KR20210024351A - Method and apparatus for providing mbms service - Google Patents

Abstract

The present disclosure provides a method for providing a MBMS service. The present disclosure provides the method for providing the redundant transmission of user data of a MBMS service over one or more cells when a terminal is located where one or more cell coverage overlaps.

Description

MBMS service provision method and device {METHOD AND APPARATUS FOR PROVIDING MBMS SERVICE}

The present disclosure relates to a method and apparatus for providing an MBMS service based on a cellular wireless communication network such as NR or LTE.

In one aspect, in the MBMS service providing method, the present embodiments provide a method of providing redundant transmission of user data of an MBMS service through one or more cells when a terminal is located in a location where one or more cell coverage overlaps. I can.

1 is a diagram schematically showing the structure of an NR wireless communication system to which the present embodiment can be applied.
2 is a diagram for explaining a frame structure in an NR system to which the present embodiment can be applied.
3 is a diagram illustrating a resource grid supported by a radio access technology to which the present embodiment can be applied.
4 is a diagram for explaining a bandwidth part supported by a wireless access technology to which the present embodiment can be applied.
5 is a diagram illustrating an exemplary synchronization signal block in a wireless access technology to which the present embodiment can be applied.
6 is a diagram for explaining a random access procedure in a radio access technology to which the present embodiment can be applied.
7 is a diagram for explaining CORESET.
8 is a diagram illustrating an example of an MBMS logical structure to which the present embodiment can be applied.
9 is a diagram illustrating a session start procedure to which the present embodiment can be applied.
10 is a diagram illustrating a layer 2 structure for a downlink in LTE to which this embodiment can be applied.
11 is a diagram showing a configuration of a base station according to another embodiment.
12 is a diagram showing a configuration of a user terminal according to another embodiment.

Hereinafter, some embodiments of the present disclosure will be described in detail with reference to exemplary drawings. In adding reference numerals to elements of each drawing, the same elements may have the same numerals as possible even if they are indicated on different drawings. In addition, in describing the embodiments, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present technical idea, a detailed description thereof may be omitted. When "include", "have", "consists of" and the like mentioned in the present specification are used, other parts may be added unless "only" is used. In the case of expressing the constituent elements in the singular, the case including the plural may be included unless there is a specific explicit description.

In addition, in describing the constituent elements of the present disclosure, terms such as first, second, A, B, (a) and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, order, or number of the component is not limited by the term.

In the description of the positional relationship of components, when two or more components are described as being "connected", "coupled" or "connected", the two or more components are directly "connected", "coupled" or "connected" "It may be, but it should be understood that two or more components and other components may be further "interposed" to be "connected", "coupled" or "connected". Here, the other constituent elements may be included in one or more of two or more constituent elements “connected”, “coupled” or “connected” to each other.

In the description of the temporal flow relationship related to the components, the operation method or the manufacturing method, for example, the temporal precedence relationship such as "after", "after", "after", "before", etc. Alternatively, a case where a flow forward and backward relationship is described may also include a case that is not continuous unless “directly” or “directly” is used.

On the other hand, when a numerical value for a component or its corresponding information (e.g., level, etc.) is mentioned, the numerical value or its corresponding information is related to various factors (e.g., process factors, internal or external impacts, It can be interpreted as including an error range that can be caused by noise, etc.).

The wireless communication system in the present specification refers to a system for providing various communication services such as voice and data packets using radio resources, and may include a terminal, a base station, or a core network.

The embodiments disclosed below can be applied to a wireless communication system using various wireless access technologies. For example, the present embodiments include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA). Alternatively, it may be applied to various various wireless access technologies such as non-orthogonal multiple access (NOMA). In addition, the wireless access technology may mean not only a specific access technology, but also a communication technology for each generation established by various communication consultation organizations such as 3GPP, 3GPP2, WiFi, Bluetooth, IEEE, and ITU. For example, CDMA may be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented with wireless technologies such as IEEE (institute of electrical and electronics engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (evolved UTRA). IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with a system based on IEEE 802.16e. UTRA is part of a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) that uses evolved-UMTSterrestrial radio access (E-UTRA), and employs OFDMA in downlink and SC- Adopt FDMA. As described above, the present embodiments may be applied to a wireless access technology currently disclosed or commercialized, and may be applied to a wireless access technology currently being developed or to be developed in the future.

Meanwhile, the terminal in the present specification is a generic concept that refers to a device including a wireless communication module that performs communication with a base station in a wireless communication system, and in WCDMA, LTE, NR, HSPA, and IMT-2020 (5G or New Radio), etc. It should be interpreted as a concept including all of the user equipment (UE) of the, as well as a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device in GSM. In addition, the terminal may be a user's portable device such as a smart phone according to the usage type, and in the V2X communication system, it may mean a vehicle, a device including a wireless communication module in the vehicle, and the like. In addition, in the case of a machine type communication system, it may mean an MTC terminal, an M2M terminal, a URLLC terminal, etc. equipped with a communication module to perform machine type communication.

The base station or cell of the present specification refers to the end of communication with the terminal in terms of the network, and Node-B (Node-B), eNB (evolved Node-B), gNB (gNode-B), LPN (Low Power Node), Sector, Site, various types of antennas, BTS (Base Transceiver System), Access Point, Point (e.g., transmission point, reception point, transmission/reception point), relay node ), a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, a remote radio head (RRH), a radio unit (RU), and a small cell. In addition, the cell may mean including a bandwidth part (BWP) in the frequency domain. For example, the serving cell may mean an activation BWP of the terminal.

In the various cells listed above, since there is a base station controlling one or more cells, the base station can be interpreted in two meanings. 1) In relation to the radio area, the device itself may provide a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, and a small cell, or 2) the radio area itself may be indicated. In 1), devices providing a predetermined wireless area are controlled by the same entity, or all devices interacting to form a wireless area in collaboration are instructed to the base station. Depending on the configuration method of the wireless area, a point, a transmission/reception point, a transmission point, a reception point, etc. become an embodiment of the base station. In 2), it is also possible to instruct the base station to the radio region itself to receive or transmit a signal from the viewpoint of the user terminal or from the viewpoint of a neighboring base station.

In this specification, a cell refers to a component carrier having coverage of a signal transmitted from a transmission/reception point or a coverage of a signal transmitted from a transmission/reception point, and the transmission/reception point itself. I can.

Uplink (Uplink, UL, or uplink) refers to a method of transmitting and receiving data to a base station by a terminal, and downlink (Downlink, DL, or downlink) refers to a method of transmitting and receiving data to a mobile station by a base station. do. Downlink may refer to a communication or communication path from multiple transmission/reception points to a terminal, and uplink may refer to a communication or communication path from a terminal to multiple transmission/reception points. In this case, in the downlink, the transmitter may be a part of the multiple transmission/reception points, and the receiver may be a part of the terminal. Also, in the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of the multiple transmission/reception points.

Uplink and downlink transmit and receive control information through control channels such as Physical Downlink Control CHannel (PDCCH), Physical Uplink Control CHannel (PUCCH), and the like, and The same data channel is configured to transmit and receive data. Hereinafter, a situation in which signals are transmitted and received through channels such as PUCCH, PUSCH, PDCCH, and PDSCH is expressed in the form of ``transmitting and receiving PUCCH, PUSCH, PDCCH and PDSCH'' do.

In order to clarify the description, hereinafter, the present technical idea is mainly described in the 3GPP LTE/LTE-A/NR (New RAT) communication system, but the present technical feature is not limited to the corresponding communication system.

3GPP develops 5G (5th-Generation) communication technology to meet the requirements of ITU-R's next-generation wireless access technology after research on 4G (4th-Generation) communication technology. Specifically, 3GPP develops a new NR communication technology separate from 4G communication technology and LTE-A pro, which has improved LTE-Advanced technology as a 5G communication technology according to the requirements of ITU-R. Both LTE-A pro and NR refer to 5G communication technology, and hereinafter, 5G communication technology will be described centering on NR when a specific communication technology is not specified.

The operation scenario in NR defines various operation scenarios by adding considerations to satellites, cars, and new verticals from the existing 4G LTE scenario.In terms of service, eMBB (Enhanced Mobile Broadband) scenario, high terminal density, but wide It is deployed in the range and supports the mMTC (Massive Machine Communication) scenario that requires a low data rate and asynchronous connection, and the URLLC (Ultra Reliability and Low Latency) scenario that requires high responsiveness and reliability and supports high-speed mobility. .

To satisfy this scenario, NR discloses a wireless communication system to which a new waveform and frame structure technology, a low latency technology, a mmWave support technology, and a forward compatible provision technology are applied. In particular, in the NR system, various technical changes are proposed in terms of flexibility in order to provide forward compatibility. The main technical features of the NR will be described below with reference to the drawings.

<NR system general>

1 is a diagram schematically showing the structure of an NR system to which the present embodiment can be applied.

Referring to FIG. 1, the NR system is divided into 5GC (5G Core Network) and NR-RAN parts, and NG-RAN controls the user plane (SDAP/PDCP/RLC/MAC/PHY) and UE (User Equipment). It consists of gNB and ng-eNB that provide plane (RRC) protocol termination. The gNB or gNB and ng-eNB are interconnected through an Xn interface. The gNB and ng-eNB are each connected to 5GC through the NG interface. The 5GC may include an Access and Mobility Management Function (AMF) in charge of a control plane such as a terminal access and mobility control function, and a User Plane Function (UPF) in charge of a control function for user data. NR includes support for both frequency bands below 6GHz (FR1, Frequency Range 1) and frequency bands above 6GHz (FR2, Frequency Range 2).

gNB means a base station that provides NR user plane and control plane protocol termination to a terminal, and ng-eNB means a base station that provides E-UTRA user plane and control plane protocol termination to a terminal. The base station described in this specification should be understood to encompass gNB and ng-eNB, and may be used as a meaning to distinguish between gNB or ng-eNB as needed.

<NR wave form, numer roller and frame structure>

In NR, a CP-OFDM waveform using a cyclic prefix is used for downlink transmission, and CP-OFDM or DFT-s-OFDM is used for uplink transmission. OFDM technology is easy to combine with MIMO (Multiple Input Multiple Output), and has the advantage of being able to use a receiver of low complexity with high frequency efficiency.

Meanwhile, in NR, since the requirements for data rate, delay rate, coverage, etc. are different for each of the three scenarios described above, it is necessary to efficiently satisfy the requirements for each scenario through the frequency band constituting an arbitrary NR system. . To this end, a technique for efficiently multiplexing a plurality of different numerology-based radio resources has been proposed.

Specifically, the NR transmission neuron is determined based on sub-carrier spacing and CP (Cyclic prefix), and the value of μ is used as an exponential value of 2 based on 15khz as shown in Table 1 below. Is changed to.

μ Subcarrier spacing Cyclic prefix Supported for data Supported for synch 0 15 Normal Yes Yes One 30 Normal Yes Yes 2 60 Normal, Extended Yes No 3 120 Normal Yes Yes 4 240 Normal No Yes

As shown in Table 1 above, the NR neuron can be classified into 5 types according to the subcarrier spacing. This is different from the fixed subcarrier spacing of 15khz of LTE, one of the 4G communication technologies. Specifically, subcarrier intervals used for data transmission in NR are 15, 30, 60, and 120khz, and subcarrier intervals used for synchronization signal transmission are 15, 30, 12, and 240khz. In addition, the extended CP is applied only to the 60khz subcarrier interval. Meanwhile, a frame structure in NR is defined as a frame having a length of 10 ms consisting of 10 subframes having the same length of 1 ms. One frame can be divided into 5 ms half frames, and each half frame includes 5 subframes. In the case of a 15khz subcarrier interval, one subframe consists of 1 slot, and each slot consists of 14 OFDM symbols.

2 is a diagram for explaining a frame structure in an NR system to which the present embodiment can be applied.

Referring to FIG. 2, in the case of a normal CP, a slot is fixedly composed of 14 OFDM symbols, but the length in the time domain of the slot may vary according to the subcarrier interval. For example, in the case of a newer roller with a 15khz subcarrier spacing, a slot is 1ms long and has the same length as the subframe. In contrast, in the case of a newer roller with a 30khz subcarrier interval, a slot consists of 14 OFDM symbols, but two slots may be included in one subframe with a length of 0.5ms. That is, the subframe and the frame are defined with a fixed time length, and the slot is defined by the number of symbols, and the time length may vary according to the subcarrier interval.

Meanwhile, NR defines a basic unit of scheduling as a slot, and a mini-slot (or sub-slot or non-slot based schedule) is also introduced in order to reduce the transmission delay of the radio section. If a wide subcarrier spacing is used, the length of one slot is shortened in inverse proportion, so that transmission delay in the radio section can be reduced. Mini-slots (or sub-slots) are for efficient support for URLLC scenarios and can be scheduled in units of 2, 4, or 7 symbols.

In addition, unlike LTE, NR defines uplink and downlink resource allocation as a symbol level within one slot. In order to reduce HARQ delay, a slot structure capable of transmitting HARQ ACK/NACK directly within a transmission slot has been defined, and this slot structure is named and described as a self-contained structure.

NR is designed to support a total of 256 slot formats, of which 62 slot formats are used in 3GPP Rel-15. In addition, a common frame structure constituting an FDD or TDD frame is supported through a combination of various slots. For example, a slot structure in which all symbols of a slot are set to downlink, a slot structure in which all symbols are set to uplink, and a slot structure in which a downlink symbol and an uplink symbol are combined are supported. In addition, NR supports that data transmission is distributed and scheduled in one or more slots. Accordingly, the base station may inform the UE of whether the slot is a downlink slot, an uplink slot, or a flexible slot using a slot format indicator (SFI). The base station can indicate the slot format by indicating the index of the table configured through UE-specific RRC signaling using SFI, and dynamically indicates through Downlink Control Information (DCI) or statically or through RRC. It can also be quasi-static.

<NR physical resource>

In relation to the physical resource in NR, an antenna port, a resource grid, a resource element, a resource block, a bandwidth part, etc. are considered. do.

The antenna port is defined so that a channel carrying a symbol on an antenna port can be inferred from a channel carrying another symbol on the same antenna port. When the large-scale property of a channel carrying a symbol on one antenna port can be inferred from a channel carrying a symbol on another antenna port, the two antenna ports are QC/QCL (quasi co-located or quasi co-location) relationship. Here, the wide-range characteristic includes one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

3 is a diagram illustrating a resource grid supported by a radio access technology to which the present embodiment can be applied.

Referring to FIG. 3, in a resource grid, since NR supports a plurality of neurons in the same carrier, a resource grid may exist according to each neuron. In addition, the resource grid may exist according to the antenna port, subcarrier spacing, and transmission direction.

A resource block consists of 12 subcarriers, and is defined only in the frequency domain. In addition, a resource element consists of one OFDM symbol and one subcarrier. Accordingly, as shown in FIG. 3, the size of one resource block may vary according to the subcarrier interval. In addition, NR defines “Point A” that serves as a common reference point for the resource block grid, a common resource block, and a virtual resource block.

4 is a diagram for explaining a bandwidth part supported by a wireless access technology to which the present embodiment can be applied.

In NR, unlike LTE in which the carrier bandwidth is fixed at 20Mhz, the maximum carrier bandwidth is set from 50Mhz to 400Mhz for each subcarrier interval. Therefore, it is not assumed that all terminals use all of these carrier bandwidths. Accordingly, in the NR, as shown in FIG. 4, a bandwidth part (BWP) can be designated within the carrier bandwidth and used by the terminal. In addition, the bandwidth part is associated with one neurology and is composed of a subset of consecutive common resource blocks, and can be dynamically activated over time. The terminal is configured with up to four bandwidth parts, respectively, in uplink and downlink, and data is transmitted/received using the active bandwidth part at a given time.

In the case of a paired spectrum, the uplink and downlink bandwidth parts are set independently, and in the case of an unpaired spectrum, unnecessary frequency re-tuning between downlink and uplink operations is prevented. For this purpose, the downlink and uplink bandwidth parts are set in pairs to share the center frequency.

<NR initial connection>

In NR, the terminal accesses the base station and performs cell search and random access procedures to perform communication.

Cell search is a procedure in which a terminal synchronizes with a cell of a corresponding base station, obtains a physical layer cell ID, and obtains system information using a synchronization signal block (SSB) transmitted by a base station.

5 is a diagram exemplarily showing a synchronization signal block in a wireless access technology to which the present embodiment can be applied.

Referring to FIG. 5, the SSB is composed of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) occupying 1 symbol and 127 subcarriers, respectively, and a PBCH spanning 3 OFDM symbols and 240 subcarriers.

The terminal receives the SSB by monitoring the SSB in the time and frequency domain.

SSB can be transmitted up to 64 times in 5ms. A plurality of SSBs are transmitted in different transmission beams within 5 ms time, and the UE performs detection on the assumption that SSBs are transmitted every 20 ms period based on one specific beam used for transmission. The number of beams that can be used for SSB transmission within 5 ms time may increase as the frequency band increases. For example, under 3GHz, up to 4 SSB beams can be transmitted, in a frequency band of 3 to 6GHz, up to 8, and in a frequency band of 6GHz or higher, SSBs can be transmitted using up to 64 different beams.

Two SSBs are included in one slot, and the start symbol and the number of repetitions in the slot are determined according to the subcarrier interval as follows.

On the other hand, the SSB is not transmitted at the center frequency of the carrier bandwidth unlike the conventional LTE SS. That is, the SSB may be transmitted even in a place other than the center of the system band, and when supporting broadband operation, a plurality of SSBs may be transmitted in the frequency domain. Accordingly, the UE monitors the SSB by using a synchronization raster, which is a candidate frequency location for monitoring the SSB. The carrier raster and synchronization raster, which are information on the center frequency of the channel for initial access, have been newly defined in NR, and the synchronization raster has a wider frequency interval than the carrier raster, thus supporting fast SSB search of the terminal. I can.

The UE can acquire the MIB through the PBCH of the SSB. The MIB (Master Information Block) includes minimum information for the terminal to receive remaining system information (RMSI, Remaining Minimum System Information) broadcast by the network. In addition, PBCH is information on the location of the first DM-RS symbol in the time domain, information for the UE to monitor SIB1 (e.g., SIB1 neurology information, information related to SIB1 CORESET, search space information, PDCCH Related parameter information, etc.), offset information between the common resource block and the SSB (the position of the absolute SSB in the carrier is transmitted through SIB1), and the like. Here, the SIB1 neurology information is equally applied to some messages used in the random access procedure for accessing the base station after the terminal completes the cell search procedure. For example, the neurology information of SIB1 may be applied to at least one of messages 1 to 4 for a random access procedure.

The aforementioned RMSI may mean SIB1 (System Information Block 1), and SIB1 is periodically broadcast (ex, 160 ms) in a cell. SIB1 includes information necessary for the UE to perform an initial random access procedure, and is periodically transmitted through the PDSCH. In order for the UE to receive SIB1, it is necessary to receive newer roller information used for SIB1 transmission and CORESET (Control Resource Set) information used for SIB1 scheduling through the PBCH. The UE checks scheduling information for SIB1 using SI-RNTI in CORESET, and acquires SIB1 on the PDSCH according to the scheduling information. SIBs other than SIB1 may be periodically transmitted or may be transmitted according to the request of the terminal.

6 is a diagram for explaining a random access procedure in a radio access technology to which the present embodiment can be applied.

Referring to FIG. 6, when the cell search is completed, the UE transmits a random access preamble for random access to the base station. The random access preamble is transmitted through the PRACH. Specifically, the random access preamble is transmitted to the base station through a PRACH consisting of consecutive radio resources in a specific slot that is periodically repeated. In general, when a terminal initially accesses a cell, a contention-based random access procedure is performed, and when a random access is performed for beam failure recovery (BFR), a contention-free random access procedure is performed.

The terminal receives a random access response to the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), a UL Grant (uplink radio resource), a temporary C-RNTI (Temporary Cell-Radio Network Temporary Identifier), and a TAC (Time Alignment Command). Since one random access response may include random access response information for one or more terminals, the random access preamble identifier may be included to inform which terminal the included UL Grant, temporary C-RNTI, and TAC are valid. The random access preamble identifier may be an identifier for the random access preamble received by the base station. TAC may be included as information for the UE to adjust uplink synchronization. The random access response may be indicated by a random access identifier on the PDCCH, that is, a Random Access-Radio Network Temporary Identifier (RA-RNTI).

Upon receiving the valid random access response, the terminal processes the information included in the random access response and performs scheduled transmission to the base station. For example, the terminal applies TAC and stores a temporary C-RNTI. In addition, by using UL Grant, data stored in the buffer of the terminal or newly generated data is transmitted to the base station. In this case, information for identifying the terminal should be included.

Finally, the terminal receives a downlink message for resolving contention.

<NR CORESET>

The downlink control channel in NR is transmitted in CORESET (Control Resource Set) having a length of 1 to 3 symbols, and transmits uplink/downlink scheduling information, SFI (Slot Format Index), and TPC (Transmit Power Control) information. .

In this way, NR introduced the concept of CORESET to secure system flexibility. CORESET (Control Resource Set) refers to a time-frequency resource for a downlink control signal. The terminal may decode the control channel candidate using one or more search spaces in the CORESET time-frequency resource. A QCL (Quasi CoLocation) assumption for each CORESET is set, and this is used to inform the characteristics of the analog beam direction in addition to the delay spread, Doppler spread, Doppler shift, and average delay, which are characteristics assumed by conventional QCL.

7 is a diagram for explaining CORESET.

Referring to FIG. 7, CORESET may exist in various forms within a carrier bandwidth within one slot, and CORESET may consist of up to three OFDM symbols in the time domain. In addition, CORESET is defined as a multiple of 6 resource blocks up to the carrier bandwidth in the frequency domain.

The first CORESET is indicated through the MIB as part of the initial bandwidth part configuration so that additional configuration information and system information can be received from the network. After connection establishment with the base station, the terminal may receive and configure one or more CORESET information through RRC signaling.

In this specification, frequencies, frames, subframes, resources, resource blocks, regions, bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals, or various messages related to NR (New Radio) May be interpreted as a meaning used in the past or present or a variety of meanings used in the future.

New Radio (NR)

NR progressed in 3GPP is a radio access technology capable of satisfying various QoS requirements required for each subdivided and specified usage scenario as well as an improved data rate compared to LTE. In particular, eMBB (enhancement mobile broadband), mMTC (massive MTC), and URLLC (Ultra Reliable and Low Latency Communications) were defined as representative usage scenarios of NR. structure is provided. The frame structure of NR supports a frame structure based on multiple subcarriers. The default SCS is 15kHz, and a total of 5 SCS types are supported at ^{15kHz*2 μ.} Slot length varies according to numerology. In other words, it can be seen that the shorter the slot length, the larger the SCS. In addition, the number of OFDM symbols constituting a slot in the NR, y value, was determined to have a value of y=14 regardless of the SCS value in case of normal CP. Accordingly, a random slot consists of 14 symbols, and according to the transmission direction of the corresponding slot, all symbols are used for DL transmission, or all symbols are used for UL transmission, or DL portion + (gap) + It can be used in the form of a UL portion. In addition, a mini-slot consisting of fewer symbols than the slot is defined in an arbitrary numerology (or SCS), and based on this, a short time-domain scheduling interval for uplink/downlink data transmission/reception is set, or slot aggregation A long time-domain scheduling interval for transmitting/receiving uplink/downlink data may be configured. In particular, in the case of transmission and reception of latency critical data such as URLLC, it is difficult to satisfy the latency requirement when scheduling is performed in a slot unit based on 1 ms (14 symbols) defined in a numerology-based frame structure with a small SCS value such as 15 kHz. Therefore, for this purpose, a mini-slot composed of fewer OFDM symbols than the corresponding slot can be defined, and based on this, the scheduling for latency critical data such as the corresponding URLLC can be defined.

In NR, the following structure is supported in the time axis. Here, the difference from existing LTE is that in NR, the basic scheduling unit is changed to a slot. Also, regardless of subcarrier-spacing, the slot consists of 14 OFDM symbols. On the other hand, it supports a non-slot structure composed of 2, 4, and 7 OFDM symbols, which are smaller scheduling units. The non-slot structure can be used as a scheduling unit for URLLC service.

MBMS(Multimedia Broadcast Multicast Service)

3GPP has developed an LTE broadcast/multicast standard for video broadcasting from Rel-9. Since then, standards have been standardized to support other services such as public safety, IoT and V2X. For NR, which is currently being standardized, the Rel-15 and Rel-16 standards do not support MBMS. It is determined that MBMS-related standards should be further developed in the NR standard of the later release.

Meanwhile, in the LTE-based conventional MBMS, two transmission methods are provided: a multimedia broadcast multicast service single frequency network (MBSFN) transmission method and a single cell point to multipoint (SC-PTM) transmission method.

The MBSFN transmission method is a method suitable for providing media broadcasting in a large-scale pre-planned area (MBSFN area). The MBSFN area is statically configured. Organized by O&M, for example. And it cannot be dynamically adjusted according to user distribution. Synchronized MBMS transmission is provided within the MBSFN area, and combining is supported for MBMS transmission from a plurality of cells. Each MCH scheduling is performed by a Multi-cell/multicast Coordination Entity (MCE), a single transport block is used for each TTI for MCH transmission, and all of the transport blocks use MBSFN resources within the subframe. MTCH and MCCH can be multiplexed on the same MCH. MTCH and MCCH use the RLC-UM mode. Even if all radio resources are not used in the frequency domain, unicast and multiplexing are not allowed in the same subframe. As described above, it was difficult to flexibly apply the MBSFN transmission method to a small broadcast service due to the difficulty of dynamic adjustment.

The SC-PTM transmission method was developed as a method to improve the inefficiency of the MBSFN transmission method. MBMS is transmitted within single cell coverage. One SC-MCCH and one or more SC-MTCH(s) are mapped to the DL-SCH. Scheduling is provided by the base station. SC-MCCH and SC-MTCH are indicated by one logical channel-specific RNTI (SC-RNTI, G-RNTI) on the PDCCH, respectively. The SC-MTCH and SC-MCCH use the RLC-UM mode. Single transmission is used for the DL-SCH to which the SC-MCCH and SC-MTCH are mapped, but blind HARQ repetition or RLC repetition is not provided. Therefore, SC-PTM transmission was difficult to provide reliable transmission.

In order to provide MBMS through the above-described transmission methods, a logical structure as shown in FIG. 8 may be used. 8 shows an example of a logical structure for providing a group communication service. In FIG. 8, each entity performs the following functions.

GCS AS

-Exchanging signaling related to terminal and GCS session and group management aspects (for example, service announcement)

-Receive uplink data from the terminal through unicast

-Transmit data to terminals belonging to one group using unicast delivery and/or multicast delivery

BM-SC: Operates as a source of MBMS transmission, and starts or stops transmission of a session for an MBMS bearer service through MBMS session control signaling.

MBMS GW

-the sending/broadcasting of MBMS packets to each eNB transmitting the service.

-The MBMS GW uses IP Multicast as the means of forwarding MBMS user data to the eNB.

-The MBMS GW performs MBMS Session Control Signalling (Session start/update/stop) towards the E-UTRAN via MME.

Multi-cell/multicast Coordination Entity (MCE)

- the admission control and the allocation of the radio resources used by all eNBs in the MBSFN area for multi-cell MBMS transmissions using MBSFN operation. The MCE decides not to establish the radio bearer(s) of the new MBMS service(s) if the radio resources are not sufficient for the corresponding MBMS service(s) or may pre-empt radio resources from other radio bearer(s) of ongoing MBMS service(s) according to ARP. Besides allocation of the time/ frequency radio resources this also includes deciding the further details of the radio configuration e.g. the modulation and coding scheme.

- deciding on whether to use SC-PTM or MBSFN.

- counting and acquisition of counting results for MBMS service(s).

- resumption of MBMS session(s) within MBSFN area(s) based on e.g. the ARP and/or the counting results for the corresponding MBMS service(s).

- suspension of MBMS session(s) within MBSFN area(s) based e.g. the ARP and/or on the counting results for the corresponding MBMS service(s).

9 shows an example of an MBMS-based session start procedure.

One. The MME sends MBMS session start request message to the MCE(s) controlling eNBs in the targeted MBMS service area. The message includes the IP multicast address, session attributes and the minimum time to wait before the first data delivery, and includes the list of cell identities if available.

2. The MCE decides whether to use SC-PTM or MBSFN to carry the MBMS bearer over the air interface.

The MCE confirms the reception of the MBMS Session Start request to the MME. This message can be transmitted before the step 4.In SC-PTM operation, the MCE only confirms the reception of the MBMS Session Start request to the MME, after the MCE receives at least one confirmation from the eNB(s) (ie Step 4 ).

3. In SC-PTM operation, the MCE includes the SC-PTM information (i.e. list of cell identities and QoS information received from the MME in Step 1), in the MBMS Session Start Request message to the relevant eNBs.

4. In SC-PTM operation, the eNB checks whether the radio resources are sufficient for the establishment of new MBMS service(s) in the area it controls. If not, eNB decides not to establish the radio bearers of the MBMS service(s), or may pre-empt radio resources from other radio bearer(s) according to ARP. eNB confirms the reception of the MBMS Session Start message.

Step 5 and 6 are only applicable to MBSFN operation.

5. MCE sends the MBMS Scheduling Information message to the eNB including the updated MCCH information which carries the MBMS service's configuration information. This message can be transmitted before the step 3.

6. eNB confirms the reception of the MBMS Scheduling Information message.

7. eNB indicates MBMS session start to UEs by MCCH change notification and updated MCCH information which carries the MBMS service's configuration information.

8. eNB joins the IP multicast group to receive the MBMS User Plane data.

9. eNB sends the MBMS data to radio interface

In order to provide MBMS, a complex control procedure was required between core network entities and wireless network. For example, it was necessary to determine a transmission method or perform scheduling through a separate MCE entity for controlling the base station within the target MBMS service area.

In the prior art, a transmission method for providing an MBMS service has disadvantages in that it is difficult to perform dynamic adjustment or reliable transmission because it requires synchronized MBMS transmission between multiple cells. In addition, network operation was complicated because the base station had to be controlled through a separate entity such as MCE.

In order to solve the above problems, the present invention proposes a method and apparatus for efficiently transmitting and receiving an MBMS service based on NR. It also provides a method of providing reliable transmission.

Hereinafter, an MBMS transmission method based on NR radio access technology according to the present invention will be described. However, this is for convenience of description, and the present invention may be applied to any wireless access technology. The embodiments described in the present invention include the contents of information elements and operations specified in TS38.300, which is an NR MAC standard, and TS 38.331, which is an NR RRC standard. Even if the contents of the terminal operation related to the definition of the corresponding information element are not included in the present specification, the corresponding contents specified in the standard specification, which is a known technique, may be included in the present invention.

The MBMS service according to the present invention can be applied not only to large-scale broadcast services provided through a single frequency network (SFN), but also to arbitrary services such as V2X, public safety, and IoT services provided through one or more cells.

For convenience of description, the following describes a method of effectively providing an MBMS service regardless of a broadcast method or a multicast method. However, this may be limitedly provided only for a broadcast method, a multicast or a groupcast method.

The methods provided below may be applied individually or by selectively combining arbitrary methods.

10 shows an example of a layer 2 structure for a downlink in the conventional LTE specified in TS 36.300 (layer 2 structure for DL with CA configured).

As shown in FIG. 10, data is transmitted based on an RLC-UM providing a segmentation function without a PDCP entity in MRB (MBMS Point to Multipoint Radio Bearer) or SC-MRB for providing MBMS according to the prior art.

For one or several MTCHs, a multicast control channel (MCCH) logical channel for transmitting MBMS control information from a network to a terminal and a multicast traffic channel (MTCH) for user data transmission of an MBMS receiving terminal (using MBSFN) are an MCH transmission channel. It is transmitted to the terminal through

For one or several SC-MTCHs, the SC-MCCH logical channel for transmitting MBMS control information from the network to the terminal and the SC-MTCH for transmitting user data of the MBMS receiving terminal using the SC-PTM use the DL-SCH transmission channel. Is transmitted to the terminal through.

For efficient data transmission, the NR may transmit a multicast traffic channel or a multicast control channel through the DL-SCH. For convenience of explanation, hereinafter, a logical channel for MBMS user data transmission in NR is denoted as NR-MTCH, and a logical channel for MBMS control information transmission in NR is denoted as NR-MCCH. This is for convenience of description and may be replaced with an arbitrary name (e.g. MTCH, MCCH, SC-MTCH, SC-MCCH, 5G-MTCH, 5G-MCCH).

The terminal may be located where one or more cell coverage overlaps. In this case, redundant transmission of user data of MBMS service may be provided through one or more cells for reliable transmission. The same MBMS service can be provided through more than one cell. For example, it is possible to transmit user data traffic for an MBMS service through one or more cells by utilizing PDCP redundancy transmission. In order to provide redundant transmission for the MBMS service, the following methods can be used individually or in combination.

Indicating a list of cells (or cell groups) providing duplicate transmission

The base station may indicate a cell list that provides redundant transmission with the corresponding cell through a specific cell for arbitrary MBMS service user data (or MBMS session or NR-MTCH) from the corresponding cell to the terminal.

As an example, the system information block type required to acquire associated control information for MBMS transmission using NR-based MBMS transmission (NR Point-to-multipoint transmission) may be broadcast and transmitted.

As another example, the information may be included and transmitted on the NR-MCCH. Alternatively, the corresponding information (applied to the entire NR-MTCH or per NR-MTCH) may be included and transmitted on the RRC message transmitted through the NR-MCCH. As another example, the information may be transmitted through a dedicated RRC message.

The corresponding cell list represents a list of neighboring cells (or cell groups) to which the ongoing MBMS session is provided with redundant transmission through the NR-MRB provided in the current cell (in conjunction with the NR-MRB or in conjunction with the NR-MRB). For example, the maximum number of the corresponding cell list may be configured up to 4, which is the maximum number of duplicate transmissions currently. As another example, the maximum number of the corresponding cell list may be configured up to 8, which is the maximum number of normal neighboring cell lists. However, the UE may configure a cell-specific NR-MRB for receiving redundant transmissions through up to four cells to perform redundant transmission reception processing. For example, the corresponding cell list may be identified including cell group identifier information. As another example, the corresponding cell list may be identified by including one or more information of a physical cell identifier (physcellId) and downlink carrier frequency (dl-carrierFreq, ARFCN-value) information. Alternatively, the cells included in the corresponding cell list are identified by including one or more information of a physical cell identifier (physcellId) and downlink carrier frequency (dl-carrierFreq, ARFCN-value) information, and the corresponding cell list may be composed of a bit string. have. In this case, the bits of the corresponding bit string may indicate whether each cell is a neighboring cell providing a service on the NR-MTCH according to the order of cells included in the corresponding cell list. For example, if the corresponding bit is 1, it indicates a neighboring cell in which a service is provided on the corresponding NR-MTCH, otherwise, it is indicated as 0. As another example, the cell list may include a cell list for each cell group. As another example, the bit order of the bit string of the corresponding cell list may be provided in order according to the order of the included cell groups.

Transmission including RNTI information for NR-MTCH data reception in a redundant transmission cell

For convenience of description, an RNTI used to identify one NR-MTCH transmission in a specific cell (eg, PCell, serving cell) is denoted as NR-G-RNTI. This is for convenience of description and may be replaced with an arbitrary name.

For example, when MBMS service user data (or MBMS session or NR-MTCH) is repeatedly transmitted through a specific cell (eg, PCell or serving cell) and another cell (eg, any SCell or neighboring cell), in each cell NR-G-RNTI for receiving one NR-MTCH may be configured to have the same value. For this, the corresponding information can be coordination between base stations. For example, the serving base station may transmit the NR-G-RNTI value for the cell linked to the neighbor base station to receive the corresponding NR-MTCH to the neighbor base station. Alternatively, the NR-G-RNTI is an anchor base station or a base station that provides a PCell, or an arbitrary node (BM-SC, MBMS GW, etc.) that provides the MBMS function of the CU or core network in the MCE or CU-DU separation structure, and the core network. Any node (eg SMF, AMF) that provides the session management/mobility management function of can be determined and transmitted to the base station. Alternatively, after the serving base station receives the session start message/instruction for the corresponding session, the serving base station may transmit it to the neighboring base station.

As another example, when the MBMS service user data (or MBMS session or NR-MTCH) is repeatedly transmitted through a specific cell (eg, PCell or serving cell) and another cell (eg, any SCell or neighboring cell), in each cell The NR-G-RNTI for receiving one NR-MTCH may have a different value. Through this, it is possible to flexibly operate the NR-MTCH for each cell. For this, the corresponding information can be coordination between base stations. For example, (according to the request of the serving base station after the serving base station receives the session start message/instruction for the corresponding session), the NR-G- for receiving the corresponding NR-MTCH from the neighboring base station to the cell associated with the neighboring base station. The RNTI value can be determined and transmitted to the serving base station.

The base station may indicate the NR-G-RNTI of a cell that provides redundant transmission with the cell through a specific cell for arbitrary MBMS service user data (or MBMS session or NR-MTCH) from the cell to the UE.

As an example, the system information block type required to acquire associated control information for MBMS transmission using NR-based MBMS transmission (NR Point-to-multipoint transmission) may be broadcast and transmitted.

As another example, the information may be included and transmitted on the NR-MCCH. Alternatively, it may be transmitted by including corresponding information (for each NR-MTCH) on the RRC message transmitted through the NR-MCCH. As another example, the information may be transmitted through a dedicated RRC message.

Transmission including PDCP configuration linkage information for NR-MTCH redundant transmission

The base station transmits MBMS service user data (or MBMS session or NR-MTCH) or MBMS control data through a plurality of cells (or cell groups), PDCP configuration information/connection information (or PDCP-related configuration information or some PDCP parameters) You can add and send. The corresponding PDCP configuration information/annual account book may include one or more parameters included in the general NR PDCP configuration used for unicast DRB as detailed information elements. Through this, one or more of the NR PDCP functions can be operated.

PDCP configuration information/annual account information for NR-MTCH redundant transmission may be configured for each NR-MTCH. Through this, the terminal can configure the PDCP entity in association with the MBMS session information. MBMS session information classified for each NR-MTCH may be transmitted to the terminal in association with PDCP configuration information/connection information. The MBMS session information indicates an ongoing MBMS session in one NR-MTCH, and can be identified through TMGI and optionally a session ID (sessionId). Alternatively, the NR-MTCH information may include MBMS session information and PDCP configuration information as lower detailed information elements. Alternatively, a default value for a PDCP configuration for NR-MTCH (or a PDCP configuration having a specific value for each PDCP parameter) may be predefined and used. Accordingly, without separately including PDCP configuration information (or including only a value/index/ID for identifying a specific PDCP configuration set or only a specific PDCP parameter value), the UE can configure and use the PDCP entity.

Alternatively, the NR-MTCH information may include MBMS session information as sub-detailed information elements, and information for indicating redundant transmission using (optionally) a PDCP entity. When information for indicating redundant transmission (using the PDCP entity) is indicated, the UE sets the PDCP entity (default configuration or indicated configuration information). Set up the RLC entity. And it is possible to perform reception processing for duplicate transmission through the corresponding PDCP entity. If information for indicating redundant transmission (using the PDCP entity) is absent (or if not indicated or indicated without setting), the UE configures the RLC entity without configuration for the PDCP entity. In addition, the RLC entity can classify the MBMS session and perform data reception processing.

Alternatively, the NR-MTCH information may include MBMS session information and information for identifying a corresponding PDCP entity as a lower detailed information element. The information for identifying the PDCP entity may be defined as a new information element for indicating identification information for the PDCP entity supporting redundant transmission. Alternatively, if the MBMS session is configured to be provided by a PDU session (or unicast IP transmission/tunneling transmission/UDP session between the MBMS server (eg BM-SC) and the base station), the information for identifying the PDCP entity is PDU session identification. It may also indicate information (or IP session identification information/tunneling identification information/UDP session identification information). Alternatively, the information for identifying the PDCP entity may be used by defining an MRB-Identity for identifying the corresponding NR-MRB. Alternatively, the information for identifying the PDCP entity may indicate an application identifier associated with a corresponding MBMS session. Alternatively, the information for identifying the PDCP entity may be arbitrary information for identifying the MBMS session.

It may be transmitted by including the above-described information on the NR-MCCH. Alternatively, it may be transmitted by including corresponding information (for each NR-MTCH) on the RRC message transmitted through the NR-MCCH. As another example, the information may be transmitted through a dedicated RRC message.

Transmission of indication information for linking PDCP entities for redundant transmission to one or more RLC entities

The PDCP entity for NR-MTCH redundant transmission may be configured in association with one or more RLC entities/RLC bearers. Through this, one or more RLC entities/RLC bearers for receiving redundant transmissions may transmit the received MBMS user data to the associated PDCP entity.

The NR-G-RNTI used to receive a specific NR-MTCH through the DL-SCH in each cell in which redundant transmission is performed may have a one-to-one mapping relationship with TMGI. Accordingly, the UE can receive the NR-MTCH specifically indicated on the NR-G-RNTI on the PDCCH in each cell in which redundant transmission is performed through the DL-SCH, and the MAC can distinguish it and transmit it to the associated RLC entity. .

For convenience of explanation, a base station including a PDCP entity for NR-MTCH redundant transmission or a base station terminating an MBMS session is indicated as a first base station, and a base station not including a PDCP entity for NR-MTCH redundant transmission is designated as a second base station. It is marked as. This is for convenience of description and may be replaced with an arbitrary name. In addition, for convenience of explanation, a cell for broadcasting system information for MBMS service user data (or MBMS session or NR-MTCH) transmission/overwrite transmission is provided as a serving cell camped on by the RRC connected terminal PCell or RRC IDLE/INACTIVE terminal. In addition to the first cell as one cell, a cell in which the UE receives redundant transmission for the corresponding NR-MTCH is denoted as a second cell. This is for convenience of description and may be replaced with an arbitrary name.

For example, if the second cell is a cell serviced/provided/linked by the first base station, the terminal may distinguish and receive NR-MTCH user data received through each cell from the same MAC entity (eg MCG MAC), This can be delivered to each associated RLC entity. In addition, each RLC entity may transmit NR-MTCH user data received through each cell to an associated PDCP entity. Each RLC entity linked to each cell may be configured with one or more of identification information for identifying a corresponding cell and information for identifying a corresponding NR-MTCH logical channel in the corresponding cell. The information for identifying the corresponding cell may be index/ID information according to the order of cells included in the corresponding cell list. The RLC entity may be identified through one or more of identification information for identifying a corresponding cell, information for identifying a corresponding NR-MTCH logical channel, NR-G-RNTI, and MBMS session information.

As another example, if the second cell is a service/provided/linked cell by the first base station, the UE can receive NR-MTCH user data received through each cell from the same MAC entity (eg MCG MAC) by classifying it, and This can be delivered to one RLC entity. In addition, the RLC entity may transmit the NR-MTCH user data received through each cell to the associated PDCP entity. The RLC entity may be identified through one or more of information for identifying a corresponding NR-MTCH logical channel, NR-G-RNTI, and MBMS session information.

As another example, if the second cell is a service/provided/linked cell by the first base station, the UE can receive NR-MTCH user data received through each cell from the same MAC entity (eg MCG MAC) by classifying it, and This can be delivered to one RLC entity. RLC PDUs received with redundant RLC SNs can be discarded. For this, the base station may allow the RLC entity to transmit redundant transmission without the PDCP entity. For example, one RLC entity may transmit RLC SDU/PDUs having the same SN through different cells.

As another example, when the second cell is a cell serviced/provided/linked by the second base station, the UE may use a MAC entity for receiving base station data (eg MCG MAC) and another MAC entity (eg SCG MAC) through each cell The received NR-MTCH user data may be classified and received, and this may be transmitted to each associated RLC entity. In addition, each RLC entity may transmit NR-MTCH user data received through each cell group/cell to an associated PDCP entity. Each RLC entity linked to each cell of each MAC entity may be configured with information for identifying the corresponding cell group, identification information for identifying the corresponding cell, and information for identifying the corresponding NR-MTCH logical channel in the corresponding cell. have. Information for identifying a corresponding cell group or information for identifying a corresponding cell may be a cell group included in the corresponding cell list or index/ID information according to an order of cells. The RLC entity may be identified through one or more of information for identifying a corresponding cell group or a corresponding cell, information for identifying a corresponding NR-MTCH logical channel, NR-G-RNTI, and MBMS session information.

The RLC entity may classify and transmit the MBMS service user data (or MBMS session or NR-MTCH) to the associated PDCP entity through the received information. As an example for this, the RLC bearer configuration information (or RLC configuration information) may include the aforementioned PDCP configuration association information. For example, the RLC bearer configuration information may include one or more of NR-G-RNTI, MBMS session information, and information for identifying an MBMS session. Alternatively, the RLC bearer configuration information may include one or more of information for identifying a corresponding cell group or a corresponding cell, information for identifying a corresponding NR-MTCH logical channel, NR-G-RNTI, and MBMS session information.

For reference, the RLC configuration for MTCH or SC-MTCH in the conventional LTE technology is used by defining a default value in TS 36.331, which is a related standard document. And since PDCP was not used, there was no need for association between L2 entities for transmitting the MBMS user data.

For convenience of explanation, the above-described redundant transmission was described assuming that it passes through one or more cells, but it is also within the scope of the present invention to perform redundant transmission in arbitrary frequency band units such as a plurality of BWP/subbands within one cell. Included. In addition, for convenience of explanation, it is assumed that MBMS service user data (or MBMS session or NR-MTCH) is transmitted through the DL-SCH, but MBMS service user data (or MBMS session or NR-MTCH) is transmitted through the MCH. It is also included in the scope of the present invention.

As described above, the present invention has the effect of reliably transmitting an MBMS service based on NR.

11 is a diagram showing a configuration of a base station 1000 according to another embodiment.

Referring to FIG. 11, a base station 1000 according to another embodiment includes a control unit 1010, a transmission unit 1020, and a reception unit 1030.

In the MBMS service providing method necessary for carrying out the present invention described above, the control unit 1010 performs redundant transmission of user data of the MBMS service through one or more cells when the terminal is located in a location where one or more cell coverage overlaps. Controls the overall operation of the base station 1000 according to the method provided.

The transmitting unit 1020 and the receiving unit 1030 are used to transmit and receive signals, messages, and data necessary for carrying out the above-described present invention with the terminal.

12 is a diagram showing the configuration of a user terminal 1100 according to another embodiment.

Referring to FIG. 12, a user terminal 1100 according to another embodiment includes a receiving unit 1110, a control unit 1120, and a transmitting unit 1130.

The receiving unit 1110 receives downlink control information, data, and a message from the base station through a corresponding channel.

In addition, in the MBMS service providing method necessary for carrying out the above-described present invention, the controller 1120 transmits redundant transmission of user data of the MBMS service through one or more cells when the terminal is located in a place where one or more cell coverage overlaps. Controls the overall operation of the user terminal 1100 according to the method of providing.

The transmitter 1130 transmits uplink control information, data, and a message to the base station through a corresponding channel.

The above-described embodiments may be supported by standard documents disclosed in at least one of IEEE 802, 3GPP and 3GPP2 wireless access systems. That is, steps, configurations, and parts not described in order to clearly reveal the present technical idea among the embodiments may be supported by the above-described standard documents. In addition, all terms disclosed in this specification may be described by the standard documents disclosed above.

The above-described embodiments can be implemented through various means. For example, the present embodiments may be implemented by hardware, firmware, software, or a combination thereof.

In the case of implementation by hardware, the method according to the embodiments includes one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), and FPGAs. (Field Programmable Gate Arrays), a processor, a controller, a microcontroller, or a microprocessor.

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

In addition, terms such as "system", "processor", "controller", "component", "module", "interface", "model", or "unit" described above generally refer to computer-related entity hardware, hardware and software. It may mean a combination of, software or running software. For example, the above-described components may be, but are not limited to, a process driven by a processor, a processor, a controller, a control processor, an object, an execution thread, a program, and/or a computer. For example, both the controller or processor and the application running on the controller or processor can be components. One or more components may reside within a process and/or thread of execution, and the components may be located on a single device (eg, a system, a computing device, etc.) or distributed across two or more devices.

The above description is merely illustrative of the technical idea of the present disclosure, and those of ordinary skill in the technical field to which the present disclosure pertains will be able to make various modifications and variations without departing from the essential characteristics of the technical idea. In addition, the present embodiments are not intended to limit the technical idea of the present disclosure, but to explain the technical idea, and thus the scope of the technical idea is not limited by these embodiments. The scope of protection of the present disclosure should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present disclosure.

Claims (1)

In the MBMS service providing method,
A method of providing redundant transmission of user data of an MBMS service through one or more cells when a terminal is located in a location where one or more cell coverage overlaps.

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