WO2012148206A2

WO2012148206A2 - Method and device for providing continuity in mbms service

Info

Publication number: WO2012148206A2
Application number: PCT/KR2012/003267
Authority: WO
Inventors: 정명철; 권기범; 안재현
Original assignee: 주식회사 팬택
Priority date: 2011-04-28
Filing date: 2012-04-26
Publication date: 2012-11-01
Also published as: KR20120122335A; WO2012148206A3

Abstract

The present invention relates to a method and a device for providing continuity in an MBMS service. Disclosed in the present invention is an MME comprising: an MME reception unit for receiving from an MCE, an MBMS support request message for requesting support of continuous MBMS service at a core network level for a terminal and an MBMS session response message for indicating that an MBMS session on the MBMS service can be initiated at a target base station; a session control unit for confirming whether the MBMS session on the MBMS service can be initiated, allocating network resources for the MBMS service transmission, and setting a bearer on the MBMS service; and an MME transmission unit for transmitting to the MCE, an MBMS session initiation message for indicating the initiation of the session on the MBMS service. The present invention ensures continuity in MBMS service for a terminal by initiating the MBMS session when the MBMS service needs to be provided due to the moving of the terminal.

Description

Apparatus and method for providing continuity of MBMS services

The present invention relates to wireless communications, and more particularly, to an apparatus and method for providing continuity of MBMS services.

Cellular is a concept proposed to overcome the limitations of coverage area, frequency and subscriber capacity. This is a method of providing a call right by replacing a high power single base station with a plurality of low power base stations. In other words, by dividing the mobile communication service area into several small cells, adjacent cells are assigned different frequencies, and two cells that are sufficiently far apart from each other and do not cause interference can use the same frequency band to spatially reuse frequencies. To make it possible.

Handover or handoff is when the terminal moves away from the current communication service area (source cell) as the terminal moves to an adjacent communication service area (target cell). It is a function that automatically tunes to a new traffic channel of an adjacent communication service area and keeps a call state continuously. That is, a terminal communicating with a specific base station is linked to another neighboring base station (target base station) when the signal strength of the specific base station (hereinafter referred to as a source base station) is weakened. . If a handover is made, the problem of call disconnection occurring when moving to an adjacent cell can be solved.

MBMS (Multimedia Broadcast / Multicast Service) is a service that transmits data packets to multiple users at the same time similarly to the existing CBS (Cell Broadcast Service). However, while CBS is a low-speed message-based service, MBMS is intended for high-speed multimedia data transmission. In addition, CBS is not based on IP (internet protocol), but MBMS is based on IP multicast. When a certain level of users exists in the same cell, by sharing the necessary resources (or channels), multiple users receive the same multimedia data to improve the efficiency of radio resources and to use multimedia services inexpensively. That is the advantage of MBMS.

The MBMS uses a common channel called a multicast channel to efficiently receive data from a plurality of terminals in one service. That is, not one dedicated channel is allocated to one service data, but only one shared channel, as many as the number of terminals to receive the service in one cell. A plurality of terminals simultaneously receive the shared channel, thereby improving the efficiency of radio resources.

An object of the present invention is to provide an apparatus and method for providing continuity of MBMS service.

Another technical problem of the present invention is to provide an apparatus and method for initiating an MBMS session for a terminal when a terminal receiving an MBMS service is handed over.

Another technical problem of the present invention is to provide a method for providing continuity of MBMS service by entities of core network level.

Another technical problem of the present invention is to provide an apparatus and method for controlling a session to continuously provide an MBMS service to a handing over terminal.

According to an aspect of the present invention, there is provided a target base station that provides a multimedia broadcast multicast service (MBMS) service to a terminal handing over from a source eNB to a target eNB. The target base station includes an MBMS support request message for requesting support of a continuous MBMS service at a core network level for the terminal, and an MBMS session indicating that a session about the MBMS service can be started at the target base station. Receiving a target transmitter for transmitting a response message to a multi-cell coordination entity (hereinafter referred to as MCE), and an MBMS continuity request indicator for requesting the terminal to continuously provide the MBMS service from a source base station; And a target receiver configured to receive an MBMS session initiation message from the MCE indicating the initiation of a session related to an MBMS service.

According to another aspect of the present invention, there is provided a method of providing an MBMS service at a target base station to a terminal handing over from a source base station to a target base station. The method includes receiving from the source base station an MBMS continuity request indicator requesting the terminal to continuously provide MBMS service, and transmitting an MBMS support request message requesting support of the continuous MBMS service at the core network level for the terminal to the MCE. Receiving an MBMS session initiation message from the MCE indicating an initiation of a session relating to the MBMS service, and receiving an MBMS session response message indicating that a session regarding the MBMS service can be initiated at a target base station; Transmitting to.

According to another aspect of the present invention, there is provided a mobility management entity (hereinafter referred to as MME) for providing an MBMS service to a terminal handing over from a source base station to a target base station. The MME receives from the MCE an MBMS support request message requesting continuous MBMS service support at the core network level for the terminal and an MBMS session response message indicating that an MBMS session for the MBMS service can be initiated at a target base station. An MME receiver, a session controller for checking whether an MBMS session for the MBMS service can be started, allocating network resources for the transmission of the MBMS service, and setting up a bearer for the MBMS service, and the MBMS service And an MME transmitter for transmitting an MBMS session initiation message indicating the initiation of a session with respect to the MCE.

According to another aspect of the present invention, there is provided a method for providing an MBMS service in an MME for a terminal handing over from a source base station to a target base station. The method includes receiving an MBMS support request message from an MCE requesting support of a continuous MBMS service at a core network level for a terminal, initiating an MBMS session for the MBMS service, and for the MBMS service at a target base station. Receiving from the MCE an MBMS Session Response message indicating that an MBMS session has been initiated.

The continuity of the MBMS service for the terminal can be guaranteed by initiating an MBMS session in a situation in which it is necessary to provide the MBMS service as the terminal moves.

1 is a block diagram illustrating a wireless communication system.

FIG. 2 is a block diagram illustrating a radio protocol architecture for a user plane and a radio protocol architecture for a control plane.

3 shows a mapping between a downlink logical channel and a downlink transport channel.

4 shows a mapping between a downlink transport channel and a downlink physical channel.

5 is a diagram illustrating a core network structure for MBMS to which the present invention is applied.

6 is an example of a general scenario to which the handover method for service continuity in the MBMS according to the present invention is applied.

7 is a flowchart illustrating a method of providing continuity of an MBMS service according to an embodiment of the present invention.

8 is a flowchart illustrating a method of receiving an MBMS service by a terminal moving from a source base station to a target base station according to an embodiment of the present invention.

9 is a flowchart illustrating an operation of a source base station transmitting an MBMS service to a terminal moving from a source base station to a target base station according to an embodiment of the present invention.

10 is a flowchart illustrating an operation of a target base station transmitting an MBMS service to a terminal moving from a source base station to a target base station according to an embodiment of the present invention.

11 is a flowchart illustrating an operation of an MCE for transmitting an MBMS service to a terminal moving from a source base station to a target base station according to an embodiment of the present invention.

12 is a flowchart illustrating an operation of an MME for transmitting an MBMS service to a terminal moving from a source base station to a target base station according to an embodiment of the present invention.

13 is a block diagram illustrating a terminal, a source base station and a target base station according to an embodiment of the present invention.

14 is a block diagram illustrating an MCE and an MME according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

In addition, the present specification describes a wireless communication network, the operation performed in the wireless communication network is performed in the process of controlling the network and transmitting data in the system (for example, the base station) that is in charge of the wireless communication network, or the corresponding wireless Work may be done at the terminal coupled to the network.

1 is a block diagram illustrating a wireless communication system. This may be a network structure of an Evolved-Universal Mobile Telecommunications System (E-UMTS). The E-UMTS system may be referred to as Long Term Evolution (LTE) or LTE-A (Advanced) system. Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and the like.

On the other hand, there is no limitation on the multiple access scheme applied to the wireless communication system. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA, OFDM-TDMA For example, various multiple access schemes such as OFDM-CDMA may be used.

Here, the uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies. .

Referring to FIG. 1, the E-UTRAN includes at least one base station (BS) 20 that provides a control plane and a user plane to the terminal. The UE 10 may be fixed or mobile and may have other mobile stations, advanced MSs (AMS), user terminals (UTs), subscriber stations (SSs), wireless devices (Wireless Devices), and the like. It may be called a term.

The base station 20 generally refers to a station communicating with the terminal 10, and includes an evolved-NodeB (eNodeB), a Base Transceiver System (BTS), an Access Point, an femto-eNB, It may be called other terms such as a pico-eNB, a home eNB, and a relay. The base station 20 may provide at least one cell to the terminal. The cell may mean a geographic area where the base station 20 provides a communication service or may mean a specific frequency band. The cell may mean a downlink frequency resource and an uplink frequency resource. Alternatively, the cell may mean a combination of a downlink frequency resource and an optional uplink frequency resource. In addition, in general, when carrier aggregation (CA) is not considered, one cell always has a pair of uplink and downlink frequency resources.

An interface for transmitting user traffic or control traffic may be used between the base stations 20. The source base station (Source BS) 21 refers to a base station in which a radio bearer is currently set up with the terminal 10, and the target base station (Target BS, 22) means that the terminal 10 disconnects the radio bearer from the source base station 21 and renews it. It means a base station to be handed over to establish a radio bearer.

The base stations 20 may be connected to each other through an X2 interface, which is used to exchange messages between the base stations 20. The base station 20 is connected to an evolved packet system (EPS), more specifically, a mobility management entity (MME) / serving gateway (S-GW) 30 through an S1 interface. The S1 interface supports a many-to-many-relation between base station 20 and MME / S-GW 30. The PDN-GW 40 is used to provide packet data services to the MME / S-GW 30. The PDN-GW 40 varies depending on the purpose or service of communication, and the PDN-GW 40 supporting a specific service can be found using APN information.

Inter-E-UTRAN handover is a basic handover mechanism used for handover between E-UTRAN access networks. It is composed of X2 based handover and S1 based handover. X2-based handover is used when the UE wants to handover from the source base station (source BS, 21) to the target base station (target BS, 22) using the X2 interface. At this time, the MME / S-GW 30 is not changed. Do not.

By S1 based handover, the first bearer set between the P-GW 40, the MME / S-GW 30, the source base station 21, and the terminal 10 is released, and the P-GW 40 is released. A new second bearer is established between the GW 40, the MME / S-GW 30, the target base station 22, and the terminal 10.

Hereinafter, downlink means communication from the base station 20 to the terminal 10, and uplink means communication from the terminal 10 to the base station 20. The downlink is also called a forward link, and the uplink is also called a reverse link. In downlink, the transmitter may be part of the base station 20 and the receiver may be part of the terminal 10. In uplink, the transmitter may be part of the terminal 10 and the receiver may be part of the base station 20.

FIG. 2 is a block diagram illustrating a radio protocol architecture for a user plane and a radio protocol architecture for a control plane. The data plane is a protocol stack for user data transmission, and the control plane is a protocol stack for control signal transmission.

Referring to FIG. 2, a physical layer (PHY) layer provides an information transfer service to a higher layer using a physical channel. The physical layer is connected to the upper layer Medium Access Control (MAC) layer through a transport channel. Data is moved between the MAC layer and the physical layer through the transport channel. Transport channels are classified according to how and with what characteristics data is transmitted over the air interface. Data moves between the physical layers, that is, between the physical layers of the transmitter and the receiver. There are several physical control channels. The physical downlink control channel (PDCCH) informs the terminal of resource allocation of a paging channel (PCH) and downlink shared channel (DL-SCH) and hybrid automatic repeat request (HARQ) information related to the DL-SCH. The PDCCH may carry an uplink scheduling grant informing the UE of resource allocation of uplink transmission. The physical control format indicator channel (PCFICH) informs the UE of the number of OFDM symbols used for PDCCHs and is transmitted every subframe. PHICH (physical Hybrid ARQ Indicator Channel) carries a HARQ ACK / NAK signal in response to uplink transmission. Physical uplink control channel (PUCCH) carries uplink control information such as HARQ ACK / NAK, scheduling request, and CQI for downlink transmission. Physical uplink shared channel (PUSCH) carries an uplink shared channel (UL-SCH).

The functions of the MAC layer include mapping between logical channels and transport channels and multiplexing / demultiplexing into transport blocks provided as physical channels on transport channels of MAC service data units (SDUs) belonging to the logical channels. The MAC layer provides a service to a Radio Link Control (RLC) layer through a logical channel. The logical channel may be divided into a control channel for transmitting control region information and a traffic channel for delivering user region information.

Functions of the RLC layer include concatenation, segmentation, and reassembly of RLC SDUs. In order to guarantee the various Quality of Service (QoS) required by the radio bearer (RB), the RLC layer has a transparent mode (TM), an unacknowledged mode (UM), and an acknowledged mode (Acknowledged Mode). Three modes of operation (AM). AM RLC provides error correction through an automatic repeat request (ARQ).

Functions of the Packet Data Convergence Protocol (PDCP) layer in the user plane include delivery of user data, header compression, and ciphering. The functionality of the Packet Data Convergence Protocol (PDCP) layer in the user plane includes the transfer of control plane data and encryption / integrity protection.

The RRC layer is responsible for the control of logical channels, transport channels, and physical channels in connection with configuration, re-configuration, and release of radio bearers. RB means a logical path provided by the first layer (PHY layer) and the second layer (MAC layer, RLC layer, PDCP layer) for data transmission between the terminal and the network. The establishment of the RB means a process of defining characteristics of a radio protocol layer and a channel to provide a specific service, and setting each specific parameter and operation method. RB can be further divided into SRB (Signaling RB), DRB (Data RB), and MRB (MBMS PTM RB). The SRB is used as a path for transmitting RRC messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane. MRB is used as a path for transmitting MBMS data.

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

Referring to FIG. 3, a paging control channel (PCCH) is mapped to a paging channel (PCH), and a broadcast control channel (BCCH) is mapped to a broadcast channel (BCH) or a downlink shared channel (DL-SCH). Common Control Channel (CCCH), Dedicated Control Channel (DCCH), Dedicated Traffic Channel (DTCH), Multicast Control Channel (MCCH) and Multicast Traffic Channel (MTCH) are mapped to DL-SCH. MCCH and MTCH are also mapped to MCH (Multicast Channel).

Each logical channel type is defined by what kind of information is transmitted. There are two types of logical channels: control channels and traffic channels.

The control channel is used for transmission of control plane information. BCCH is a downlink channel for broadcasting system control information. PCCH is a downlink channel that transmits paging information and is used when the network does not know the location of the terminal. CCCH is a channel for transmitting control information between the terminal and the network, and is used when the terminal does not have an RRC connection with the network. The MCCH is a point-to-multipoint downlink channel used to transmit MBMS control information and is used for terminals receiving MBMS. DCCH is a point-to-point one-way channel for transmitting dedicated control information between the terminal and the network, and is used by a terminal having an RRC connection.

The traffic channel is used for transmission of user plane information. DTCH is a point-to-point channel for transmitting user information and exists in both uplink and downlink. MTCH is a point-to-multipoint downlink channel for transmission of traffic data, and is used for a terminal receiving an MBMS.

Transport channels are classified according to how and with what characteristics data is transmitted over the air interface. The BCH has a predefined transmission format that is broadcast and fixed in the entire cell area. DL-SCH supports hybrid automatic repeat request (HARQ). Support for dynamic link adaptation by changing modulation, coding and transmission power, possibility of broadcast, possibility of beamforming, support for dynamic / semi-static resource allocation, and support for discontinuous reception (DRX) to save terminal power And MBMS transmission support. PCH is characterized by DRX support for terminal power saving and broadcast to the entire cell area. The MCH is characterized by broadcast to the entire cell and MBMS Single Frequency Network (MBSFN) support. MBSFN uses a common scrambling code and spreading code to simultaneously broadcast the same MBMS channel in a plurality of cells forming an MBMS cell group.

Referring to FIG. 4, a BCH is mapped to a physical broadcast channel (PBCH), an MCH is mapped to a physical multicast channel (PMCH), and a PCH and a DL-SCH are mapped to a PDSCH. PBCH carries the BCH transport block, PMCH carries the MCH, and PDSCH carries the DL-SCH and PCH.

MBMS uses two logical channels. MCCH as a control channel and MTCH as a traffic channel. User data such as actual voice or video is transmitted on the MTCH, and setting information for receiving the MTCH is transmitted on the MCCH. MTCH and MCCH are a point-to-many downlink channel for a plurality of terminals, and may be referred to as a shared channel. The MBMS does not allocate radio resources as many as the number of terminals receiving a service, but allocates only radio resources for a shared channel, and simultaneously receives a shared channel from a plurality of terminals, thereby improving efficiency of radio resources.

If the UE changes the cell due to a location movement while receiving the MBMS service, it may be in a state in which the MBMS service cannot be continuously received. Even in this state, if the UE continuously performs the decoding operation for receiving the MBMS service, it may cause battery consumption. There is a need for an apparatus and method for allowing a terminal using an MBMS service to continuously receive an MBMS service without wasting resources during handover.

A source cell refers to a cell in which a terminal is currently receiving a service. A base station providing a source cell is called a source base station. A neighbor cell refers to a cell that is geographically adjacent to a source cell or on a frequency band. An adjacent cell using the same band with respect to the source cell is called an intra-frequency neighbor cell. In addition, adjacent cells using different bands based on the source cell are called inter-frequency neighbor cells. That is, not only a cell using the same band as the source cell but also a cell using another band, all of the cells adjacent to the source cell may be referred to as adjacent cells.

The UE handover from the source cell to the neighboring cell in frequency is called intra-frequency handover. On the other hand, the UE handover from the source cell to the inter-frequency neighbor cell is referred to as inter-frequency handover. An adjacent cell to which the UE moves in handover is called a target cell. The base station providing the target cell is called a target base station.

The source cell and the target cell may be provided by one base station or may be provided by different base stations. Hereinafter, for convenience of description, it is assumed that the source cell and the target cell are provided by different base stations, that is, the source base station and the target base station. Therefore, the source base station and the source cell, the target base station and the target cell can be used interchangeably with each other.

Referring to FIG. 5, a radio access network (EUTRAN) 500 includes a multi-cell coordination entity (hereinafter referred to as MCE) 510 and a base station eNB 520. The MCE 510 is a main entity controlling the MBMS, and plays a role of radio resource allocation or admission control in the MBSFN region. MCE 510 may be implemented within base station 520 or may be implemented independently of base station 520. The interface between the MCE 510 and the base station 520 is called an M2 interface. The M2 interface is an internal control plane interface of the wireless access network 500, and MBMS control information is transmitted. If the MCE 510 is implemented in the base station 520, the M2 interface may only exist logically.

An Evolved Packet Core (EPC) 550 includes an MME 560 and an MBMS Gateway (MBMS GW) 570. MME 560, NAS signaling, roaming (authentication), authentication (authentication), PDN gateway and S-GW selection, MME selection for handover by MME change, accessibility to the idle mode terminal, AS security Performs operations such as security control.

The MBMS gateway 570 is an entity that transmits MBMS service data and is located between the base station 520 and the BM-SC and performs MBMS packet transmission and broadcast to the base station 520. The MBMS gateway 570 uses PDCP and IP multicast to transmit user data to the base station 520, and performs session control signaling for the radio access network 500.

The interface between the MME 560 and the MCE 510 is a control plane interface between the radio access network 500 and the EPC 550, which is called an M3 interface, and transmits control information related to MBMS session control.

The interface between the base station 520 and the MBMS gateway 570 is an interface of a user plane, which is called an M1 interface, and transmits MBMS service data.

Referring to FIG. 6, the MBMS service may be managed based on cell or location. The MBMS service area is a general term for the area where a particular MBMS service is provided. For example, if an area where a specific MBMS service A is performed is called an MBMS service area A, the network may be in a state of transmitting an MBMS service A in the MBMS service area A. In this case, the terminal may or may not receive the MBMS service A according to the capability of the terminal. The MBMS service area may be defined in terms of applications and services as to whether or not a particular service is provided in a certain area.

Cell A, Cell B, Cell C, Cell D, and Cell E are included in MBSFN Region 1, and Cell F is included in MBSFN Region 2. Cell G is a cell serving a frequency band f2 other than a cell in the MBSFN region. The MBSFN region refers to a region in which a particular MBMS service is provided in a single frequency band. For example, in case of MBSFN region 1, a specific MBMS service A is supported in an MBSFN subframe of frequency f1. In the case of MBSFN Region 2, MBMS Service A is supported, but MBMS Service A may be supported by using f3 different from the frequency resource f1 in MBSFN Region 1. In the same MBSFN region, even when the UE moves, the UE may receive the MBMS service based on the same MBMS configuration.

Meanwhile, Cell B and Cell E are reserved cells that are included in MBSFN Region 1 but do not transmit MBMS service in a specific situation. A preliminary cell may be defined as a cell that does not currently perform MBMS service through the MRB. At this time, the preliminary cell may be a cell that currently does not support the MBMS service at all, or may be a cell that supports the MBMS service through a dedicated bearer without supporting the MBMS service but through the MRB. Alternatively, the MBMS service may be limitedly provided so that a specific MBMS service can be provided only in a specific region. In other words, as an example of a location-based service, only a specific region may support a specific MBMS service, and a region outside of the specific region may not support a specific MBMS service. Even in this case, a region or a cell in which a specific MBMS service is supported may be changed. In this case, the management of the reserved cell may be used not only in terms of radio efficiency, but also as a method for managing the MBMS service area itself.

The spare cell is included in MBSFN region 1 along with other cells providing MBMS service. In the general case, cells in MBSFN are configured to use the same MBSFN subframe for MBMS and can always be considered to transmit MBMS service to all cells in MBSFN area for MBMS. However, in special cases, such as when the service is supported through the MRB only in a localized position smaller than the region defined as the MBSFN region, or in a specific region, only a few terminals are expected to receive the MBMS service. It is efficient to support the MBMS service through a dedicated bearer rather than a dedicated bearer. Therefore, in the case of Cell B and Cell E, the cells in the same MBSFN region as Cell A, Cell C, and Cell D, but may not perform MBMS service through the MRB.

The preliminary cell may be determined based on the MBMS location range. MBMS location range is a concept used to manage to receive MBMS service through MRB only within a specific region or location range within the same MBSFN region, whereas MBMS service can be serviced through MRB in all cells in MBSFN region. to be. In this case, the MBMS location range may be managed in units of cells, or may be managed by a method such as positioning (geography-based localization) based on geography or exact region. have.

When the UE UE moves from the current cell D to another cell, it will be described how MBMS service continuity is provided to the UE.

First, a case in which the UE moves between cells in the same MBSFN region will be described. As an example, assume that the terminal moves to Cell A. Since the cell A is in the same MBSFN region 1 as the cell D, even if the UE moves to the cell A, it can continue to receive the MBMS service using the same MBSFN subframe. Therefore, there is no particular problem in receiving the MBMS service in the cell A from the terminal side.

As another example, assume that the terminal moves to Cell G. Cell G is a cell in MBSFN region 1 that is the same as Cell D, but does not support MBMS service and provides a service through frequency f2. Therefore, after the UE moves to the cell G, it cannot continue to receive the MBMS service.

As another example, assume that the UE moves to Cell B, which is a preliminary cell. For example, there may be very few UEs receiving MBMS service using MRB in cell B due to the distribution of terminals using MBMS service in different regions. In this case, it is not preferable for Cell B to support the service through MRB in terms of radio efficiency. Accordingly, Cell B may support MBMS service through a dedicated bearer or a point-to-point bearer dedicated only to a specific UE.

As such, when the UE moves to Cell A, the terminal may continue to receive the service through the MRB that has been used previously. However, when the UE moves to Cell A, the UE may not receive the service through the MRB. At this time, there is no way for the UE to know whether the MBMS service can receive the service through the MRB, so that the UE may unnecessarily attempt to receive the service through the MRB. Therefore, when the terminal receives the MBMS service from the source base station through the MRB, the target base station needs to provide the source base station or the terminal with information on whether the MBMS service can be used.

Next, a case in which the UE moves between MBSFN regions will be described. Assume that the terminal moves from MBSFN region 1 to another MBSFN region 2. The moved MBSFN region 2 may or may not service the same MBMS service on the same frequency band. For example, when the UE moves to cell F, MBSFN region 1 provides MBMS service through frequency f1 in MBSFN subframe, and MBMSN region 2 provides MBMS service through frequency f3 in MBSFN subframe. Assume that In this case, the UE cannot automatically receive the MBMS service even in the MBSFN region 2 (ie, through the frequency f1 in the MBSFN subframe) configured in the MBSFN region 1.

If both MBSFN region 1 and MBSFN region 2 provide MBMS service through frequency f1 in the MBSFN subframe, despite the change in MBSFN region, the MRB frequency for MBMS service is actually the same, so the UE continues to receive MBMS service. I can think of it as possible.

As such, when the UE moves to another MBSFN region, receiving the same MBMS service at the same frequency is not necessarily guaranteed. Accordingly, the terminal must reconfigure the MRB based on the new configuration according to the capability of the terminal in order to receive the MBMS service with a new frequency (or carrier) of the cell of the new MBSFN region. Or, the terminal should receive the MBMS service through the dedicated bearer or the point-to-point bearer.

In the MBSFN area, in principle, an MBMS session is initiated for the base station and the MCE, and the MBMS service is transmitted. However, depending on the situation, a particular cell in the MBSFN region may not actually provide the MBMS service. For example, there may be a case where the MBMS service or session is not initiated even though the MBMS service can be transmitted on the same carrier as the MBSFN region 1 in the cell F of the MBSFN region 2. However, in a situation where it is necessary to provide the same MBMS service in the cell F as the terminal moves, the core network level entities (or nodes) (for example, MCE or MME) check whether the MBMS service or session can proceed. And, if necessary, initiate an MBMS session. As a result, continuity of the service may be guaranteed as the UE receiving the MBMS service moves.

Referring to FIG. 7, the UE transmits an MBMS service indication to a source eNB (S700). The MBMS service indicator indicates whether the UE receives the MBMS service through the MRB and / or the type of the MBMS service received. The MBMS service indicator may be included in a message used in the handover procedure, for example, a measurement reporting message. Alternatively, the MBMS service indicator may be a separate message irrelevant to the handover procedure.

The source base station transmits the MBMS continuity request indicator to the target eNB (S705). The MBMS continuity request indicator is information for requesting the MBMS control from the source base station to the target base station in order to ensure MBMS service continuity of the terminal, and may include the same form or the same information as the MBMS service indicator. The MBMS continuity request indicator may be included in the handover request message or may be one independent message separate from the handover request message.

The target base station transmits a first MBMS support request message to the MCE requesting the support of the MBMS service at the core network level for the MBMS (S710). This is to request the initiation of a specific MBMS service or MBMS session in the case where the MBMS service is currently not supported even though the MBMS service is supportable in a specific cell, CC or frequency. Here, the MCE may be a different entity from the target base station or may be an entity integrated with the target base station. When the MCE is an entity integrated with the target base station, the first MBMS support request message may be defined logically or virtually only. In this case, step S710 may be omitted. However, it will be described here on the premise that the MCE is a different entity from the target base station.

The MCE transmits a second MBMS support request message to the MME (S715). The second MBMS support request message is a message requesting the MME for initiation of an MBMS service or initiation of an MBMS session. The second MBMS support request message may have the same function and contents as the first MBMS support request message, because distinguishing them is because different transmission subjects are used. However, as described in step S710, when the MCE is an entity integrated with the target base station, the first MBMS support request message and the second MBMS support request message may be the same message.

Although the MCE is not currently transmitting the MBMS service requested by the UE or has not started a session, information on the MBMS service may be known in advance. Information about the MBMS service may be obtained by the core network component or the radio access network components in the MBMS related registration procedure.

The MME checks whether an MBMS session can be initiated with respect to the target base station (S720). For example, the MME may determine whether the type of MBMS service received by the UE is an MBMS service that can be supported by the target base station. Alternatively, the MME may check whether the MBMS service received by the UE may be provided through a cell, component carrier, or frequency provided by the target base station. Here, initiating the MBMS session means that the MME allocates network resources for MBMS service transmission, sets up a necessary bearer, and informs downstream nodes such as the MCE and the target base station that the MBMS service transmission is about to start. It includes the process of doing.

If it is confirmed that the MBMS session can be started, the MME transmits a first MBMS session start message to the MCE (S725). This triggers or initiates an MBMS session initiation procedure. The first MBMS session initiation message may include MBMS Radio Access Bearer (E-RAB) QoS parameters for supporting the MBMS service. In this case, the MBMS E-RAB refers to a radio bearer established between the terminal and the source base station or the target base station for the MBMS, and the MBMS M1 data bearer.

Receiving the first MBMS Session Initiation message, the MCE determines whether the MBMS E-RAB of the upcoming MBMS session is acceptable by the radio access network (E-UTRAN) based on the MBMS E-RAB QoS parameters, and logically. Establish an MBMS service associated with the M3 connection.

If the MBMS E-RAB of the MBMS session is acceptable by the E-UTRAN, the MCE transmits a second MBMS session initiation message to the target base station (S730). The second MBMS session initiation message is a message indicating the initiation of an MBMS session not currently initiated through the target base station. The second MBMS session initiation message may include MBMS E-RAB QoS parameters to support the MBMS service. Upon receiving the second MBMS session initiation message, the target base station notifies the terminal that the MBMS session in a given MBMS bearer service is imminent, and establishes an MBMS E-RAB and a logical M2 connection.

The target base station transmits an MBMS continuity response indication to the source base station (S735). The MBMS continuity response indicator indicates that an MBMS session is imminent at the target base station or indicates whether the target base station can support the MBMS service through the MRB. Here, the MBMS service may include not only services supported through the MRB but also services supported through the RB. In addition, the MBMS continuity response indicator may include MBMS session identity information for informing the terminal of the information of the impending MBMS session. The MBMS continuity response indicator may be transmitted in a handover request response message or in a separate message.

The source base station transmits an MBMS service response indication to the terminal (S740). The MBMS service response indicator may be included in the handover command message or may be a separate independent message. The UE may obtain information on whether the MBMS service can be supported in the target cell using information included in the MBMS service response indicator, and information on a cell, CC, or frequency provided with the MBMS service.

The target base station transmits the first MBMS session response message to the MCE (S745). The first MBMS Session Response message indicates to the MCE that it can initiate for the MBMS session. The first MBMS session response message may include the result of the setting of the MBMS E-RAB. At this time, the target base station joins a transport network IP multicast address including the IP address of the multicast source. Here, the transport network IP multicast address is specified by TNL (Transport Network Layer) information enabling the reception of the MBMS service. If the target base station cannot initiate the MBMS session (for example, if no MBMS resource is set up in any cell of the target base station), the target base station sends the first MBMS session failure message to the MCE instead of the first MBMS session response message. Will transmit. The MCE then determines that it cannot initiate an MBMS session at the target base station.

The MCE transmits a second MBMS session response message to the MME (S750). The MME may initiate the MBMS service or session by the second MBMS session response message. If the MCE determines that it cannot initiate an MBMS session at the target base station (e.g. when no MBMS resource can be set up in any cell of the target base station), the MCE may cause an appropriate cause value instead of the second MBMS session response message. send a second MBMS session failure message to the MME. The MME then determines that it cannot initiate an MBMS session at the target base station.

The target base station transmits the same MBMS service that the terminal received from the source base station to the terminal (S755). The terminal may receive the MBMS service from the target base station by using MBMS service information that can be supported in a specific cell or frequency in the target base station for each MBMS service.

Referring to FIG. 8, the terminal transmits an MBMS service indicator to a source base station (S800). Here, the terminal may move from the source base station to the target base station. The MBMS session for the MBMS service is started at the source base station, but it is unclear whether the MBMS session is started at the target base station.

As an example, the MBMS service indicator is an indicator indicating whether the terminal receives the MBMS service through the MRB. For example, the form of the MBMS service indicator is a flag and may indicate 0 or 1. If the MBMS service indicator is 1, the terminal is a terminal that receives the MBMS service through the MRB. If 0, the terminal is a terminal that does not receive the MBMS service through the MRB. Here, the MBSM service indicator may be set to 1 even if the terminal receives only at least one MBMS service among the plurality of MBMS services.

As another example, the MBMS service indicator may be an indicator indicating the type of MBMS service received by the terminal. This means that the UE can receive multiple MBMS services at the same time, and the MBMS area or MBSFN area for each MBMS service may be different, and which MBMS service is currently in progress at the location where the UE receives the MBMS service. Because you need to tell. The type of MBMS service may be distinguished by a Temporary Mobile Group Identity (TMGI) for the MBMS service.

For example, if the MBMS service indicator is receiving a plurality of MBMS terminals MBMS service A, B, C MBMS service indicator may be configured in the form of a list, such as TMGI A, B, C. Alternatively, one MBMS service indicator may indicate one type of MBMS service. That is, the type of MBMS service may be configured and transmitted separately in the MBMS service indicator. For example, it may be configured as MBMS service indicator 1 = TMGI A, MBMS service indicator 2 = TMGI B, MBMS service indicator 3 = TMGI C.

As another example, the MBMS service indicator may indicate the type of MBMS service and whether the MBMS is received. That is, the MBMS service indicator indicates whether the MBMS is received through the MRB as a flag, and also indicates all types of MBMS services to be received.

The terminal receives the MBMS service response indicator from the source base station (S805). The MBMS service response indicator may mean that the target base station negotiates the procedure of initiating the MBMS session with entities at the core network level, thereby enabling the target base station to provide the MBMS service. Here, negotiation with entities at the core network level means that the target base station exchanges a message related to the MBMS session initiation with the MCE or the MME.

Thereafter, the terminal receives the MBMS service from the target base station (S810). As a result, even after the mobile station moves to the target base station, the terminal can seamlessly receive the MBMS service. That is, continuity of MBMS service is guaranteed for the terminal.

9, the source base station receives the MBMS service indicator from the terminal (S900). The source base station may recognize that the source base station should hand over the terminal to the target base station from the MBMS service indicator based on the MBMS service indicator. In addition, the source base station may determine whether to receive continuity of the MBMS service even after the terminal handovers to the target base station based on the MBMS service indicator. However, it may be unclear whether or not the MBMS session is initiated for the MBMS service at the target base station. If the MBMS session for the MBMS service is not initiated at the target base station, the terminal cannot continuously receive the MBMS service after handing over to the target base station.

Therefore, the source base station transmits an MBMS continuity request indicator requesting a continuous MBMS service for the terminal to the target base station (S905). The MBMS continuity request indicator is information for requesting the MBMS control from the source base station to the target base station in order to ensure MBMS service continuity of the terminal, and may include the same form or the same information as the MBMS service indicator. For example, the MBMS continuity request indicator may indicate whether the terminal receives the MBMS service. Alternatively, the MBMS continuity request indicator may indicate the type of MBMS service received by the terminal. The MBMS continuity request indicator may be information defined in the X2 interface. The MBMS continuity request indicator may be included in the handover request message or may be one independent message separate from the handover request message.

The source base station receives an MBMS continuity response indicator from the target base station indicating that continuity of the MBMS service is provided (S910). The MBMS continuity response indicator indicates whether the target base station can support the MBMS service through the MRB. Here, the MBMS service may include not only services supported through the MRB but also services supported through the dedicated RB. In addition, the MBMS continuity response indicator may include MBMS session identifier information for informing the terminal of the MBMS session information. The MBMS continuity response indicator may be included in the handover request response message and transmitted, or may be transmitted in a separate message.

The source base station transmits the MBMS service response indicator to the terminal (S915). The MBMS service response indicator may be included in the handover command message or may be a separate independent message. The UE may obtain information on whether the MBMS service can be supported in the target cell using information included in the MBMS service response indicator, and information on a cell, CC, or frequency provided with the MBMS service.

Referring to FIG. 10, the target base station receives the MBMS continuity request indicator from the source base station (S1000). If the MBMS session for the MBMS service is not initiated for the target base station, the MBMS service cannot be seamlessly transmitted to the terminal. Therefore, the target base station determines whether it can support the continuity of the MBMS service for the terminal. Here, the determination of the support of the MBMS service continuity includes a determination of whether the terminal is a terminal receiving the MBMS service. If the terminal is a terminal receiving an MBMS service, the target base station determines support for the MBMS service continuity of the terminal. On the other hand, if the terminal is a terminal that does not receive the MBMS service, the target base station does not determine the support for the MBMS service continuity of the terminal.

Alternatively, the determination of whether to support the MBMS service continuity includes determining whether the MBMS service provision itself is possible or impossible.

Or, if the target base station is changed, the determination of the support of the MBMS service continuity includes a determination of which cell, component carrier or frequency to provide each MBMS service by the target base station. This is because a specific MBMS service may be supported only through a specific cell, component carrier or frequency. Carrier aggregation (CA) supports a plurality of carriers, also referred to as spectrum aggregation or bandwidth aggregation. Individual unit carriers bound by carrier aggregation are called component carriers (CC). In order to transmit and receive packet data through a specific cell, the terminal must first complete configuration of a specific cell or CC. Herein, the setting means a state in which system information required for data transmission and reception for a corresponding cell or CC is completed. In handover considering carrier aggregation, a primary serving cell (PCell) and a secondary serving cell (SCell) should be considered at the same time. For example, if the main serving cell is changed to a secondary serving cell in the same base station, it is a handover in the base station (intra BS or intra eNB), and if the main serving cell is changed to a specific cell in another base station, the base station (inter BS or inter eNB) is Handover.

Alternatively, the determination of the support of the MBMS service continuity includes the determination of what kind of MBMS service the terminal is receiving. This is because there may be an MBMS service that the target base station can support, and there may be an unsupportable MBMS service.

If it is determined that the target base station can provide the MBMS service, the target base station performs a procedure for initiating the MBMS session. To this end, the target base station transmits to the MCE a first MBMS support request message requesting the support of the MBMS service at the core network level for the MBMS (S1005). This is to request the initiation of a specific MBMS service or MBMS session in the case where the MBMS service is currently not supported even though the MBMS service is supportable in a specific cell, CC or frequency. Here, the MCE may be a different entity from the target base station or may be an entity integrated with the target base station. When the MCE is an entity integrated with the target base station, the first MBMS support request message may be defined logically or virtually only. In this case, step S1005 can be omitted. However, it will be described here on the premise that the MCE is a different entity from the target base station.

The target base station receives the second MBMS session start message from the MCE (S1010). The second MBMS session initiation message is a message indicating initiation of an MBMS session not currently initiated through the target base station. The second MBMS session initiation message may include MBMS E-RAB QoS parameters to support the MBMS service. Upon receiving the second MBMS session initiation message, the target base station should inform the terminal that the MBMS session in the given MBMS bearer service is imminent and set up the MBMS E-RAB and logical M2 connection.

To this end, the target base station transmits the MBMS continuity response indicator to the source base station (S1015). The MBMS continuity response indicator indicates whether the target base station can support the MBMS service through the MRB. Here, the MBMS service may include not only services supported through the MRB but also services supported through the dedicated RB. In addition, the MBMS continuity response indicator may include MBMS session identifier information for informing the terminal of the MBMS session information. The MBMS continuity response indicator may be included in the handover request response message and transmitted, or may be transmitted in a separate message.

As an example, the MBMS continuity response indicator may indicate only whether the MBMS service can be supported. For example, as a result of determining that the target cell supports the MBMS service continuity, if the terminal is found to use the MBMS service, the target cell sets the MBMS continuity response indicator to 1. This indicates that the MBMS service for the UE can be continuously supported in the target cell. That is, the UE may receive the MBMS service in the serving cell as in the MRB. On the contrary, if it is determined that the target cell does not use the MBMS service, the target cell sets the MBMS continuity response indicator to zero. This means that the MBMS service for the UE cannot be continuously supported in the target cell.

As another example, the MBMS continuity response indicator may include information about a cell, a CC, or a frequency to be used to provide an MBMS service to a terminal.

As another example, as shown in Table 1, the MBMS continuity response indicator may include information on the type of MBMS service received by the UE and information on a cell, CC, or frequency that can be supported for each MBMS service in the target cell.

Table 1

MBMS Service Type	TMGI	enable / disable	frequency
MBMS Service 1	A	enable	CC1
MBMS Service 2	B	disable	CC2
MBMS Service 3	C	enable	CC3

Referring to Table 1, the MBMS continuity response indicator indicates a TMGI identifying each MBMS service, whether the corresponding MBMS service is enabled (disable / disable) in the target cell, and a supported frequency band (CC1, CC2, CC3, etc.). Contains information.

The target base station transmits the first MBMS session response message to the MCE (S1020). The first MBMS session response message is a response to the second MBMS session initiation message, informing the MCE that the MBMS session will be initiated. The first MBMS session response message may include the result of the setting of the MBMS E-RAB. The target base station subscribes to a transport network IP multicast address that includes the IP address of the multicast source. Here, the transport network IP multicast address is specified by the TNL information that enables the reception of the MBMS service. If the target base station cannot initiate the MBMS session (for example, if no MBMS resource is set up in any cell of the target base station), the target base station sends the first MBMS session failure message to the MCE instead of the first MBMS session response message. Will transmit. The MCE then determines that it cannot initiate an MBMS session at the target base station.

The target base station transmits the same MBMS service that the terminal has received from the source base station to the terminal (S1025). The terminal may receive the MBMS service from the target base station by using MBMS service information that can be supported in a specific cell or frequency in the target base station for each MBMS service.

Referring to FIG. 11, the MCE receives a first MBMS support request message from a target base station (S1100). When the MCE is an entity integrated with the target base station, the first MBMS support request message may be defined logically or virtually only. In this case, step S1100 may be omitted.

The MCE transmits a second MBMS support request message to the MME (S1105). The second MBMS support request message is a message requesting the MME to start an MBMS service or MBMS session. The second MBMS support request message may have the same function and contents as the first MBMS support request message, because distinguishing them is because the transmission subjects at the core network level are different. However, when the MCE is an entity integrated with the target base station, the first MBMS support request message and the second MBMS support request message are the same message, and the distinction between them may be meaningless.

The MCE receives the first MBMS session initiation message from the MME (S1110). The first MBMS session initiation message may be a response message to the second MBMS support request message and may include MBMS E-RAB QoS parameters for supporting the MBMS service. In this case, the MBMS E-RAB refers to a radio bearer established between the terminal and the source base station or the target base station for the MBMS, and the MBMS M1 data bearer.

Receiving the first MBMS Session Initiation message, the MCE determines whether the MBMS E-RAB of the impending MBMS session is acceptable by the radio access network (EUTRAN) based on the MBMS E-RAB QoS parameters, and the MBMS associated with the logical M3 connection. Set up the service.

The MCE transmits a second MBMS session start message to the target base station (S1115). The second MBMS session initiation message is a message indicating the initiation of an MBMS session not currently initiated through the target base station.

The MCE receives the first MBMS session response message from the target base station (S1120). The first MBMS Session Response message indicates to the MCE that it can initiate for the MBMS session.

The MCE transmits a second MBMS session response message to the MME (S1125). The MME may initiate the MBMS service or session by the second MBMS session response message. If the MCE determines that it cannot initiate an MBMS session at the target base station (e.g. when no MBMS resource can be set up in any cell of the target base station), the MCE includes an appropriate cause value instead of the second MBMS session response message. The second MBMS session failure message will be sent to the MME. The MME then determines that it cannot initiate an MBMS session at the target base station.

Referring to FIG. 12, the MME receives a second MBMS support request message from the MCE (S1200).

The MME checks whether an MBMS session can be initiated (S1205). For example, the MME may determine whether the type of MBMS service that the UE receives from the source base station is an MBMS service that can be supported by the target base station. Alternatively, the MME may check whether the MBMS service received by the terminal from the source base station can be provided through a cell, component carrier, or frequency provided by the target base station. Here, initiating the MBMS session means that the MME allocates network resources for MBMS service transmission, sets up a necessary bearer, and notifies lower stream nodes such as an MCE, a target base station, etc. that the MBMS service transmission starts soon.

If it is confirmed that the MBMS session can be started, the MME transmits a first MBMS session start message to the MCE (S1210). This triggers or initiates an MBMS session initiation procedure.

The MME receives the second MBMS session response message from the MCE (S1215). The MME may initiate the MBMS service or session by the second MBMS session response message.

Referring to FIG. 13, the terminal 1300 includes a terminal transmitter 1305 and a terminal receiver 1310.

The terminal transmitter 1305 transmits the MBMS service indicator to the source base station 1330. In the source base station 1330, the MBMS session for the MBMS service is started, but in the target base station 1350, it is unclear whether the MBMS session is started.

As an example, the MBMS service indicator is an indicator indicating whether the terminal 1300 receives the MBMS service through the MRB. For example, the form of the MBMS service indicator is a flag and may indicate 0 or 1. If the MBMS service indicator is 1, the terminal 1300 is a terminal that receives the MBMS service, and if 0, the terminal 1300 is a terminal that does not receive the MBMS service. Here, the MBSM service indicator may be set to 1 even if the terminal 1300 receives only at least one MBMS service among a plurality of MBMS services.

As another example, the MBMS service indicator may be an indicator indicating the type of MBMS service that the terminal 1300 receives. This means that the terminal 1300 may simultaneously receive a plurality of MBMS services, and may have different MBMS regions or MBSFN regions for each MBMS service, and any MBMS services may be located at a location where the terminal 1300 receives MBMS services. You need to tell if it's going on. The type of MBMS service may be distinguished by a temporary mobile group identifier (TMGI) for the MBMS service.

For example, if the MBMS service indicator is receiving a plurality of MBMS terminals MBMS service A, B, C MBMS service indicator may be configured in the form of a list, such as TMGI A, B, C. Alternatively, one MBMS service indicator may indicate one MBMS service type. That is, the type of MBMS service may be separately configured and transmitted in the MBMS service indicator. For example, it may be configured as MBMS service indicator 1 = TMGI A, MBMS service indicator 2 = TMGI B, MBMS service indicator 3 = TMGI C.

As another example, the MBMS service indicator may indicate the type of MBMS service and whether the MBMS is received. That is, the MBMS service indicator indicates whether or not to receive MBMS as a flag, and indicates all types of MBMS services being received.

The terminal receiver 1310 receives the MBMS service response indicator from the source base station 1330. The MBMS service response indicator indicates that the target base station 1350 is able to provide the MBMS service at the target base station 1350 as a result of negotiating the procedure of initiating the MBMS session with the entities at the core network level.

Meanwhile, the terminal receiver 1310 receives an MBMS service from the target base station 1350. As a result, even after the mobile station moves to the target base station 1350, the UE can seamlessly receive the MBMS service. That is, continuity of MBMS service is guaranteed for the terminal.

The source base station 1330 includes a source transmitter 1335 and a source receiver 1340.

The source transmitter 1335 transmits an MBMS continuity request indicator requesting a continuous MBMS service for the terminal 1300 to the target base station 1350. The MBMS continuity request indicator is information that the source base station 1330 requests MBMS control to the target base station 1350 in order to ensure MBMS service continuity of the terminal 1300, and may include the same form or the same information as the MBMS service indicator. have. For example, the MBMS continuity request indicator may indicate whether the terminal 1300 receives the MBMS service. Alternatively, the MBMS continuity request indicator may indicate the type of MBMS service that the terminal 1300 is receiving. The MBMS continuity request indicator may be information defined in the X2 interface. The MBMS continuity request indicator may be included in the handover request message or may be one independent message separate from the handover request message.

Meanwhile, the source transmitter 1335 transmits the MBMS service response indicator to the terminal 1300 as a response to the MBMS service indicator received from the terminal 1300. The MBMS service response indicator may be included in the handover command message or may be a separate independent message. The source transmitter 1335 is based on the information included in the MBMS continuity response indicator received from the target base station 1350, whether the target cell can be supported by the MBMS service, the cell, CC or frequency provided with the MBMS service The MBMS service response indicator including at least one of the information about the terminal 1300 is transmitted.

The source receiver 1340 receives the MBMS service indicator from the terminal 1300. The source base station 1330 may recognize from the MBMS service indicator that the terminal 1300 should be handed over to the target base station 1350. However, it may be unclear whether or not the MBMS session for the MBMS service is started at the target base station 1350. If the MBMS session for the MBMS service is not started at the target base station 1350, the terminal 1300 may not receive the MBMS service continuously after handing over to the target base station 1350.

Meanwhile, the source receiver 1340 receives an MBMS continuity response indicator from the target base station 1350 indicating that continuity of the MBMS service is provided. The MBMS continuity response indicator indicates whether the target base station 1350 can support the MBMS service through the MRB. Here, the MBMS service may include not only services supported through the MRB but also services supported through the RB. In addition, the MBMS continuity response indicator may include MBMS session identifier information for informing the terminal 1300 of the MBMS session information. The MBMS continuity response indicator may be included in the handover request response message and transmitted, or may be transmitted in a separate message.

The target base station 1350 includes a target receiving unit 1355 and a target transmitting unit 1360.

The target receiver 1355 receives the MBMS continuity request indicator from the source base station 1330. If the MBMS session for the MBMS service is not initiated with respect to the target base station 1350, the MBMS service cannot be continuously transmitted to the terminal 1300. Accordingly, the target base station 1350 may determine whether it can support the continuity of the MBMS service for the terminal 1300.

The target transmitter 1360 transmits the MBMS continuity response indicator to the source base station 1330. As an example, the MBMS continuity response indicator may indicate only whether the MBMS service can be supported. For example, as a result of determining that the target cell supports MBMS service continuity, when the terminal 1300 is found to use the MBMS service, the target cell sets the MBMS continuity response indicator to one. This indicates that the MBMS service for the terminal 1300 may continue to be supported in the target cell. That is, the UE 1300 may receive the MBMS service in the serving cell as in the MRB. In contrast, when the target cell determines that the UE 1300 does not use the MBMS service, the target cell sets the MBMS continuity response indicator to zero. This means that the MBMS service for the terminal 1300 may not be continuously supported in the target cell.

As another example, the MBMS continuity response indicator may include information about a cell, a CC, or a frequency to be used to provide an MBMS service to the terminal 1300.

As another example, as shown in Table 2, the MBMS continuity response indicator may include information on the type of MBMS service received by the UE 1300 and information on a cell, CC, or frequency that can be supported for each MBMS service in the target cell.

TABLE 2

Referring to Table 2, the MBMS continuity response indicator indicates the TMGI identifying each MBMS service, whether the corresponding MBMS service is enabled (disable / disable) in the target cell, and the supported frequency band (CC1, CC2, CC3, etc.). Contains information.

The target transmitter 1360 transmits the same MBMS service that the terminal 1300 has received from the source base station 1330 to the terminal 1300. The terminal 1300 may receive the MBMS service from the target base station 1350 by using MBMS service information supported by a specific cell or frequency in the target base station 1350 for each MBMS service.

Referring to FIG. 14, the target base station 1400 includes a target transmitter 1405 and a target receiver 1410.

The target transmitter 1405 transmits a first MBMS support request message to the MCE 1430 requesting support of the MBMS service at the core network level for the MBMS to perform a procedure for initiating the MBMS session. This is to request the initiation of a specific MBMS service or MBMS session when the MBMS service is supported at a specific cell, CC or frequency but is not currently supported. Here, the MCE 1430 may be a different entity from the target base station 1400, or may be an entity integrated with the target base station 1400. When the MCE 1430 is an entity integrated with the target base station 1400, the first MBMS support request message may be defined logically or virtually only.

In addition, the target transmitter 1405 transmits the first MBMS session response message to the MCE 1430. The first MBMS session response message informs the MCE 1430 that the MBMS session will be initiated. The first MBMS session response message may include the result of the setting of the MBMS E-RAB. The target base station 1400 subscribes to a transport network IP multicast address that includes the IP address of the multicast source. Here, the transport network IP multicast address is specified by the TNL information that enables the reception of the MBMS service. If the target base station 1400 cannot initiate an MBMS session (for example, if no MBMS resource can be set up in any cell of the target base station 1400), the target base station 1400 replaces the first MBMS session response message. The first MBMS session failure message will be sent to the MCE 1430. The MCE 1430 then determines that it cannot initiate the MBMS session at the target base station 1400.

The target receiver 1410 receives a second MBMS session initiation message from the MCE 1430. The second MBMS session initiation message is a message for requesting initiation of an MBMS session not currently initiated through the target base station 1400. The second MBMS session initiation message may include MBMS E-RAB QoS parameters to support the MBMS service. Upon receiving the second MBMS session initiation message, the target base station 1400 notifies the terminal that an MBMS session in a given MBMS bearer service is imminent, and establishes an MBMS E-RAB and a logical M2 connection.

The MCE 1430 includes an MCE transmitter 1435 and an MCE receiver 1440.

The MCE transmitter 1435 transmits a second MBMS support request message to the MME 1450. The second MBMS support request message is a message requesting the MME 1450 to start MBMS service or MBMS session. The second MBMS support request message may have the same function and contents as the first MBMS support request message, because distinguishing them is because the transmission subjects at the core network level are different. However, when the MCE 1430 is an entity integrated with the target base station 1400, the first MBMS support request message and the second MBMS support request message are the same message, and the distinction between them may be meaningless.

In addition, the MCE transmitter 1435 transmits the second MBMS session initiation message to the target base station 1400. The second MBMS session initiation message is a message for requesting initiation of an MBMS session not currently initiated through the target base station 1400.

In addition, the MCE transmitter 1435 transmits the second MBMS session response message to the MME 1450. The MME 1450 may initiate the MBMS service or session by the second MBMS session response message. If the MCE 1430 determines that it cannot initiate an MBMS session at the target base station 1400 (for example, when no MBMS resource is set in any cell of the target base station 1400), the MCE transmitter 1435 ) Will send a second MBMS session failure message to the MME 1450 containing the appropriate cause value instead of the second MBMS session response message. The MME 1450 then determines that the target base station 1400 cannot initiate the MBMS session.

The MCE receiver 1440 receives the first MBMS support request message from the target base station 1400. When the MCE 1430 is an entity integrated with the target base station 1400, the first MBMS support request message may be defined logically or virtually only. The MCE 1430 may not be currently transmitting the MBMS service requested by the UE or have not started a session, but may know information about the MBMS service in advance. Information about the MBMS service may be obtained by the core network component or the radio access network components in the MBMS related registration procedure.

In addition, the MCE receiver 1440 receives a first MBMS session initiation message from the MME 1450. The first MBMS session initiation message may include an MBMS E-RAB QoS parameter for supporting the MBMS service. The MBMS E-RAB refers to a radio bearer established between the terminal and the source base station or the target base station 1400 and the MBMS M1 data bearer for the MBMS. Receiving the first MBMS session initiation message, the MCE 1430 determines whether the MBMS E-RAB of the impending MBMS session is acceptable by the radio access network (E-UTRAN) based on the MBMS E-RAB QoS parameter, and logically. Sets the MBMS service associated with the M3 connection.

In addition, the MCE receiver 1440 receives the first MBMS session response message from the target base station 1400. The first MBMS session response message informs the MCE 1430 that the MBMS session can be initiated.

The MME 1450 includes an MME receiver 1455, a session controller 1460, and an MME transmitter 1465.

The MME receiver 1455 receives a second MBMS support request message from the MCE 1430. In addition, the MME receiver 1455 receives a second MBMS session response message from the MCE 1430. The MME 1450 may initiate the MBMS service or session by the second MBMS session response message.

The session controller 1460 checks whether the MBMS session can be initiated. For example, the session controller 1460 may determine whether the type of MBMS service received by the terminal is an MBMS service that can be supported by the target base station 1400. Alternatively, the session controller 1460 may determine whether the MBMS service received by the terminal may be provided through a cell, component carrier, or frequency provided by the target base station 1400. In this case, initiating the MBMS session means that the session controller 1460 allocates network resources for MBMS service transmission, sets up a necessary bearer, and indicates that the MBMS service transmission is about to start. The MCE 1430, the target base station 1400, etc. Inform lower stream nodes.

If the session controller 1460 determines that the MBMS session can be initiated, the MME transmitter 1465 transmits the first MBMS session initiation message to the MCE 1430. This triggers or initiates an MBMS session initiation procedure.

All of the above functions may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), or the like according to software or program code coded to perform the function. The design, development and implementation of the code will be apparent to those skilled in the art based on the description of the present invention.

Although the present invention has been described above with reference to the embodiments, it will be apparent to those skilled in the art that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention. I can understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

Claims

In a terminal performing a handover from a source eNB to a target eNB and receiving a multimedia broadcast multicast service (MBMS) service,

A terminal transmitter for indicating that the terminal receives the MBMS service through a radio bearer (MRB) for an MBMS and transmitting an MBMS service indicator indicating the type of the MBMS service to the source base station; And

In response to the MBMS service indicator, an MBMS service response indicator indicating that the MBMS service can be provided at the target base station is received from the source base station, and the handover from the target base station after the handover to the target base station; Terminal comprising a terminal receiving unit for receiving the MBMS service.
The method of claim 1, wherein the terminal transmission unit,

And transmitting the MBMS service indicator to the source base station through a measurement report message related to the handover.
The method of claim 1, wherein the terminal receiving unit,

And receiving the MBMS service response indicator from the source base station through a handover command message related to the handover.
The method of claim 1, wherein the terminal transmission unit

And transmitting the MBMS service indicator for identifying the type of the MBMS service to the source base station as a temporary mobile group identity (TMGI) for the MBMS service.
A method for receiving a MBMS service from a terminal performing a handover from a source base station to a target base station, the method comprising:

Instructing that the terminal receives the MBMS service through a radio bearer (MRB) for an MBMS, and transmitting an MBMS service indicator indicating the type of the MBMS service to the source base station; And

Receiving an MBMS service response indicator from the source base station indicating that the MBMS service can be provided by the target base station as a response to the MBMS service indicator; And

Receiving the MBMS service from the target base station after the handover to the target base station.
The method of claim 5,

The MBMS service indicator is transmitted to the source base station through a measurement report message related to the handover, MBMS service receiving method.
The method of claim 5,

And the MBMS service response indicator is received from the source base station through a handover command message related to the handover.
The method of claim 5,

And the MBMS service indicator identifies the type of the MBMS service as a temporary mobile group identifier for the MBMS service.
A target base station that provides a multimedia broadcast multicast service (MBMS) service to a terminal handing over from a source eNB to a target eNB,

MBMS support request message requesting support of continuous MBMS service at the core network level for the terminal, and MBMS session response message indicating that a session about the MBMS service can be started at the target base station. A target transmitter for transmitting a multi-cell coordination entity (hereinafter referred to as MCE); And

A target receiving unit receiving an MBMS continuity request indicator from the source base station requesting the terminal to continuously provide the MBMS service, and receiving an MBMS session initiation message from the MCE indicating the initiation of a session related to the MBMS service; Target base station, characterized in that.
The method of claim 9,

And the target transmitter transmits an MBMS continuity response indicator indicating that the MBMS service is continuously provided in response to the MBMS continuation request indicator to the source base station.
The method of claim 9,

The target transmission unit,

And the MBMS session response message includes a result of setting the MBMS radio access bearer (E-RAB) by the target base station.
A method for providing an MBMS service in a target base station to a terminal handing over from a source base station to a target base station,

Receiving an MBMS continuity request indicator from the source base station requesting the terminal to continuously provide an MBMS service;

Transmitting an MBMS support request message to MCE requesting support of a continuous MBMS service at a core network level for the terminal;

Receiving an MBMS Session Initiation message from the MCE indicating the initiation of a session for the MBMS service; And

And transmitting, at the target base station, an MBMS session response message to the MCE indicating that a session relating to the MBMS service can be initiated.
The method of claim 12,

And transmitting to the source base station an MBMS continuity response indicator indicating that the MBMS service is continuously provided in response to the MBMS continuation request indicator.
The method of claim 12,

The MBMS session response message includes a result of the MBMS E-RAB setup by the target base station, MBMS service providing method.
In a mobility management entity (MME) that provides an MBMS service to a terminal handing over from a source base station to a target base station,

MME receiving an MBMS support request message for requesting support of a continuous MBMS service at the core network level for the terminal and an MBMS session response message indicating that an MBMS session for the MBMS service can be started at the target base station from an MCE. Receiving unit;

A session control unit checking whether an MBMS session for the MBMS service can be started, allocating network resources for the transmission of the MBMS service, and setting up a bearer for the MBMS service; And

And an MME transmitter for transmitting an MBMS session initiation message to the MCE indicating the initiation of a session related to the MBMS service.
The method of claim 15,

The session controller checks whether the MBMS service can be provided through a cell or a frequency provided by the target base station.
The method of claim 15,

The session controller checks whether the type of the MBMS service can be supported by the target base station.
The method of claim 15,

The MME transmitter, the mobile management object, characterized in that for transmitting the MBMS E-RAB Quality of Service (QoS) parameters for supporting the MBMS service in the MBMS session initiation message.
A method for providing an MBMS service in an MME for a terminal handing over from a source base station to a target base station,

Receiving an MBMS support request message from an MCE requesting support of a continuous MBMS service at a core network level for the terminal;

Initiating an MBMS session for the MBMS service; And

And receiving, from the MCE, an MBMS session response message indicating that an MBMS session relating to the MBMS service is started at the target base station.
The method of claim 19,

Initiating the MBMS session,

Allocating network resources for transmission of the MBMS service and establishing a bearer for the MBMS service; And

And transmitting to the MCE an MBMS Session Initiation message indicating the initiation of a session relating to the MBMS service.
The method of claim 20,

Determining whether the MBMS service can be provided through a cell or frequency provided by the target base station or whether the type of the MBMS service can be supported by the target base station. Way.
The method of claim 20,

And the MBMS session initiation message includes an MBMS E-RAB QoS parameter for supporting the MBMS service.