KR20200112002A - Method and apparatus for paging in communication system - Google Patents

Abstract

A paging method of user equipment (UE) in a radio resource control (RRC) inactive state and an apparatus thereof in a communication system are disclosed. According to the present invention, an operation method of a first base station may comprise the steps of: receiving a first paging message including a UE context of UE operating in a RRC inactive state from a second base station belonging to the same RAN-based notification area (RNA) as the first base station; transmitting a second paging message indicating the presence of downlink data to the UE operating in the RRC inactive state; receiving an RRC resume request message from the UE operating in the RRC inactive state; and performing a procedure for transitioning the operating state of the UE from the RRC inactive state to an RRC connected state.

Description

Paging method and apparatus in communication system {METHOD AND APPARATUS FOR PAGING IN COMMUNICATION SYSTEM}

The present invention relates to a paging method and an apparatus for a terminal in an inactive (RRC_INACTIVE) state in a communication system, and more particularly, to a method for setting a ran-based notification area (RNA) for paging.

One of the characteristics changed as the 3GPP-based 4G LTE-A system evolved to a 5G NR system is the state of the terminal. In the LTE-A system, the RRC (radio resource control) idle (IDLE) and the RRC connected (CONNECTED) state were operated in two terminal states, but in the 5G NR system, a new RRC inactive (INACTIVE) state was added to operate in three terminal states. can do. In the inactive state, there is no RRC connection, but it may have a connection with the 5G core network.

The base station may change the terminal receiving the service from the connected state to the inactive state. When the terminal in the inactive state leaves the RNA (ran-based notification area) set by the base station, the terminal can perform an RNA update procedure. The UE may transmit an RRC Resume Request message to the base station for RNA update, and the base station may obtain the UE context of the UE from the connected base station before it becomes inactive.

When the terminal in the inactive state receives downlink traffic or signals, the base station may perform paging to transition the terminal in the inactive state to the RRC connected state. The base station that was connected before the terminal was deactivated can transmit a paging message to cells in the RNA list of the terminal. When the terminal moves to a cell of another base station, the last access base station can check whether there is an Xn connection setup with a neighbor base station in the RNA list, and if there is no connection setup, the last access base station performs an Xn setup procedure to the neighbor base station. And Xn connections can be made. Then, the last access base station may send a RAN paging message to a neighbor base station to notify the terminal of paging, and configure and transmit a paging message to the terminal. The terminal receiving the paging message may transmit an RRC resume request message to the base station. The base station may obtain UE context information of the terminal from the last access base station. Whenever the UE operating in the RRC deactivated state moves, the UE context information must be obtained, so there may be a time delay for the UE to update the RNA or switch to the connected state.

An object of the present invention for solving the above problems relates to a paging method and apparatus for a terminal in an RRC inactive state in a communication system, and more particularly, to an RNA (RAN-based notification area) for paging It is to provide a set method.

In a cellular communication system according to an embodiment of the present invention for achieving the above object, a method of operating a first base station includes a radio resource (RRC) from a second base station belonging to the same RAN-based notification area (RNA) as the first base station. control) receiving a first paging message including a UE context of a terminal operating in an INACTIVE state, and operating a second paging message indicating the presence of downlink data in the RRC inactive state Transmitting to the terminal, receiving an RRC resume request message from the terminal operating in the RRC inactive state, and transitioning the operating state of the terminal from the RRC inactive state to an RRC connected (CONNECTED) state It may include the step of performing a procedure for ordering.

Here, the operating method of the first base station is, after the step of receiving the first paging message, if the RRC resume request message is not received from the terminal operating in the RRC inactive state within a preset time, the UE context is deleted. It may further include the step of.

Here, the first paging message may further include a globally unique access management function (AMF) ID (GUAMI).

Here, the information on the RNA to which the terminal belongs may be included in the RRC release message received by the terminal from the second base station.

Here, the RNA to which the terminal belongs may be configured as cells in the second base station.

Here, the RNA to which the terminal belongs may be configured as cells in the second base station and base stations that are Xn-connected to the second base station.

Here, the method of operating the first base station includes: transmitting an RRC resume message to the terminal, receiving an RRC resume completion message from the terminal, and transmitting a path switch request message to AMF, It may further include receiving a path switch response message from the AMF and transmitting a downlink signal to the terminal.

Here, the method of operating the first base station may further include transmitting a UE context release message of the terminal to the second base station.

In a cellular communication system according to another embodiment for achieving the above object of the present invention, a method of operating a first base station includes receiving a downlink signal to be transmitted to a terminal, and the terminal does not exist in a cell of the first base station. Checking the terminal, identifying one or more base stations belonging to a RAN-based notification area (RNA) to which the terminal belongs, transmitting a first paging message to the one or more base stations belonging to the RNA, the one or more base stations Including the step of receiving a UE context (context) release (release) message of the UE from the second base station and deleting the UE context message of the UE, wherein the second base station is the one or more base stations. It may be a base station connected to the terminal.

Here, the first paging message may further include UE context information of the terminal.

Here, the first paging message may further include a globally unique AMF ID (GUAMI).

Here, the RNA to which the terminal belongs may be included in the RRC release message received by the terminal from the first base station.

Here, the RNA to which the terminal belongs may be configured as cells in the first base station.

Here, the RNA to which the terminal belongs may be configured as cells in the first base station and base stations that are Xn-connected to the first base station.

In a cellular communication system according to another embodiment of the present invention, a method of operating a terminal includes: connecting to a first base station, receiving an RRC release message from the first base station, the terminal The operating state of is transitioning from an RRC connected state to an RRC (radio resource control) inactive state, moving to a cell of a second base station belonging to the same RAN-based notification area (RNA) as the first base station, the Receiving a paging message indicating the presence of downlink data from the second base station, transmitting an RRC resume request message to the second base station, receiving an RRC resume message from the second base station The step, transmitting an RRC resume complete message to the second base station, may include receiving a downlink signal from the second base station.

Here, the operating method of the terminal may further include receiving an RRC release message from the second base station and releasing the RRC connection with the second base station.

Here, the RNA to which the terminal belongs may be included in the RRC release message received by the terminal from the first base station.

Here, the RNA to which the terminal belongs may be configured as cells in the first base station.

Here, the RNA to which the terminal belongs may be configured as cells in the first base station and base stations that are Xn-connected to the first base station.

According to the present invention, a RAN-based notification area (RNA) for paging of a terminal in an RRC inactive state in a 5G NR communication system can be efficiently set. When RNA is composed of cells in a base station, since cells in the base station can share user equipment (UE) context information with each other, a procedure for requesting UE context information between cells and obtaining information may be omitted. Therefore, when the terminal moves to another cell in the base station, the RNA update procedure can be performed quickly. When the RNA is composed of cells of neighboring base stations for which Xn connection is established, even if the terminal moves to a cell of another base station, there may be an Xn connection between base stations. Therefore, since there is no need to perform a new Xn connection procedure to request UE context information and obtain information, the RNA update procedure can be performed quickly. Therefore, the performance of the communication system can be improved.

1 is a conceptual diagram showing an embodiment of a communication system.
2 is a block diagram showing a first embodiment of a communication node constituting a communication system.
3 is a flow chart showing an embodiment of a method for updating a random RNA (ran-based notification area) of a terminal.
4 is a flowchart illustrating a first embodiment of a RAN paging method.
5 is a flowchart showing a second embodiment of a RAN paging method.
6 is a conceptual diagram showing the structure of a 5G mobile communication system.
7 is a conceptual diagram showing a first embodiment of a method for setting RNA of a terminal in a communication system.
8 is a conceptual diagram showing a second embodiment of a method for setting RNA of a terminal in a communication system.
9 is a flowchart illustrating a RAN paging procedure in a communication system according to an embodiment of the present invention.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate an overall understanding, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

A communication system to which embodiments according to the present invention are applied will be described. The communication system to which the embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various communication systems. Here, the communication system may be used with the same meaning as a communication network.

1 is a conceptual diagram showing a first embodiment of a communication system.

Referring to FIG. 1, a communication system 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). In addition, the communication system 100 includes a core network (eg, a serving-gateway (S-GW), a packet data network (PDN)-gateway), and a mobility management entity (MME)). It may contain more.

The plurality of communication nodes may support 4G communication (eg, long term evolution (LTE), LTE-A (advanced)), 5G communication, and the like specified in the 3rd generation partnership project (3GPP) standard. 4G communication may be performed in a frequency band of 6 GHz or less, and 5G communication may be performed in a frequency band of 6 GHz or more as well as a frequency band of 6 GHz or less. For example, for 4G communication and 5G communication, a plurality of communication nodes may include a code division multiple access (CDMA)-based communication protocol, a wideband CDMA (WCDMA)-based communication protocol, a time division multiple access (TDMA)-based communication protocol, Frequency division multiple access (FDMA)-based communication protocol, OFDM (orthogonal frequency division multiplexing)-based communication protocol, Filtered OFDM-based communication protocol, CP (cyclic prefix)-OFDM-based communication protocol, DFT-s-OFDM (discrete) Fourier transform-spread-OFDM) based communication protocol, OFDMA (orthogonal frequency division multiple access) based communication protocol, SC (single carrier)-FDMA based communication protocol, NOMA (non-orthogonal multiple access), GFDM (generalized frequency) Division multiplexing)-based communication protocol, filter bank multi-carrier (FBMC)-based communication protocol, universal filtered multi-carrier (UFMC)-based communication protocol, and space division multiple access (SDMA)-based communication protocol can be supported. . Each of the plurality of communication nodes may have the following structure.

2 is a block diagram showing a first embodiment of a communication node constituting a communication system.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transmission/reception device 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, and a storage device 260. Each of the components included in the communication node 200 may be connected by a bus 270 to perform communication with each other.

However, each of the components included in the communication node 200 may be connected through an individual interface or an individual bus centering on the processor 210 instead of the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transmission/reception device 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface. .

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260. The processor 210 may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be configured with at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may be formed of at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1, the communication system 100 includes a plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2, and a plurality of terminals 130- 1, 130-2, 130-3, 130-4, 130-5, 130-6). Base stations (110-1, 110-2, 110-3, 120-1, 120-2) and terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) The containing communication system 100 may be referred to as an “access network”. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong within the cell coverage of the third base station 110-3. have. The first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB, an evolved NodeB, gNB, ng-eNB, and BTS (base transceiver station), radio base station, radio transceiver, access point, access node, road side unit (RSU), radio remote head (RRH), TP ( transmission point), transmission and reception point (TRP), and may be referred to as f (flexible)-TRP. Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a user equipment (UE), a terminal, an access terminal, and a mobile device. Mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, internet of things (IoT) It may be referred to as a device supporting a function, a mounted module/device/terminal, an on board unit (OBU), or the like.

Meanwhile, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul link or a non-ideal backhaul link, , Information can be exchanged with each other through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to the core network through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding terminal 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and the signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Can be transferred to.

In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits MIMO (e.g., single user (SU)-MIMO, multi-user (MU)- MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, direct communication between terminals (device to device communication, D2D) (or, ProSe ( proximity services)). Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a base station 110-1, 110-2, 110-3, 120-1 , 120-2) and operations supported by the base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be performed. For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO scheme, and the fourth terminal 130-4 may transmit a signal to the fourth terminal 130-4 by the SU-MIMO scheme. A signal may be received from the second base station 110-2. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO method, and the fourth terminal 130-4 And each of the fifth terminal 130-5 may receive a signal from the second base station 110-2 by the MU-MIMO method.

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, and The terminal 130-4 may receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by the CoMP method. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 has terminals 130-1, 130-2, 130-3, and 130-4 belonging to their cell coverage. , 130-5, 130-6) and the CA method can transmit and receive signals.

3 is a flowchart illustrating an embodiment of a method for updating a RAN-based notification area (RNA) of a terminal.

Referring to FIG. 3, the communication system of FIG. 3 may be the same as or similar to the communication system of FIG. 1. The terminal 301 of FIG. 3 may be the communication nodes 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 of FIG. 1. The first base station 310 of FIG. 3 may be the communication node 110-1 of FIG. 1, and the second base station 320 of FIG. 3 may be the communication node 110-2 of FIG. 1. The terminal 301 and the base stations 310 and 320 may perform communication based on a communication protocol (eg, 4G communication protocol, 5G communication protocol).

The terminal 301 may obtain system information from the first base station 310 (S301). The system information received from the first base station 310 may include RNA information of the first base station 310. The terminal 301 may obtain system information from the second base station 320 (S302). The system information received from the second base station 320 may include RNA information of the second base station 320. RNA to which the first base station 310 belongs and RNA to which the second base station 320 belongs may be different.

The terminal 301 may operate in a radio resource control (RRC) inactive (INACTIVE) state. The terminal 301 may have been RRC-connected to the first base station 310 before transitioning to the RRC inactive state. When the terminal 301 operating in the RRC inactive state is out of the set RNA, the terminal 301 may perform a cell reselection procedure (S303). In addition, the terminal 301 may perform an RNA update procedure. In order to perform the RNA update, the terminal 301 may transmit an RRC resume request message to the second base station 320 (S304). The second base station 320 may request a user equipment (UE) context of the terminal 301 from the first base station 310, which is a previous serving base station of the terminal 301 (S305). The first base station 310 may receive the UE context request from the second base station 320 and transmit the UE context of the terminal 301 to the second base station 320 in response thereto (S306).

The second base station 320 may determine whether the terminal 301 operates in an RRC deactivated state (S307). The second base station 320 may transmit a path switch request message to the access management function (AMF) 340 (S308). The AMF 340 may receive a route change request message from the second base station 320, and the AMF 340 may know that the base station connected to the terminal 301 and RRC is changed. In response to this, a route change response message may be transmitted to the second base station 320 (S309). A tunnel endpoint identifier (TEID) between the serving-gateway (S-GW) and the second base station 320 may be newly established. The second base station 320 may transmit an RRC release message to the terminal 301 when it is determined that the terminal remains in the RRC deactivated state (S310). Upon receiving the RRC release message, the terminal 301 may release the RRC connection with the first base station 310.

New RNA information may be included in the RRC release message. The second base station 320 may transmit a UE context release message to the first base station 310 (S311). Upon receiving the UE context release message from the second base station 320, the first base station 310 may delete the UE context of the terminal 301.

4 is a flowchart illustrating a first embodiment of a RAN paging method.

Referring to FIG. 4, the communication system of FIG. 4 may be the same as or similar to the communication system of FIG. 1. The terminal 301 of FIG. 4 may be the communication nodes 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 of FIG. 1. The first base station 310 of FIG. 4 may be the communication node 110-1 of FIG. 1, and the second base station 320 of FIG. 4 may be the communication node 110-2 of FIG. 1, and FIG. The third base station 330 of may be the communication node 110-3 of FIG. 1. The terminal 301 and the base stations 310, 320, and 330 may perform communication based on a communication protocol (eg, 4G communication protocol, 5G communication protocol). The first to third base stations 310, 320, and 330 may belong to the same RNA.

The terminal 301 may operate in an RRC deactivated state. The terminal 301 may have been RRC-connected to the first base station 310 before transitioning to the RRC inactive state. When the first base station 310 receives downlink traffic or signals to be transmitted to the terminal 301 in the RRC deactivated state (S401), the first base station 310 paging to transition the terminal 301 to the RRC connected state. Can be done.

The first base station 310 may transmit a paging message to cells in the RNA list of the terminal 301 (ie, cells in the first to third base stations 310, 320, 330) (S402 ). The terminal 301 receiving the paging message from the first base station 310 may transmit an RRC resumption request message to the first base station 310 (S403). The first base station 310 receiving the RRC resume request message from the terminal 301 may transmit the RRC resume message to the terminal 301 (S404). The terminal 301 receiving the RRC resume message from the first base station 310 may transmit the RRC resume completion message to the first base station 310 (S405). The terminal 301 may return to the RRC connected state.

Hereinafter, a paging procedure when a UE in an RRC inactive state moves to a cell of another base station is described.

5 is a flowchart showing a second embodiment of a RAN paging method.

Referring to FIG. 5, the communication system of FIG. 5 may be the same as or similar to the communication system of FIG. 4. The terminal 301 and the base stations 310, 320, and 330 may perform communication based on a communication protocol (eg, 4G communication protocol, 5G communication protocol). The first to third base stations 310, 320, and 330 may belong to the same RNA.

The terminal 301 may operate in an RRC deactivated state. The terminal 301 may have been RRC-connected to the first base station 310 before transitioning to the RRC inactive state. When the first base station 310 receives downlink traffic or signals to be transmitted to the terminal 301 in the RRC deactivated state (S501), the first base station 310 paging to transition the terminal 301 to the RRC connected state. Can be done.

When the terminal 301 moves to a cell of another base station, the first base station 310 is a neighboring base station (e.g., the second base station 320, the third base station 330) in the RNA list of the terminal 301 And whether the first base station 310 is configured for Xn connection. If there is no Xn connection setup, the first base station 310 may transmit an Xn setup request message to the second base station 320 (S502). The second base station 320 may receive an Xn setup request message from the first base station 310. The second base station 320 may transmit an Xn setup response message to the first base station 310 (S503), and the first base station 310 and the second base station 320 may establish an Xn connection. The first base station 310 may transmit an Xn setup request message to the third base station 330 (S504). The third base station 330 may receive an Xn setup request message from the first base station 310. The third base station 330 may transmit an Xn setup response message to the first base station 310 (S505), and the first base station 310 and the third base station 330 may establish an Xn connection.

The first base station 310 may inform the second base station 320 of the paging of the terminal 301 through the RAN paging message (S506). The second base station 320 may receive the RAN paging message from the first base station 310 and can confirm that downlink data to be transmitted to the terminal 301 exists in the first base station 310. The first base station 310 may notify the third base station 330 of the paging of the terminal 301 through the RAN paging message (S507). The third base station 330 may receive the RAN paging message from the first base station 310 and confirm that downlink data to be transmitted to the terminal 301 is present in the first base station 310. The second base station 320 may transmit a paging message to the terminal 301 (S508), and the third base station 330 may transmit a paging message to the terminal 301 (S509).

The terminal 301 may receive a paging message from the second base station 320 and the third base station 330. The terminal 301 may transmit an RRC resumption request message to a neighboring base station (eg, the second base station 320) (S510). When the second base station 320 receives the RRC resume request message from the terminal 301, the second base station 320 transmits a message requesting the UE context of the terminal 301 to the first base station 310, which is a previous serving base station of the terminal 301. Can be (S511). When receiving the UE context request message of the terminal 301 from the second base station 320, the first base station 310 may transmit the UE context of the terminal 301 to the second base station 320 (S512 ).

The second base station 320 that has received the UE context from the first base station 310 may transmit an RRC resume message to the terminal 301 (S513). The terminal 301 receiving the RRC resume message from the second base station 320 may transmit the RRC resume completion message to the second base station 320 (S514). The terminal 301 may return to the RRC connected (CONNECTED) state.

The second base station 320 may transmit a path switch request message to the AMF 340 (S515). The AMF 340 may receive a route change request message from the second base station 320, and the AMF 340 may know that the base station connected to the terminal 301 is changed. In response to this, a route change response message may be transmitted to the second base station 320 (S516). The second base station 320 may transmit a UE context release message of the terminal 301 to the first base station 310 (S517). The terminal 301 may receive downlink traffic from the second base station 320. Hereinafter, a method for quickly performing paging when a terminal in an inactive state moves to a cell of another base station is described.

6 is a conceptual diagram showing the structure of a 5G mobile communication system.

Referring to FIG. 6, a 5G NR mobile communication system includes a terminal 601, base stations (first base station 602, second base station 603), and AMF 604 that manages authentication and mobility of the terminal 601. And a UPF 605 that distributes traffic to the base stations 602 and 603.

An NG-C interface may be applied between the base stations (the first base station 602 and the second base station 603) and the AMF 604. The NG-U interface may be applied between the base stations (the first base station 602 and the second base station 603) and the user plane function (UPF) 605. An Xn interface may be applied between the first base station 602 and the second base station 603, and messages such as a UE context may be transmitted and received through the Xn interface.

7 is a conceptual diagram showing a first embodiment of a method for setting RNA of a terminal in a communication system.

Referring to FIG. 7, the communication system may include a first base station 710, a second base station 720, a third base station 730, and a terminal 701. Cell A, cell B, and cell C may be cells of the first base station 710, cell D, cell E, and cell F may be cells of the second base station 720, and cells G and H are third These may be cells of the base station 730. RNA can be configured as cells in one base station.

The terminal 701 may be located in cell B in the first base station 710 and may be connected to the first base station 710 to operate in an RRC connected state. While the terminal 701 is located in cell B, the terminal 701 may receive an RRC release message from the first base station 710. The operating state of the terminal 701 may transition from the RRC connected state to the RRC deactivated state. The RRC release message may include RNA configuration information to which the terminal 701 belongs. The RNA to which the terminal 701 belongs may be set to cell A, cell B, and cell C, which are cells in the first base station 710.

When the terminal 701 leaves the existing RNA (ie, cell A, cell B, and cell C) in the RRC inactive state, the terminal 701 may perform an RNA update procedure. That is, when the terminal 701 moves to the cell E of the second base station 720, the terminal 701 may perform an RNA update procedure.

After the terminal 701 performs the RNA update procedure, if the second base station 720 determines to keep the terminal in the RRC inactive state, the second base station 720 transmits an RRC release message to the terminal 701. I can. The terminal 701 may receive an RRC release message from the second base station 720. The operating state of the terminal 701 may transition from the RRC connected state to the RRC deactivated state. The RRC release message may include new RNA configuration information. The new RNA to which the terminal 701 belongs may be set to cell D, cell E, and cell F, which are cells of the second base station 720.

RNA can be limited to cells within the base station. Accordingly, when the terminal 701 moves to a cell in the base station, since UE context information is shared between cells, a procedure of requesting UE context information between cells and obtaining UE context information may be omitted. That is, the RNA update needs to be performed only when the terminal 701 is out of RNA, and when the terminal moves within the RNA, the UE context information transmission/reception procedure may not be performed.

8 is a conceptual diagram showing a second embodiment of a method for setting RNA of a terminal in a communication system.

Referring to FIG. 8, the communication system includes a first base station 810, a second base station 820, a third base station 830, a fourth base station 840, a fifth base station 850, and a terminal 801. can do. Cell A, cell B, and cell C may be cells of the first base station 810, cell D, cell E, and cell F may be cells of the second base station 820, and cell G, cell H, and cell I May be cells of the third base station 830, cell J, cell K, and cell L may be cells of the fourth base station 840, and cells M, N, and O are cells of the fifth base station 850. It can be cells. The first base station 810 may be Xn-connected to the second base station 820 and the fourth base station 840, and the second base station 820 is a first base station 810, a third base station 830, and a 5 The base station 850 may be Xn connected, the third base station 830 may be Xn connected to the second base station 820, and the fourth base station 840 may be connected to the first base station 810 and the fifth base station. The base station 850 may be Xn connected, and the fifth base station 850 may be Xn connected to the second base station 820 and the fourth base station 840. RNA can be configured with cells of base stations that have an Xn connection established.

The terminal 801 may be located in cell B in the first base station 810 and may be connected to the first base station 810 to operate in an RRC connected state. The terminal 801 may receive an RRC release message from the first base station 810 while being located in cell B. The operating state of the terminal 801 receiving the RRC release message may transition from the RRC connected state to the RRC deactivated state. The RRC release message may include RNA configuration information to which the terminal 801 belongs. The RNA to which the terminal 801 belongs is a base station Xn connected to the first base station 810 and the first base station 810 (ie, cells A, B, and C, which are cells of the second base station 820 and the fourth base station 840) , D, E, F, J, K and L can be set.

When the terminal 801 leaves the existing RNA (i.e., cells A, B, C, D, E, F, J, K and L) in the RRC inactive state, the terminal 801 can perform the RNA update procedure. have. That is, when the terminal 801 moves to the cell M of the fifth base station 850, the terminal 801 may perform an RNA update procedure.

After the terminal 801 performs the RNA update procedure, when the fifth base station 850 determines to keep the terminal in the RRC inactive state, the fifth base station 850 transmits an RRC release message to the terminal 801 I can. The terminal 801 may receive an RRC release message from the fifth base station 850. The operating state of the terminal 801 may transition from the RRC connected state to the RRC deactivated state.

The RRC release message may include new RNA configuration information. The new RNA to which the terminal 801 belongs is cells D, E, F, J, which are cells of the second base station 820 and the fourth base station 840 that are Xn-connected with the fifth base station 850 and the fifth base station 850, It can be set to K, L, M, N and O.

RNA may be limited to cells of base stations that are configured for Xn connection. Therefore, when the terminal 801 moves to a cell within base stations for which Xn connection is established, UE context information is shared between cells, so that the UE context information is requested between cells, and the Xn connection establishment procedure for acquiring UE context information is omitted. Can be. That is, the RNA update needs to be performed only when the terminal 801 is out of the RNA, and when the terminal moves within the RNA, the Xn connection establishment procedure between base stations may not be performed.

9 is a flowchart illustrating a RAN paging procedure in a communication system according to an embodiment of the present invention.

Referring to FIG. 9, the communication system of FIG. 9 may be the same as or similar to the communication system of FIG. 8. The terminal 901 of FIG. 9 may be the terminal 801 of FIG. 8. The first base station 910 of FIG. 9 may be the first base station 810 of FIG. 8, and the second base station 920 of FIG. 9 may be the second base station 820 of FIG. 3 The base station 930 may be the third base station 830 of FIG. 8. The terminal 901 and base stations (the first base station 910, the second base station 920, and the third base station 930) communicate based on a communication protocol (e.g., 4G communication protocol, 5G communication protocol). Can be done. The RAN paging message may include a UE context and a globally unique AMF ID (GUAMI).

The terminal 901 may operate in an RRC deactivated state. The terminal 901 may have been RRC connected to the first base station 910 before the operation state transitions to the RRC inactive state. When the first base station 910 receives downlink traffic or a signal to be transmitted to the terminal 901 in the RRC inactive state (S901), the first base station 910 transitions the operating state of the terminal 901 to the RRC connected state. You can do paging to do it. Neighboring base stations (eg, the second base station 920 and the third base station 930) existing in the RNA list may all be Xn-connected to the first base station 910. That is, the RNA may be set to a cell in the previous serving base station of the terminal 901 and neighboring base stations Xn connected to the previous serving base station.

When the terminal 901 moves to a cell of another base station, the first base station 910 may transmit a RAN paging message to the second base station 920 and the third base station 930 in the RNA list of the terminal 901. (S902, S903). The RAN paging message may include the UE context of the terminal 901.

The second base station 920 and the third base station 930 may receive a RAN paging message from the first base station 910. The second base station 920 and the third base station 930 may store UE context information included in the RAN paging message and may operate a preset timer (S904). The second base station 920 and the third base station 930 may transmit a paging message to the terminal 901 (S905 and S906).

The terminal 901 may receive a paging message from the second base station 920 and the third base station 930. The terminal 901 may transmit an RRC resumption request message to the currently located target base station (eg, the second base station 920) (S907). When the second base station 920 receives the RRC resume request message from the terminal 901, a procedure for stopping the timer operated in S904 and transitioning the operating state of the terminal 901 from the RRC inactive state to the RRC connected state Can be performed (S908). The second base station 920 may transmit an RRC resume message to the terminal 901 (S909). The terminal 901 may receive an RRC resume message from the second base station 920, and the terminal 901 may transmit an RRC resume completion message to the second base station 920 (S910). The terminal 901 may return to the connected state. Meanwhile, the third base station 930 that has not received the RRC resume request message from the terminal 901 may delete the UE context when the timer expires (S911).

The second base station 920 may transmit a path change request message to the AMF 940 (S912). The AMF 940 may receive a path change request message from the second base station 920, and the AMF 940 may know that the base station connected to the terminal 901 is changed. In response to this, a route change response message may be transmitted to the second base station 920 (S913). The terminal 901 may receive downlink traffic from the second base station 920.

The second base station 920 may transmit a UE context release message of the terminal 901 to the first base station 910 (S914). The first base station 910 receiving the UE context release message from the second base station 920 may delete the UE context of the terminal 901.

The methods according to the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in computer software.

Examples of computer-readable media include hardware devices specially configured to store and execute program instructions, such as rom, ram, flash memory, and the like. Examples of program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The above-described hardware device may be configured to operate as at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (19)

As a method of operating a first base station in a cellular communication system,
Receiving a first paging message including a UE context of a terminal operating in a radio resource control (RRC) INACTIVE state from a second base station belonging to the same RAN-based notification area (RNA) as the first base station Step to do;
Transmitting a second paging message indicating the presence of downlink data to the terminal operating in the RRC inactive state;
Receiving an RRC resume request message from the terminal operating in the RRC inactive state; And
And performing a procedure for transitioning the operating state of the terminal from the RRC inactive state to an RRC connected (CONNECTED) state. The method according to claim 1,
The operating method of the first base station,
After receiving the first paging message,
If the RRC resume request message is not received from the terminal operating in the RRC deactivated state within a preset time, deleting the UE context further comprising the step of deleting the UE context. The method according to claim 1,
The first paging message further includes a globally unique access management function (AMF) ID (GUAMI). The method according to claim 1,
Information on the RNA to which the terminal belongs,
The terminal is included in the RRC release message received from the second base station, the operating method of the first base station. The method of claim 4,
The RNA to which the terminal belongs is configured as cells in the second base station. The method of claim 4,
The RNA to which the terminal belongs is configured as cells in the second base station and base stations that are Xn-connected to the second base station. The method according to claim 1,
The operating method of the first base station,
Transmitting an RRC resume message to the terminal;
Receiving an RRC resume complete message from the terminal;
Transmitting a path switch request message to AMF;
Receiving a path switch response message from the AMF; And
The method of operating a first base station further comprising transmitting a downlink signal to the terminal. The method of claim 7,
The operating method of the first base station,
Further comprising transmitting a UE context release message of the terminal to the second base station. As a method of operating a first base station in a cellular communication system,
Receiving a downlink signal to be transmitted to a terminal;
Confirming that the terminal does not exist in the cell of the first base station;
Identifying one or more base stations belonging to an RNA (RAN-based notification area) to which the terminal belongs;
Transmitting a first paging message to the one or more base stations belonging to the RNA;
Receiving a UE context release message of the terminal from a second base station among the one or more base stations; And
Including the step of deleting the UE context message of the terminal,
The second base station is a base station connected to the terminal from among the one or more base stations. The method of claim 9,
The first paging message further includes UE context information of the terminal. The method of claim 9,
The first paging message further includes a globally unique AMF ID (GUAMI). The method of claim 9,
Information on the RNA to which the terminal belongs,
The terminal is included in the RRC release message received from the first base station, the operating method of the first base station. The method of claim 12,
RNA to which the terminal belongs is configured as cells in the first base station. The method of claim 12,
The RNA to which the terminal belongs is configured as cells in the first base station and base stations that are Xn-connected to the first base station. As a method of operating a terminal in a cellular communication system,
Connecting to a first base station;
Receiving an RRC release message from the first base station;
Transitioning from an RRC connected state to an RRC (radio resource control) inactive (INACTIVE) state;
Moving to a cell of a second base station belonging to the same RAN-based notification area (RNA) as the first base station;
Receiving a paging message indicating the presence of downlink data from the second base station;
Transmitting an RRC resume request message to the second base station;
Receiving an RRC resume message from the second base station;
Transmitting an RRC resume complete message to the second base station;
Receiving a downlink signal from the second base station. The method of claim 15,
The operating method of the terminal,
Receiving an RRC release message from the second base station; And
The method of operating the terminal further comprising the step of releasing the RRC connection with the second base station. The method of claim 15,
Information on the RNA to which the terminal belongs,
The terminal is included in the RRC release message received from the first base station, the operating method of the terminal. The method of claim 17,
RNA to which the terminal belongs is configured as cells in the first base station. The method of claim 17,
The RNA to which the terminal belongs is configured as cells in the first base station and base stations that are Xn-connected to the first base station.

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