WO2016178554A1 - Method of transmitting/receiving signal in iops mode in wireless communication system, and device for same - Google Patents

Abstract

An embodiment of the present invention, with respect to a method of transmitting/receiving a signal in IOPS (Isolated E-UTRAN Operation for Public Safety) mode by means of a relay in a wireless communication system, comprises the steps of: discerning that a network has been switched to IOPS mode; attaching to a local EPC (Evolved Packet Core); receiving an IP (Internet Protocol) address from the local EPC; and transmitting information related to the IP address of the remote terminal that served before the attachment was implemented to the local EPC, and is a method of transmitting/receiving a signal in IOPS mode, in which the information related to the IP address of the remote terminal is mapping information between the IP address of the relay terminal allocated from the local EPC and the IP address of the remote terminal.

Description

Method for transmitting / receiving signal in IOPS mode 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 selecting and relaying a signal through a relay.

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.

In the present invention, the technical problem is to recognize the IOPS mode, the operation of the relay node in the IOPS mode.

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.

An embodiment of the present invention provides a method for a relay in a wireless communication system for transmitting and receiving a signal in an isolated E-UTRAN operation for public safety (IOPS) mode, the method comprising: identifying that the network has switched to the IOPS mode; Attaching to a local Evolved Packet Core (EPC); Receiving an IP address from the local EPC; And transmitting information related to the IP address of the remote terminal serving before performing the attach to the local EPC, wherein the information related to the IP address of the remote terminal is the IP of the relay terminal allocated by the local EPC. A signal transmission / reception method in an IOPS mode, which is mapping information between an address and an IP address of the remote terminal.

An embodiment of the present invention, a relay terminal device for transmitting and receiving a signal in an isolated E-UTRAN Operation for Public Safety (IOPS) mode in a wireless communication system, the relay device; And a processor, wherein the processor identifies that the network has switched to IOPS mode, attaches to a local Evolved Packet Core (EPC), receives an IP (Internet Protocol) address from the local EPC, and performs the attach The information related to the IP address of the remote terminal, which has been served before, is transmitted to the local EPC, and the information related to the IP address of the remote terminal is between the IP address of the relay terminal allocated by the local EPC and the IP address of the remote terminal. The relay terminal device which is mapping information of.

The information related to the IP address of the remote terminal may be to force the packet data network gateway (PGW) of the local EPC to transmit traffic to the remote terminal to the relay terminal.

The relay terminal may perform registration with an IP Multimedia Subsystem (IMS) / Session Initiation Protocol (SIP) core connected to the local EPC of the remote terminal.

The message transmitted by the relay terminal for registration in the IMS / SIP core may include both registration information of the relay terminal and registration information of the remote terminal.

The registration information of the relay terminal may include an IP address of the relay terminal, and the registration information of the remote terminal may include an IP address of the remote terminal.

The IP address of the relay terminal may be received from the local EPC, and the IP address of the remote terminal may be independent of the local EPC.

The relay terminal may omit new IP address assignment to the remote terminal.

The local EPC may include only one PGW, and the PGW may be the one PGW.

The relay terminal may identify that the network has switched to the IOPS mode through information included in a system information block (SIB).

The information included in the SIB may be a flag indicating the start of the IOPS mode.

Attaching to the local EPC may include transmitting an attach request to the MME of the local EPC.

According to the present invention, the remote UE does not need to be reassigned an IP address, and does not need to register with the IMS core individually, which is efficient.

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 data path through EPS.

8-9 show data paths in direct mode.

10 shows a ProSe UE-Network relay procedure.

11 illustrates an IOPS operation based on local EPC.

12 is a view for explaining the problems of the prior art.

FIG. 13 illustrates an IOPS mode operation according to an embodiment of the present invention. FIG.

14 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).

ProSe communication: Means communication through a ProSe communication path between two or more ProSe capable terminals. Unless specifically stated otherwise, ProSe communication may mean one of ProSe E-UTRA communication, ProSe-assisted WLAN direct communication between two terminals, ProSe group communication, or ProSe broadcast communication.

-ProSe E-UTRA communication: ProSe communication using ProSe E-UTRA communication path

ProSe-assisted WLAN direct communication: ProSe communication using a direct communication path

ProSe communication path: As a communication path supporting ProSe communication, a ProSe E-UTRA communication path may be established between ProSe-enabled UEs or through a local eNB using E-UTRA. ProSe-assisted WLAN direct communication path can be established directly between ProSe-enabled UEs using WLAN.

EPC path (or infrastructure data path): user plane communication path through EPC

ProSe Discovery: A process of identifying / verifying a nearby ProSe-enabled terminal using E-UTRA

ProSe Group Communication: One-to-many ProSe communication using a common communication path between two or more ProSe-enabled terminals in close proximity.

ProSe UE-to-Network Relay: ProSe-enabled public safety terminal acting as a communication relay between ProSe-enabled network using E-UTRA and ProSe-enabled public safety terminal

ProSe UE-to-UE Relay: A ProSe-enabled public safety terminal operating as a ProSe communication relay between two or more ProSe-enabled public safety terminals.

-Remote UE: In the UE-to-Network Relay operation, a ProSe-enabled public safety terminal that is connected to the EPC network through ProSe UE-to-Network Relay without receiving service by E-UTRAN, that is, provides a PDN connection, and is a UE. In -to-UE Relay operation, a ProSe-enabled public safety terminal that communicates with other ProSe-enabled public safety terminals through a ProSe UE-to-UE Relay.

ProSe-enabled Network: A network that supports ProSe Discovery, ProSe Communication, and / or ProSe-assisted WLAN direct communication. Hereinafter, the ProSe-enabled Network may be referred to simply as a network.

ProSe-enabled UE: a terminal supporting ProSe discovery, ProSe communication and / or ProSe-assisted WLAN direct communication. Hereinafter, the ProSe-enabled UE and the ProSe-enabled Public Safety UE may be called terminals.

Proximity: Satisfying proximity criteria defined in discovery and communication, respectively.

SULP Location Platform (SLP): An entity that manages Location Service Management and Position Determination. SLP includes a SPL (SUPL Location Center) function and a SPC (SUPL Positioning Center) function. For details, refer to the Open Mobile Alliance (OMA) standard document OMA AD SUPL: "Secure User Plane Location Architecture".

User Service Description (USD): The application / service layer includes Temporary Mobile Group Identity (TMGI) for each MBMS service, session start and end time, frequencies, MBMS service area identities (MBMS SAIs) information belonging to the MBMS service area. To put in USD to the terminal. See 3GPP TS 23.246 for details.

ISR (Idle mode Signaling Reduction): When a terminal frequently moves between E-UTRAN and UTRAN / GERAN, waste of network resources occurs by repeated location registration procedure. As a way to reduce this, when the terminal is in idle mode, two RATs (Radio Access Technology) already registered after the location registration with MME and SGSN (hereinafter referred to as mobility management node) via E-UTRAN and UTRAN / GERAN, respectively. This is a technology that does not register a separate location when moving between cells or performing cell reselection. Therefore, when DL (downlink) data arrives to the terminal, paging is simultaneously sent to the E-UTRAN and UTRAN / GERAN, thereby successfully finding the terminal and delivering the DL data. [See 3GPP TS 23.401 and 3GPP TS 23.060]

MBMS Single Frequency Network (MBSFN): A simulcast transmission technique implemented by simultaneously transmitting the same waveform to multiple grouped cells covering a certain area.

Evolved Packet Core (EPC)

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

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.

ProSe  (Proximity Service)

Prose service means a service capable of discovery and direct communication between physically adjacent devices, communication through a base station, or communication through a third device.

FIG. 7 illustrates a default data path through which two UEs communicate in EPS. This basic route goes through the operator's base station (eNodeB) and the core network (ie, EPC). In the present invention, such a path will be referred to as an infrastructure data path (or EPC path). In addition, communication through such an infrastructure data path will be referred to as infrastructure communication.

8 shows a direct mode communication path between two UEs based on Prose. This direct mode communication path does not go through an eNodeB and a core network (ie, EPC) operated by an operator. FIG. 8 (a) illustrates a case where UE-1 and UE-2 camp on different eNodeBs while transmitting and receiving data through a direct mode communication path. FIG. 8 (b) illustrates camping on the same eNodeB. FIG. 2 illustrates a case in which two UEs that are on exchange data via a direct mode communication path.

9 shows a communication path (locally-routed data path) through an eNodeB between two UEs based on Prose. The communication path through the eNodeB does not go through the core network (ie, EPC) operated by the operator.

Meanwhile, 3GPP Release 13 is studying a solution for providing a mobile communication service in an E-UTRAN without a backhaul (ie, a core network) or a connection with a backhaul that is limited. (3GPP SP-140714) As described above, the E-UTRAN without a backhaul (that is, the core network) and the connection with the backhaul and the E-UTRAN having a limited connection with the backhaul are called isolated E-UTRAN, in particular, such an isolated E-UTRAN. The mobile communication service in UTRAN is for public safety terminal / scenario. The operation of the isolated E-UTRAN is called IOPS (Isolated E-UTRAN Operation for Public Safety). IOPS is? No backhaul ?,? Limited bandwidth signaling only backhaul ?,? Limited bandwidth signaling and user data backhaul? Assume such cases.

FIG. 10 illustrates a process in which a remote UE prepares a connection service to a network by searching for a UE-to-Network Relay to form a one-to-one direct communication with each other. For more details, refer to TR 23.713. Can be.

In step S1001, the UE-Network Relay performs an initial E-UTRAN attach procedure and / or establish a PDN connection for the relay. In the IPv6 case, the relay gets the IPv6 prefix from the prefix delegation function.

In step S1002, the remote UE performs discovery of the UE-Network Relay through model A discovery or model B discovery.

Model A discovery is a direct discovery in which an announce UE operates to inform its neighboring UEs of its presence, and monitors whether the announce UE is in a proximate location where the monitoring UE announces information of interest. Model B discovery is a direct discovery in which a Discoveree UE responds with information related to the request when the Discoverer UE sends a request including information to be discovered.

In step S1003, the remote UE selects a UE-Network Relay and establishes a connection for one-to-one communication.

In step S1004, when IPv6 is used on PC5, the remote UE performs IPv6 Stateless Address auto-configuration. The remode UE transmits a Router Solicitation message to the network using a Destination Layer-2 ID. Router Advertisement messages contain an assigned IPv6 prefix. After the remote UE receives the Router Advertisement message, the remote UE configures a full IPv6 address through IPv6 stateless address auto-configuration. However, the remote UE should not use any identifiers defined in TS 23.003 as the basis for generating the interface identifier. For privacy, the remote UE changes the interface identifier used to generate a full IPv6 address without involving the network. The remote UE must use an auto-configured IPv6 address while transmitting the packet.

In step S1005, the remote UE uses DHCPv4 'when IPv4 is used on PC5. The remote UE must send a DHCPv4 discovery message using the Destination Layer-2 ID. The relay, acting as a DHCPv4 server, transmits a DHCPv4 Offer with an assigned Remote UE IPv4 address. When the remote UE receives the lease offer, it transmits a DHCP REQUEST message including the received IPv4 address. The relay operating as a DHCPv4 server transmits a DHCPACK message including a lease duration and configuration information requested by the client to the remote UE. Upon receiving the DHCPACK message, the remote UE completes the TCP / IP configuration process.

The IOPS solution is being studied in TR 23.797. Below is a solution for the case where there is no / disconnected connection to the backhaul worked in section 6.1 of TR 23.797.

This solution assumes that the eNB is co-sited or reachable by a Local EPC instance (including at least the MME, SGW / PGW and means to locally deliver security / access control as required by 3GPP SA3) used in IOPS mode. This allows to replicate the behavior of nomadic EPSs isolated from the macro network.

Support of application services on the IOPS network is based on EPS bearer services supported by the LTE-Uu air interface and Local EPC.

If the backhaul to the macro EPC is lost, the following is expected.

If the eNB can reach the local EPC for the IOPS mode, the eNB must use the local EPC. If the eNB cannot reach the local EPC for IOPS mode, it enters a state where the UE does not attempt to select a cell.

Nomadic EPS assists public safety services in uncovered areas, either via an IOPS network using local EPC or an eNB serving macro EPC. The eNB enters an IOPS mode operation after detecting that the S1 connection to the macro EPC is lost. In this mode, the eNB starts advertising the PLMN ID dedicated to IOPS. Only authorized UEs can access this PLMN. The UE should be configured to handle this PLMN ID with lower preference (for EUTRAN access) so that other PLMNs in Macro EPC are preferentially selected in automatic PLMN selection.

The dedicated IOPS PLMN, like the Access Class status of 11 or 15, needs to be configured within the USIM as an HPLMN. In the IOPS mode operation, the eNB sends the IOPS PLMN cell to? Not Barred ?. &? reserved? Should be directed / broadcasted. Cell reserved for operator use? The feature allows a public safety terminal to gain access to an IOPS network while barring other users in the same area.

Authorized PS (Public Safety) When a UE selects an IOPS-mode cell, it attaches to a dedicated PLMN and authenticates using a security procedure. If the service range of the Local EPC is a single eNB, all cells served by the eNB must share the same TAI (allocated for use in ISOP mode). And neighbor eNBs operating in IOPS mode, which are assigned the same dedicated PLMN-Id, are assigned different TAIs and thus the TAU is triggered according to mobility. This TAU results in TAU rejection due to the lack of proper credentials / identity and allows the UE to re-attach to the co-sited EPC via the new eNB.

However, if multiple eNBs are configured to be served by a single local EPC, the TAI configuration for IOPS is in accordance with the local operator policy, in which reselection to a cell operating in normal mode PLMN always triggers the TAU. In the allowed, normal mode, the EUTRAN PLMN operation is configured to the terminal with a higher priority than the IOPS PLMN. If the same PLMN-Id is shared, the TAI assigned to the cell in the Nomadic EPS to trigger the TAU between these systems is assumed to be different from the TAI assigned to the IOPS mode. During the attach procedure to the local EPC, according to a general procedure, such as when attaching to the Macro EPC, a local IP address is assigned to the terminal.

The local EPC acts as an IP router between terminals attached locally to the same IOPS network. If the backhaul to the macro EPC is reestablished, the S1 connection to the local EPC is released according to the IOPS network policy to move the UE into idle mode.

The following describes the IOPS network configuration / establishment.

The IOPS network may consist of a local EPC instance and a single isolated eNB (which may be co-located). Or, it may be configured with a local EPC instance and two or more eNBs, and one eNB may be co-located with the local EPC.

The procedure defined in LTE standard document TS 36.300 can be used for the dynamic configuration of the S1-MME interface. IOPS capable eNB can be pre-provisioned with IP endpoint information. For each MME, the eNB may attempt to initialize the SCTP association in turn. Once the SCTP is established, the eNB and the eNB exchange application-level configuration data with the S1 Setup Procedure through the S1-MME application protocol. Depending on the operator policy, the eNB can be provisioned with an IP endpoint of the preferred Local EPC MME instance and one or more alternative EPC MME instances. Alternative local EPC instances are used when the S1-MME route cannot be established with the MME of the preferred local EPC instance.

The eNB's decision whether to enter IOPS mode should be made according to the local policy of the RAN operator. This policy is affected by the RAN sharing agreement, which may be in place.

All local EPC instances introduced by the public safety authentication / operator must assume the same PLMN-Id. To achieve broadcast of different TAIs on separate IOPS networks, TACs broadcast by cells of eNBs connected to different local EPCs must be distinguished to assure the required UE mobility behavior. Therefore, the TAC broadcast by the eNB's cell operating in IOPS mode should be dependent on the local EPC with which the S1-MME connection is established with the eNB. Support of S1-flex by IOPS depends on local operator policy and configuration.

Some distinct UE mobility scenarios can be identified by the following assumptions. Multiple eNBs may be configured to be served by a single local EPC. A single, dedicated PLMN-Id may be advertised by all eNBs operating in IOPS mode. All cells served by the IOPS-eNB must share the same TAI, and the TAIs broadcast by cells served by different local EPCs must be different.

The mobility scenario is as follows.

First, UE movement from a cell controlled by normal macro EPC to a cell operating in IOPS mode

Second, the UE moves from a cell operating in IOPS mode to a cell controlled by normal macro EPC

Third, moving from a cell having an eNB served by a single local EPC and operating in an IOPS mode to a cell operating in an IOPS mode with an eNB served by a different local EPC.

Fourth, UE movement between cells having eNBs served by the same local EPC and operating in IOPS mode

The UE mobility behavior expected by each of these scenarios is shown in Table 2 below.

	ECM state
MOBILITYTRANSITION	IDLE MODE	CONNECTED MODE
Normal mode cell to IOPS mode cell	Cell re-selection followed by TAU Reject:-UE performs cell re-selection based upon radio measurements.- TAI of new cell not in UE? S TAI list so UE requests TAU.- TAU rejected because of lack of recognised identity / credentials in new network.- UE enters De-registered state and initiates Attach procedure towards Local / Normal EPC.	Radio link failure followed by cell re-selection:-UE performs radio measurements but source and target cells are on different networks so HO not possible.- Radio link failure occurs and UE returns to Idle mode.- UE performs cell selection based upon radio measurements -UE proceeds as per behavior for Idle Mode.
IOPS mode cell to Normal mode cell
Inter-IOPS network cell transition
Intra-IOPS network cell transition	Idle Mode mobility as per normal:-UE performs cell re-selection based upon radio measurements.- TAI of new cell is the same as in the old cell or is in TAI list.- UE camps on new cell	Connected Mode mobility as per normal:-E-UTRAN initiated HO based upon radio measurements.- TAI of new cell is the same as in the old cell or is in TAI list.- Handover of active bearers

11 illustrates an IOPS operation based on local EPC.

In step S1101, it is detected that the backhaul is lost by the eNB.

In step S1102, the eNB supporting the IOPS mode, by a) preventing the UE from selecting a cell using a method such as cell barring, b) activate the local EPC, c) establish an S1 link with the local EPC, Transition to IOPS mode.

In step S1103, the eNB advertises a PLMN ID for IOPS mode operation. The announced TAI is from (selected) the TAI pool allocated for nomadic systems and IOPS. It can only be reused by an eNB that is not expected to be connected to the same local EPC.

In step S1104, the UE that detects the IOPS PLMN ID attempts to reselect another suitable cell serving the Macro EPC. According to the user preferences, for example, even if a cell operating in the normal mode is selectable, the user may switch to the manual PLMN selection mode and select the IOPS PLMN to maintain group communication.

In step S1105, if the UE does not find a suitable cell serving the Macro EPC or manually selects the IOPS PLMN, the UE attaches to the local EPC and obtains a local IP address.

In step S1106, if the public safety service is supported by the IOPS network, it is started at this time.

At step S1107, at any time, the eNB may detect that the backhaul to the macro EPC has been restored.

In step S1108, the S1 connection to the local EPC is released according to the IOPS network policy to put the UE into idle mode and the eNB stops IOPS mode operation. The PLMN ID of the macro EPC is announced, the normal TAI of the macro EPC is advertised to allow the UE to reselect the normal PLMN, and the TAU procedure is triggered. The TAU is rejected due to lack of proper credentials / identity, and a new attach to the macro EPC is performed.

In step S1109, if authentication is successful, the UE attaches to the macro EPC.

FIG. 12A illustrates a network connection through UE-2, which is a remote UE, and UE-1, which is a UE-to-Network Relay. Also, UE-5 and UE-6, which are remote UEs, are UE-to- FIG. The following shows a scenario where a network connection is provided through UE-4, a network relay. Here UE-1 and UE-4 are in coverage of eNodeB # 1 and eNodeB # 2, respectively. FIG. 12B illustrates a situation in which the eNodeB # 1 has a failure in connection to the backhaul in the situation of FIG. 12A and is disconnected to the backhaul (ie, Macro EPC) and instead connected to the Local EPC. That is, eNodeB # 1 operates in IOPS mode.

In the prior art, there is no mention of how to handle the UE-to-Network Relay service in this case.

In particular, UE # 1, which is a UE-to-Network Relay, acquires an IP address by attaching to Local EPC as eNodeB # 1, which has been serviced, changes to IOPS mode (see step S1105 of FIG. 11). Afterwards, there is a need for a method of processing an IP address of a remote UE in order to continuously provide UE-to-Network Relay service to UE # 2 and UE # 3, which have provided UE-to-Network Relay service. Accordingly, the present invention proposes a ProSe UE-to-Network Relay mechanism for efficiently supporting the isolated E-UTRAN operation.

Example  One

After the relay terminal (relay or UE-to-network relay) according to an embodiment of the present invention identifies that the network has switched to the IOPS mode, it may attach to a local Evolved Packet Core (EPC). In addition, the relay terminal may receive an IP (Internet Protocol) address from the local EPC.

Here, the relay terminal may transmit the information related to the IP address of the remote terminal (remote UE) that was serving before performing the attach to the local EPC, and the information related to the IP address of the remote terminal may be the IP of the relay terminal allocated by the local EPC. The mapping information between the address and the IP address of the remote terminal or the IP address used before the switch to the IOPS mode. This can be done after the UE-to-Network relay attaches to the local EPC to obtain a new IP address (or after creating a PDN connection) or while creating a PDN connection by attaching to the local EPC. You may.

This allows the PGW of the local EPC to route traffic transmitted to the remote UE to the UE-to-Network relay. That is, the information related to the IP address of the remote terminal may be to force the PGW of the local EPC to transmit traffic to the remote terminal to the relay terminal. Thereafter, when the UE-to-Network relay receives the traffic destined for the remote UE, it may transmit it to the remote UE. In addition, in case of traffic transmitted by the remote UE, the UE-to-Network relay may receive it and transmit it to the network / P-GW.

The relay terminal may perform registration with an IP Multimedia Subsystem (IMS) / Session Initiation Protocol (SIP) core connected to the local EPC of the remote terminal. In this regard, the relay terminal may replace / substitute for registration in the IMS / SIP core of the remote terminals it serves.

Specifically, the message transmitted by the relay terminal for registration in the IMS / SIP core may include both registration information of the relay terminal and registration information of the remote terminal. That is, when the relay terminal itself registers with the IMS / SIP core, the relay terminal performs registration with all the remote UEs served by the relay terminal. In this case, the registration information of the relay terminal may include the IP address of the relay terminal, and the registration information of the remote terminal may include the IP address of the remote terminal. In this case, the IP address of the relay terminal is received from the local EPC, and the IP address of the remote terminal is independent of the local EPC. Alternatively, after the relay terminal performs registration with the IMS / SIP core or before the relay terminal, the relay terminal may perform registration for all the remote UEs that it serves. This may include the registration information of all the remote UEs (including the IP addresses of the remote UEs) in one registration message. Alternatively, after the relay terminal performs registration with the IMS / SIP core, or before the relay terminal, the relay terminal may perform registration with respect to all the remote UEs that it serves. This may include the registration information of one remote UE (which includes the IP address of the remote UE) in one registration message. The registration message may be a SIP REGISTER message, and may explicitly or implicitly include information that the UE-to-Network relay supports the relay to the remote UE.

Through the above-described configuration, after the UE-to-Network relay attaches to the local EPC to obtain an IP address, an operation of allocating a new IP address to the remote UE that has been serving (example of FIG. 10) Step S1004 to S1005) may be omitted in the ProSe UE-Network relay procedure. As a result, the UE-to-Network relay, which is receiving the service from the eNB switched to the IOPS mode, can save signaling and PC5 resources due to reallocating the IP address all the time to the remote UE providing the relay service. This may be more effective when there are a large number of UE-to-Network relays serviced from the eNB.

In the above description, the local EPC may be assumed to include only one PGW or to operate only one PGW. Even if multiple Public Safety Servers (or Public Safety Application Servers or MCPTT Servers / ASs, Group Communication Service Servers / ASs, etc.) exist in the local EPC, they are all connected to the same P-GW, so all traffic is routed through the P-GWs. Can be routed. In addition, if the local EPC has an IMS or SIP core (i.e., has a connection with the IMS / SIP core), a P-CSCF or a corresponding SIP server is connected to the P-GW. / SIP messages can be routed through the P-GW.

In the above description, the terminal is one of the following to identify / whether the network (where the network may be a radio access network (RAN), a core network (CN) and / or a public safety application domain) has switched to the IOPS mode The above method can be used. (This acknowledgment may be interpreted as acknowledging that the IP address is changed / updated. This acknowledgment may be interpreted as acknowledging that one-to-one direct communication connection with the remote UE should be changed / updated. May be interpreted as knowing that the remote UE needs to change / update the IP address, or such acknowledgment may be interpreted as recognizing that a normal connection to the network is not possible. It may be interpreted as recognizing that it is no longer able to provide a -to-Network Relay service.) The relay terminal may identify that the network has switched to the IOPS mode through information included in the SystemInformationBlock (SIB). That is, the switch to the IOPS mode can be identified through the information indicating that the switch to the IOPS mode transmitted by the eNB. Here, the existing SIB may be extended or may be a new SIB. However, the present invention is not limited thereto, and various methods may be used, such as the eNodeB transmitting the information in a dedicated channel to the UE-to-Network relay. For example,? Start_IOPS_mode 뮸? The same IE / flag can be set to TRUE / YES / 1. That is, the information included in the SIB may be a flag indicating the start of the IOPS mode. Alternatively, the PLMN ID sent by the eNodeB is the PLMN ID for IOPS, which identifies the transition to IOPS mode. This means that the eNodeB broadcasts the PLMN ID dedicated to the IOPS mode, proposed in Section 6.1 of the above-mentioned TR 23.797. Alternatively, the cell sent by the eNodeB may identify the switching to the IOPS mode of the network through the information indicating that the cell which is allowed to use the IOPS network may be selected / reselected. The eNodeB is not Barred for the cell. &? reserved for operator use 뮯? Broadcast may be an example. Both IEs are included in SIB1 and cellBarred =? Not barred \? cellReservedForOperatorUse =? reserved 뮮? Is set. As another example, the information indicating that the normal mode sent by the eNodeB is stopped may indicate that the network has switched to the IOPS mode. Such information may be, for example, a System Information Block (SIB) transmitted by the eNodeB. This may be an extension of an existing SIB or may be a new SIB. However, the present invention is not limited thereto, and various methods may be used, such as the eNodeB transmitting the information in a dedicated channel to the UE-to-Network Relay. As an example of the information,? Stopped_normal_mode 뮸? Set to TRUE / YES / 1, etc. There may be the same IE / flag. Information that prevents the eNodeB from selecting or reselecting the sending cell indicates that the network has switched to IOPS mode. Such information may be barring information (cellBarred (IE type:? Barred? Or? Not barred?)) Of a cell transmitted through the existing SIB1. Or, for example, the eNodeB may extend the existing SIB and send it through a new SIB. However, the present invention is not limited thereto, and various methods may be used, such as the eNodeB transmitting the information in a dedicated channel to the UE-to-Network Relay. Alternatively, when the UE-to-Network Relay cell (camping-on cell or serving cell) is no longer caught or if no information is received from the eNodeB, it may be recognized that the network has switched to the IOPS mode. For example, the eNodeB / cell (s) that normally operated even though the UE-to-Network Relay did not move at all stop.

In addition, the UE-to-Network relay message includes information indicating that the remote UE will continuously provide the UE-to-Network relay service and / or information indicating that the UE-to-Network relay service will be provided without changing the IP address. Can also be transmitted.

13 illustrates an example of the above description. Referring to FIG. 13, in step S1301, UE-1 and UE-2 perform a relay discovery operation and a ProSe one-to-one communication setting operation (see the ProSe UE-Network relay procedure shown in FIG. 10). UE-1 is a remote UE and UE-2 is a UE-to-Network relay. In step S1302 to step S1303, the UE-1 is assigned an IP address from UE-2, and registers the newly obtained IP address into the IMS network. In steps S1304 to S1305, the IMS network performs 3rd party registration with the MCPTT AS (Application Server). In the present embodiment, the MCPTT AS is illustrated as a third party AS, but may be an AS (eg, MMTel AS) that provides various types of services instead of the MCPTT service. In step S1306, the operation is switched to the IOPS mode operation and the IOPS mode operation is started. The detailed operation may correspond to steps S1101 to S1104 of FIG. 11. In step S1307, UE-2 (UE-to-Network Relay) attaches to the local EPC. This obtains a new IP address from the local EPC. In steps S1308 to S1309, UE-2 assigns the IP address (the IP address used by UE-1 before switching to IOPS mode) of UE-1, which is a remote UE, to P-GW (this is a P-GW belonging to the local EPC). To send). The message containing the information is transmitted to the MME using a NAS message (an existing message or a newly defined message), and the MME transmits this information to the P-GW through the S-GW. In step S1310, UE-2 registers with the local IMS network on behalf of UE-1.

Example  2

In Embodiment 1, the relay relates to a method of supporting the use of an existing IP address of a remote UE. In Embodiment 2, the relay relates to a method of changing / updating the address of a remote UE.

Recognizing that the network switches to the IOPS mode by the method described above, the UE-to-Network Relay performs an operation of changing / updating an IP address for the remote UE that provided the network connection service. The operation may be performed after the UE-to-Network Relay attaches to the Local EPC to obtain a new IP address (or after creating a PDN connection), and the UE-to-Network Relay is being served by the UE-to-Network Relay. You can do this immediately after recognizing that the network has switched to an IOPS network. The operation of changing / updating the IP address to the remote UE by the UE-to-Network Relay may be interpreted as a one-to-one direct communication change / update operation with the remote UE. The UE-to-Network Relay can send to the remote UE when an IP address is available to update (or assign) to the remote UE. In detail, the UE-to-Network Relay transmits an IP address to the remote UE. For example, when an IPv6 address is used, a Router Advertisement message including an IPv6 prefix is transmitted to the remote UE. Alternatively, the message including the information may be transmitted as a direct discovery related message, a direct communication related message, or a PC5 signaling message. The UE-to-Network Relay sends a message to the remote UE to initiate the IP address acquisition procedure. This message may be sent to each remote UE individually or may be broadcast. The message may be transmitted as a direct discovery related message, a direct communication related message, or a PC5 signaling message. The message may explicitly indicate to the remote UE to initiate an IP address acquisition procedure (either by information or by the message name itself) or by implicit information (e.g., information indicating that it is connected to an IOPS network). Initiation of an address acquisition procedure may be encouraged.

The remote UE receiving the message initiates an IP address acquisition procedure (e.g., sends a Router Solicitation message to the UE-to-Network Relay if an IPv6 address is used, a DHCPv4 Discovery message or a DHCPv4 if an IPv4 address is used). Send request message to UE-to-Network Relay). The UE-to-Network Relay receives a request for obtaining an IP address from the remote UE, and then transmits a new IP address to the remote UE.

When the isolated E-UTRAN to which the UE-to-Network Relay belongs is connected to the Local EPC and the connection to the Macro EPC is restored, the UE-to-Network Relay may recognize the connection restoration based on one or more of the following information. . i) Information indicating that the eNodeB has switched to normal mode (this information may be informed, for example, by a SystemInformationBlock (SIB) transmitted by the eNodeB. This may be an extension of an existing SIB or a new SIB. Various methods may be used such that the eNodeB transmits the information to the UE-to-Network Relay in a dedicated channel, for example, IE / flag such as? End_IOPS_mode? Set to TRUE / YES / 1, etc.). ii) The PLMN ID sent by the eNodeB is the PLMN ID for normal mode (this may be a PLMN ID that broadcasts in normal / normal mode rather than the PLMN ID dedicated to IOPS mode proposed in the solution worked in Section 6.1 of TR 23.797). ) Information indicating that the cell sent by the eNodeB may be selected / reselected by a UE other than the UEs allowed to use the IOPS network (Example of such information is that the eNodeB sends? Not Barred? &? Not res for the cell. erved for operator use? ”For reference, both IEs are included in SIB1, and cellBarred =? not barred 뮮? cellReservedForOperatorUse =? not reserved 뮮?)

The UE-to-Network Relay, aware of the restoration of the connection, can change / update the IP address to the remote UE. That is, the UE-to-Network Relay performs an operation of changing / updating an IP address for a remote UE that has provided a network connection service. The operation may be performed after the UE-to-Network Relay attaches to the Macro EPC to obtain a new IP address, or may be performed immediately after recognition of the restoration.

Example  3

The UE-to-Network Relay identifying that the network is transitioning or switching to the IOPS mode may inform other UEs that the UE-to-Network Relay service cannot be provided. As a method of identifying that the network is in the IOPS mode, the network is switched to the IOPS mode through the information indicating that the network described in the first embodiment has switched to the IOPS mode and additionally indicating that the eNodeB is in the IOPS mode. You may notice that you are transitioning. Such information may be, for example, a System Information Block (SIB) transmitted by the eNodeB. This may be an extension of an existing SIB or may be a new SIB. However, the present invention is not limited thereto, and various methods may be used, such as the eNodeB transmitting the information in a dedicated channel to the UE-to-Network Relay. As an example of the information,? Processing_IOPS_mode_transition 뮥? Set to TRUE / YES / 1, etc. There may be the same IE / flag. The UE-to-Network Relay may inform other UE with one or more of the following information that it cannot provide and / or provide UE-to-Network Relay service. Such a notification may be interpreted as indicating that the network to which the UE-to-Network Relay belongs is being switched to or switched to an IOPS network. a) information indicating that the UE-to-Network Relay service cannot be provided, b) information indicating that there is no connection / disconnection to the network, and c) no connection / connection to the normal network (or Macro EPC). Information indicating that a connection has been made, d) information indicating / indicating to select another UE-to-Network Relay, e) information indicating that a connection to / from an IOPS network (or Local EPC) is in progress, and f) in the PLMN for IOPS. This information may include information indicating that a connection has been made, g) information indicating a transition from a normal mode to an IOPS mode, and h) information indicating / indicating to use a direct group communication through a network instead of a group communication through a network. .

Or, the UE-to-Network Relay identifying that the network has switched to IOPS mode recognizes that there is no normal network (or cell) that can be selected / reselected. Or before or after) as a result.

Unlike the above, the UE-to-Network Relay may inform other UEs of one or more of the information of a) to h) only under certain conditions. As a specific example, if the number of UEs in the group to which the UEs providing the UE-to-Network Relay service belongs (or the group in which the UEs are being served) is below (or below) any threshold value, for example, Group # 1. In case of 5 UE and Group # 2, UE-to-Network Relay service was provided to 7 UEs. If any threshold value (which can be provisioned to UE-to-Network Relay) is 5, Group # For 1, the information of a) to h) may be informed to other UEs, but not for Group # 2. Or together with the information of a) to h), further provides group information that can no longer provide a UE-to-Network Relay service, or adds group information that can continue to provide a UE-to-Network Relay service. You can also provide.

Alternatively, one or more of the information of a) to h) may be informed to the other UE depending on whether the IOPS network provides the MBMS. For example, if the IOPS network does not provide MBMS, the UE-to-Network Relay informs another UE of the information of a) to h). You can broadcast when notifying other UEs, and you can also notify each of the remote UEs you have been serving. The UE-to-Network Relay may transmit a message for advertising the information in the form of advertise / announce, and may transmit a message from another UE (a remote UE that is already serving and / or a UE searching for a UE-to-Network Relay). If received, the response may be included and sent. For example, the information may utilize various UE-to-Network Relay discovery parameters proposed in Section 6.1 (Solution for Direct Discovery (public safety use)) of the above-mentioned TR 23.713, or may define and use new parameters. . An example of using an existing UE-to-Network Relay discovery parameter is to use a Status / maintenance flags parameter, a Radio Layer Information parameter, a PLMN ID parameter, and the like.

The remote UE receiving the message including the above information from the UE-to-Network Relay may perform one or more of the following operations. i) Searching for another UE-to-Network Relay (especially when receiving a) to d). ii) Maintaining an existing UE-to-Network Relay (this is i) followed by other available / If there is no selectable UE-to-Network Relay, ii) may be performed, or ii) may be performed without i) and iii) disconnecting from the existing UE-to-Network Relay. That is, it decides not to receive network connection service from UE-to-Network Relay, iv) decides to use direct group communication without network instead of group communication through network, v) decides to use only ProSe direct discovery / communication. Can be.

The above description mainly describes the case where there is no connection / disconnection to the backhaul, but the present invention can be extended to the limited backhaul scenario.

In addition, the above-described invention is an operation in which the UE-to-Network relay is connected to the normal network and then to the IOPS network, but this is because the UE-to-Network relay is connected to the normal network but the IP address is changed / updated. It can also be extended.

In addition, the above-described invention is that the IP address of the remote UE is changed as the UE-to-Network relay is connected to the normal network and connected to the IOPS network, but the IP address of the remote UE is maintained. IP addresses can also be extended to use existing ones. In this case, the P-GW can tell the IP address that it was using so that the P-GW can route properly.

The present invention is not limited to the LTE / EPC network, but can be applied to the entire UMTS / EPS mobile communication system including both 3GPP access networks (eg, UTRAN / GERAN / E-UTRAN) and non-3GPP access networks (eg, WLAN, etc.). have. In addition, it can be applied in all other wireless mobile communication system environments in the environment where control of the network is applied.

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

Referring to FIG. 14, the terminal device 100 according to the present invention 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. In addition, the processor 120 may be configured to perform a terminal operation proposed in the present invention. 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).

Referring to FIG. 14, the network node device 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. In addition, the processor 220 may be configured to perform the network node operation proposed in the present invention. 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 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 (12)

1. In a wireless communication system, a relay transmits and receives a signal in an isolated E-UTRAN operation for public safety (IOPS) mode,

   Identifying that the network has switched to IOPS mode;

   Attaching to a local Evolved Packet Core (EPC);

   Receiving an IP address from the local EPC; And

   Transmitting information related to the IP address of the remote terminal serving before performing the attach to the local EPC;

   Including;

   And the information related to the IP address of the remote terminal is mapping information between the IP address of the relay terminal and the IP address of the remote terminal allocated by the local EPC.
2. The method of claim 1,

   The information related to the IP address of the remote terminal is a packet data network-gateway (PGW) of the local EPC to force to send traffic to the remote terminal, the signal transmission and reception method in the IOPS mode.
3. The method of claim 1,

   The relay terminal is a signal transmission and reception method in the IOPS mode to perform registration to the IP Multimedia Subsystem (IMS) / Session Initiation Protocol (SIP) core connected to the local EPC of the remote terminal.
4. The method of claim 3,

   The message transmitted by the relay terminal for registration with the IMS / SIP core includes both the registration information of the relay terminal and the registration information of the remote terminal.
5. The method of claim 4, wherein

   The registration information of the relay terminal includes the IP address of the relay terminal, the registration information of the remote terminal includes the IP address of the remote terminal, the signal transmission and reception method in the IOPS mode.
6. The method of claim 5,

   The IP address of the relay terminal is received from the local EPC, the IP address of the remote terminal is independent of the local EPC, signal transmission and reception method in the IOPS mode.
7. The method of claim 1,

   And the relay terminal omits allocation of a new IP address to the remote terminal.
8. The method of claim 2,

   The local EPC includes only one PGW, and the PGW is the one PGW.
9. The method of claim 1,

   The relay terminal is a signal transmission and reception method in the IOPS mode to identify that the network has switched to the IOPS mode through the information contained in the System Information Block (SIB).
10. The method of claim 9,

    The information included in the SIB is a flag indicating the start of the IOPS mode, the method of transmitting and receiving signals in the IOPS mode.
11. The method of claim 1,

    Attaching to the local EPC includes transmitting an attach request to the MME of the local EPC.
12. In the relay terminal device for transmitting and receiving a signal in an isolated E-UTRAN Operation for Public Safety (IOPS) mode in a wireless communication system,

    A transceiver; And

    Includes a processor,

    The processor identifies that the network has switched to IOPS mode, attaches to a local Evolved Packet Core (EPC), receives an IP (Internet Protocol) address from the local EPC, and serves the remote terminal before serving the attach. Send information related to the IP address of the local EPC,

    And the information related to the IP address of the remote terminal is mapping information between the IP address of the relay terminal allocated by the local EPC and the IP address of the remote terminal.

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