tone.

(83) Thereafter, if reaching the predetermined number of times, the source MME 510a reports paging failure to the S-GW. As a result, the calling side has inconvenience of call failure without any special reason, and the user of the UE 100 does not produce a bell sound or vibration because he has not received the paging for call reception, and thus, the user cannot receive any notification.

(84) Schemes to address such inconvenience are now described. A brief description, prior to advancing to the details, is given below with the following two schemes.

(85) (1) A Scheme for Enhancing Quality of User Service by Reducing Call Reception Delay

(86) The target MME 510b, after receiving a context response from the source MME 510a during a TAU procedure, i) identifies whether there is a specific indication as suggested herein. The specific indication indicates that the source MME 510a has done an activity for conducting paging on the UE or that the target MME 510b has received a downlink data notification on the UE from the S-GW. Subsequently, the target MME 510b ii) includes the specific indication in a TAU accept message and transmits the same to the UE 100. The specific indication may be contained in the TAU accept message to indicate that there is an operation that should be conducted when receiving a paging message or to inform the UE of presence of downlink data. The target MME 510b iii) conducts an operation for separately configuring a user plane bearer. For example, the target MME 510b transmits an initial context setup message to the target eNodeB 200b or may conduct a process for activating the user plane bearer of radio section for downlink data transmission.

(87) (2) A Scheme for Avoiding Waste of Network Resources Due to Repetitive Paging

(88) The target MME 510b, when receiving a context response from the source MME 510a during a TAU procedure, i) identifies whether there is a specific indication as suggested herein. The specific indication indicates that the source MME 510a has done an activity for conducting paging on the UE or that the target MME 510b has received a downlink data notification on the UE from the S-GW. ii) Subsequently, the target MME 510b may transmit to the source MME 510a a message for stopping paging. iii) Further, the target MME 510b may inform the S-GW that the previous downlink data notification should be canceled by separately sending to the S-GW information indicating that the UE has moved. The information allows the S-GW to stop waiting for a response to the paging transmitted previously. More actively, the target MME 510b may send to the source MME 510a a message for requesting to stop paging.

(89) The above described two schemes may be summarized as follows in light of activity.

(90) 1) The target MME 510b determines whether the UE to which a paging signal is to be sent has moved, and if so, whether a TAU procedure proceeds. For example, the target MME 510b determines whether the UE to which a paging signal is to be transmitted has moved during the context exchange process between the target MME 510b and the source MME 510a and whether the TAU procedure is underway, and accordingly, the target MME 510b may request the source MME 510a to stop paging.

(91) 2) The target MME 510b may inform the S-GW 520 of what it has recognized in process 1) above during the message exchange for modifying bearer between the target MME 510b and the S-GW 520. In this process, the target MME 510b may send a request for stopping paging to the S-GW 520. Or, when receiving what has been recognized, the S-GW 520 may recognize that the paging procedure is not further required and conduct a subsequent procedure for canceling/stopping the paging procedure.

(92) 3) When transmitting a TAU accept message to the UE, the target MME 510b may add to the message information for enabling the UE 100 to start a task that the UE 100 should do when receiving a paging signal in the future. This allows the UE to get ready before receiving a paging signal to reduce a delay before receiving the paging signal, thus immediately enabling a user plane bearer to be set up.

(93) 4) When receiving the TAU accept message, the UE 100 immediately performs setup of a user plane bearer. Or, setup of a user plane bearer which is initiated by a network is immediately done by the network.

(94) A more detailed description is given below in connection with the drawings.

(95) FIG. 10 is a view illustrating an exemplary TAU (Tracking Area Update) procedure as proposed herein.

(96) The overall process is similar to that described above in connection with FIG. 9. Hereinafter, differences between the two processes are primarily described, with no repetitive description made.

(97) As per the procedure illustrated in FIG. 10, a condition is added to trigger the setup of a user plane bearer to put the setup of the user plane bearer in an earlier time.

(98) 1) The S-GW 520, upon reception of downlink data to be transmitted to the UE 100, stores the downlink data in a buffer and identifies which MME is in charge of the UE 100.

(99) 2) The S-GW 520 transmits a downlink data notification to the source MME 510a. The downlink data notification may include an ARP, an EPS, a bearer ID, etc.

(100) 3) The source MME 510a transmits a downlink data notification acknowledgement message to the S-GW 520.

(101) 4) Subsequently, the source MME 510a transmits paging signals to all the eNodeBs (including the source eNodeB 200a) belonging to the tracking area where the UE 100 is in registration in order to convey the paging signal to the UE 100. In this case, the source MME 510a may use the EPS bearer ID included in the downlink data notification message received from the S-GW 520 in order to apply and control a paging-related policy. That is, the source MME 510a may identify the EPS bearer context information stored in the MME by the EPS bearer ID.

(102) However, the idle UE 100 departs from the coverage of the source eNodeB 200a to the coverage of the target eNodeB 200b. Accordingly, the UE 100 cannot receive the paging signal.

(103) 5-6) Accordingly, the UE 100 transmits a TAU request message to the target MME 510b through the target eNodeB 200b, and the target MME 510b transmits a context request message to the source MME 510a.

(104) 7) The source MME 510a transmits a context response message to the target MME 510b. In this process, the source MME 510a may inform the target MME 510b that the paging signal has been transmitted to the UE 100. This information may be direct information or may be transferred in various forms of implicit information so that the target MME 510b may recognize the same. Or, the target MME 510b may realize any problematic situation based on additional information collected from the eNodeB or other network node.

(105) 8) An authentication/security procedure is performed as described above.

(106) 9) The target MME 510b transmits a context acknowledgement message to the source MME 510a. In this process, the target MME 510b may include in the message information for canceling or stopping the existing paging.

(107) 10) The target MME 510b transmits a bearer modification request message to the S-GW 520. In this process, the target MME 510b may inform the S-GW 520 of what it has recognized. Additionally, in this process, the target MME 510b may include in the message information for canceling or stopping paging. That is, when obtaining the recognized information, the S-GW 520 realizes no further paging process is required, conducting a subsequent procedure for canceling or stopping the previous paging.

(108) 11) The S-GW 520 transmits a bearer modification response message to the target MME 510b. In this process, the S-GW 520 may include in the message information indicating advancing the time of setup of a user plane bearer. This information may contain information that may have an effect on when the target MME 510b creates a message to be transmitted to the UE 100, and additional information to be used for setup of a user plane bearer, if needed, may be transmitted together. Or, the information included in the downlink data notification may be additionally included.

(109) 12) As described above, the target MME 510b transmits a location update request message to the HSS 590.

(110) 13-14) As described above, the HSS 590 transmits a location cancel message to the source MME 510a and receives a location cancel acknowledgement message. In this case, some of the above mentioned pieces of information may be stored in the HSS 590.

(111) 15) The target MME 510b transmits a TAU accept message to the UE 100. In this process, the TAU accept message may include an indication for indicating that setup of a user plane bearer be immediately performed like the UE 100 is the UE targeted for the previous paging and a service request procedure should be performed in response to the paging. For example, the indication may be of a form similar to the “active flag.” The “active flag” is included in the TAU request message as shown in Table 2, and this may be included in the TAU accept message according to an embodiment of the present invention.

(112) Meanwhile, the target MME 510b may first initiate an operation for user plane bearer setup. For example, in case the active flag is conventionally included in the TAU request message, the user plane bearer setup may be performed immediately when the TAU accept message is transmitted. As an application thereto, the target MME 510b may include the active flag in the TAU accept message and transmit the same, so that the user plane bearer setup procedure may be immediately conducted.

(113) 16) The UE may transmit a TAU complete message to the source MME 510a as necessary.

(114) 17) Meanwhile, the UE 100 may perform a service request procedure when receiving the TAU accept message like it receives a paging signal. For example, in case the TAU accept message includes the active flag, it may perform a service request procedure like it received a paging signal. Or, other processes necessary for user plane bearer setup (procedure for setup of a radio bearer between the UE and the eNodeB) may come along.

(115) FIG. 11 is a view illustrating an exemplary TAU (Tracking Area Update) procedure according to a first embodiment of the present invention.

(116) FIG. 11 illustrates a scheme that may be conducted by the source MME 510a according to the first embodiment of the present invention.

(117) All the processes shown are similar to those shown in FIGS. 9 and 10. Hereinafter, differences between the two schemes are primarily described, with no repetitive description made.

(118) 1-5) the same as those shown in FIG. 10

(119) 6-7) The target MME 510b transmits a context request message to the source MME 510a to obtain EPS bearer context information of the UE.

(120) 7) The source MME 510a, if receiving the context request in the state where it has transmitted a paging signal after receiving a downlink data notification message as described above, happens to recognize that the paging may fail.

(121) Accordingly, the source MME 510a includes one of the following information pieces in the context response message to be sent to the target MME 510b and transmits the same.

(122) TABLE-US-00009 TABLE 9 i) Indication to simply inform occurrence of problem in paging  downlink data notification for the UE has been received  paging for the UE is underway  target MME 510b requires paging or user plane bearer setup This information may be direct or may be transmitted in various forms of implicit information so that target MME 510b may recognize the same ii) Information necessary to trigger active behavior of target MME 510b Additionally, source MME 510a may transmit information necessary for target MME 510b to directly perform paging or information necessary for user plane bearer setup (for example, information pieces included in the downlink data notification) iii) In CSFB MT call scenario, source MME 510a receives a paging request from MSC, and considering this situation, source MME 510a transmits to target MME 510b information indicating whether the call for current paging is CS (circuit switching) call or PS (packet switching) call also. Besides, information received from MSC may be sent as well. iv) Source MME 510a requests target MME 510b not to perform S-GW reselection (or relocation). S-GW swapping may occur during TAU procedure, e.g., due to load balancing. As such, in case ME with downlink data relocates to a new MME during paging, if S-GW swapping happens, a reception call has a high chance of failure. This is to prevent possible S- GW swapping.

(123) 8) Then, the source MME 510a, even when not receiving a response from the UE until the paging timer, e.g., the T3423 timer, expires, {circle around (1)} does not re-transmit a paging signal, {circle around (2)} nor does the source MME 510a send a message for the paging failure (see TS 29.274, Downlink Data Notification Failure Indication) to the S-GW 520. According to the prior art, the source MME 510a is able to conduct a paging re-transmission policy, and in case the S-GW 520 receives a message for paging failure, it deletes the downlink data buffered for the UE. The above is to prevent this.

(124) In a more active scheme, the source MME 510a may transmit a downlink data handling request including one of the following information pieces to the S-GW 520.

(125) TABLE-US-00010 TABLE 10 Request to maintain buffering the downlink data request to re-transmit downlink data notification after recognizing target MME 510b

(126) Process 8) above may be performed in conjunction with other processes without bothered by the order as shown.

(127) 9) similar to the process shown in FIG. 10.

(128) 10) The target MME 510b transmits a context acknowledgement message to the source MME 510a. In this case, the target MME 510b may include in the context acknowledgement message information relating to paging handling such as information to request the source MME 510a to cancel or stop the existing paging. After receiving this message, the source MME 510a may send a downlink data handling request message to the S-GW 520 as in process 8) above.

(129) 11-17) similar to the process shown in FIG. 10.

(130) FIG. 12 is a view illustrating an exemplary TAU (Tracking Area Update) procedure according to a second embodiment of the present invention.

(131) FIG. 12 illustrates a scheme that may be conducted by the target MME 510b according to the second embodiment of the present invention. That is, according to the second embodiment, the target MME 510b may immediately transmit a paging signal.

(132) All the processes shown are similar to those shown in FIGS. 9 to 11, and accordingly, differences between the two schemes are primarily described, with no repetitive description made.

(133) 1-8) similar to each process shown in FIG. 11.

(134) 9a-9b) as in process 7) of FIG. 11, when receiving a context response, the target MME 510b immediately performs paging if recognizing a problematic situation (where the source MME 510a has been transmitting a paging signal to the UE or there is downlink data for the UE).

(135) In this case, various schemes may come along to perform paging.

(136) As a first scheme, the target MME 510b immediately creates a TAI list for the UE 100 and transmits paging signals to all the eNodeBs included in the list. Of course, even according to the prior art, the MME may create a TAI list during a TAU procedure, includes the list in a TAU accept message, and sends the same to the UE while transmitting paging signals to all the eNodeBs in the list. However, according to the second embodiment of the present invention, the target MME 510b recognizes a problematic situation and conducts paging immediately when receiving the context response message, thus advancing the time of paging, which makes the present invention distinct from the prior art.

(137) As a second scheme, the target MME 510b may know which eNodeB it has been through from the TAU request message, i.e., in the coverage of which eNodeB the UE is in. Accordingly, rather than sending paging signals to all the eNodeBs in the TAI list, the target MME 510b may transmit a paging signal only to a corresponding eNodeB.

(138) As a third scheme, the target MME 510b may have information regarding more exact location of the UE, such as the cell ID of the UE, from the TAU request message. Accordingly, the target MME 510b may add a specific indication or cell ID information to a paging signal that is to be sent to a corresponding eNodeB rather than sending paging signals to all the eNodeBs in the TAI list, so that the paging signal is sent to the corresponding cell only.

(139) Meanwhile, when receiving the paging signal, the UE 100 may conduct an RRC connection configuration procedure or transmit a service request message as shown in FIGS. 15 and 16.

(140) Procedures 9a) and 9b) above may be done together with other processes.

(141) 10-17) similar to the process shown in FIG. 11.

(142) FIG. 13 is a view illustrating an exemplary TAU (Tracking Area Update) procedure according to a third embodiment of the present invention.

(143) FIG. 13 illustrates a scheme that may be performed by the target MME 510b according to the third embodiment of the present invention. The target MME 510b may send a request for downlink data notification to the S-GW 520.

(144) All of the processes shown are similar to those shown in FIGS. 9 to 12. The description thus focuses on the differences between the two schemes, with similar processes skipped therefrom.

(145) 1-8) similar to those shown in FIGS. 11 to 13.

(146) 9a) as in process 7) of FIG. 11, when receiving a context response, the target MME 510b may recognize a problematic situation (where the source MME 510a has been sending a paging signal to the UE or there is downlink data for the UE).

(147) 10) similar to the process shown in FIG. 12.

(148) 11) the target MME 510b transmits a bearer modification request message to the S-GW 520. In this case, the target MME 510b has recognized the problematic situation as described above, and thus the target MME 510b includes in the bearer modification request message information indicating the problematic situation or information requesting to re-transmit a downlink data notification.

(149) Then, the S-GW 520 may re-transmit the downlink data notification message to the target MME 510b. Further, the S-GW 520 may conduct a subsequent procedure and a task for organizing the downlink data notification message sent from the source MME 510a (for example, performing an internal procedure to cancel or stop the previous paging or sending a message for paging canceling or stopping to the source MME 510a).

(150) When receiving the downlink data notification message from the S-GW 520, the target MME 510b may conduct a procedure for paging. Or, according to a combination of other embodiments of the present invention, the target MME 510b may conduct paging optimization or create and transmit a TAU accept message including specific information or a message for user plane bearer setup.

(151) 12) the S-GW 520 transmits a bearer modification request response message to the target MME 510b. In this case, the bearer modification request response message may contain information indicating to advance the time of user plane bearer setup. This information may have influence when the target MME 510b creates a message to be sent to the UE 100, and if needed, additional information used to for user plane bearer setup may be transmitted together. Or, the information included in the downlink data notification may be additionally included.

(152) 13) the target MME 510b may register the UE's new location in the HSS 590. In this case, some of what has been mentioned above may be stored in the HSS 590.

(153) 13-17) similar to the process shown in FIG. 11.

(154) FIG. 14 is a view illustrating an exemplary TAU (Tracking Area Update) procedure according to a fourth embodiment of the present invention.

(155) FIG. 14 illustrates a scheme that may be conducted by the target MME 510b according to the fourth embodiment of the present invention. The target MME 510b may transmit an indication of transmission of a service request to the UE.

(156) Most of the processes shown are similar to those shown in FIGS. 9 to 13. The description focuses on the differences between the two schemes, with similar processes skipped therefrom.

(157) 1-8) similar to the processes shown in FIGS. 11 to 13.

(158) 9a) as in process 7) of FIG. 11, when receiving a context response, the target MME 510b may recognize a problematic situation (where the source MME 510a has been sending a paging signal to the UE or there is downlink data for the UE).

(159) 9b) then, the source MME 510a may send to the UE 100 an indication including one of the following information pieces independently or in conjunction with several combinations of the embodiments of the present disclosure. Although in the drawings the indication is in the form of a new NAS (Non-Access Stratum) message, the indication may be included and transmitted in a TAU accept message.

(160) TABLE-US-00011 TABLE 11  should immediately perform user plane bearer setup like service request should be conducted in response to paging  information regarding, upon paging response, whether to send a service request (for receiving general PS data) or an extended service request (for CSFB (Circuit Switch-Fallback) MT call)  call type information indicating which one of a user plane bearer setup procedure for CS calland a user plane bearer setup procedure for PS call is needed

(161) The above process may be conducted in conjunction with a TAU procedure.

(162) Then, the UE 100 may prepare for a subsequent procedure based on the information shown in Table 11. Accordingly, the subsequent procedure may be very quickly done.

(163) 10-15) similar to the process shown in FIG. 11.

(164) 16) the target MME 510b transmits a TAU accept message.

(165) The TAU accept message may include an indication as provided in process 9b as described above. The indication included in the TAU accept message may be, e.g., Active flag as described above.

(166) The active flag is the one that used to be included in the TAU request message. According to an embodiment of the present invention, the same may be included in a TAU accept message. The target MME 510b includes the active flag in the TAU accept message and transmits the same, so that the UE may immediately perform a user plane bearer setup procedure.

(167) FIG. 15 is a view illustrating an exemplary TAU (Tracking Area Update) procedure according to a fifth embodiment of the present invention.

(168) FIG. 15 illustrates a scheme that may be performed by the target MME 510b according to the fifth embodiment of the present invention. The target MME 510b may request the target eNodeB 200b to set up a user plane bearer.

(169) 1-10) similar to each process shown in FIGS. 11 to 14.

(170) 10a) as in process 7) of FIG. 11, when receiving a context response, the target MME 510b may recognize a problematic situation (where the source MME 510a has been transmitting a paging signal to the UE or there is downlink data for the UE). Then, the target MME 510b sends an initial context setup request to the target eNodeB 200b for performing user plane bearer setup. In this case, as shown in FIG. 12, with the recognition, the target MME 510b may immediately perform paging.

(171) 10b) the target eNodeB 200b configures a radio section for a user plane bearer through a process for RRC connection setup. That is, the target eNodeB 200b may enable RRC connection setup to be triggered by transmitting a higher level signal to the UE 100. Or, the target eNodeB 200b may perform RRC connection setup by transmitting an RRC connection reconfiguration message to the UE 100 and receiving an RRC reconfiguration complete message from the UE 100. Or, the target eNodeB 200b may perform RRC connection setup by transmitting an RRC-based radio bearer setup message to the UE 100 and receiving an RRC-based radio bearer setup complete message from the UE 100. Or, as shown in FIG. 12, the target MME 510b may perform a paging procedure immediately after the recognition, and the target eNodeB 200b may receive the paging signal and transfer the same to the UE 100, allowing RRC connection setup to be triggered. Then, the UE 100 may transmit an RRC connection request message to the target eNodeB 200b, and the target eNodeB 200b may transmit an RRC connection setup message to the UE 100, and the UE 100 may transmit an RRC connection setup complete message to the target eNodeB 200b. RRC connection setup may be done so.

(172) The UE 100 may perform an RRC connection setup procedure when receiving a higher level signal or paging signal from the target eNodeB 200b.

(173) 10c) subsequently, the target eNodeB 200b transmits an initial context setup response message to the target MME 510b.

(174) 11-17) similar to each process shown in FIGS. 11 to 14.

(175) FIG. 16 is a view illustrating an exemplary TAU (Tracking Area Update) procedure according to a sixth embodiment of the present invention.

(176) FIG. 16 illustrates a scheme that may be performed by the UE 100 according to the sixth embodiment of the present invention.

(177) 1-15) similar to each process shown in FIGS. 11 to 15.

(178) 16) as in process 7) of FIG. 11, when receiving a context response, the target MME 510b may recognize a problematic situation (where the source MME 510a has been transmitting a paging signal to the UE or there is downlink data for the UE). Then, the target MME 510b transmits a TAU accept message to the UE 100.

(179) The TAU accept message may contain the information shown in Table 11. Alternatively, the information in Table 11 may be transmitted in a new separate NAS message, rather than included in the TAU accept message. The use of the new NAS message advantageously allows the UE 100 to start user plane bearer setup relatively earlier because the UE 100 may receive the information earlier. The benefits that come from the method in which information as shown in Table 11 is contained and transmitted in the TAU accept message would not change the procedure according to the prior art.

(180) 17) similar to the processes shown in FIGS. 11 to 15.

(181) 18) when receiving information indicating a request for user plane bearer setup, the UE 100 transmits a service request message to the target eNodeB 200b. As per the prior art, the UE 100 does not receive information requesting user plane bearer setup from a network during a TAU process or as a result of a TAU process. In other words, the UE 100 does not attempt to request a service, while according to an embodiment as shown in FIG. 16, it can be made possible. The service request message is an NAS-based message. When receiving the service request message, the target eNodeB 200b includes it in an initial UE message (i.e., Initial UE Message) and transmits the same to the target MME 510b.

(182) 19) similar to the processes shown in FIGS. 11 to 15.

(183) 20) the target MME 510b transmits an initial context setup request message to the target eNodeB 200b to perform user plane bearer setup.

(184) 21) the target eNodeB 200b and the UE 100 configure a radio section for user plane bearer setup through a process for RRC connection setup. To that end, the target eNodeB 200b transmits an RRC-based radio bearer setup message to the UE 100 and receives an RRC-based radio bearer setup complete message from the UE 100. Or, the UE 100 transmits an RRC connection request message to the target eNodeB 200b, and the target eNodeB 200b transmits an RRC connection setup message to the UE 100, and the UE 100 transmits a connection setup complete message to the target eNodeB 200b. RRC connection setup is done so.

(185) 22-24) similar the processes shown in FIGS. 11 to 15.

(186) Then, the downlink data buffered in the S-GW 520 may be transferred to the UE 100 via the target eNodeB 200b.

(187) FIG. 17 is a view illustrating a TAU (Tracking Area Update) procedure according to a seventh embodiment of the present invention.

(188) FIG. 17 illustrates a scheme that may be performed by the S-GW 520 according to the seventh embodiment of the present invention.

(189) 1-7) similar to each process shown in FIGS. 11 to 15.

(190) 8) the source MME 510a, even when subsequently failing to receive a response from the UE until the paging timer, e.g., T3423 timer, expires, □ does not re-transmit a paging signal, □ nor does the source MME 510a send a message regarding the paging failure to the S-GW 520. According to the prior art, the source MME 510a may perform a paging re-transmission policy, and when receiving a message regarding paging failure, the S-GW 520 deletes the downlink data buffered for the UE. The above prevents this.

(191) In a more active method, the source MME 510a may transmit to the S-GW 520 a downlink data handling request message including one or more of a request for keeping buffering the downlink data and a request for re-transmitting a downlink data notification after recognizing the target MME 510b.

(192) Process 8) above may be performed in conjunction with other processes without bothered by the order as shown.

(193) Then, the S-GW 520 keeps buffering the downlink data and re-transmits the downlink data notification to the target MME 510b. When receiving the request from the target MME 510b, the S-GW 520, even receiving a notification of paging failure from the target MME 510b, does not discard but may maintain the buffered downlink data.

(194) 9) similar to the process shown in FIG. 10.

(195) 11) as in process 7) of FIG. 11, when receiving a context response, the target MME 510b may recognize a problematic situation (where the source MME 510a has been transmitting a paging signal to the UE or there is downlink data for the UE). Then, the target MME 510b transmits a bearer modification request message to the S-GW 520. The bearer modification request message may contain information indicating the problematic situation or information requesting re-transmission of the downlink data notification.

(196) 11a) then, the S-GW 520 may re-transmit the downlink data notification message to the target MME 510b. Further, the S-GW 520 may organize or perform a subsequent process on the downlink data notification message sent to the source MME 510a (e.g., performing an internal procedure to cancel or stop the previous paging or transmitting a message regarding canceling or stopping the paging to the source MME 510a).

(197) When receiving the downlink data notification message from the S-GW 520, the target MME 510b may perform a procedure for paging, or according to a combination of the embodiments of the present invention, may conduct paging optimization or create a TAU accept message containing specific information or a message for user plane bearer setup and send the same.

(198) 11b) the target MME 510b transmits a downlink data notification acknowledgement message.

(199) 12) the S-GW 520 transmits a bearer modification response message to the target MME 510b. The bearer modification response message may contain information triggering a procedure for advancing the time of user plane bearer setup. This information may have an influence when the source MME 510a creates a message to be sent to the UE 100, and if needed, additional information for use in user plane bearer setup may be transmitted together. Or, the information included in the downlink data notification may be additionally included.

(200) 13-17) similar to each process shown in FIGS. 11 to 16.

(201) The above embodiments assume an E-UTRAN TAU procedure without a change of responsible S-GW, and the description thereof may be expanded to the situation where several TAU procedures are performed according to the prior art or to other access networks/core networks such as RAU/LAU.

(202) Further, varied or added information may be obtained by adding new parameters/fields/information, by expanding existing parameters/fields/information or by combining various parameters/fields/information, or may come with a newly defined message that has not been existent in the prior art.

(203) The above-described embodiments may be combined with one another. It should be appreciated by those skilled in the art that the embodiments may be easily combined with each other, and thus, detailed description of the combinations is skipped. Nonetheless, it should be noted that such combinations are not excluded from the scope of the present invention.

(204) FIG. 18 is a view illustrating an exemplary protocol and interfaces between a UE, an eNodeB, and an MME.

(205) As shown in FIG. 18, the messages communicated between the UE 100 and the eNodeB 200 are based on an RRC (Radio Resource Control) protocol. The messages communicated between the eNodeB 200 and the MME 510 are based on an S1-AP (S1 Application Protocol). The messages communicated between the UE 100 and the MME 510 are based on an NAS (Non-Access Stratum) protocol. The NAS protocol-based messages are capsulated into RRC protocol-based messages and S1-AP-based messages and transmitted.

(206) The embodiments described thus far may be implemented in hardware, which is described below in connection with FIG. 19.

(207) FIG. 19 is a block diagram illustrating the configuration of an MTC device 100, an MME 510, and an SGSN 520 according to an embodiment of the present invention.

(208) As shown in FIG. 19, the UE 100 includes a storage means 101, a controller 102, and a communication unit 103. The MME 510 includes a storage means 511, a controller 512, and a communication unit 513. Likewise, the S-GW 520 includes a storage means 521, a controller 522, and a communication unit 523.

(209) The storage means 101, 511, and 521 store the methods described above in connection with FIGS. 9 to 18.

(210) The controllers 102, 512, and 522 control the storage means 101, 511, and 521, and the communication units 103, 513, and 523. Specifically, the controllers 102, 512, and 522 respectively execute the methods stored in the storage means 101, 511, and 521. The controllers 102, 512, and 522 transmit the above-described signals through the communication units 103, 513, and 523.

(211) Although the present invention has been shown or described in connection with preferred embodiments thereof, the present invention is not limited thereto, and rather, various changes or modifications may be made thereto without departing from the scope of the present invention defined by the following claims.