WO2017150953A1

WO2017150953A1 - Method for performing operation related to local network pdn connection in wireless communication system and device therefor

Info

Publication number: WO2017150953A1
Application number: PCT/KR2017/002387
Authority: WO
Inventors: 김래영
Original assignee: 엘지전자 주식회사
Priority date: 2016-03-04
Filing date: 2017-03-06
Publication date: 2017-09-08

Abstract

One embodiment of the present invention is a method by which a network node performs an operation related to a packet data network (PDN) connection of user equipment (UE) in a wireless communication system, comprising the steps of: allowing the network node to instruct an evolved node B (eNB) to report a position of UE having a first local network PDN connection; allowing the network node to determine that the first local network PDN connection cannot be maintained, on the basis of the position report received from the eNB; and allowing the network node to perform a release of the first local network PDN connection and a second local network PDN connection, wherein, when the release of the first local network PDN connection is performed prior to the second local network PDN connection, the network node does not detach the UE even if the first local network PDN connection is released.

Description

Method for performing operation related to local network PDN connection in wireless communication system and apparatus therefor

The following description relates to a wireless communication system, and more particularly, to a method and apparatus for performing a local network PDN connection related operation of a network node in a V2X service.

Wireless communication systems are widely deployed to provide various kinds of communication services such as voice and data. In general, a wireless communication system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier frequency (SC-FDMA). division multiple access (MCD) systems and multi-carrier frequency division multiple access (MC-FDMA) systems.

Device-to-Device (D2D) communication establishes a direct link between user equipments (UEs), and directly communicates voice and data between terminals without passing through an evolved NodeB (eNB). Say the way. The D2D communication may include a scheme such as UE-to-UE communication, Peer-to-Peer communication, and the like. In addition, the D2D communication scheme may be applied to machine-to-machine (M2M) communication, machine type communication (MTC), and the like.

D2D communication has been considered as a way to solve the burden on the base station due to the rapidly increasing data traffic. For example, according to the D2D communication, unlike the conventional wireless communication system, since the data is exchanged between devices without passing through a base station, the network can be overloaded. In addition, by introducing the D2D communication, it is possible to expect the effect of reducing the procedure of the base station, the power consumption of the devices participating in the D2D, increase the data transmission speed, increase the capacity of the network, load balancing, cell coverage expansion.

Currently, a discussion on vehicle to everything (V2X) communication is being conducted as a form linked to D2D communication. V2X is a concept including V2V between vehicle terminals, V2P between a vehicle and other types of terminals, and V2I communication between a vehicle and a roadside unit (RSU).

In the present invention, in the V2X service, the technical task of the local network PDN connection operation of the network node.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

According to an embodiment of the present invention, in a method in which a network node performs a packet data network (PDN) connection related operation of a user equipment (UE) in a wireless communication system, the network node transmits a first message to an evolved node B (eNB). Instructing to report a location of a UE having a local network PDN connection; Determining that the network node does not maintain the first local network PDN connection based on the location report received from the eNB; And performing, by the network node, the release of the first local network PDN connection and the second local network PDN connection, wherein the release of the first local network PDN connection is performed before the second local network PDN connection. In this case, the network node does not detach the UE even when the first local network PDN connection is released.

An embodiment of the present invention, a network node device performing a packet data network (PDN) connection-related operation of a user equipment (UE) in a wireless communication system, comprising: a transceiver; And a processor, the processor instructing an eNB (Evolved Node B) to report a location of a UE having a first local network PDN connection, and based on the location report received from the eNB, the first Determine that a local network PDN connection is not maintained, wherein the network node performs the release of the first local network PDN connection and the second local network PDN connection, wherein the release of the first local network PDN connection is performed by the second local If performed prior to the network PDN connection, the network node is a UE device that does not detach the UE even if the first local network PDN connection is released.

When the release of the first local network PDN connection is performed later than the second local network PDN connection, two PDN connections to the same access point name (APN) may be allowed.

Two PDN connections to the same APN may be allowed only until the second local network PDN connection is completed.

The first local network PDN connection of the UE may be a last PDN connection of the UE.

The network node may further include determining whether the first local network PDN connection is the last PDN connection of the UE.

The determination of whether the first local network PDN connection is the last PDN of the UE may be performed whenever the UE creates a PDN connection or whenever the UE enters a connected mode.

The location report may be sent by the eNB when the UE starts receiving serving from the eNB or when the eNB determines to hand over the UE to an eNB of the second local network.

The eNB may be adjacent to the second local network and located in the first local network.

The APN for the first local network PDN connection may be related to a vehicle to everything (V2X) service.

The UE may receive or transmit a V2X message on an LTE-Uu interface.

When the release of the first local network PDN connection is performed before the second local network PDN connection, the network node may transmit a PDN Re-connection Request message to the UE.

The network node may be an MME.

According to the present invention, service continuity of a V2X UE that transmits and receives a V2X message through an LTE Uu interface can be guaranteed.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings appended hereto are for the purpose of providing an understanding of the present invention and for illustrating various embodiments of the present invention and for describing the principles of the present invention together with the description of the specification.

1 is a diagram illustrating a schematic structure of an EPS (Evolved Packet System) including an Evolved Packet Core (EPC).

2 is an exemplary view showing the architecture of a general E-UTRAN and EPC.

3 is an exemplary view showing the structure of a radio interface protocol in a control plane.

4 is an exemplary view showing the structure of a radio interface protocol in a user plane.

5 is a flowchart illustrating a random access procedure.

6 is a diagram illustrating a connection process in a radio resource control (RRC) layer.

7 shows a procedure for establishing a 1: 1 connection between UEs.

8 shows an example of transmitting and receiving a V2X message through the LTE Uu interface.

Figure 9 shows the SIPTO @ LN and local MBMS architecture for local routing of V2X messages.

10 illustrates a V2X message transmission and reception procedure through the LTE-Uu interface.

11 shows an exemplary structure of a local network for the transmission and reception of V2X messages.

12 shows a procedure for changing and related local network as the UE moves.

13 to 14 are views for explaining an embodiment of the present invention.

15 is a diagram illustrating a configuration of a node device according to an embodiment of the present invention.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

Embodiments of the present invention may be supported by standard documents disclosed in relation to at least one of the Institute of Electrical and Electronics Engineers (IEEE) 802 series system, 3GPP system, 3GPP LTE and LTE-A system, and 3GPP2 system. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.

The following techniques can be used in various wireless communication systems. For clarity, the following description focuses on 3GPP LTE and 3GPP LTE-A systems, but the technical spirit of the present invention is not limited thereto.

Terms used in this document are defined as follows.

UMTS (Universal Mobile Telecommunications System): A third generation mobile communication technology based on Global System for Mobile Communication (GSM) developed by 3GPP.

Evolved Packet System (EPS): A network system composed of an Evolved Packet Core (EPC), which is a packet switched (PS) core network based on Internet Protocol (IP), and an access network such as LTE / UTRAN. UMTS is an evolutionary network.

NodeB: base station of GERAN / UTRAN. It is installed outdoors and its coverage is macro cell size.

eNodeB: base station of E-UTRAN. It is installed outdoors and its coverage is macro cell size.

UE (User Equipment): a user device. The UE may be referred to in terms of terminal, mobile equipment (ME), mobile station (MS), and the like. In addition, the UE may be a portable device such as a laptop, a mobile phone, a personal digital assistant (PDA), a smart phone, a multimedia device, or the like, or may be a non-portable device such as a personal computer (PC) or a vehicle-mounted device. In the context of MTC, the term UE or UE may refer to an MTC device.

Home NodeB (HNB): A base station of a UMTS network, which is installed indoors and has a coverage of a micro cell.

HeNB (Home eNodeB): A base station of an EPS network, which is installed indoors and its coverage is micro cell size.

Mobility Management Entity (MME): A network node of an EPS network that performs mobility management (MM) and session management (SM) functions.

Packet Data Network-Gateway (PDN-GW) / PGW: A network node of an EPS network that performs UE IP address assignment, packet screening and filtering, charging data collection, and the like.

Serving Gateway (SGW): A network node of an EPS network that performs mobility anchor, packet routing, idle mode packet buffering, and triggers the MME to page the UE.

Non-Access Stratum (NAS): Upper stratum of the control plane between the UE and the MME. A functional layer for exchanging signaling and traffic messages between a UE and a core network in an LTE / UMTS protocol stack, which supports session mobility and establishes and maintains an IP connection between the UE and the PDN GW. Supporting is the main function.

Packet Data Network (PDN): A network in which a server supporting a specific service (eg, a Multimedia Messaging Service (MMS) server, a Wireless Application Protocol (WAP) server, etc.) is located.

PDN connection: A logical connection between the UE and the PDN, represented by one IP address (one IPv4 address and / or one IPv6 prefix).

RAN (Radio Access Network): a unit including a NodeB, an eNodeB and a Radio Network Controller (RNC) controlling them in a 3GPP network. It exists between UEs and provides a connection to the core network.

Home Location Register (HLR) / Home Subscriber Server (HSS): A database containing subscriber information in the 3GPP network. The HSS may perform functions such as configuration storage, identity management, and user state storage.

Public Land Mobile Network (PLMN): A network composed for the purpose of providing mobile communication services to individuals. It may be configured separately for each operator.

Proximity Service (or ProSe Service or Proximity based Service): A service that enables discovery and direct communication between physically close devices or communication through a base station or through a third party device. In this case, user plane data is exchanged through a direct data path without passing through a 3GPP core network (eg, EPC).

Evolved Packet Core (EPC)

EPC is a key element of System Architecture Evolution (SAE) to improve the performance of 3GPP technologies. SAE is a research project to determine network structure supporting mobility between various kinds of networks. SAE aims to provide an optimized packet-based system, for example, supporting various radio access technologies on an IP basis and providing enhanced data transfer capabilities.

Specifically, the EPC is a core network of an IP mobile communication system for a 3GPP LTE system and may support packet-based real-time and non-real-time services. In a conventional mobile communication system (i.e., a second generation or third generation mobile communication system), the core network is divided into two distinct sub-domains of circuit-switched (CS) for voice and packet-switched (PS) for data. The function has been implemented. However, in the 3GPP LTE system, an evolution of the third generation mobile communication system, the sub-domains of CS and PS have been unified into one IP domain. That is, in the 3GPP LTE system, the connection between the terminal and the terminal having the IP capability (capability), IP-based base station (for example, eNodeB (evolved Node B)), EPC, application domain (for example, IMS ( IP Multimedia Subsystem)). That is, EPC is an essential structure for implementing end-to-end IP service.

The EPC may include various components, and in FIG. 1, some of them correspond to a serving gateway (SGW), a packet data network gateway (PDN GW), a mobility management entity (MME), and a serving general packet (SGRS) Radio Service (Supporting Node) and Enhanced Packet Data Gateway (ePDG) are shown.

The SGW (or S-GW) acts as a boundary point between the radio access network (RAN) and the core network, and is an element that functions to maintain a data path between the eNodeB and the PDN GW. In addition, when the UE moves over the area served by the eNodeB, the SGW serves as a local mobility anchor point. That is, packets may be routed through the SGW for mobility in the E-UTRAN (Universal Mobile Telecommunications System (Evolved-UMTS) Terrestrial Radio Access Network defined in 3GPP Release-8 or later). SGW also provides mobility with other 3GPP networks (RANs defined before 3GPP Release-8, such as UTRAN or GERAN (Global System for Mobile Communication (GSM) / Enhanced Data rates for Global Evolution (EDGE) Radio Access Network). It can also function as an anchor point.

The PDN GW (or P-GW) corresponds to the termination point of the data interface towards the packet data network. The PDN GW may support policy enforcement features, packet filtering, charging support, and the like. In addition, mobility management between 3GPP networks and non-3GPP networks (for example, untrusted networks such as Interworking Wireless Local Area Networks (I-WLANs), code-division multiple access (CDMA) networks, or trusted networks such as WiMax) Can serve as an anchor point for.

Although the example of the network structure of FIG. 1 shows that the SGW and the PDN GW are configured as separate gateways, two gateways may be implemented according to a single gateway configuration option.

The MME is an element that performs signaling and control functions to support access to the network connection of the UE, allocation of network resources, tracking, paging, roaming and handover, and the like. The MME controls control plane functions related to subscriber and session management. The MME manages a number of eNodeBs and performs signaling for the selection of a conventional gateway for handover to other 2G / 3G networks. The MME also performs functions such as security procedures, terminal-to-network session handling, and idle terminal location management.

SGSN handles all packet data, such as user's mobility management and authentication to other 3GPP networks (eg GPRS networks).

The ePDG acts as a secure node for untrusted non-3GPP networks (eg, I-WLAN, WiFi hotspots, etc.).

As described with reference to FIG. 1, a terminal having IP capability is an IP service network provided by an operator (ie, an operator) via various elements in the EPC, based on 3GPP access as well as non-3GPP access. (Eg, IMS).

1 illustrates various reference points (eg, S1-U, S1-MME, etc.). In the 3GPP system, a conceptual link defining two functions existing in different functional entities of E-UTRAN and EPC is defined as a reference point. Table 1 below summarizes the reference points shown in FIG. 1. In addition to the examples of Table 1, there may be various reference points according to the network structure.

Table 1

Reference point	Explanation
S1-MME	Reference point for the control plane protocol between E-UTRAN and MME
S1-U	Reference point between E-UTRAN and Serving GW for the per bearer user plane tunneling and inter eNodeB path switching during handover
S3	Reference point between the MME and SGSN providing user and bearer information exchange for mobility between 3GPP access networks in idle and / or active state. This reference point can be used in PLMN-to-PLMN-to-PLMN-to-for example (for PLMN-to-PLMN handover). This reference point can be used intra-PLMN or inter-PLMN (eg in the case of Inter-PLMN HO).)
S4	(Reference point between SGW and SGSN that provides related control and mobility support between the GPRS core and SGW's 3GPP anchor functionality.It also provides user plane tunneling if no direct tunnel is established.) and the 3GPP Anchor function of Serving GW.In addition, if Direct Tunnel is not established, it provides the user plane tunnelling.)
S5	Reference point providing user plane tunneling and tunnel management between the SGW and the PDN GW. It provides user plane tunneling and tunnel management between Serving GW and PDN GW. for Serving GW relocation due to UE mobility and if the Serving GW needs to connect to a non-collocated PDN GW for the required PDN connectivity.)
S11	Reference point between MME and SGW
SGi	Reference point between the PDN GW and the PDN. The PDN may be an operator external public or private PDN or, for example, an in-operator PDN for the provision of IMS services. It is the reference point between the PDN GW and the packet data network.Packet data network may be an operator external public or private packet data network or an intra operator packet data network, eg for provision of IMS services.This reference point corresponds to Gi for 3GPP accesses.)

Among the reference points shown in FIG. 1, S2a and S2b correspond to non-3GPP interfaces. S2a is a reference point that provides the user plane with associated control and mobility support between trusted non-3GPP access and PDN GW. S2b is a reference point that provides the user plane with relevant control and mobility support between the ePDG and PDN GW.

2 is an exemplary view showing the architecture of a general E-UTRAN and EPC.

As shown, an eNodeB can route to a gateway, schedule and send paging messages, schedule and send broadcaster channels (BCHs), and resources in uplink and downlink while an RRC (Radio Resource Control) connection is active. Can perform functions for dynamic allocation to the UE, configuration and provision for measurement of the eNodeB, radio bearer control, radio admission control, and connection mobility control. Within the EPC, paging can occur, LTE_IDLE state management, user plane can perform encryption, SAE bearer control, NAS signaling encryption and integrity protection.

3 is an exemplary diagram illustrating a structure of a radio interface protocol in a control plane between a terminal and a base station, and FIG. 4 is an exemplary diagram illustrating a structure of a radio interface protocol in a user plane between a terminal and a base station. .

The air interface protocol is based on the 3GPP radio access network standard. The air interface protocol is composed of a physical layer, a data link layer, and a network layer horizontally, and a user plane and control for data information transmission vertically. It is divided into a control plane for signal transmission.

The protocol layers are based on the lower three layers of the Open System Interconnection (OSI) reference model, which is widely known in communication systems, and includes L1 (first layer), L2 (second layer), and L3 (third layer). ) Can be separated.

Hereinafter, each layer of the radio protocol of the control plane shown in FIG. 3 and the radio protocol in the user plane shown in FIG. 4 will be described.

The physical layer, which is the first layer, provides an information transfer service using a physical channel. The physical layer is connected to a medium access control layer on the upper side through a transport channel, and data between the medium access control layer and the physical layer is transmitted through the transport channel. In addition, data is transferred between different physical layers, that is, between physical layers of a transmitting side and a receiving side through a physical channel.

The physical channel is composed of several subframes on the time axis and several sub-carriers on the frequency axis. Here, one subframe includes a plurality of symbols and a plurality of subcarriers on the time axis. One subframe consists of a plurality of resource blocks, and one resource block consists of a plurality of symbols and a plurality of subcarriers. The transmission time interval (TTI), which is a unit time for transmitting data, is 1 ms corresponding to one subframe.

According to 3GPP LTE, the physical channels existing in the physical layer of the transmitting side and the receiving side are physical downlink shared channel (PDSCH), physical uplink shared channel (PUSCH) and physical downlink control channel (PDCCH), which are control channels, It may be divided into a Physical Control Format Indicator Channel (PCFICH), a Physical Hybrid-ARQ Indicator Channel (PHICH), and a Physical Uplink Control Channel (PUCCH).

There are several layers in the second layer.

First, the medium access control (MAC) layer of the second layer serves to map various logical channels to various transport channels, and also logical channel multiplexing to map several logical channels to one transport channel. (Multiplexing). The MAC layer is connected to the upper layer RLC layer by a logical channel, and the logical channel includes a control channel for transmitting information of a control plane according to the type of information to be transmitted. It is divided into a traffic channel that transmits user plane information.

The Radio Link Control (RLC) layer of the second layer adjusts the data size so that the lower layer is suitable for transmitting data to the radio section by segmenting and concatenating data received from the upper layer. It plays a role.

The Packet Data Convergence Protocol (PDCP) layer of the second layer is an IP containing relatively large and unnecessary control information for efficient transmission in a wireless bandwidth where bandwidth is small when transmitting an IP packet such as IPv4 or IPv6. Performs Header Compression which reduces the packet header size. In addition, in the LTE system, the PDCP layer also performs a security function, which is composed of encryption (Ciphering) to prevent third-party data interception and integrity protection (Integrity protection) to prevent third-party data manipulation.

The radio resource control layer (hereinafter RRC) layer located at the top of the third layer is defined only in the control plane, and the configuration and resetting of radio bearers (abbreviated as RBs) are performed. It is responsible for the control of logical channels, transport channels and physical channels in relation to configuration and release. In this case, RB means a service provided by the second layer for data transmission between the terminal and the E-UTRAN.

If there is an RRC connection (RRC connection) between the RRC of the terminal and the RRC layer of the wireless network, the terminal is in the RRC connected mode (Connected Mode), otherwise it is in the RRC idle mode (Idle Mode).

Hereinafter, the RRC state and the RRC connection method of the UE will be described. The RRC state refers to whether or not the RRC of the UE is in a logical connection with the RRC of the E-UTRAN. If the RRC state is connected, the RRC_CONNECTED state is called, and the RRC_IDLE state is not connected. Since the UE in the RRC_CONNECTED state has an RRC connection, the E-UTRAN can grasp the existence of the UE in units of cells, and thus can effectively control the UE. On the other hand, the UE in the RRC_IDLE state cannot identify the existence of the UE by the E-UTRAN, and the core network manages the unit in a larger tracking area (TA) unit than the cell. That is, the terminal in the RRC_IDLE state is only detected whether the terminal exists in a larger area than the cell, and the terminal must transition to the RRC_CONNECTED state in order to receive a normal mobile communication service such as voice or data. Each TA is identified by a tracking area identity (TAI). The terminal may configure a TAI through a tracking area code (TAC), which is information broadcast in a cell.

When the user first turns on the power of the terminal, the terminal first searches for an appropriate cell, then establishes an RRC connection in the cell, and registers the terminal's information in the core network. Thereafter, the terminal stays in the RRC_IDLE state. The terminal staying in the RRC_IDLE state (re) selects a cell as needed and looks at system information or paging information. This is called camping on the cell. When it is necessary to establish an RRC connection, the UE staying in the RRC_IDLE state makes an RRC connection with the RRC of the E-UTRAN through an RRC connection procedure and transitions to the RRC_CONNECTED state. There are several cases in which a UE in RRC_IDLE state needs to establish an RRC connection. For example, a user's call attempt, a data transmission attempt, etc. are required or a paging message is received from E-UTRAN. Reply message transmission, and the like.

A non-access stratum (NAS) layer located above the RRC layer performs functions such as session management and mobility management.

The following describes the NAS layer shown in FIG. 3 in detail.

ESM (evolved Session Management) belonging to the NAS layer performs functions such as default bearer management and dedicated bearer management, and is responsible for controlling the terminal to use the PS service from the network. The default bearer resource is characterized in that it is allocated from the network when it is connected to the network when it first accesses a specific Packet Data Network (PDN). At this time, the network allocates an IP address usable by the terminal so that the terminal can use the data service, and also allocates QoS of the default bearer. LTE supports two types of bearer having a guaranteed bit rate (GBR) QoS characteristic that guarantees a specific bandwidth for data transmission and reception, and a non-GBR bearer having a best effort QoS characteristic without guaranteeing bandwidth. In case of Default bearer, Non-GBR bearer is assigned. In the case of a dedicated bearer, a bearer having a QoS characteristic of GBR or non-GBR may be allocated.

The bearer allocated to the terminal in the network is called an evolved packet service (EPS) bearer, and when the EPS bearer is allocated, the network allocates one ID. This is called EPS Bearer ID. One EPS bearer has a QoS characteristic of a maximum bit rate (MBR) or / and a guaranteed bit rate (GBR).

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

The random access procedure is used for the UE to get UL synchronization with the base station or to be allocated UL radio resources.

The UE receives a root index and a physical random access channel (PRACH) configuration index from the eNodeB. Each cell has 64 candidate random access preambles defined by a Zadoff-Chu (ZC) sequence, and the root index is a logical index for the UE to generate 64 candidate random access preambles.

Transmission of the random access preamble is limited to a specific time and frequency resource for each cell. The PRACH configuration index indicates a specific subframe and a preamble format capable of transmitting the random access preamble.

The UE sends the randomly selected random access preamble to the eNodeB. The UE selects one of the 64 candidate random access preambles. Then, the corresponding subframe is selected by the PRACH configuration index. The UE transmits the selected random access preamble in the selected subframe.

Upon receiving the random access preamble, the eNodeB sends a random access response (RAR) to the UE. The random access response is detected in two steps. First, the UE detects a PDCCH masked with random access-RNTI (RA-RNTI). The UE receives a random access response in a medium access control (MAC) protocol data unit (PDU) on the PDSCH indicated by the detected PDCCH.

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

As shown in FIG. 6, the RRC state is shown depending on whether the RRC is connected. The RRC state refers to whether or not an entity of the RRC layer of the UE is in a logical connection with an entity of the RRC layer of the eNodeB. When the RRC state is connected, the RRC state is referred to as an RRC connected state. The non-state is called the RRC idle state.

Since the UE in the connected state has an RRC connection, the E-UTRAN may determine the existence of the corresponding UE in units of cells, and thus may effectively control the UE. On the other hand, the UE in the idle state (idle state) can not be identified by the eNodeB, the core network (core network) is managed by the tracking area (Tracking Area) unit that is larger than the cell unit. The tracking area is a collection unit of cells. That is, the idle state (UE) is determined only in the presence of the UE in a large area, and in order to receive a normal mobile communication service such as voice or data, the UE must transition to the connected state (connected state).

When a user first powers up a UE, the UE first searches for an appropriate cell and then stays in an idle state in that cell. When the UE staying in the idle state needs to establish an RRC connection, the UE establishes an RRC connection with the RRC layer of the eNodeB through an RRC connection procedure and transitions to an RRC connected state. .

There are several cases in which the UE in the idle state needs to establish an RRC connection. For example, a user's call attempt or uplink data transmission is required, or a paging message is received from EUTRAN. In this case, the response message may be transmitted.

In order to establish an RRC connection with the eNodeB, the UE in an idle state must proceed with an RRC connection procedure as described above. The RRC connection process is largely a process in which a UE sends an RRC connection request message to an eNodeB, an eNodeB sends an RRC connection setup message to the UE, and a UE completes RRC connection setup to the eNodeB. (RRC connection setup complete) message is sent. This process will be described in more detail with reference to FIG. 6 as follows.

1) When a UE in idle mode attempts to establish an RRC connection due to a call attempt, a data transmission attempt, or a response to an eNodeB's paging, the UE first sends an RRC connection request message. Send to eNodeB.

2) When the RRC connection request message is received from the UE, the eNB accepts the RRC connection request of the UE when the radio resources are sufficient, and transmits an RRC connection setup message, which is a response message, to the UE. .

3) When the UE receives the RRC connection setup message, it transmits an RRC connection setup complete message to the eNodeB. When the UE successfully transmits an RRC connection establishment message, the UE establishes an RRC connection with the eNodeB and transitions to the RRC connected mode.

7 shows a procedure for establishing a 1: 1 connection between UEs. A UE establishing a 1: 1 connection through the procedure as shown in FIG. 7 may transmit and receive a V2X message through a PC5 interface (D2D interface or sidelink at the physical layer). For further details regarding this procedure, reference is made to the information disclosed in Section 5.4.5.2 (Establishment of secure layer-2 link over PC5) of TS 23.303. The V2X message transmission and reception through the 1: 1 PC5 interface connection can be used when the UE sends and receives V2X messages and UE-type RSU and V2X messages. In addition, V2X message transmission and reception in the form of 1: many broadcast rather than V2X message transmission and reception through the 1: 1 PC5 interface connection as described above may be commonly used, which is referred to the contents disclosed in TS 23.285.

In addition, as a method of V2X message transmission and reception, a LTE-Uu based V2X message transmission and reception method as well as a PC5 interface between the UE and the UE may be used. 8 shows an example of transmitting and receiving a V2X message through the LTE Uu interface. Referring to FIG. 8, a UE may transmit a V2X message through an LTE-Uu interface, and the V2X message may be delivered to various UEs through the LTE-Uu. To reduce delays in sending and receiving V2X messages, local routing of V2X messages may be used. To this end, SIPTO @ LN (Selected IP Traffic Offload at Local Network) presented in 3GPP TS 23.401 may be considered. 9 illustrates a SIPTO @ LN and local MBMS architecture for local routing of V2X messages. 9, the core network entity and the V2X application server are located close to the access network to reduce latency.

10 illustrates a V2X message transmission and reception procedure through the LTE-Uu interface. Referring to FIG. 10, in step S1001, the UE acquires information necessary for MBMS reception of a V2X message for V2V / P services. In step S1002, UE-1 transmits a V2X message via LTE-Uu. UE-1 has already set up a SIPTO on the local network PDN connection to send V2X messages for V2V / P services over LTE-Uu as described in TS 23.401. The eNB receives the V2X message and the V2X message is routed to the V2X application server via the S-GW / L-GW. In step S1003, the V2X application server decides to forward the V2X message and the target area of the message. The V2X application server sends the V2X message to the target area of the message through MBMS delivery. The MBMS bearer used for MBMS delivery may be preset. In the following description, the local network may be interpreted as a local network for V2X service, a local network for local routing of V2X messages, and the like.

In the local network (LN) structure illustrated in FIG. 9, one local network may include one or more eNBs as shown in FIG. 11. In this specification, the local network includes a local network for V2X service, a local network for local routing of V2X messages, and the like. In the LTE-Uu-based V2X message transmission method through such a local network, the local network receiving a service while driving at a high speed is likely to be changed. For example, in FIG. 11, when the serving eNB of UE # 1 is eNB # 1-m and transmits / receives a V2X message through a first local network # 1, the mobile network receives a serving from eNB # 2-1. Is changed to the second local network (local network # 2). In this case, the UE must regenerate the PDN connection in the second local network for unicast transmission. At this time, in order to regenerate the PDN connection, that is, the SIPTO @ LN PDN connection through the local network, the PDN connection generated through the first local network must be disconnected and then a connection establishment must be established through the second local network. However, if the PDN connection is the last PDN connection at the time of disconnecting the PDN connection, that is, if no other PDN connection exists, the MME detaches the UE first and attaches again. (See section 4.3.15a.2 (SIPTO at the Local Network with stand-alone GW (with S-GW and L-GW collocated) function) in 3GPP TS 23.401 for more details on this.) When the local network changes due to the movement of the V2X UE, the existing local network PDN connection is released and the new local network PDN connection is performed, and the UE must perform attach procedure on the first local network and attach procedure on the second local network. In addition, during this time, the LTE-Uu-based V2X message transmission and reception will not be allowed, and the PC5-based V2X message transmission and reception will also be prevented, resulting in the problem of service interruption. 12 specifically illustrates a situation in which such a problem occurs. FIG. 12 illustrates a procedure for moving from eNB # 1-m belonging to local network # 1 to eNB # 2-1 belonging to local network # 2 as the UE moves in the local network scenario illustrated in FIG. 11.

Specifically, in step S1201, the UE has a PDN connection with the L-GW # 1 belonging to the local network # 1. Accordingly, the UE may transmit a V2X message using this PDN connection. In step S1202, as the UE moves, a handover procedure is performed from eNB # 1-m belonging to local network # 1 to eNB # 2-1 belonging to local network # 2. Refer to Section 5.5.1 (Intra-E-UTRAN Handover) of TS 23.401 for the detailed handover procedure.

In step S1203, the MME is based on the information received from the target eNB or the source MME (if the MME is changed) during the handover procedure, the source eNB eNB # 1-m and the target eNB eNB # 2-1 mutually Be aware that it belongs to another local network. As the L-GW is changed, it is determined that the PDN connection can no longer be maintained and should be disconnected. However, since the PDN connection to be disconnected is the UE's only last PDN connection, the MME decides to detach and reattach the UE. In step S1204, the MME sends a Detach Request message instructing the UE to reattach after detaching. For this purpose, the message includes detach with reattach required information. In step S1205, the MME transmits a Delete Session Request message to L-GW # 1, which is a GW to which a PDN connection is established. In step S1206, L-GW # 1 responds with a Delete Session Response message. In step S1207, the UE receiving the Detach Request message from the MME may transmit a Detach Accept message to the MME at any time thereafter.

In step S1208, the Detach Request message received from the MME in step 4 includes information indicating to reattach, and the UE transmits an Attach Request message to the MME. In step S1209, the MME transmits a Create Session Request message to L-GW # 2, which is a GW, to establish a PDN connection. In step S12010, L-GW # 2 responds with a Create Session Response message. In step S12011, the MME transmits an Initial Context Setup Request message including context information on a PDN connection established to eNB # 2-1 and an Attach Accept message, which is a NAS message to be transmitted to the UE. In step S12012, eNB # 2-1 transmits an RRC Connection Reconfiguration message including bearer information and Attach Accept message for the PDN connection to the UE. In step S12013, the UE responds to the eNB # 2-1 with an RRC Connection Reconfiguration Complete message. In step S12014, eNB # 2-1 transmits an Initial Context Setup Response message to the MME. In step S12015, the UE transmits an Attach Complete message to the MME. Thereafter, the UE may transmit uplink data.

In step S12016, the MME transmits a Modify Bearer Request message including information on the eNB # 2-1 to enable the downlink data transmission to the UE to the L-GW # 2. In step S12017, L-GW # 2 responds with a Modify Bearer Response message. Thereafter, L-GW # 2 may transmit downlink data to the UE.

As can be seen in each procedure of FIG. 12, as the UE moves to the local network, the UE cannot transmit a V2X message between steps S1202 to S12015, that is, until the PDN connection is established by reattaching in the target local network, the V2X service The continuity of is broken. In the following, a method for efficiently transmitting a V2X message for a V2X service and a procedure related to disconnecting and generating a PDN of a network node will be described.

실시예Example

The following description basically assumes the situation as shown in FIG. That is, as shown in Figure 11, the eNB is adjacent to the second local network and located in the first local network, the APN for the first local network PDN connection is related to the V2X (Vehicle to Everything) service, the UE is V2X message May be received on the LTE-Uu interface.

The network node according to an embodiment of the present invention (the network node performing all / part of the function of the MME or the MME) may instruct the eNB to report the location of the UE having the first local network PDN connection. This report determines that the MME determines that the PDN connection is a UE's only PDN connection and a SIPTO @ LN type PDN connection for a UE that creates / creates a PDN connection for a V2X service, and the PDN connection is the UE's only PDN connection. If the connection is a PDN connection of the SIPTO @ LN type may be indicated. As a result, it is possible to determine whether the UE can maintain the SIPTO @ LN PDN connection before leaving the old local network. That is, it may be determined that reconstruction of the SIPTO @ LN PDN connection is required when the UE intends to move from the old local network to the new local network. And the location report may be sent by the eNB when the UE starts receiving serving from the eNB or when the eNB determines to hand over the UE to an eNB of the second local network.

Based on the location report received from the eNB, the network node may determine that it does not maintain the first local network PDN connection. In this case, the network node may perform the release of the first local network PDN connection and the second local network PDN connection. A change may be made in relation to detach and APN connections defined in the existing LTE / LTE-A according to a release relationship between the first local network PDN connection and the second local network PDN connection.

Specifically, when the release of the first local network PDN connection is performed before the second local network PDN connection, the network node may not detach the UE even if the first local network PDN connection is released. Here, the first local network PDN connection may be the last PDN connection in the first local network of the UE, even in this case, the MME does not detach the UE. In this case, even if the last PDN is released, the UE may not attach and perform PDN connection without performing an attach procedure in the next local network. Thus, service continuity of the V2X UE transmitting and receiving the V2X message through the LTE Uu interface can be guaranteed.

Alternatively, if the release of the first local network PDN connection is performed later than the second local network PDN connection, two PDN connections to the same access point name (APN) may be allowed. In this case, two PDN connections to the same APN may be allowed only until the completion of the second local network PDN connection. As such, in the case of a V2X UE transmitting and receiving a V2X message through the LTE Uu interface, by allowing a plurality of PDN connections for the same APN, service continuity of the V2X UE can be guaranteed in the same manner.

As mentioned above, the first local network PDN connection of the UE may be the last PDN connection of the UE, so that the network node may determine whether the first local network PDN connection is the last PDN of the UE. There is a need. In this case, whether the first local network PDN connection is the last PDN of the UE may be performed whenever the UE creates the PDN connection or whenever the UE enters the connected mode.

If the MME further describes the operation of instructing the location reporting to the eNB, the MME may instruct the eNB to report the location of the UE to the MME when transmitting an S1 message. The eNB that should perform the location report of the UE may indicate that the eNB is located at the edge / end of the local network. The location information of the UE to be reported may be one or more of ECGI in which the UE is located, serving eNB ID of the UE, and information indicating that the UE is at the boundary of the local network. The eNB receiving the above instruction from the MME stores it in the UE context. As a result, when X2 / S1 handover is performed, the UE context including this indication is transferred to the target eNB.

In the above description, if the release of the first local network PDN connection is performed before the second local network PDN connection, the MME is i) APN for the SIPTO @ LN PDN connection for the V2X service, ii) the SIPTO @ LN APN for PDN connection allows SIPTO, iii) not detach even if it is last PDN connection for APN for SIPTO @ LN PDN connection, iv) even if it is last PDN connection for APN for SIPTO @ LN PDN connection Allow remodeling without detaching, v) Checks if one or more of the conditions are met when the UE is in connected mode. The above information may be subscriber information and / or information provided by the UE and / or information configured in the MME and / or information obtained from another network node. If one or more of the above conditions are met, the MME disconnects the PDN connection established in the Old LN. At this time, although the PDN connection is the last PDN connection, the UE does not detach and disconnects only the PDN connection. And, form a PDN connection to New LN. In order to perform the operation, the MME may instruct / request / trigger / initiate each of the operations of the MME to the UE, or may instruct it in a combined form. In the latter case, for example, as described in Section 5.10.3 (UE or MME requested PDN disconnection) of TS 23.401, the MME may include cause information called reactivation requested when requesting disconnection of a PDN connection to the UE.

In addition, if the release of the first local network PDN connection is performed later than the second local network PDN connection, MME is i) the APN for the SIPTO @ LN PDN connection for the V2X service, ii) the SIPTO @ LN PDN connection APN for allow SIPTO, iii) APN for SIPTO @ LN PDN connection allows make-before-break (this is necessary when rebuilding a PDN connection for the same APN, after forming a new PDN connection) Means to disconnect the PDN connection), iv) the APN for the SIPTO @ LN PDN connection allows duplicate PDN connections (this is temporarily applied to the same APN for the make-before-break operation described in iii). Means to allow duplicate PDN connections), v) not to detach even if the last PDN is connected to the APN for the SIPTO @ LN PDN connection, vi) if the UE is in connected mode, vii) the SIPTO @ LN APNs for PDN connections have the same purpose (or the same To the service) of two (or any number of pieces). This may mean that a plurality of APNs are operated to form a PDN connection through a local network for V2X service. Alternatively, one APN may mean that there are a plurality of sub-APNs. Alternatively, it may mean that a plurality of APNs are grouped or connected for the same purpose. It is checked whether one or more conditions are satisfied. Such information may be subscriber information and / or information provided by the UE and / or information configured in the MME and / or information obtained from another network node. The APN for the SIPTO @ LN PDN connection may be interpreted as the SIPTO @ LN PDN connection. In the above, permission may be interpreted as possible. Such interpretations can be applied throughout the invention.

When one or more of the conditions i) to vi) are satisfied, the MME forms a PDN connection with New LN, and disconnects the PDN connection formed in the Old LN. In order to perform the operation, the MME may instruct / request / trigger / initiate each of a connection request and a release to the UE, or may instruct the combined form. In the latter case, for example, it may be instructed / requested / trigger / initiate to disconnect the old PDN connection to the same APN after the PDN connection is formed.

Further, when one or more of the conditions i) to vii) are satisfied, the MME forms a PDN connection with a new LN for another APN having the same purpose as the APN associated with the PDN connection formed in the Old LN. For example, suppose that there are two APNs, such as APN_for_V2X # 1 and APN_for_V2X # 2, to form a PDN connection through the local network for V2X service, and the PDN connections formed in the old LN are formed for APN_for_V2X # 1. Form a PDN connection with new LN for APN_for_V2X # 2. Then, the PDN connection established in the Old LN is disconnected. That is, the PDN connection established to APN_for_V2X # 1 is disconnected.

In order to perform the operation, the MME may instruct / request / trigger / initiate each of the connection and disconnection to the UE, or may instruct it in a combined form. In the latter case, for example, it may be instructed / requested / trigger / initiate to disconnect the old PDN connection to another grouped APN after the PDN connection is formed. This operation may be applied even if the SIPTO @ LN PDN connection is not the last PDN connection.

12 to 13, the case where the release of the first local network PDN connection is performed before and after the second local network PDN connection will be described. 12 to 13 of the contents that are not described in detail in the description that is not contrary to the above description can be applied as it is.

Example a

13 is eNB # 2 belonging to a second local network (local network # 2) from eNB # 1-m belonging to a first local network (first local network) as the UE moves in the local network scenario illustrated in FIG. Show the procedure for moving to -1. As the UE moves to the local network, the UE establishes the PDN connection with the L-GW # 2 belonging to the second local network before disconnecting the PDN connection previously established with the L-GW # 1 belonging to the first local network.

In step S1301, the UE establishes a PDN connection with L-GW # 1 belonging to the first local network. Accordingly, the UE may transmit a V2X message using this PDN connection. The MME indicates to the UE that location reporting of the UE is required to the eNB. In step S1302, the UE transmits a measurement report to eNB # 1-m. For details, TS 36.300 shall apply mutatis mutandis. In step S1303, eNB # 1-m determines the handover of the UE based on the measurement report received from the UE. In step S1304, the eNB # 1 reports the location information of the UE to the MME. In step S1305, a handover procedure is initiated for the UE from eNB # 1-m belonging to the first local network to eNB # 2-1 belonging to the second local network.

In step S1306, the MME recognizes that the L-GW of the UE is changed based on the information received in step 4, so that the PDN connection established in the previous local network can no longer be maintained. And instead of determining detach for this UE, after creating a PDN connection in the target local network, it decides to release the PDN connection established in the source local network. Step S1306 may be performed regardless of or before step S1305.

In step S1307, the MME transmits a PDN Re-connection Request message to the UE. In this manner, the preconfigured PDN connection is re-formed while instructing to disconnect the old PDN connection to the same APN. In step S1308 ~ step S1317, the UE forms a PDN connection to L-GW # 2 belonging to the second local network. This follows the conventional operation and complies with the content of TS 23.401. In step S1318, the UE transmits a PDN Disconnection Request message to the MME in order to release the old PDN connection generated with the L-GW # 1. In steps S1319 to S1320, the MME performs a PDN disconnection operation with the L-GW # 1.

Example b

FIG. 14 shows a procedure of moving from eNB # 1-m belonging to the first local network to eNB # 2-1 belonging to the second local network as the UE moves in the local network scenario illustrated in FIG. 11. As the UE moves the local network, the UE releases the PDN connection previously established with the L-GW # 1 belonging to the first local network, and then establishes a PDN connection with the L-GW # 2 belonging to the second local network. Since the PDN connection is the only PDN connection of the UE, when the UE releases the UE, the PDN connection is detached, but the PDN connection is not detached and reconfigures the PDN connection.

In step S1401, the UE establishes a PDN connection with L-GW # 1 belonging to the first local network. Accordingly, the UE may transmit a V2X message using this PDN connection. The MME indicates to the UE that location reporting of the UE is required to the eNB. In step S1402, the UE transmits a measurement report to eNB # 1-m. For details, TS 36.300 shall apply mutatis mutandis. In step S1403, eNB # 1-m determines the handover of the UE based on the Measurement Report received from the UE. In step S1404, eNB # 1 reports the location information of the UE to the MME. In step S1405, a handover procedure is initiated for the UE from eNB # 1-m belonging to the first local network to eNB # 2-1 belonging to the second local network.

In step S1406, the MME recognizes that the L-GW of the UE is changed based on the information received in step 4, so that the PDN connection established in the previous local network can no longer be maintained. After releasing the PDN connection established in the source local network without detaching the UE, the UE decides to create the PDN connection in the target local network. Step S1406 may be performed regardless of or before step S1405.

In steps S1407 to S1408, the MME performs a PDN disconnection operation with the L-GW # 1. In step S1409, the MME sends a Deactivate EPS Bearer Context Request message to the UE. The preconfigured PDN connection is released while instructing to form a new PDN connection to the same APN. In step S1410, the UE responds to the MME with a Deactivate EPS Bearer Context Accept message. In step S1411 to step S1420, the UE establishes a PDN connection to L-GW # 2 belonging to the second local network. This follows the conventional operation and complies with the content of TS 23.401.

In the above description, the uplink transmission may be a unicast transmission, and the downlink transmission may be a unicast, broadcast, or multicast transmission. In the case of broadcast / multicast scheme, it may be MBMS or SC-PTM transmission. In the above description, although the PDN connection through the local network is described as a SIPTO @ LN PDN connection, the PDN connection through the local network is not necessarily limited to the SIPTO @ LN PDN connection.

15 is a diagram showing the configuration of a preferred embodiment for a terminal device and a network node device according to an example of the present invention.

The terminal device 100 according to the present invention with reference to FIG. 15 may include a transceiver 110, a processor 120, and a memory 130. The transceiver 110 may be configured to transmit various signals, data and information to an external device, and to receive various signals, data and information to an external device. The terminal device 100 may be connected to an external device by wire and / or wirelessly. The processor 120 may control the overall operation of the terminal device 100, and may be configured to perform a function of the terminal device 100 to process and process information to be transmitted and received with an external device. The memory 130 may store the processed information for a predetermined time and may be replaced with a component such as a buffer (not shown). In addition, the processor 120 may be configured to perform a terminal operation proposed in the present invention. Specifically, the processor 120 instructs an eNB (Evolved Node B) to report the location of the UE having a first local network PDN connection, and based on the location report received from the eNB, the first local network Determine that a PDN connection is not maintained, wherein the network node releases the first local network PDN connection and performs a second local network PDN connection,

When the release of the first local network PDN connection is performed before the second local network PDN connection, the network node does not detach the UE even if the first local network PDN connection is released.

Referring to FIG. 15, the network node apparatus 200 according to the present invention may include a transceiver 210, a processor 220, and a memory 230. The transceiver 210 may be configured to transmit various signals, data and information to an external device, and to receive various signals, data and information to an external device. The network node device 200 may be connected to an external device by wire and / or wirelessly. The processor 220 may control the overall operation of the network node device 200, and may be configured to perform a function of calculating and processing information to be transmitted / received with an external device. The memory 230 may store the processed information for a predetermined time and may be replaced with a component such as a buffer (not shown). In addition, the processor 220 may be configured to perform the network node operation proposed in the present invention.

In addition, the specific configuration of the terminal device 100 and the network device 200 as described above, may be implemented so that the above-described matters described in various embodiments of the present invention can be applied independently or two or more embodiments are applied at the same time, overlapping The description is omitted for clarity.

Embodiments of the present invention described above may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

For implementation in hardware, a method according to embodiments of the present invention may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), and Programmable Logic Devices (PLDs). It may be implemented by field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of an apparatus, procedure, or function for performing the above-described functions or operations. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Various embodiments of the present invention as described above have been described with reference to the 3GPP system, but may be applied to various mobile communication systems in the same manner.

Claims

In a method for a network node to perform a packet data network (PDN) connection operation of a user equipment (UE) in a wireless communication system,

Instructing the network node to report the location of a UE having a first local network PDN connection to an Evolved Node B (eNB);

Determining that the network node does not maintain the first local network PDN connection based on the location report received from the eNB; And

The network node releasing the first local network PDN connection and performing a second local network PDN connection;

Including;

When the release of the first local network PDN connection is performed before the second local network PDN connection, the network node does not detach the UE even if the first local network PDN connection is released. How to perform related actions.
The method of claim 1,

When the release of the first local network PDN connection is performed later than the second local network PDN connection, two PDN connections to the same access point name (APN) are allowed.
The method of claim 2,

Two PDN connection to the same APN is allowed only until the completion of the second local network PDN connection, the method of performing a PDN connection-related operation.
The method of claim 1,

And the first local network PDN connection of the UE is a last PDN connection of the UE.
The method of claim 4, wherein

Determining, by the network node, whether the first local network PDN connection is the last PDN connection of the UE;

Further comprising, PDN connection-related operation method.
The method of claim 5,

The determination of whether the first local network PDN connection is the last PDN of the UE is performed whenever the UE creates a PDN connection or whenever the UE enters a connected mode.
The method of claim 1,

The location report is sent by the eNB when the UE starts receiving service from the eNB or when the eNB determines to hand over the UE to an eNB of the second local network. .
The method of claim 1,

The eNB is adjacent to the second local network and located in the first local network.
The method of claim 1,

The APN for the first local network PDN connection is related to a vehicle to everything (V2X) service.
The method of claim 1,

The UE receives or transmits a V2X message on an LTE-Uu interface.
The method of claim 1,

If the release of the first local network PDN connection is performed before the second local network PDN connection, the network node transmitting a PDN Re-connection Request message to the UE.
The method of claim 1,

And the network node is an MME.
A network node device that performs a packet data network (PDN) connection related operation of a user equipment (UE) in a wireless communication system,

A transceiver; And

Includes a processor,

The processor instructs an eNB (Evolved Node B) to report a location of a UE having a first local network PDN connection, and maintain the first local network PDN connection based on a location report received from the eNB. Determine that the network node does not perform the network node, the network node performs the release of the first local network PDN connection and the second local network PDN connection,

If the release of the first local network PDN connection is performed before the second local network PDN connection, the network node does not detach the UE even if the first local network PDN connection is released. .