KR20130038763A - Apparatus and method for performing handover providing continuity in multimedia broadcast multicast service - Google Patents

Abstract

PURPOSE: A handover device for the continuity of an MBMS(Multimedia Broadcast Multicast Service) and a method thereof are provided to offer information related to the MBMS for the continuity of the MBMS when data is transferred to a CSG(Closed Subscriber Group) cell. CONSTITUTION: A terminal transmission unit(1405) transmits a measurement indication message including an MBMS indicator to a source base station linked with a terminal. The MBMS indicator indicates the MBMS reception state of the terminal. The terminal transmission unit transmits a measurement report message including information related to the MBMS to the source base station. The information related to the MBMS includes frequency information, a service state, a service kind of the MBMS related to the reception state of the terminal. A terminal reception unit(1410) receives the MBMS from a target base station based on the information related to the MBMS indicator and the MBMS. [Reference numerals] (1405) Terminal transmission unit; (1410) Terminal reception unit; (1435) Source reception unit; (1440) Source transmission unit; (1465) Target reception unit; (1470) Target control unit; (1475) Target transmission unit; (AA) MBMS frequency indicator, Delay offset; (BB) MBMS indicator, MBMS related information; (CC) Neighboring MBMS related information, MBMS service;

Description

A handover apparatus and method for continuity of multimedia broadcasting multicasting service {APPARATUS AND METHOD FOR PERFORMING HANDOVER PROVIDING CONTINUITY IN MULTIMEDIA BROADCAST MULTICAST SERVICE}

The present invention relates to wireless communications, and more particularly, to a handover apparatus and method for 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 help.

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 (hereinafter referred to as a source base station) links to another neighboring base station (hereinafter referred to as a target base station) when the signal strength of a specific base station in service becomes weak. do. 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, the necessary resources (or channels) are shared when they are transmitted to each user so that multiple users receive the same multimedia data to improve the efficiency of radio resources and to provide multimedia services from the user's point of view. It is an advantage of MBMS that it is available cheaply.

MBMS uses a common channel to efficiently receive data from a plurality of terminals in one service. That is, only one shared channel is allocated to one service data instead of allocating a dedicated 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.

When the target cell of the handover is a CSG cell, if the CSG cell does not consider the MBMS, it is not known whether the UE is receiving the MBMS service or is interested in receiving the MBMS service and cannot support the MBMS service smoothly. Accordingly, there is a need for a method of supporting continuity of an MBMS service by transmitting and receiving MBMS related information of a terminal with a network.

An object of the present invention is to provide a handover apparatus and method for service continuity in MBMS.

Another technical problem of the present invention is to provide an apparatus and method for providing MBMS related information for continuity of MBMS service in handover to a CSG cell.

Another technical problem of the present invention is to provide an apparatus and a method for allowing a terminal to receive MBMS service from a source cell for as long as possible when handing over to a CSG cell.

According to an aspect of the present invention, a method for performing handover of a terminal receiving a multimedia broadcast multicast service (MBMS) service includes a measurement indication message including an MBMS indicator indicating whether the terminal is receiving or interested in receiving an MBMS service Transmitting a measurement report message including MBMS-related information including service type, service availability, or frequency information of the MBMS that the terminal is receiving or is interested in receiving; Transmitting to a source base station, performing a handover from the source base station to a target base station, and receiving the MBMS service from the target base station based on the MBMS indicator and the MBMS related information.

And receiving, from the source base station, a measurement control message including an MBMS frequency indicator for setting a measurement for a frequency of interest by the terminal, wherein the measurement report message is for an MBMS related frequency through the MBMS frequency indicator. May include monitoring results.

And receiving system information from the target base station including neighbor MBMS related information on whether the MBMS related information can be received in a neighbor cell, and configuring the MBMS related information based on the neighbor MBMS related information. The measurement report message including the information may be transmitted to the source base station.

Receiving a measurement control message from the source base station, the measurement control message including measurement setting information including a delay offset value for delaying a timing at which the terminal triggers an A3 event, and based on the measurement control message including the delay offset The method may further include measuring whether the signal strength of the signal of the target base station is stronger than the signal strength of the source base station by more than a predetermined threshold. The measurement report message may include the result of the measurement.

Type information of the MBMS service included in the MBMS related information may be distinguished by a temporary mobile group identifier for the MBMS service.

According to another aspect of the present invention, a method for performing a handover of a source base station transmitting an MBMS service includes receiving a measurement indication message from the terminal including an MBMS indicator indicating whether the terminal is receiving or interested in receiving an MBMS service Receiving, from the terminal, a measurement report message including MBMS related information including service type, service availability, or frequency information of the MBMS that the terminal is receiving or is interested in receiving, the MBMS indicator; And transmitting a handover request message including the MBMS related information to a target base station, and performing a handover to the target base station when receiving the acknowledgment of the handover request message.

Before receiving the measurement report message from the terminal, the terminal may further include transmitting a measurement control message including an MBMS frequency indicator for setting the measurement for the frequency of interest to the terminal.

After receiving the measurement indication message from the terminal, transmitting the measurement control message including measurement setting information including a delay offset value for delaying the time point at which the terminal triggers an A3 event to the terminal; can do.

According to another aspect of the present invention, a method for performing a handover of a target base station to which the MBMS service is to be transmitted includes a CSG ID for identifying a closed subscriber group identifier (CSG) of the target base station to which the terminal intends to perform handover, and wherein the terminal is an MBMS. MBMS indicator indicating whether the service is receiving or interested in receiving at least one of MBMS-related information including the type of service, availability or frequency information of the MBMS that the terminal is receiving or interested in receiving; Receiving a handover request message from the source base station, comparing the CSG ID of the target base station with a CSG ID included in the handover request message, and verifying whether the CSG member is a CSG member; Resource allocation for handover, handover with the source base station And performing an MBMS service and transmitting the MBMS service to the terminal based on the MBMS indicator and the MBMS related information.

The method may further include transmitting system information including neighbor MBMS related information on whether the terminal may receive the MBMS related information even in a neighbor cell, to the terminal.

According to another aspect of the present invention, a terminal performing a handover capable of continuously receiving an MBMS service may include a measurement indication message including an MBMS indicator indicating whether the terminal is receiving or is interested in receiving an MBMS service. Transmitting the measurement report message to the source base station linked with the terminal and including the MBMS related information including service type, service availability or frequency information of the MBMS that the terminal is receiving or is interested in receiving; And a terminal receiver configured to receive the MBMS service from a target base station based on the MBMS indicator and the MBMS related information.

The terminal receiving unit further receives, from the source base station, a measurement control message including an MBMS frequency indicator for setting a measurement for a frequency of interest by the terminal before transmitting the measurement report message to the source base station. The report message may include a result of monitoring the MBMS related frequency through the MBMS frequency indicator.

The terminal receiver further receives system information including neighbor MBMS related information regarding whether the MBMS related information can be received even from a neighbor cell from the target base station, and the terminal transmitter based on the neighbor MBMS related information. The measurement report message including the MBMS-related information can be further transmitted to the source base station.

After receiving the measurement instruction message to the source base station, the terminal receiving unit transmits a measurement control message including measurement setting information including a delay offset value for delaying a time point at which the terminal triggers an A3 event. Can be received further from.

When the UE intends to handover in the state of receiving the MBMS service, the MBMS service reception may be continuously performed.

Before the UE changes the cell, there is an advantage of obtaining related information so that the UE can receive the MBMS in the cell to be changed.

The UE may receive the MBMS service from the source cell for as long as possible before handing over to the target cell.

1 is a block diagram illustrating a wireless communication system.
2 is a block diagram illustrating a radio protocol structure for a user plane and a radio protocol structure for a control plane.
3 shows a structure of an LTE MBMS system to which the present invention is applied.
4 illustrates an example in which a structure of an LTE MBMS system to which the present invention is applied is arranged.
5 shows a mapping between a downlink logical channel and a downlink transport channel.
6 shows a mapping between a downlink transport channel and a downlink physical channel.
7 shows an example of a scenario of cell-based localization to which the present invention is applied.
8 illustrates an example of a method for handover of a terminal from a source cell to a target cell according to the present invention.
9 shows another example of a method for handover of a terminal from a source cell to a target cell according to the present invention.
10 shows another example of a method for handover of a terminal from a source cell to a target cell according to the present invention.
11 is a flowchart illustrating an operation of a terminal performing handover from a macro cell to a CSG cell according to the present invention.
12 is a flowchart illustrating an operation of a source cell for performing handover from a macro cell to a CSG cell according to the present invention.
13 is a flowchart illustrating an operation of a target cell for performing handover from a macro cell to a CSG cell according to the present invention.
14 is a block diagram illustrating a terminal, a source base station and a target base station performing a handover method for continuity of MBMS according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to exemplary 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 the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

In addition, the present invention will be described with respect to a wireless communication network. The work performed in the wireless communication network may be performed in a process of controlling a network and transmitting data by a system (e.g., a base station) Work can be done at a terminal connected 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 a multiple access technique applied to a 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, TDD (Time Division Duplex) scheme in which uplink and downlink transmission are transmitted using different time periods or FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies may be used .

Referring to FIG. 1, an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) includes at least one base station 20 providing a control plane (CP) and a user plane (UP) to a terminal. , BS). 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 fixed station communicating with the terminal 10, and includes an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and a femto base station (eNodeB). femto-eNB), a pico base station (pico-eNB), a home base station (Home eNB), relay (relay), etc. may be called. 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 to which the current terminal 10 and a radio bearer (RB) are set. The target base station (Target BS, 22) indicates that the terminal 10 is connected to the source base station 21. The base station intends to handover to disconnect the radio bearer of the radio bearer newly set up.

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. S1 interface supports many-to-many-relations between the base station 20 and the 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. The X2-based handover is used when the UE wants to handover from the source base station 21 to the target base station 22 using the X2 interface. At this time, the MME / S-GW 30 is not changed.

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 refers to communication from the base station 20 to the terminal 10, and uplink refers to 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.

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

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 a medium access control (MAC) layer, which is an upper layer, through a transport channel. Data is transferred between the MAC layer and the physical layer through the transport channel. The transport channel is classified according to how the data is transmitted through the air interface. Data is transferred between the different physical layers, that is, between the transmitter and the physical layer of the receiver through a physical channel. There are several physical control channels.

The physical downlink control channel (PDCCH) informs the UE of resource allocation of a paging channel (PCH), a 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. A 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. A 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 can be divided into a control channel for transferring control area information and a traffic channel for transferring user area information.

The function of the RLC layer includes concatenation, segmentation and reassembly of the RLC SDUs. In order to guarantee the various quality of service (QoS) required by the radio bearer, the RLC layer has three types: transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). Provides an operation mode of. AM RLC provides error correction via automatic repeat request (ARQ).

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

The Radio Resource Control (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 setting 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 an 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 the RRC message in the control plane, and the DRB is used as a path for transmitting the user data in the user plane. MRB is used as a path for transmitting MBMS data.

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

3 shows an architecture of an LTE MBMS system to which the present invention is applied. General structure to which E-UTRAN MBMS is applied.

Referring to FIG. 3, an MBMS gateway (GW) is an entity through which MBMS data is transmitted and is located between a base station and a broadcast multicast-service center (BM-SC), and transmits or broadcasts an MBMS packet to a base station. Cast The BM-CS is a network device capable of initiating and managing MBMS-related services and may be in charge of managing MBMS services.

Multi-Cell / Multicast Coordination Entity (MCE) is an MBMS control entity, that is, a main entity for control related to MBMS, and the radio resource allocation within the area of Multimedia Broadcast / multicast service Single Frequency Network (MBSFN) Radio resource allocation or admission control is performed. MCE may be implemented simultaneously in a base station or may be implemented independently.

M1 is a user plane interface. MBMS data is transmitted to the interface between the MBMS GW and the base station. M2 is an E-UTRAN internal control plane interface. MBMS control information is transmitted to the interface between the MCE and the base station. As an example, the MCE may be implemented in a base station, where the M2 interface may only exist logically. M3 is the control plane interface between the E-UTRAN and the Evolved Packet Core (EPC). Control information related to MBMS session control is transmitted to an interface between the MCE and the MME. The Sm interface is an interface between the MBMS control plane (CP) and the MME to transmit control information for MBMS control. The MME follows the definition in 3GPP TS36.300 as a node for control related to the base station and the terminal in the EUTRAN.

4 shows an example in which an architecture of an LTE MBMS system to which the present invention is applied is deployed. MME, MBMS GW, MCE, etc. may be used for MBMS packet transmission and control information transmission in association with LTE MBMS.

Referring to FIG. 4, the MCE may be used for session management and resource control of the base station, and may exist separately from the base station as shown in (a) or inside the base station as shown in (b). At this time, the MCE may be a block of logical functions inside the base station. A session start / stop message is sent to the base station via the MME and the MCE for session control signaling such as session start or session stop. The base station receiving the session start / stop message may notify the cell to inform that the corresponding MBMS service is started or stopped.

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

Referring to FIG. 5, 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 according to what kind of information is transmitted. There are two types of logical channels: control channel and traffic channel.

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.

The transport channel is classified according to how the data is transmitted through the air interface. The BCH is broadcast in the entire cell area and has a fixed predefined transmission format. 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 MBSFN support.

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

Referring to FIG. 6, 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.

The 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 in a frequency band. An adjacent cell using the same carrier frequency with respect to the source cell is called an intra-frequency neighbor cell. In addition, adjacent cells using different carrier frequencies based on the source cell are called inter-frequency neighbor cells. That is, not only a cell using the same frequency as the source cell but also a cell using a different frequency, 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.

7 shows an example of a scenario of cell-based localization to which the present invention is applied.

Referring to FIG. 7, 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 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.

In addition, the MBMS service area may mean an area in which the MBMS service itself is supported. Multiple MBMS services can be supported in one MBMS service area. For example, MBMS service a, b, or c may be supported in MBMS service area A, and may be provided for each MBSFN area. That is, MBMS services a, b or c may be provided in MBSFN regions 1, 2 or 3 respectively.

In this case, the MBSFN area means an area where a specific MBMS service is provided in a single frequency band. For example, in the case of MBSFN region 1, an MBSFN subframe is allocated to frequency f1 to support a specific MBMS service A. At this time, in the MBSFN region, the MBSFN subframe may be allocated to the same frequency f1 to support the MBMS service A.

For example, the MBSFN region 2 may support the MBMS service A, but may support the MBMS service A using a frequency f2 different from the frequency resource f1 in the MBSFN region 1. In the same MBSFN region, even when the UE moves, it may receive an MBMS service based on the same MBMS configuration. In other words, the UE may continue to receive the MBMS service received in the previous cell without receiving a new MBMS configuration in the same MBSFN region.

Alternatively, in the case of a regional change, a service may be provided using different frequencies even within the same MBSFN region, which may be determined based on an MBMS location range. In the MBMS location range, the MBMS service can be received through the MRB (MBMS point to multipoint Radio Bearer, or MBMS radio bearer) in all the cells in the MBSFN region, whereas the MRB is only available within a specific region or location range within the same MBSFN region. This is a concept used to manage to receive MBMS service through.

In this case, the MBMS location range may be managed in units of cells as shown in FIG. 7. Cells D, F, and G are the location ranges associated with the MBMS service, while other cells (cells A, B, C, and E) are in the same MBSFN region but are not included in the MBMS location range.

In addition, the MBMS location range may be managed by a geography based localization method, for example, a positioning method.

Now, a method and apparatus for providing continuity of MBMS in performing handover according to the present invention will be described.

8 illustrates an example of a method for handover of a terminal from a source cell to a target cell according to the present invention. In this case, the source cell may be a macro cell and the target cell may be a closed subscriber group (CSG) cell. That is, handover from the macro cell to the CSG cell in the connected mode. In this case, the connection mode may be an RRC connected mode. The present invention also relates to inbound mobility in consideration of MBMS continuity. In this case, inbound mobility means that the UE moves from the macro cell to the CSG cell.

Hereinafter, a CSG (closed subscriber group) cell refers to a femto cell that provides a service by providing a connection only to a UE authenticated to be subscribed to the corresponding CSG among UEs. Unlike a general CSG cell, a hybrid CSG cell allows access to a UE subscribed to a CSG and all UEs not subscribed to it. However, at this time, a high quality service is preferentially provided to a subscribed terminal, and a method of providing a service with a minimum service to a non-subscribed terminal is provided. An open CSG cell refers to a CSG cell in which all terminals allow access regardless of whether or not a CSG cell member is subscribed to.

Referring to FIG. 8, the source cell transmits a proximity configuration message to the terminal (S800). The access establishment message includes information on whether the terminal can operate an access indication (proximity indication) within a specific radio access technology (RAT). For example, when the CSG cell included in the whitelist of the UE is detected by the E-UTRAN of the LTE system or the UTRAN of the wideband code division multiple access (WCDMA) system, the parameter "proximityIndicationEUTRA" included in the access configuration message is detected. Alternatively, the access indication operation may be performed by checking whether the status of "proximityIndicationUTRA" is "enable" or "disable". That is, if one of the parameters is determined to be "enabled", the access instruction operation is performed. In addition, the access configuration message may be included in an RRC message, such as an RRC connection reconfiguration message, or transmitted, or may be transmitted together with an RRC message.

The terminal transmits a proximity indication message to the source cell (S805). The access indication message informs the source cell that the terminal is approaching a CSG cell having a specific frequency and a physical cell ID (PCI).

In general, the handover of the terminal is controlled by the macro cell. However, in the case of a handover between the macro cell and the CSG cell, it is difficult for the macro cell to perform coordination between the macro cell and the CSG cell. When the frequency of the macro cell and the frequency of the CSG cell are different from each other, measurement configuration for the CSG cell cannot be performed in advance. Accordingly, the UE transmits information on the CSG cell to be measured through the access indication message to the source cell. The access indication message may include frequency information and PCI information. In addition, the access indication message may be an RRC message.

In addition, a method of selecting a CSG cell may follow autonomous search procedures. The automatic search procedure can be confirmed through the history or fingerprint information of the CSG cell previously visited by the UE.

According to the present invention, the terminal may transmit an MBMS indicator (MBMSInd) in the access indication message to the source cell. The MBMS indicator is information related to the MBMS service of the terminal. For example, the MBMS indicator may inform that the terminal is receiving the MBMS service through the MBMS bearer or may indicate that the terminal is interested in receiving the MBMS service. For example, the form of the MBMS indicator is a flag and may indicate 0 or 1. If the MBMS indicator is 1, the terminal is a terminal receiving or interested in receiving an MBMS service, and if 0, the terminal is a terminal not interested in receiving without receiving an MBMS service. The opposite may be true. Here, the MBMS indicator may be set to 1 even if the terminal receives only at least one MBMS service among the plurality of MBMS services.

The source cell receiving the MBMS indicator can know whether the UE preferentially prefers the MBMS service.

The source cell transmits a measurement control message to the terminal (S810). The measurement control message includes configuration information of an object to be measured by the terminal. In the situation where the UE detects the CSG cell through the access indication message, the source cell needs measurement information of the CSG cell in order to hand over to the CSG cell. The terminal may proceed to measure the CSG cell according to the setting of the measurement control information.

According to the present invention, the measurement control message transmitted from the source cell to the terminal may include an MBMS frequency indicator (MBMS FreqInd). The MBMS frequency indicator indicates the MBMS frequency set by the source cell when the frequency for serving the MBMS is not set. In other words, although there is an MBMS service and the like that the user wants to receive, the UE may not proceed with a process of measuring a frequency band capable of receiving the MBMS service. For example, the terminal wants to receive a specific MBMS service A, but can support only the MBMS service B in the cell to which it is currently connected. In this case, the MBMS service A may be provided at a different frequency from the cell to which the terminal is connected. The UE may not be aware of the situation in which the MBMS service is provided by the MBMS service at another frequency, and the BS may inform the UE by using the MBMS frequency indicator.

In addition, when the measurement for the frequency (or RAT) that the terminal is interested in is not set, the source cell may set the measurement for this and indicate to the terminal. The source cell may include information about the measurement configuration in an RRC connection reconfiguration message and transmit the information.

The terminal performs the measurement based on the measurement setting information included in the measurement control message received from the source cell. In this case, the MBMS related information included in the measurement setting information may be set together. The MBMS frequency indicator can also be used to monitor MBMS related frequencies.

Meanwhile, the source cell receiving the MBMS indicator information included in the access indication message knows that the terminal is receiving (or interested in receiving the MBMS service) the MBMS service. In this case, it is preferable to perform an operation for allowing the terminal to receive the MBMS service through the source cell for as long as possible.

As an example according to the present invention, the source cell may further include an operation of delaying the time point at which the measurement control message is transmitted to the terminal.

As another example of the present invention, when the UE performs the measurement, measurement configuration information including a delay offset may be determined in advance so as to trigger an A3 event late. At this time, the A3 event refers to an event triggered when the measurement value of the target cell is larger than a specific threshold value than the measurement value of the source cell. At this time, the terminal transmits and reports the measurement result to the source cell.

The measurement reporting time point for the A3 event may be determined using the following equation.

M _n is a measurement value of a neighbor cell measured by the UE, and may be a reference signal received power (RSRP) value. O _fn is an offset value specifically assigned to a frequency corresponding to a neighbor cell. O _cn is an offset value specifically assigned to a cell corresponding to a neighbor cell. Hys is a value of a takeover value added so that the UE does not frequently select between the neighbor cell and the main serving cell.

In addition, M _p is a measured value of the main serving cell measured by the terminal may be an RSRP value. O _fp is an offset value specifically assigned to a frequency corresponding to a main serving cell. O _cp is an offset value specifically assigned to a cell corresponding to the main serving cell. Off is the value imposed on the E-UTRAN system.

In Equation 1, an A3 event is triggered based on an event in which "f" becomes greater than 0. At this time, the measurement report of the terminal is performed.

According to the present invention, a delay offset value "Off _m " may be added to delay the timing of triggering the A3 event so that the UE may receive the MBMS service through the source cell for as long as possible. This is as follows.

If the A3 event is triggered for an event in which "f2" becomes greater than 0, a time point at which the A3 event is triggered may be further delayed than when using "f" in Equation 1 above. At this time, the delay offset "Off _m " value may be determined by the system's decision.

As described above, delaying the triggering time of the A3 event according to the present invention assumes that the highest priority of the UE is MBMS. That is, it is assumed that the terminal prefers to receive the MBMS service rather than handover to the CSG cell. The UE may observe the situation for the MBMS by delaying the handover time as much as possible without immediately handing over to the CSG cell.

The terminal transmits a measurement report message to the source cell (S815). The measurement report message is transmitted when the A3 event is triggered, and indicates that the handover is necessary because the signal strength of the CSG cell, which is the target cell, is stronger than the signal threshold of the source cell, greater than or equal to a preset threshold. That is, the terminal performing the measurement according to the setting of the received measurement control message triggers the measurement report when the measurement result exceeds the threshold for handover. The measurement report message includes the PCI information of the target cell.

According to the present invention, the measurement report message transmitted by the terminal may further include MBMS information (MBMS information: MBMSInfo). The MBMS related information includes information on the MBMS being received by the terminal or MBMS information (or frequency information) that the terminal is interested in.

For example, the MBMS related information may include information regarding the type of MBMS service received by the terminal. The terminal may simultaneously receive a plurality of MBMS services, the MBMS service area or MBSFN area for each MBMS service may be different, and it is necessary to inform which MBMS service is currently in progress at the location where the terminal receives the MBMS service. Because there is. The type of MBMS service may be distinguished by a Temporary Mobile Group Identity (TMGI) for the MBMS service.

For example, when a plurality of MBMS terminals are receiving MBMS services A, B, and C, the MBMS related information may be configured in a list form as shown in TMGI A, B, and C of the following table.

MBMS Service Type TMGI enable / disable frequency MBMS Service 1 A Enable a MBMS Service 2 B Disable a MBMS Service 3 C Enable a MBMS Service 4 D Enable b

According to Table 1, the MBMS-related information includes a service being received by the terminal or a service of receiving interest 1 TMGI A, a service being received by the terminal or receiving service 2 is a TMGI B, a service being received by the terminal or a service of receiving interest 3 Is TMGI C, and may include information that is transmitted on the frequency 'a'. In addition, the service 4 that the terminal is interested in receiving may include information that TMGI D is transmitted through the frequency 'b'. In addition, the dual MBMS service 2 may include information that is "impossible", the rest is "enabled". This is merely an example, and information about TMGI, MBMS service enable / disable, or frequency on which the MBMS service is transmitted may be set differently according to the type of MBMS service.

The source cell transmits a system information request message to the terminal (S820). After receiving the measurement report message including the PCI of the target cell, the source cell checks the PCI to determine whether the target cell corresponds to the CSG cell (or femto cell), and if the target cell is the CSG cell, sends a system information request message. Requests that the terminal receives the system information of the target cell by transmitting.

The target cell (CSG cell) broadcasts the system information of the target cell, and the terminal receiving the system information request message receives the system information broadcast by the target cell (S825). The system information includes a Cell Global Identifier (CGI), an E-UTRAN CGI (ECGI), a Tracking Area Identifier (TAI), or a Closed Subscriber Group Identifier (CSG ID). CGI or ECGI is an identifier for distinguishing cells globally and may be used as an identifier for distinguishing cells when PCI is confused. The TAI is an identifier for the tracking area of the target cell, and the CSG ID is an identifier for identifying the CSG of the target cell.

In this case, the target cell may broadcast neighbor MBMS information together with system information of the target cell. It can be seen that the UE can receive MBMS related information even in the neighboring cell through the neighbor MBMS related information. The neighbor MBMS related information provided by the target cell may be MBMS service progress related information in a neighbor cell which the source cell does not provide. For example, the source cell may provide service information for MBMS services A, B, etc. at frequency a. The target cell may provide the UE with information about MBMS services A and B at frequency a and information about MBMS services A, C and D at frequency b. The terminal may receive more accurate information on the MBMS service that the source cell and the target cell have from the MBMS related information. In addition, the terminal may check frequency information provided with the desired MBMS service.

Based on the system information received from the target cell, the terminal receives the MBMS service from the frequency at which the desired MBMS service is provided according to capability, or measures the frequency at which the MBMS service is provided based on neighboring MBMS related information. By performing the handover to the neighboring cell instead of the target cell.

The terminal transmits a measurement report message to the source cell (S830). The measurement report message may include a CGI, ECGI, TAI or CSG ID. In addition, when the MBMS information (MBMSinfo) is not transmitted in step S815, the MBMS information may be transmitted through the measurement report message of step S830.

The source cell transmits a handover request message to the MME (S835). The handover request message may include context information of the terminal, and may include information such as an access mode or a CSG ID of the CSG cell. The access mode may exist when the CSG cell is a hybrid cell.

According to the present invention, the handover request message may include MBMS related information. Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the MME. Since the MBMS related information cannot be directly transmitted to the target cell in the network structure as shown in FIG. 3, the terminal first transmits the information to the MME. The MME may transmit the MBMS-related information to the MCE or BM-SC, and may transmit the MBMS-related information from the MCE or the BM-SC to the HeNB GW or CSG cell. By connecting to an application server that provides MBMS services such as BM-SC, etc., the terminal may provide MBMS services when point-to-point is connected to the corresponding CSG cell.

The MME performs an access control based on the CSG ID included in the handover request message (S840). If the access control fails, a handover preparation fail message is transmitted to the source cell. If the access control is successful and a cell access mode exists, a handover request message is transmitted to the target cell (CSG cell) through the HeNB GW. do.

The MME transmits a handover request message to the HeNB GW (S845). The handover request message may include a CSG ID and membership status information. In addition, the handover request message may include MBMS related information. Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the HeNB GW.

The HeNB GW transmits a handover request message to the target cell (CSG cell) (S850). The handover request message may include a CSG ID and membership status information. In addition, the handover request message may include MBMS related information. Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the target cell.

The target cell (CSG cell) validates by comparing the CSG ID in the handover request message with the CSG ID broadcasted by the target cell (S855). Once verified as a CSG member, resources are allocated for handover.

The target cell (CSG cell) transmits a handover request acknowledgment message to the HeNB GW (S860), and the HeNB GW transmits a handover request acknowledgment message to the MME (S865). The handover request confirmation message informs whether the target cell is ready for handover and can perform handover.

The MME transmits a handover command message to the source cell (S870), and the source cell transmits a handover command message to the UE (S875). The handover command message informs whether the UE can handover from the source cell to the target cell.

The UE initiates a handover procedure from the source cell to the target cell (CSG cell) and performs handover (S880). Based on the handover, the terminal receives the MBMS service through the CSG cell (or its neighbor cells) (S885).

9 shows another example of a method for handover of a terminal from a source cell to a target cell according to the present invention. In this case, the source cell may be a macro cell, and the target cell may be a CSG cell.

Referring to FIG. 9, the terminal receives an access setup message from a source cell (S900). The access configuration message includes information on whether the terminal can access the operation within a specific RAT. For example, when the CSG cell included in the whitelist of the UE is detected by the E-UTRAN of the LTE system or the UTRAN of the WCDMA system, the state of the parameter "proximityIndicationEUTRA" or "proximityIndicationUTRA" included in the access configuration message is "possible". Alternatively, the access indication operation may be performed by checking whether it is “not possible”. That is, if one of the parameters is determined to be "enabled", the access instruction operation is performed. In addition, the access configuration message may be transmitted in an RRC message such as an RRC connection reconfiguration message or transmitted together with the RRC message.

The terminal transmits an access instruction message to the source cell (S905). The access indication message informs the source cell that the terminal is approaching a CSG cell having a specific frequency and PCI. The access indication message may include frequency information and PCI information. The access indication message may be an RRC message. In addition, the method of selecting the CSG cell may follow an automatic search procedure.

The source cell transmits a measurement control message to the terminal (S910). The measurement control message includes setting information of an object to be measured by the terminal. The terminal may proceed to measure the CSG cell according to the setting of the measurement control information.

The terminal transmits a measurement report message to the source cell (S915). The measurement report message is transmitted when an A3 event is triggered, and indicates that a situation in which a handover is necessary because the signal strength of the target cell CSG cell is stronger than the signal threshold of the source cell is greater than the preset threshold. The measurement report message includes the PCI information of the target cell.

According to the present invention, the UE may transmit an MBMS indicator (MBMSInd) in the measurement report message to the source cell. The MBMS indicator is information related to the MBMS service of the terminal. For example, the MBMS indicator may inform that the terminal is receiving the MBMS service through the MBMS bearer or may indicate that the terminal is interested in receiving the MBMS service. For example, the form of the MBMS indicator is a flag and may indicate 0 or 1. The MBMS indicator may be set to 1 even if the UE receives only at least one MBMS service among a plurality of MBMS services. When the source cell receives the MBMS indicator, it can be seen that the UE preferentially prefers the MBMS service.

According to the present invention, the measurement report message transmitted by the terminal may further include MBMS information (MBMS information: MBMSInfo). The MBMS related information includes information on the MBMS being received by the terminal or MBMS information (or frequency information) that the terminal is interested in.

For example, the MBMS related information may include information regarding the type of MBMS service received by the terminal. The terminal may simultaneously receive a plurality of MBMS services, the MBMS service area or MBSFN area for each MBMS service may be different, and it is necessary to inform which MBMS service is currently in progress at the location where the terminal receives the MBMS service. Because there is. The type of MBMS service may be distinguished by a temporary mobile group identifier for the MBMS service.

For example, when a plurality of MBMS terminals are receiving MBMS services A, B, and C, the MBMS related information may be configured in a list form as shown in TMGI A, B, and C of Table 1 above.

The terminal receives a system information request message from a source cell (S920). The source cell receiving the measurement report message including the PCI of the target cell checks the PCI to determine whether the target cell corresponds to the CSG cell or the femto cell, and if the target cell is the CSG cell, transmits a system information request message. The terminal requests to receive system information of the target cell.

The target cell (CSG cell) broadcasts the system information of the target cell, and the terminal receiving the system information request message receives the system information broadcast by the target cell (S925). The system information includes CGI, ECGI, TAI or CSG ID.

In this case, the target cell may broadcast the neighbor MBMS related information together with the system information of the target cell. It can be seen that the UE can receive MBMS related information even in the neighboring cell through the neighbor MBMS related information. In addition, the terminal may check frequency information provided with the desired MBMS service.

The UE receives the MBMS service from the frequency at which the desired MBMS service is provided according to the performance based on the system information received from the target cell, or measures the frequency at which the MBMS service is provided based on neighboring MBMS related information. Handover to a neighbor cell other than the target cell may be performed.

The terminal transmits a measurement report message to the source cell (S930). The measurement report message may include a CGI, ECGI, TAI or CSG ID. It may also include MBMS information (MBMSinfo).

The source cell transmits a handover request message to the MME (S935). The handover request message may include context information of the terminal, and may include information such as access mode or CSG ID of the CSG cell. The access mode may exist when the CSG cell is a hybrid cell.

According to the present invention, the handover request message may include MBMS information (MBMSInfo). Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the MME. When the terminal accesses the CSG cell in point-to-point, it may be able to provide the MBMS service.

The MME performs access control based on the CSG ID included in the handover request message (S940). If the access control fails, the handover preparation failure message is transmitted to the source cell. If the access control is successful and the cell access mode exists, the handover request message is transmitted to the target cell through the HeNB GW.

The MME transmits a handover request message to the HeNB GW (S945). The handover request message may include a CSG ID and membership status information. In addition, the handover request message may include MBMS information (MBMSInfo). Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the HeNB GW.

The HeNB GW transmits a handover request message to the target cell (S950). The handover request message may include a CSG ID and membership status information. In addition, the handover request message may include MBMS information (MBMSInfo). Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the target cell.

The target cell verifies the CSG ID in the handover request message by comparing it with the CSG ID broadcasted by the target cell (S955). Once verified as a CSG member, resources are allocated for handover.

The target cell transmits a handover request confirmation message to the HeNB GW (S960), and the HeNB GW transmits a handover request confirmation message to the MME (S965). The handover request confirmation message informs that the target cell is ready for handover and thus can perform handover.

The MME transmits a handover command message to the source cell (S970), and the source cell transmits a handover command message to the UE (S975). The handover command message informs that the UE can handover from the source cell to the target cell.

The UE initiates a handover procedure from the source cell to the target cell and performs handover (S980). Based on the handover, the terminal receives the MBMS service through the CSG cell (or its neighbor cells) (S985).

10 shows another example of a method for handover of a terminal from a source cell to a target cell according to the present invention. In this case, the source cell may be a macro cell, and the target cell may be a CSG cell.

Referring to FIG. 10, the terminal receives an access setup message from a source cell (S1000). The access configuration message includes information on whether the terminal can access the operation within a specific RAT. For example, when the CSG cell included in the whitelist of the UE is detected by the E-UTRAN of the LTE system or the UTRAN of the WCDMA system, the state of the parameter "proximityIndicationEUTRA" or "proximityIndicationUTRA" included in the access configuration message is "possible". Alternatively, the access indication operation may be performed by checking whether it is “not possible”. That is, if one of the parameters is determined to be "enabled", the access instruction operation is performed. In addition, the access configuration message may be transmitted in an RRC message such as an RRC connection reconfiguration message or transmitted together with the RRC message.

The terminal transmits an access instruction message to the source cell (S1005). The access indication message informs the source cell that the terminal is approaching a CSG cell having a specific frequency and PCI. The access indication message may include frequency information and PCI information. The access indication message may be an RRC message. In addition, the method of selecting the CSG cell may follow an automatic search procedure.

The source cell transmits a measurement control message to the terminal (S1010). The measurement control message includes setting information of an object to be measured by the terminal. The terminal may proceed to measure the CSG cell according to the setting of the measurement control information.

The terminal transmits a measurement report message to the source cell (S1015). The measurement report message is transmitted when an A3 event is triggered, and indicates that a situation in which a handover is necessary because the signal strength of the target cell CSG cell is stronger than the signal threshold of the source cell is greater than the preset threshold. The measurement report message includes the PCI information of the target cell.

The terminal receives a system information request message from a source cell (S1020). The source cell receiving the measurement report message including the PCI of the target cell checks the PCI to determine whether the target cell corresponds to the CSG cell or the femto cell, and if the target cell is the CSG cell, transmits a system information request message. The UE requests to receive system information of the target cell.

The target cell broadcasts system information of the target cell, and the terminal receiving the system information request message receives system information broadcast by the target cell (S1025). The system information includes CGI, ECGI, TAI or CSG ID.

In this case, the target cell may broadcast the neighbor MBMS related information together with the system information of the target cell. It can be seen that the UE can receive MBMS related information even in the neighboring cell through the neighbor MBMS related information. In addition, the terminal may check frequency information provided with the desired MBMS service.

The UE receives the MBMS service from the frequency at which the desired MBMS service is provided according to the performance based on the system information received from the target cell, or measures the frequency at which the MBMS service is provided based on neighboring MBMS related information. Handover to a neighbor cell other than the target cell may be performed. The base station stops the handover-related progress with the target cell in progress for handover based on the information informed by the terminal in relation to the MBMS and measures the new cell, that is, the cell supporting the preferred services of the terminal in relation to the MBMS. You can give a new command. For example, the target cell to which the terminal is currently handing over does not support the MBMS services A and B preferred by the terminal, but the neighbor cells and frequencies that support the services A and B in the neighbor MBMS related information known to the target cell. If the source cell receives information about the data, etc., the UE may operate to allow the UE to perform handover after a new measurement. At this time, the source cell or the base station may stop the handover process being progressed to the target cell.

The terminal transmits a measurement report message to the source cell (S1030). The measurement report message may include a CGI, ECGI, TAI or CSG ID.

According to the present invention, the UE may transmit an MBMS indicator (MBMSInd) in the measurement report message to the source cell. The MBMS indicator is information related to the MBMS service of the terminal. For example, the MBMS indicator may inform that the terminal is receiving the MBMS service through the MBMS bearer or may indicate that the terminal is interested in receiving the MBMS service. For example, the form of the MBMS indicator is a flag and may indicate 0 or 1. The MBMS indicator may be set to 1 even if the UE receives only at least one MBMS service among a plurality of MBMS services. When the source cell receives the MBMS indicator, it can be seen that the UE preferentially prefers the MBMS service.

According to the present invention, the measurement report message transmitted by the terminal may further include MBMS information (MBMSInfo). The MBMS related information includes information on the MBMS being received by the terminal or MBMS information (or frequency information) that the terminal is interested in.

For example, the MBMS related information may include information regarding the type of MBMS service received by the terminal. The terminal may simultaneously receive a plurality of MBMS services, the MBMS service area or MBSFN area for each MBMS service may be different, and it is necessary to inform which MBMS service is currently in progress at the location where the terminal receives the MBMS service. Because there is. The type of MBMS service may be distinguished by a temporary mobile group identifier for the MBMS service.

For example, when a plurality of MBMS terminals are receiving MBMS services A, B, and C, the MBMS related information may be configured in a list form as shown in TMGI A, B, and C of Table 1 above.

The source cell transmits a handover request message to the MME (S1035). The handover request message may include context information of the terminal, and may include information such as access mode or CSG ID of the CSG cell. The access mode may exist when the CSG cell is a hybrid cell.

According to the present invention, the handover request message may include MBMS information (MBMSInfo). Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the MME. When the terminal accesses the CSG cell in point-to-point, it may be able to provide the MBMS service.

The MME performs access control based on the CSG ID included in the handover request message (S1040). If the access control fails, the handover preparation failure message is transmitted to the source cell. If the access control is successful and the cell access mode exists, the handover request message is transmitted to the target cell through the HeNB GW.

The MME transmits a handover request message to the HeNB GW (S1045). The handover request message may include a CSG ID and membership status information. In addition, the handover request message may include MBMS information (MBMSInfo). Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the HeNB GW.

The HeNB GW transmits a handover request message to the target cell (S1050). The handover request message may include a CSG ID and membership status information. In addition, the handover request message may include MBMS information (MBMSInfo). Through this, information on the MBMS that the UE is receiving or of interest may be transmitted to the target cell.

The target cell verifies the CSG ID in the handover request message by comparing it with the CSG ID broadcasted by the target cell (S1055). Once verified as a CSG member, resources are allocated for handover.

The target cell transmits a handover request confirmation message to the HeNB GW (S1060), and the HeNB GW transmits a handover request confirmation message to the MME (S1065). The handover request confirmation message informs that the target cell is ready for handover and thus can perform handover.

The MME transmits a handover command message to the source cell (S1070), and the source cell transmits a handover command message to the terminal (S1075). The handover command message informs that the UE can handover from the source cell to the target cell.

The UE initiates a handover procedure from the source cell to the target cell and performs handover (S1080).

Based on the handover, the terminal receives the MBMS service through the CSG cell (or its neighbor cells) (S1085).

11 is a flowchart illustrating an operation of a terminal performing handover from a macro cell to a CSG cell according to the present invention.

Referring to FIG. 11, the terminal receives an access setup message from a source cell (S1100). The access configuration message includes information on whether the terminal can access the operation in a specific RAT. In addition, the access establishment message may be included in an RRC message such as an RRC connection reestablishment message, or transmitted with an RRC message.

The terminal transmits an access instruction message to the source cell (S1105). The access indication message informs the source cell that the terminal is approaching a CSG cell having a specific frequency and PCI. The terminal transmits information on the CSG cell to be measured through the access indication message to the source cell. The access indication message may include frequency information and PCI information. The access indication message may be an RRC message.

According to the present invention, the access indication message transmitted by the terminal may include an MBMS indicator (MBMSInd). When the source cell receives the MBMS indicator, it can be seen that the UE preferentially prefers the MBMS service.

The terminal receives a measurement control message from the source cell (S1110). The measurement control message includes setting information of an object to be measured by the terminal. The terminal may proceed to measure the CSG cell according to the setting of the measurement control information.

According to the present invention, the measurement control message transmitted from the source cell to the terminal may include an MBMS frequency indicator (MBMSFreqInd). In addition, when the measurement for the frequency (or RAT) that the terminal is interested in is not set, the source cell may set the measurement for this and indicate to the terminal. Information regarding the measurement configuration may be received from the source cell through an RRC connection reestablishment message.

The terminal performs the measurement based on the measurement setting information included in the measurement control message received from the source cell. In this case, the MBMS related information included in the measurement setting information may be set together. The MBMS frequency indicator can also be used to monitor the frequency associated with MBMS.

As an example according to the present invention, the measurement control message may include measurement setting information including the delay offset value of Equation 2 to trigger the A3 event late when the UE performs the measurement.

The terminal transmits a measurement report message to the source cell (S1115). The measurement report message is transmitted when an A3 event is triggered, and indicates that a situation in which a handover is necessary because the signal strength of the target cell CSG cell is stronger than the signal threshold of the source cell is greater than the preset threshold. The measurement report message includes the PCI information of the target cell.

According to the present invention, the measurement report message may include an MBMS indicator (MBMSInd). When the source cell receives the MBMS indicator, it can be seen that the UE preferentially prefers the MBMS service.

According to the present invention, the measurement report message may further include MBMS information (MBMSInfo). The MBMS related information includes information on the MBMS being received by the terminal or MBMS information (or frequency information) that the terminal is interested in. For example, the MBMS-related information may include information on the type of MBMS service received by the terminal as shown in Table 1 above.

The terminal receives a system information request message from a source cell (S1120). The source cell receiving the measurement report message including the PCI of the target cell checks the PCI to determine whether the target cell corresponds to the CSG cell or the femto cell, and if the target cell is the CSG cell, transmits a system information request message. The terminal requests the terminal to receive system information of the target cell.

The terminal receives system information broadcast by the target cell (S1125). The system information includes CGI, ECGI, TAI or CSG ID. In this case, the system information may further include neighbor MBMS related information. It can be seen that the UE can receive MBMS related information even in the neighboring cell through the neighbor MBMS related information. In addition, the terminal may check frequency information provided with the desired MBMS service. The UE receives the MBMS service from the frequency at which the desired MBMS service is provided according to the performance based on the system information received from the target cell, or measures the frequency at which the MBMS service is provided based on neighboring MBMS related information. Handover to a neighbor cell other than the target cell may be performed.

The terminal transmits a measurement report message to the source cell (S1130). The measurement report message may include a CGI, ECGI, TAI or CSG ID. In addition, the measurement report message may include an MBMS indicator (MBMSInd), and may include MBMS related information (MBMSinfo). When the source cell receives the MBMS indicator, it can be seen that the UE preferentially prefers the MBMS service.

The terminal receives a handover command message from the source cell (S1135). The handover command message informs that the UE can handover from the source cell to the target cell. Subsequently, the UE initiates a handover procedure from a source cell to a target cell (CSG cell) and performs a handover (S1140). Based on the handover, the UE performs MBMS service through a CSG cell (or its neighbor cells). It receives (S1145).

12 is a flowchart illustrating an operation of a source cell for performing handover from a macro cell to a CSG cell according to the present invention.

Referring to FIG. 12, the source cell transmits an access setup message to the terminal (S1200). The access configuration message includes information on whether the terminal can access the operation in a specific RAT. In addition, the access establishment message may be included in the RRC connection reconfiguration message or the like, or may be transmitted together.

The source cell receives an access indication message from the terminal (S1205). The access indication message informs the source cell that the terminal is approaching a CSG cell having a specific frequency and PCI. The access indication message may include frequency information and PCI information. The access indication message may be an RRC message. According to the present invention, the access indication message may include an MBMS indicator (MBMSInd). When the source cell receives the MBMS indicator, it can be seen that the UE preferentially prefers the MBMS service.

The source cell transmits a measurement control message to the terminal (S1210). The measurement control message includes setting information of an object to be measured by the terminal.

According to the present invention, the measurement control message transmitted from the source cell to the terminal may include an MBMS frequency indicator (MBMSFreqInd). In addition, when the measurement for the frequency (or RAT) that the terminal is interested in is not set, the source cell may set the measurement for this and indicate to the terminal. Information about the measurement setup may be transmitted through an RRC connection reestablishment message.

As an example according to the present invention, the source cell may further include an operation of delaying the time point at which the measurement control message is transmitted to the terminal.

As another example according to the present invention, the measurement control message may include measurement setting information including the delay offset value of Equation 2 to trigger the A3 event late when the UE performs the measurement.

The source cell receives a measurement report message from the terminal (S1215). Measurement report messages are sent when an A3 event is triggered. The measurement report message includes the PCI information of the target cell. According to the present invention, the measurement report message may include an MBMS indicator (MBMSInd). When the source cell receives the MBMS indicator, it can be seen that the UE preferentially prefers the MBMS service. According to the present invention, the measurement report message may further include MBMS information (MBMSInfo). The MBMS related information includes information on the MBMS being received by the terminal or MBMS information (or frequency information) that the terminal is interested in. For example, the MBMS-related information may include information on the type of MBMS service received by the terminal as shown in Table 1 above.

The source cell transmits a system information request message to the terminal (S1220). The source cell receiving the measurement report message including the PCI of the target cell checks the PCI to determine whether the target cell corresponds to the CSG cell or the femto cell, and if the target cell is the CSG cell, transmits a system information request message. The terminal requests the terminal to receive system information of the target cell.

The source cell receives a measurement report message from the terminal (S1225). The measurement report message may include a CGI, ECGI, TAI or CSG ID. In addition, the measurement report message may include an MBMS indicator (MBMSInd), and may include MBMS related information (MBMSinfo). When the source cell receives the MBMS indicator, it can be seen that the UE preferentially prefers the MBMS service.

The source cell transmits a handover request message to the MME (S1230). The handover request message may include context information of the terminal, and may include information such as access mode or CSG ID of the CSG cell. The access mode may exist when the CSG cell is a hybrid cell. According to the present invention, the handover request message may include MBMS related information.

The source cell receives a handover command message from the MME (S1235). The handover command message informs that the UE can handover from the source cell to the target cell. The source cell transmits the handover command message to the terminal (S1240). Subsequently, the UE initiates a handover procedure from the source cell to the target cell (CSG cell) and performs handover (S1245).

13 is a flowchart illustrating an operation of a target cell (CSG cell) performing a handover from a macro cell to a CSG cell according to the present invention.

Referring to FIG. 13, the target cell broadcasts system information of the target cell (S1300). The system information includes CGI, ECGI, TAI or CSG ID. In this case, the target cell may broadcast neighbor MBMS information together with system information of the target cell. It can be seen that the UE can receive MBMS related information even in the neighboring cell through the neighbor MBMS related information. In addition, the terminal may check frequency information provided with the desired MBMS service. The UE receives the MBMS service from the frequency at which the desired MBMS service is provided according to the performance based on the system information received from the target cell, or measures the frequency at which the MBMS service is provided based on neighboring MBMS related information. Handover to a neighbor cell other than the target cell may be performed.

The target cell receives a handover request message from the HeNB GW (S1305). The handover request message may include a CSG ID and membership status information. In addition, the handover request message may include MBMS related information. The MBMS-related information includes information on the MBMS that the terminal is receiving or interested in.

The target cell (CSG cell) verifies the CSG ID in the handover request message by comparing it with the CSG ID broadcasted by the target cell (S1310). Once verified as a CSG member, resources are allocated for handover.

The target cell (CSG cell) transmits a handover request acknowledgment message to the HeNB GW (S1315). The handover request acknowledgment message informs that the target cell is ready for handover and can perform handover.

The UE, the source cell and the target cell (CSG cell) initiate a handover procedure and perform a handover (S1320). Based on the handover, the CSG cell (or its neighbor cells), which is a target cell, transmits an MBMS service to the terminal (S1325).

14 is a block diagram illustrating a terminal, a source base station and a target base station performing a handover method for continuity of MBMS according to an embodiment of the present invention. The source base station is a base station providing a source cell, and the target base station is a base station providing a target cell.

Referring to FIG. 14, the terminal 1400 includes a terminal transmitter 1405 and a terminal receiver 1410.

The terminal transmitter 1405 generates an MBMS indicator and transmits the MBMS indicator to the source base station 1430. As an example, the MBMS indicator is an indicator indicating whether the terminal 1400 is receiving or is interested in receiving an MBMS service. Alternatively, the MBMS indicator may be an indicator indicating the type of MBMS service that the terminal 1400 receives. The type of MBMS service may be distinguished by a temporary mobile group identifier (TMGI) for the MBMS service. This may be referred to Table 1 above. The MBMS indicator may be included in an access indication message or a measurement report message and transmitted to the source base station 1430.

The terminal transmitter 1405 transmits MBMS related information to the source base station 1430. The MBMS related information includes information on the MBMS being received by the terminal or MBMS information (or frequency information) that the terminal is interested in. The type of MBMS service may be distinguished by a temporary mobile group identifier (TMGI) for the MBMS service. This may be referred to Table 1 above. The MBMS related information may be included in the measurement report message and transmitted to the source base station 1430.

The terminal receiver 1410 receives the MBMS frequency indicator from the source base station 1430. The MBMS frequency indicator indicates the MBMS frequency set by the source base station when the frequency for serving the MBMS is not set. In addition, when the measurement for the frequency (or RAT) that the terminal is interested in is not set, the source base station may set the measurement for this and instruct the terminal. The MBMS frequency indicator may be received from the source base station through a measurement control message, and may be transmitted by including information on the measurement configuration in the RRC connection reconfiguration message. The MBMS frequency indicator can also be used to monitor the frequency associated with MBMS.

The terminal receiver 1410 may receive a delay offset from the source base station 1430. The delay offset value is a value for delaying the timing of triggering the A3 event so that the UE can receive the MBMS service through the source cell for as long as possible, and may be determined as shown in Equation 2 above. The delay offset may be received through measurement setting information included in a measurement control message. The UE may observe the situation for the MBMS by delaying the handover time as much as possible without immediately handing over to the CSG cell.

The terminal receiver 1410 receives system information of the target cell from the target base station 1460. The system information includes CGI, ECGI, TAI or CSG ID. The system information may include neighbor MBMS related information of a target cell. It can be seen that the terminal 1400 can receive MBMS-related information in the neighbor cell through the neighbor MBMS-related information. In addition, the terminal 1400 may check frequency information provided with a desired MBMS service. Based on the system information, the terminal 1400 receives an MBMS service from a frequency at which the desired MBMS service is provided, or performs measurement on a frequency at which the MBMS service is provided based on neighboring MBMS-related information according to performance. It can be handed over to the neighbor cell instead.

In addition, the terminal receiving unit 1410 receives a system information request message or a handover command message from the source base station 1430. In addition, after performing the handover, the terminal receiving unit 1410 receives the MBMS service from the target base station 1460.

The source base station 1430 includes a source receiver 1435 and a source transmitter 1440.

The source receiver 1435 receives the MBMS indicator from the terminal 1400. The MBMS indicator may be included in the access indication message or the measurement report message.

The source receiver 1435 receives the MBMS related information from the terminal 1400. The MBMS-related information includes information on the MBMS that the terminal 1400 is receiving or MBMS information that the terminal 1400 is interested in. Refer to Table 1 above. The MBMS related information may be included in a measurement report message and received.

The source receiver 1435 may receive a handover command message from the target base station 1460.

The source transmitter 1440 transmits the MBMS frequency indicator to the terminal 1400. If the frequency for serving the MBMS is not set, it indicates the MBMS frequency set by the source base station. The MBMS frequency indicator may be transmitted through a measurement control message, and may include information on measurement configuration in an RRC connection reconfiguration message.

The source transmitter 1440 may transmit an access setup message, a system information request message, or a handover command message to the terminal 1400. In addition, the handover request message may be transmitted to the MME. The handover request message may include MBMS related information received from the terminal.

The target base station 1460 includes a target receiver 1465, a target controller 1470, and a target transmitter 1475.

The target receiver 1465 receives MBMS related information transmitted from the source base station 1430 from the HeNB GW. The MBMS related information may be included in a handover request message.

The target controller 1470 compares the CSG ID in the received handover request message with the CSG ID broadcasted by the target controller 1470. Once verified as a CSG member, resources are allocated for handover.

The target transmitter 1475 transmits a handover request confirmation message to the HeNB GW. In addition, after performing the handover, the target transmitter 1475 transmits the MBMS service to the terminal 1400.

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.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, it is intended that the present invention covers all embodiments falling within the scope of the following claims, rather than being limited to the above-described embodiments.

Claims (17)

In the method for performing a handover of a terminal receiving a MBMS (Multimedia Broadcast Multicast Service) service,
Transmitting a measurement indication message including an MBMS indicator indicating whether the terminal is receiving or is interested in receiving an MBMS service to a source base station linked with the terminal;
Transmitting, to the source base station, a measurement report message including MBMS-related information including service type, service availability, or frequency information of an MBMS that the terminal is receiving or is interested in receiving;
Performing handover from the source base station to a target base station; And
Receiving the MBMS service from the target base station based on the MBMS indicator and the MBMS related information.
The method of claim 1,
Receiving, from the source base station, a measurement control message including an MBMS frequency indicator for setting a measurement for a frequency of interest by the terminal;
The measurement report message is a method for performing a handover, characterized in that for monitoring the MBMS-related frequency through the MBMS frequency indicator.
The method of claim 1,
Receiving from the target base station system information including neighboring MBMS related information on whether the neighboring cell can also receive the MBMS related information;
And transmitting the measurement report message including the MBMS-related information configured based on the neighbor MBMS-related information to the source base station.
The method of claim 1,
Receiving a measurement control message from the source base station, the measurement control message including measurement setting information including a delay offset value for delaying a time point at which the terminal triggers an A3 event; And
Based on the measurement control message including the delay offset, measuring whether the strength of the signal of the target base station is greater than a magnitude of a preset threshold value than the strength of the signal of the source base station;
And the measurement report message comprises the measured result.
The method of claim 1,
The information on the type of MBMS service included in the MBMS related information is distinguished by a temporary mobile group identifier for the MBMS service.
In the handover method of the source base station for transmitting the MBMS service,
Receiving from the terminal a measurement indication message including an MBMS indicator indicating whether the terminal is receiving or is interested in receiving an MBMS service;
Receiving, from the terminal, a measurement report message including MBMS related information including service type, service availability, or frequency information of MBMS that the terminal is receiving or is interested in receiving;
Transmitting a handover request message including the MBMS indicator and the MBMS related information to a target base station; And
And if the acknowledgment of the handover request message is received, performing a handover to the target base station.
The method according to claim 6,
And before receiving the measurement report message from the terminal, transmitting a measurement control message to the terminal, the measurement control message including an MBMS frequency indicator setting the measurement for the frequency of interest to the terminal. How to do it.
The method according to claim 6,
After receiving the measurement indication message from the terminal, transmitting the measurement control message including measurement setting information including a delay offset value for delaying the time point at which the terminal triggers an A3 event to the terminal; Handover method characterized in that the.
The method according to claim 6,
The type information of the MBMS service included in the MBMS related information is distinguished by a temporary mobile group identifier for the MBMS service.
In the handover method of the target base station to transmit the MBMS service,
The CSG ID identifying the Closed Subscriber Group Identifier (CSG) of the target base station to which the terminal intends to perform handover, the MBMS indicator indicating whether the terminal is receiving or interested in receiving MBMS service, and the terminal is receiving or Receiving a handover request message from the source base station, the handover request message including at least one of MBMS-related information including service type, availability, or frequency information of an MBMS interested in receiving;
Comparing the CSG ID of the target base station with the CSG ID included in the handover request message and verifying whether the CSG member is a CSG member;
Allocating resources for handover and performing a handover with the source base station if it is determined that the verification is a CSG member; And
And transmitting an MBMS service to the terminal based on the MBMS indicator and the MBMS related information.
11. The method of claim 10,
And transmitting the system information including the neighbor MBMS related information on whether the terminal can receive the MBMS related information even in a neighboring cell to the terminal.
11. The method of claim 10,
The type information of the MBMS service included in the MBMS related information is distinguished by a temporary mobile group identifier for the MBMS service.
A terminal for performing a handover capable of continuously receiving an MBMS service,
A MBMS indication to the source base station linked with the terminal, the measurement indication message including a MBMS indicator indicating whether the terminal is receiving or interested in receiving MBMS service, and the terminal is receiving or interested in receiving A terminal transmitter for transmitting a measurement report message including MBMS-related information including service type, service availability or frequency information of the mobile station to the source base station; And
And a terminal receiver for receiving the MBMS service from a target base station based on the MBMS indicator and the MBMS related information.
The method of claim 13,
Before receiving the measurement report message to the source base station, the terminal receiver further receives a measurement control message from the source base station including an MBMS frequency indicator configured to set a measurement for a frequency of interest to the terminal,
The measurement report message, characterized in that it comprises a result of monitoring the MBMS-related frequency through the MBMS frequency indicator.
The method of claim 13,
The terminal receiver,
Further receiving system information from the target base station including neighbor MBMS related information on whether the neighbor cell can also receive the MBMS related information;
The terminal transmission unit,
And transmitting the measurement report message including the MBMS related information to the source base station based on the neighbor MBMS related information.
The method of claim 13,
The terminal receiver,
After receiving the measurement instruction message to the source base station, the terminal further receives from the source base station a measurement control message including measurement setting information including a delay offset value for delaying the time when the terminal triggers an A3 event. .
The method of claim 13,
The type information of the MBMS service included in the MBMS-related information is characterized in that the terminal is distinguished by the temporary mobile group identifier for the MBMS service.

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