MBS data transmission method and device

Abstract

The present disclosure relates to a method and apparatus for sending / receiving a multicast / broadcast service (MBS) in an NR radio access network, and provides a method for a terminal to receive MBS data, the method comprising the following steps: receiving configuration information for receiving MBS session data from a base station; configuring an MBS radio bearer for receiving the MBS session data based on the configuration information; and receiving a MAC protocol data unit (PDU), in which two or more mutually different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for transmitting / receiving multicast / broadcast service data in an NR radio access network. Background Art

[0002] Cellular mobile communication networks have been mainly developed to provide end-to-end / point-to-point transmission services, but the development of broadband wireless transmission technologies and terminals that provide various functions has led to the demand for various services. In particular, Multimedia Broadcast Multicast Service (MBMS) is a technology that can use cellular mobile communication networks to provide mobile broadcast services. Recently, various technologies are being developed to provide disaster relief communication services using enhanced MBMS (hereinafter referred to as "eMBMS").

[0003] Unlike end-to-end transmission services, MBMS is an end-to-many end / one-to-many point transmission service, and can advantageously improve the use efficiency of radio resources by sending the same packet to multiple terminals in a single cell. In addition, the MBMS service adopts a multi-cell transmission scheme in which multiple base stations simultaneously send the same packet, and the use of this multi-cell transmission scheme allows the terminals receiving the service to obtain diversity gain in the physical layer.

[0004] However, when a base station sends MBMS service data, the efficiency varies depending on the number of UEs that receive the corresponding data. Therefore, a technology based on NR is needed to control MBS sessions and provide service continuity.

[0005] Furthermore, a technique for efficiently providing MBS data to a UE according to a QoS flow is needed. Summary of the invention

[0006]

Technical issues

[0007] The present disclosure provides a technology for a UE to receive MBS data.

[0008]

Technical solution

[0009] In one aspect, the present embodiment provides a method for receiving multicast / broadcast service (MBS) data by a UE, comprising: receiving configuration information for receiving MBS session data from a base station; configuring an MBS radio bearer for receiving the MBS session data based on the configuration information; and receiving a MAC protocol data unit (PDU), in which two or more different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed.

[0010] In another aspect, the present embodiment provides a method for sending multicast / broadcast service (MBS) data by a base station, comprising: sending configuration information for receiving MBS session data by the UE to a UE; configuring an MBS radio bearer for sending the MBS session data based on the configuration information; and sending a MAC protocol data unit (PDU), in which two or more different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed.

[0011] In another aspect, the present embodiment provides a UE for receiving multicast / broadcast service (MBS) data, comprising: a receiver that receives configuration information for receiving MBS session data from a base station; and a controller that configures an MBS radio bearer for receiving the MBS session data based on the configuration information, wherein the receiver receives a MAC protocol data unit (PDU) in which two or more different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed.

[0012] In another aspect, the present embodiment provides a base station for sending multicast / broadcast service (MBS) data, comprising: a transmitter that sends configuration information for receiving MBS session data by the UE to a UE; and a controller that configures an MBS radio bearer for sending the MBS session data based on the configuration information, wherein the transmitter sends a MAC protocol data unit (PDU) in which two or more different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed.

[0013]

Beneficial Effects

[0014] The present disclosure provides an effect of a UE receiving and processing MBS data. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a view schematically showing the structure of an NR wireless communication system to which the present embodiment can be applied.

[0016] Figure 2 is a view showing a frame structure in an NR system to which the present embodiment can be applied.

[0017] Figure 3 : is a diagram showing a resource grid supported by a radio access technology to which the present embodiment can be applied.

[0018] Figure 4 is a diagram showing a bandwidth portion supported by a radio access technology to which the present embodiment can be applied.

[0019] Figure 5 exemplarily shows a synchronization signal block in a radio access technology to which the present embodiment can be applied.

[0020] Figure 6 : is a diagram showing a random access procedure in a radio access technology to which the present embodiment can be applied.

[0021] Figure 7 is a view showing CORESET.

[0022] Figure 8 is a view showing the MBMS user plane protocol architecture.

[0023] Fig. 9 is a view showing the overall NG-RAN architecture.

[0024] Fig.10 is a view for describing the operation of a UE according to one embodiment.

[0025] Fig.11 is a view for describing the operation of a base station according to one embodiment.

[0026] Fig.12 is a view showing an example of a layer 2 structure for transmitting / receiving MBS data.

[0027] Fig.13 is a view showing another example of a layer 2 structure for transmitting / receiving MBS data.

[0028] Fig.14 is a diagram showing a logical channel identifier value according to one embodiment.

[0029] Fig.15 is a view exemplarily showing a MAC subheader format including an extended LCID field according to one embodiment.

[0030] Fig.16 is a view showing allocation information of an extended LCID value according to each octet length for a DL-SCH according to one embodiment.

[0031] Fig.17 is a view showing a configuration of a UE according to one embodiment.

[0032] Fig.18 is a view showing a configuration of a base station according to one embodiment. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. Throughout the specification and the accompanying drawings, the same or substantially the same reference numerals are used to refer to the same or substantially the same elements. When it is determined that the subject matter of the present invention is unclear, the detailed description of known technologies or functions can be skipped. The terms "include" and / or "include ... ", "have" and / or "have ... " or "include" specify the presence of the features, regions, wholes, steps, operations, elements and / or components described when used in this specification, but do not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components and / or their groups. As used herein, the singular forms "a", "an" and "the" are also intended to include plural forms, unless the context clearly indicates otherwise.

[0034] Expressions such as "first", "second", "A", "B", "(a)", and "(b)" may be used to describe components of the present invention. These expressions are provided only to distinguish one component from another, and the nature of the components is not limited by the expressions in order or sequence.

[0035] When describing the positional relationship between components, when two or more components are described as being “connected,” “coupled,” or “linked,” the two or more components may be directly “connected,” “coupled,” or “linked,” or another component may intervene. Here, other components may be included in one or more of the two or more components that are “connected,” “coupled,” or “linked” to each other.

[0036] With respect to a component, an operating method or a manufacturing method, when A is referred to as "after," "subsequently," "next," and "before," A and B may not be sequential to each other unless mentioned together with the term "immediately" or "directly."

[0037] When a component is specified using a numerical value or its corresponding information (eg, level), the numerical value or the corresponding information may be interpreted as including tolerances due to various factors (eg, process factors, internal or external influences, or noise).

[0038] In the present disclosure, a 'wireless communication system' means a system for providing various communication services such as voice and data packets using radio resources, and may include a UE, a base station, or a core network.

[0039] The present embodiment disclosed below can be applied to wireless communication systems using various radio access technologies. For example, the present embodiment can be applied to various radio access technologies, such as 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) or non-orthogonal multiple access (NOMA). In addition, radio access technology can refer not only to a specific access technology, but also to a communication technology for each generation established by various communication organizations such as 3GPP, 3GPP2, Wi-Fi, Bluetooth, IEEE and ITU. For example, CDMA can be implemented as a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented as GSM (Global System for Mobile Communications) / GPRS (General Packet Radio Service) / EDGE (Enhanced Data Rate for GSM Evolution). OFDMA can be implemented using wireless technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802-20, Evolved UTRA (E-UTRA), etc. IEEE 802.16m is an evolution of IEEE 802.16e, and provides backward compatibility with systems based on IEEE802.16e. UTRA is part of UMTS (Universal Mobile Telecommunications System). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is part of E-UMTS (Evolved UMTS) using Evolved UMTS Terrestrial Radio Access (E-UTRA), and adopts OFDMA for downlink and SC-FDMA for uplink. Therefore, the present embodiment can be applied to currently disclosed or commercialized radio access technologies, and can also be applied to radio access technologies that are currently being developed or to be developed in the future.

[0040] Meanwhile, in the present disclosure, "UE" is a comprehensive concept, meaning a device including a wireless communication module that communicates with a base station in a wireless communication system, and should be interpreted as a concept that includes not only user equipment (UE) in, for example, WCDMA, LTE, NR, HSPA, and IMT-2020 (5G or new air interface) but also a mobile station (MS), user terminal (UT), subscriber station (SS), or wireless device in GSM. In addition, depending on the type of use, UE may be a user portable device (such as a smart phone), and in a V2X communication system, UE may refer to a vehicle or a device including a wireless communication module in a vehicle. In addition, in the case of a machine type communication system, UE may refer to an MTC terminal, an M2M terminal, or a URLLC terminal equipped with a communication module for performing machine type communication.

[0041] In the present disclosure, a "base station" or "cell" refers to a terminal that communicates with a UE in terms of a network, and conceptually covers various coverage areas, such as a Node B, an evolved Node B (eNB), a gNode B (gNB), a low power node (LPN), a sector, a site, various types of antennas, a base transceiver system (BTS), an access point, a point (e.g., a transmission point, a reception point, or a transmission / reception point), a relay node, a macro cell, a macro cell, a micro cell, a pico cell, a femto cell, a remote radio head (RRH), a radio unit (RU), or a small cell. In addition, a "cell" may refer to a cell including a bandwidth part (BWP) in the frequency domain. For example, a "service cell" may refer to an activated BWP of a UE.

[0042] Since there is a base station controlling one or more cells in the various cells listed above, the base station can be interpreted as two meanings. The base station can be 1) a device itself that provides a giant cell, a macro cell, a micro cell, a pico cell, a femto cell or a small cell associated with a radio area, or 2) the radio area itself. In 1), all devices that provide a predetermined radio area and are controlled by the same entity or interact via collaboration to configure the radio area are represented as base stations. One embodiment of a base station is a sending / receiving point, a sending point, or a receiving point depending on the scheme for configuring the radio area. In 2), from the perspective of a UE or a neighboring base station, the radio area itself in which a signal is received or sent can be a base station.

[0043] In the present disclosure, a "cell" may refer to the coverage of a signal transmitted from a transmission / reception point, a component carrier having coverage of a signal transmitted from a transmission / reception point (transmission point or transmission / reception point), or the transmission / reception point itself.

[0044] Uplink (UL) refers to a scheme in which a UE transmits and receives data to and from a base station, while downlink (DL) refers to a scheme in which a base station transmits and receives data to and from a UE. A downlink may refer to a communication or communication path from multiple transmission / transmission points to a UE, while an uplink may refer to a communication or communication path from a UE to multiple transmission / reception points. In this case, in the downlink, a transmitter may be part of multiple transmission / reception points, and a receiver may be part of a UE. In addition, in the uplink, a transmitter may be part of a UE, and a receiver may be part of multiple transmission / reception points.

[0045] The uplink and downlink transmit / receive control information through control channels such as the Physical Downlink Control Channel (PDCCH) or the Physical Uplink Control Channel (PUCCH), and configure data channels such as the Physical Downlink Shared Channel (PDSCH) or the Physical Uplink Shared Channel (PUSCH) to transmit / receive data. Hereinafter, the context of transmitting / receiving signals through channels such as PUCCH, PUSCH, PDCCH, and PDSCH is expressed as "transmitting or receiving PUCCH, PUSCH, PDCCH, and PDSCH".

[0046] Although, for clarity of description, the technical spirit is mainly focused on 3GPP LTE / LTE-A / New Radio (NR) communication systems, the technical features are not limited to such communication systems.

[0047] After researching fourth-generation (4G) communication technologies, 3GPP developed fifth-generation (5G) communication technologies to meet the requirements of the next-generation radio access technologies of the ITU-R. Specifically, 3GPP developed a new NR communication technology that is separate from LTE-A Pro and 4G communication technologies (which have enhanced LTE-Advanced technologies to meet the requirements of the ITU-R) as the 5G communication technology. Both LTE-A Pro and NR refer to 5G communication technologies. Hereinafter, unless specified as a specific communication technology, 5G communication technologies are focused on NR for description.

[0048] The operation scenarios in NR define various operation scenarios by adding considerations for satellites, automobiles, and new verticals to the existing 4G LTE scenarios. And from the perspective of services, it supports the enhanced mobile broadband (eMBB) scenario, the massive machine type communication (MMTC) scenario with a high UE density but deployed over a wide range to require low data rates and asynchronous access, and the ultra-reliable and low-latency (URLLC) scenario that requires high responsiveness and reliability and can support high-speed mobility.

[0049] To meet such scenarios, NR discloses a wireless communication system that adopts new waveform and frame structure technologies, low-latency technologies, millimeter wave (mmWave) support technologies, and forward compatibility provision technologies. In particular, the NR system proposes various technical changes in terms of the flexibility of providing forward compatibility. The main technical features of NR are described below with reference to the accompanying drawings.

[0050] <Overview of NR System>

[0051] Figure 1 is a view schematically showing the structure of an NR system to which the present embodiment can be applied.

[0052] Refer to Figure 1 , the NR system is divided into a 5G core network (5GC) and an NR-RAN part. The NG-RAN consists of gNBs and ng-eNBs that provide user plane (SDAP / PDCP / RLC / MAC / PHY) and user equipment (UE) control plane (RRC) protocol terminations. The gNBs or the gNBs and ng-eNBs are interconnected through the Xn interface, and the gNBs and ng-eNBs are connected to the 5GC through the NG interface. The 5GC may include an access and mobility management function (AMF) responsible for the control plane access and mobility management functions such as UE access and mobility control functions, and a user plane function (UPF) responsible for user data control functions. NR supports frequency bands below 6 GHz (frequency range 1 (FR1)) and above 6 GHz (frequency range 2 (FR2)).

[0053] A gNB is a base station that provides NR user plane and control plane protocol terminations to the UE, while an ng-eNB is a base station that provides E-UTRA user plane and control plane protocol terminations to the UE. In the present disclosure, the base station should be understood to cover both gNBs and ng-eNBs and is used to individually represent a gNB or an ng-eNB when necessary.

[0054] <NR Waveform, Numerology, and Frame Structure>

[0055] NR adopts the CP-OFDM waveform with a cyclic prefix for downlink transmission and uses CP-OFDM or DFT-s-OFDM for uplink transmission. OFDM technology is easy to combine with multiple-input multiple-output (MIMO), and has the advantages of high frequency efficiency and the ability to use a low-complexity receiver.

[0056] At the same time, since in NR, the above three scenarios have different requirements for data rate, latency, and coverage, it is necessary to effectively meet the requirements of each scenario through the frequency bands that make up any NR system. For this purpose, techniques for effectively multiplexing radio resources based on multiple different numerologies have been proposed.

[0057] Specifically, the NR transmission numerology is determined based on the subcarrier spacing and the cyclic prefix (CP), and as shown in Table 1 below, it changes exponentially. For 15 kHz, the exponential value 2 is used as μ.

[0058] [Table 1]

[0059] μ Subcarrier spacing Cyclic prefix Support for data Support for synchronization 0 15 normal yes yes 1 30 normal yes yes 2 60 Normal, Extended yes no 3 120 normal yes yes 4 240 normal no yes

[0060] As shown in Table 1 above, NR parameter sets can be divided into five types according to the subcarrier spacing. This is different from the subcarrier spacing fixed to 15kHz in LTE as a 4G communication technology. Specifically, in NR, the subcarrier spacing for data transmission is 15, 30, 60 and 120kHz, and the subcarrier spacing for synchronization signal transmission is 15, 30, 120 and 240kHz. In addition, the extended CP is only applied to 60kHz subcarrier spacing. At the same time, as a frame structure in NR, a frame with a length of 10ms consisting of 10 subframes with the same length of 1ms is defined. A frame can be divided into half frames of 5ms, and each half frame can include 5 subframes. In the case of 15kHz subcarrier spacing, a subframe consists of one time slot, and each time slot consists of 14 OFDM symbols. Figure 2 is a view showing a frame structure in an NR system to which the present embodiment can be applied.

[0061] Reference Figure 2 , in the case of normal CP, the time slot is fixedly composed of 14 OFDM symbols, but the length of the time slot in the time domain can vary according to the subcarrier spacing. For example, in the case of a parameter set with a 15kHz subcarrier spacing, the time slot has the same length as the subframe due to the length of 1ms. On the contrary, in the case of a parameter set with a 30kHz subcarrier spacing, the time slot is composed of 14 OFDM symbols, but due to the length of 0.5ms, two time slots can be included in one subframe. In other words, subframes and frames are defined as having a fixed length, while the time slot is defined by the number of symbols, and the time length can vary according to the subcarrier spacing.

[0062] At the same time, NR defines the time slot as the basic unit for scheduling, and in order to reduce the transmission delay in the radio sector, a micro-time slot (or sub-time slot, or non-time slot based scheduling) is adopted. If a wide subcarrier spacing is used, the length of a time slot is inversely shortened, so that the transmission delay in the radio sector can be reduced. Micro-time slots are used to effectively support URLLC scenarios and enable scheduling in units of 2, 4 or 7 symbols.

[0063] In addition, unlike LTE, NR defines uplink and downlink resource allocation at the symbol level in one slot. In order to reduce HARQ latency, a slot structure has been defined that enables HARQ ACK / NACK to be transmitted directly in the transmission slot, and this slot structure is referred to as a self-contained structure in this description.

[0064] NR is designed to support a total of 256 time slots, of which 62 time slot formats are used in 3GPP Rel-15. In addition, the common frame structure that constitutes the FDD or TDD frame is supported through various combinations of time slots. For example, it supports a time slot structure in which all symbols of the time slot are configured as downlink, a time slot structure in which all symbols are configured as uplink, and a time slot structure that combines downlink symbols and uplink symbols. In addition, NR supports data transmission distributed and scheduled in one or more time slots. Therefore, the base station can use the Time Slot Format Indicator (SFI) to notify the UE whether the time slot is a downlink time slot, an uplink time slot, or a flexible time slot. The base station can indicate the time slot format by indexing a table configured by UE-specific RRC signaling indicated by the SFI, and can dynamically indicate the time slot format through Downlink Control Information (DCI), or statically or semi-statically indicate the time slot format through RRC.

[0065] <NR Physical Resources>

[0066] Combined with the physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, and bandwidth parts are considered.

[0067] An antenna port is defined such that a channel carrying one symbol on the antenna port can be inferred from a channel carrying another symbol on the same antenna port. When the large-scale characteristics of a channel carrying a symbol on one antenna port can be inferred from a channel carrying a symbol on a different antenna port, it can be said that these two antenna ports have a QC / QCL (Quasi-Co-Located or Quasi-Co-Location) relationship. Here, the large-scale characteristics include one or more of delay spread, Doppler spread, frequency shift, average received power, and reception timing.

[0068] Figure 3 is a view showing the resource grid supported by the radio access technology to which this embodiment can be applied.

[0069] Refer to Figure 3 , since NR supports multiple parameter sets in the same carrier, the resource grid can exist according to each parameter set. In addition, the resource grid can exist according to antenna ports, subcarrier spacing, or transmission direction.

[0070] 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. Therefore, as Figure 3 shown, the size of one resource block can vary according to the subcarrier spacing. In addition, in NR, "Point A" which serves as a common reference point for the resource block grid, as well as common resource blocks and virtual resource blocks, are defined.

[0071] Figure 4This is a view showing the bandwidth part supported by the radio access technology to which this embodiment can be applied.

[0072] In NR, different from LTE where the carrier bandwidth is fixed at 20 MHz, for each subcarrier spacing, the maximum carrier bandwidth is set from 50 MHz to 400 MHz. Therefore, it is not assumed that all UEs use all these carrier bandwidths. Thus, in NR, as Figure 4 shown, a bandwidth part (BWP) can be specified within the carrier bandwidth and used by the UE. In addition, the bandwidth part is associated with a parameter set, consists of a subset of consecutive common resource blocks, and can be dynamically activated over time. For each of the uplink and downlink, up to four bandwidth parts can be configured in the UE. The bandwidth part activated at a given time is used to transmit / receive data.

[0073] In the case of paired spectrum, the bandwidth parts of the uplink and downlink are set independently, while in the case of unpaired spectrum, the bandwidth parts of the uplink and downlink are set as a pair to share the center frequency, thus preventing unnecessary frequency retuning between downlink and uplink operations.

[0074] <NR Initial Access>

[0075] In NR, the UE performs a cell search and a random access process to access the base station and perform communication.

[0076] Cell search is a process of synchronizing the UE with the cell of the base station using the Synchronization Signal Block (SSB) sent from the base station, obtaining the physical layer cell ID, and obtaining system information.

[0077] Figure 5 This is a view exemplarily showing the Synchronization Signal Block in the radio access technology to which this embodiment can be applied.

[0078] Referring to Figure 5 , the SSB consists of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) that respectively occupy 1 symbol and 127 subcarriers, and a Physical Broadcast Channel (PBCH) that spans 3 OFDM symbols and 240 subcarriers.

[0079] The UE monitors and receives the SSB in the time domain and frequency domain.

[0080] SSB can be transmitted up to 64 times in 5ms. Multiple SSBs are transmitted on different transmission beams in 5ms, and the UE performs detection based on the assumption that the SSB is transmitted every 20ms period based on one specific beam used for transmission. The number of beams available for SSB transmission in 5ms may increase with the frequency band. For example, up to 4 SSB beams can be transmitted below 3GHz, up to 8 different beams can be used to transmit SSB in the frequency band from 3GHz to 6GHz, and up to 64 different beams can be used to transmit SSB in the frequency band of 6GHz or higher.

[0081] Two SSBs are included in one slot, and the start symbol and the number of repetitions within the slot are determined as follows according to the subcarrier spacing.

[0082] At the same time, unlike the SS of traditional LTE, SSB is not sent at the center frequency of the carrier bandwidth. In other words, SSB can be sent even outside the center of the system frequency band, and multiple SSBs can be sent in the frequency domain if broadband operation is supported. Therefore, the UE monitors SSB through the synchronization raster, which is a candidate frequency position for monitoring SSB. The carrier raster and synchronization raster are newly defined in NR, which are the center frequency position information of the channel used for initial access, and the synchronization raster has a wider frequency interval than the carrier raster, enabling the UE to perform fast SSB search.

[0083] The UE can obtain the MIB through the PBCH of the SSB. The master information block (MIB) includes the minimum information for the UE to receive the remaining system information (remaining minimum system information (RMSI)) broadcast by the network. In addition, the PBCH may include information about the position of the first DM-RS symbol in the time domain, information for the UE to monitor SIB1 (for example, SIB1 parameter set information, information related to SIB1CORESET, search space information, PDCCH related parameter information, etc.), offset information between common resource blocks and SSBs (the absolute position of SSBs within the carrier is sent through SIB1), etc. Here, the SIB1 parameter set information is equally applied to some messages used in the random access process of the UE to access the base station after completing the cell search process. For example, parameter set information about SIB1 can be applied to at least one of messages 1 to 4 used for the random access process.

[0084] The above-mentioned RMSI may mean system information block 1 (SIB1). SIB1 is broadcast periodically (e.g., 160ms) in the cell. SIB1 includes information required for the UE to perform the initial random access procedure and is periodically transmitted through the PDSCH. In order to receive SIB1, the UE needs to receive parameter set information for SIB1 transmission and control resource set (CORESET) information for SIB1 scheduling through the PBCH. The UE identifies the scheduling information of SIB1 using the SI-RNTI in the CORESET and obtains SIB1 on the PDSCH according to the scheduling information. The remaining SIBs except SIB1 may be transmitted periodically and may be transmitted at the request of the UE.

[0085] Figure 6 : is a diagram showing a random access procedure in a radio access technology to which the present embodiment can be applied.

[0086] Reference Figure 6 , if the cell search is completed, the UE sends a random access preamble for random access to the base station, which is sent through PRACH. Specifically, the random access preamble is sent to the base station through PRACH composed of continuous radio resources in a specific time slot that is repeated periodically. Generally, when the UE initially accesses a cell, a contention-based random access procedure is performed, and when random access is performed for beam failure recovery (BFR), a non-contention-based random access procedure is performed.

[0087] The UE receives a random access response to the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), uplink radio resources (UL grant), a temporary cell radio network temporary identifier (C-RNTI), and a time alignment command (TAC). Since a random access response may include random access response information for one or more UEs, a random access preamble identifier may be included to indicate which UE the included UL grant, temporary C-RNTI, and TAC are valid for. The random access preamble identifier may be an identifier of a random access preamble received by a 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 (i.e., a random access radio network temporary identifier (RA-RNTI)) on the PDCCH.

[0088] When a valid random access response is received, the UE processes the information included in the random access response and performs scheduled transmission to the base station. For example, the UE applies the TAC and stores the temporary C-RNTI. In addition, the UE uses the UL grant to send data stored in the UE's buffer or newly generated data to the base station. In this case, information that can identify the UE should be included.

[0089] Finally, the UE receives a downlink message for contention resolution.

[0090] <NR CORESET>

[0091] In NR, the downlink control channel is transmitted in a control resource set (CORESET) of 1 to 3 symbols in length, and transmits uplink / downlink scheduling information, slot format index (SFI), transmit power control (TPC) information, etc.

[0092] Therefore, NR introduces the concept of CORESET to ensure the flexibility of the system. A control resource set (CORESET) refers to the time-frequency resources used for downlink control signals. The UE can use one or more search spaces in the CORESET time-frequency resources to decode control channel candidates. A quasi-co-location (QCL) assumption for each CORESET has been set, the purpose of which is to indicate the characteristics of the simulated beam direction in addition to the delay spread, Doppler spread, Doppler shift and average delay (which are the characteristics assumed by the traditional QCL).

[0093] Figure 7 is a view showing CORESET.

[0094] Reference Figure 7 , a CORESET can exist in various forms within the carrier bandwidth within a time slot. In the time domain, a CORESET can consist of up to 3 OFDM symbols. In addition, a CORESET is defined as a multiple of 6 resource blocks up to the carrier bandwidth in the frequency domain.

[0095] The first CORESET is indicated via the MIB as part of the initial bandwidth portion configuration to allow receiving additional configuration and system information from the network. After establishing a connection with the base station, the UE may receive and configure one or more CORESET information via RRC signaling.

[0096] As used herein, frequency, frame, subframe, resource, resource block, area, frequency band, subband, control channel, data channel, synchronization signal, various reference signals, various signals, and various messages related to the New Radio (NR) may be interpreted as various meanings currently used or used in the future.

[0097] NR (New Radio)

[0098] As described above, the NR recently carried out in 3GPP has been designed to meet various QoS requirements required for each further divided and specified usage scenario and an enhanced data rate compared to LTE. In particular, as representative usage scenarios of NR, enhanced mobile broadband (eMBB), massive MTC (mMTC), and ultra-reliable and low-latency communication (URLLC) have been defined, and as a method for meeting the requirements of each usage scenario, it is necessary to design a flexible frame structure compared to LTE. Each usage scenario has different requirements for data rate, latency, reliability, coverage, etc. Therefore, as a method for effectively meeting the requirements of each usage scenario by constituting a frequency band of an arbitrary NR system, it has been designed to effectively reuse radio resource units based on different parameter sets (e.g., subcarrier spacing, subframe, TTI, etc.).

[0099] For example, a method for multiplexing and supporting parameter sets with different subcarrier spacings based on TDM, FDM or TDM / FDM through one or more NR component carriers has been discussed. A scheme for supporting one or more time units when configuring a scheduling unit in the time domain has also been discussed. At this point, NR defines a subframe as a time domain structure. As a reference parameter set for defining the subframe duration, it has been determined to define a single subframe duration consisting of a normal CP overhead of 14 OFDM symbols based on a 15kHz subcarrier spacing (SCS) the same as LTE. Therefore, in NR, the duration of the subframe is 1ms. However, unlike LTE, the subframe of NR is an absolute reference duration, and as a time unit used as the basis for actual uplink / downlink data scheduling, time slots and microslots can be defined. In this case, in the case of a normal CP, regardless of the SCS value, the number of OFDM symbols (y value) constituting the corresponding time slot is determined to be y=14.

[0100] Therefore, any slot consists of 14 symbols. In addition, according to the transmission direction of the corresponding slot, all symbols may be used for DL ​​transmission, or all symbols may be used for UL transmission, or symbols may be used in the form of DL part + (slot) + UL part.

[0101] In addition, in any parameter set (or SCS), a micro-time slot consisting of a smaller number of symbols than the above-mentioned time slot is defined. For uplink / downlink data transmission / reception based on micro-time slots, a short-length time domain scheduling interval can be set, or a long-length time domain scheduling interval for uplink / downlink data transmission / reception can be configured via time slot aggregation. In particular, in the case of sending or receiving delay-sensitive data (such as URLLC), if scheduling is performed in units of time slots, the time slot unit is based on 1ms (14 symbols) defined in a frame structure based on a parameter set with a small SCS value (e.g., 15kHz), then the delay requirements may be difficult to meet. Therefore, a micro-time slot consisting of a smaller number of OFDM symbols than a time slot consisting of 14 symbols can be defined, and based on the micro-time slot, scheduling that can meet the URLLC requirements can be performed.

[0102] Meanwhile, in NR, the default scheduling unit has been changed to a time slot. In addition, a time slot consists of 14 OFDM symbols regardless of the subcarrier spacing. In contrast, NR supports a non-time slot structure consisting of 2, 4, or 7 OFDM symbols, which is a smaller scheduling unit. The non-time slot structure can be used as a scheduling unit for URLLC services.

[0103] MBMS (Multimedia Broadcast Multicast Service) in LTE Networks

[0104] 3GPP has developed LTE broadcast / multicast standards for video broadcasting from Rel-9. Since then, standards have been specified to support other services in LTE, such as public safety, IoT and V2X. For NR, Rel-15 and Rel-16 standards do not support MBMS. It is determined that MBMs related standards should be further developed in subsequent versions of the NR standard.

[0105] Meanwhile, in the conventional MBMS based on LTE, two transmission schemes are provided: Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN) transmission; and Single Cell Point-to-Multipoint (SC-PTM) transmission.

[0106] The MBSFN transmission scheme is suitable for providing media broadcasting in large-scale pre-planned areas (MBSFN areas). MBSFN areas are statically configured. For example, this is configured by O&M. Dynamic adjustment can be performed without depending on user distribution. Synchronous MBMS transmission is provided within the MBSFN area, and MBMS transmission merging of multiple cells is supported. Each MCH scheduling is performed by a multi-cell / multicast coordination entity (MCE), and each TTI uses a single transport block for MCH transmission. In addition, the transport block uses MBSFN resources in the subframe, and 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. Therefore, the MBSFN transmission scheme is difficult to be dynamically adjusted and applied to small-scale broadcast services.

[0107] The SC-PTM transmission scheme was developed to enhance the inefficiency of the MBSFN transmission scheme. MBMS is transmitted within a single cell coverage area via SC-PTM. One SC-MCCH and one or more SC-MTCHs are mapped to DL-SCH. Scheduling is provided by the base station. SC-MCCH and SC-MTCH are each indicated by a logical channel specific RNTI (SC-RNTI or G-RNTI) on the PDCCH. SC-MTCH and SC-MCCH use the RLC-UM mode. Although a single transmission is used for the DL-SCH to which the SC-MCCH and SC-MTCH are mapped, no blind HARQ repetition or RLC repetition is provided.

[0108] Figure 8 is a diagram showing the MBMS user plane protocol architecture.

[0109] Reference Figure 8 In the LTE network, MBMS user data is transmitted between the BM-SC and the UE through the mobile communication network. Therefore, the corresponding packet may not be an IP packet. In addition, only the broadcast transmission scheme is supported in the LTE MBMS. Therefore, the protocol structure is designed based on the RLC-UM without using the PDCP layer that provides header compression or security functions.

[0110] High-level functional division / base station division structure

[0111] NR can provide a split structure that divides the base station (gNB) into a central unit (hereinafter referred to as "gNB-CU" for the convenience of description) and a distributed unit (hereinafter referred to as "gNB-DU" for the convenience of description) to support efficient network construction.

[0112] Fig. 9 is a view showing the overall NG-RAN architecture.

[0113] Reference Fig. 9 , the next generation radio network can be composed of a group of base stations connected to the 5G core network (5GC) via the NG interface. These base stations are connected to each other via the Xn interface. A base station can be composed of one gNB-CU and one or more gNB-DUs. The gNB-CU and gNB-DU are connected to each other via the F1 interface. A gNB-DU can be connected to only one gNB-CU. The NG interface and the Xn-C interface of a base station composed of a gNB-CU and a gNB-DU terminate at the gNB-CU. The gNB-DU connected to the gNB-CU is shown as only one base station to other base stations and the 5GC. The gNB-CU is a logical node that hosts the RRC, SDAP and PDCP protocols of the base station. The gNB-DU is a logical node that hosts the RLC, MAC and PHY layers of the base station. A gNB-DU supports one or more cells. A cell is supported by only one gNB-DU. The node hosting the user plane part of the NR PDCP shall perform user inactivity monitoring and notify the node with the control plane connection of the inactivity or (re)activation. The node hosting the NR RLC may perform user inactivity monitoring and notify the control plane hosting node of inactivity or (re)activation.

[0114] Therefore, according to the user plane protocol structure in the 5G / NR radio network using the base station split structure, the gNB-CU and gNB-DU are connected through the F1 interface between PDCP and RLC.

[0115] 3GPP Rel-15 and Rel-16, which provide NR standards, do not disclose technical content for multicast / broadcast services (MBS). In particular, from the perspective of the user plane structure, the base station split structure consists of a gNB-CU hosting PDCP and a gNB-DU hosting RLC or lower layers. When a 5G / NR radio network is established alone, no method for transmitting multicast / broadcast service data is provided.

[0116] The present disclosure, conceived to solve these problems, proposes a method and apparatus for efficiently and separately processing multicast / broadcast service data in a 5G / NR radio network.

[0117] In the following, a method for providing multicast / broadcast service (MBS) continuity based on NR radio access technology according to the present disclosure is described. However, this is for ease of description, and the embodiments can be applied to any radio access technology. For example, the present embodiment can be applied to a radio access network that provides base station segmentation at any layer (e.g., PHY, MAC, RLC, or PDCP). The embodiments described in the present disclosure may include the content of the information elements and operations set forth in the 3GPP NR MAC standard TS 38.321 and the NRRRC standard TS 38.331. Although the present disclosure does not include the content of UE operations related to the detailed definition of the corresponding information elements, the content set forth in these standards may be incorporated into the present disclosure.

[0118] Fig.10 is a view for describing an operation of a UE according to one embodiment.

[0119] Reference Fig.10 , a UE receiving multicast / broadcast service (MBS) data may perform a step of receiving configuration information for receiving MBS session data from a base station ( S1010 ).

[0120] For example, the UE needs to perform various operations such as configuration of MBS radio bearers, identification of associated logical channels, and identification of MBS Quality of Service (QoS) flows to receive MBS session data. Therefore, the UE may receive configuration information for receiving MBS session data from the base station in advance.

[0121] As an example, the configuration information for receiving MBS session data may be included in an RRC reconfiguration message and received by the UE. As another example, the configuration information for receiving MBS session data may be received via an MBS control channel (MCCH) message. MCCH refers to a channel for transmitting MBS control information, but is not limited to this term.

[0122] The configuration information for receiving MBS session data may include various information required for the UE to receive the MBS session data. For example, the configuration information for receiving MBS session data may include MBS radio bearer identifier information. The MBS radio bearer identifier information may include identification information for identifying a radio bearer for the UE to receive MBS session data. In addition, the logical channel identifier associated with the MBS radio bearer may include identification information indicating one or more logical channels associated with the radio bearer for the UE to receive MBS session data. The configuration information for receiving MBS session data may include both an MBS radio bearer identifier and a logical channel identifier associated with the MBS radio bearer.

[0123] As an example, the MBS radio bearer identifier may be configured in association with at least one of the MBS session identification information and the MBS QoS flow identification information. In other words, the MBS radio bearer identifier may be allocated in association with the MBS session identification information for identifying the MBS session. Alternatively, the MBS radio bearer identifier may be allocated in association with the QoS flow identification information indicating the MBS QoS flow. Alternatively, the MBS radio bearer identifier may be configured in association with both the MBS session identification information and the MBS QoS flow identification information.

[0124] For example, the logical channel identifier associated with the MBS radio bearer may be assigned a different value than the logical channel identifier assigned to the unicast radio bearer for DL-SCH. For example, when the logical channel identifiers 1-32 are assigned to the unicast radio bearer for DL-SCH, the logical channel identifier associated with the MBS radio bearer may be assigned a value other than 1-32.

[0125] Alternatively, a logical channel identifier associated with an MBS radio bearer may be allocated using an extended logical channel ID (LCID). For example, a logical channel identifier associated with an MBS radio bearer may be allocated using a 1-octet or 2-octet extended LCID (eLCID) value on the DL-SCH.

[0126] Therefore, the logical channel identifier associated with an MBS radio bearer may be distinguished from a unicast radio bearer.

[0127] Meanwhile, the UE may perform a step of configuring an MBS radio bearer for receiving MBS session data based on the configuration information ( S1020 ).

[0128] The UE may configure the MBS radio bearer in the UE according to the configuration information received from the base station. As described above, the UE configures the MBS radio bearer for receiving MBS session data in the UE by using the MBS radio bearer identifier and the logical channel identifier associated with the MBS radio bearer. When configuring the MBS radio bearer, the UE may configure the MBS radio bearer by identifying the MBS session identification information or the MBS QoS flow identifier configured in association with the MBS radio bearer identifier included in the configuration information.

[0129] As described above, the logical channel identifier associated with an MBS radio bearer may be assigned a different value than the logical channel identifier of a unicast radio bearer.Alternatively, the logical channel identifier associated with an MBS radio bearer may be assigned as an extended LCID codepoint / index.

[0130] The UE may perform a step of receiving a MAC protocol data unit (PDU) in which two or more different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed (S1030).

[0131] The UE may receive a MAC PDU in which a plurality of logical channels configured in association with one G-RNTI are multiplexed from the base station. Two or more different logical channels may be multiplexed in the MAC PDU.

[0132] Therefore, the UE may receive the MBS session data through the MBS radio bearer.

[0133] Fig.11 is a view for describing the operation of a base station according to one embodiment.

[0134] Reference Fig.11 , a base station transmitting multicast / broadcast service (MBS) data may perform a step of transmitting configuration information for receiving MBS session data by the UE to the UE ( S1110 ).

[0135] As an example, the configuration information for receiving MBS session data may be included in an RRC reconfiguration message and transmitted to the UE. As another example, the configuration information for receiving MBS session data may be transmitted through an MBS control channel (MCCH) message.

[0136] The configuration information for receiving MBS session data may include various information required for the UE to receive the MBS session data. For example, the configuration information for receiving MBS session data may include MBS radio bearer identifier information. The MBS radio bearer identifier information may include identification information for identifying a radio bearer for the UE to receive MBS session data. In addition, the logical channel identifier associated with the MBS radio bearer may include identification information indicating one or more logical channels associated with the radio bearer for the UE to receive MBS session data. The configuration information for receiving MBS session data may include both an MBS radio bearer identifier and a logical channel identifier associated with the MBS radio bearer.

[0137] As an example, the MBS radio bearer identifier may be configured in association with at least one of the MBS session identification information and the MBS QoS flow identification information. In other words, the MBS radio bearer identifier may be allocated in association with the MBS session identification information for identifying the MBS session. Alternatively, the MBS radio bearer identifier may be allocated in association with the QoS flow identification information indicating the MBS QoS flow. Alternatively, the MBS radio bearer identifier may be configured in association with the MBS session identification information and the MBS QoS flow identification information.

[0138] For example, the logical channel identifier associated with the MBS radio bearer may be assigned a different value than the logical channel identifier assigned to the unicast radio bearer for DL-SCH. For example, when the logical channel identifiers 1-32 are assigned to the unicast radio bearer for DL-SCH, the logical channel identifier associated with the MBS radio bearer may be assigned a value other than 1-32.

[0139] Alternatively, a logical channel identifier associated with an MBS radio bearer may be allocated using an extended logical channel ID (LCID). For example, a logical channel identifier associated with an MBS radio bearer may be allocated using a 1-octet or 2-octet extended LCID (eLCID) value on the DL-SCH.

[0140] The base station may perform a step of configuring an MBS radio bearer for transmitting the MBS session data based on the configuration information ( S1120 ).

[0141] The base station may configure an MBS radio bearer for sending MBS session data to the UE. When configuring the MBS radio bearer, the base station may use information included in the configuration information sent to the UE. Thus, the base station and the UE may configure the MBS radio bearer.

[0142] As described above, the base station may use the MBS radio bearer identifier and the logical channel identifier associated with the MBS radio bearer when configuring the MBS radio bearer. In addition, the base station may configure the MBS radio bearer by configuring the MBS session identification information or the MBS QoS flow identifier in association with the MBS radio bearer identifier.

[0143] The execution order of steps S1110 and S1120 may be changed. For example, the base station may configure an MBS radio bearer to send MBS session data to the UE, and may generate and send configuration information of the configured MBS radio bearer to the UE. In other words, step S1110 may be performed after step S1120. In the present disclosure, for ease of description, an example of performing step S1120 after step S1110 is described, but even if step S1110 is performed after step S1120, the embodiments of the present disclosure are also applicable.

[0144] The base station may perform a step of transmitting a MAC protocol data unit (PDU) in which two or more different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed (S1130).

[0145] The UE may receive a MAC PDU in which a plurality of logical channels configured in association with one G-RNTI are multiplexed from the base station. Two or more different logical channels may be multiplexed in the MAC PDU. Thus, the UE may receive MBS session data through the MBS radio bearer.

[0146] The following describes in more detail various embodiments of the UE and the base station and the specific operations of each step. The embodiments described below may be applied individually or in any combination thereof.

[0147] By adding PDCP to the user plane protocol structure between the UE and the base station (gNB) for MBS user data transmission, Embodiments using header compression and / or gNB-CU and gNB-DU split structures

[0148] In conventional LTE, MBMS targets media (e.g., video or audio) services, such as TV broadcasts and public safety services. Therefore, multicast mode, which requires complex group management, is not supported, but only broadcast mode is supported. Therefore, media services based on LTE MBMS can broadcast media data in a specific area without using IP multicast technology.

[0149] However, multicast / broadcast technology in 5G networks requires support for various applications, such as public safety, V2X applications, transparent IPv4 / IPv6 multicast delivery, IPTV, wireless software delivery, group communication, and IoT applications. In other words, 5G networks need to support both small-scale multicast transmission and large-scale multicast / broadcast transmission. In addition, with the widespread use of IPTV, 5G networks need to support transparent transmission of IP multicast to utilize IPTV facilities through mobile communication networks.

[0150] Therefore, it is expected that 5G networks will adopt traditional IP transmission technology. In this case, from the perspective of overall data transmission efficiency, it is expected to reduce the overhead on the IP header.

[0151] To this end, it is preferred to add a PDCP layer on the radio interface (Uu interface) between the base station and the UE for MBS session data transmission. In other words, the use of the header compression technology provided by the PDCP can effectively improve the transmission efficiency. For example, the PDCP on the MBS radio bearer can support header compression. Alternatively, when configuring the MBS radio bearer in the UE, the base station can include and send information indicating whether to add a PDCP entity on the RRC dedicated message / RRC common message / NR MBS control channel. Therefore, the UE can configure an MBS radio bearer with or without a PDCP entity.

[0152] In addition, even for MBS session data transmission, the use of PDCP enables the configuration and application of normal radio bearers transmitted in unicast mode and MBS radio bearers transmitted in multicast / broadcast mode in the gNB-CU and gNB-DU split structure.

[0153] For ease of description, a radio bearer used to transmit MBS session data is referred to as an MBS radio bearer. This is only for convenience of description, and it may be replaced by any other term. An MBS radio bearer may represent a multicast / broadcast / point-to-multipoint radio bearer used to transmit data included in a corresponding MBS session.

[0154] The MBS radio bearer can be a downlink dedicated radio bearer. The MBS radio bearer used in the multicast / broadcast delivery mode can only support RLC UM. As described above, the gNB-CU and gNB-DU are connected through the F1 interface between the hosted PDCP layer and the RLC layer respectively hosted by them. If PDCP is used for the MBS radio bearer, MBS session data transmission under the base station split structure can be easily supported.

[0155] Embodiments supporting 1-to-1 mapping, 1-to-N mapping, and N-to-1 mapping between MBS sessions and MBS radio bearers

[0156] In the MBMS transmission technology based on LTE, an MBMS session is mapped one-to-one to a radio bearer and sent to the UE through the base station. An MBMS session is distinguished from the TMGI used to identify it by an (optional) session identifier (sessionId), and is mapped to an MBMS point-to-multipoint radio bearer (MRB) and sent through the radio interface between the base station and the UE.

[0157] At the same time, 5G supports QoS processing on a flow basis. For MBS services, it may be expected to support QoS processing on a flow basis in the same way.

[0158] For ease of description, a multicast session / service is described below. This is only for ease of description, and the same applies to a broadcast session / service. Therefore, a broadcast session / service is also included in the scope of this embodiment.

[0159] In a 5G mobile communication network, a PDU session represents an association between a UE and a data network that provides a PDU connection service. The current PDU session represents a unicast-based session and is UE-specifically configured. Therefore, the core network entity or base station has unicast session information and can manage a UE context specific to the UE. On the other hand, in the case of a multicast session / service, it can represent a session of one or more UEs / UE groups / group UEs belonging to the multicast session / service. The core network entity or base station can manage a core network entity-specific, base station-specific, or cell-specific multicast session context for the corresponding multicast session / service.

[0160] In a core network entity or a base station, a multicast session context may be identified by an identifier (e.g., a multicast context identifier) ​​for identifying the multicast session context. A multicast context associated with a multicast session may include at least one of the following: a multicast address (e.g., an IP multicast address or a MAC multicast address or any identifier / address for identifying the group), information for identifying the corresponding multicast session (e.g., a TMGI or a session ID), information for identifying a geographical area in which the corresponding multicast session is to be transmitted (e.g., a cell ID list, a service area code list, a service area ID list, a zone ID list), and information for identifying a UE configured with an MBS radio bearer (e.g., a UE identity list, a 5G-S-TMSI list, a C-RNTI list, or an I-RNTI list), the MBS radio bearer corresponding to or authenticated in a service corresponding to / concerned with / subscribed to / belonging to the corresponding multicast session.

[0161] The core network entity or the base station may manage, for a UE configured with an MBS radio bearer corresponding to a session service focused on / subscribed to / belonging to a corresponding multicast session or authenticated in the service, information for identifying the corresponding multicast session on a UE context provided specifically to the UE. The base station may configure a UE-specific unicast radio bearer associated with the MBS radio bearer in the UE to send the corresponding multicast service / session data. Therefore, the base station may effectively change the MBS service / session data delivery scheme according to the context and send it to the UE.

[0162] Fig.12 is a view showing one example of a layer 2 structure for transmitting / receiving MBS data.

[0163] Reference Fig.12 , describes the MBS radio bearers. The MBS radio bearers used for MBS session data transmission can transmit the data contained in the MBS session by multicast / broadcast / point-to-multipoint through multicast / broadcast scheduling in the MAC entity. A common RNTI (e.g., G-RNTI) can be used to identify the transmission of the corresponding MBS session data. Based on the common RNTI, the group-common PDSCH can be scrambled. For multicast / broadcast scheduling on the group-common PDSCH, a group-common PDCCH scrambled by the G-RNTI can be used.

[0164] Fig.13 is a view showing another example of a layer 2 structure for transmitting / receiving MBS data.

[0165] Reference Fig.13Another example of describing an MBS radio bearer. An MBS radio bearer for MBS session data transmission can transmit data included in an MBS session by multicast / broadcast / point-to-multipoint scheduling in a MAC entity. A common RNTI (e.g., G-RNTI) can be used to identify the transmission of corresponding MBS session data. Based on the common RNTI, the group-common PDSCH can be scrambled. For multicast / broadcast scheduling on the group-common PDSCH, a group-common PDCCH scrambled by G-RNTI can be used. In addition, the MBS radio bearer can send data included in the corresponding MBS session by unicast / point-to-point scheduling in a MAC entity. A UE-specific RNTI (e.g., C-RNTI) can be used to identify the transmission of corresponding MBS session data. The PDSCH can be scrambled based on the C-RNTI. For unicast scheduling of the PDSCH, a PDCCH scrambled by CRC by C-RNTI can be used.

[0166] like Fig.13 As shown, the MBS radio bearer may have a split structure with two branches / paths / RLC bearers. Unicast scheduling may be performed in the MAC entity for point-to-point transmission in one branch / path / RLC bearer of the MBS radio bearer. The RLC entity of the unicast branch / path / RLC bearer may be configured in association with a logical channel identifier. Multicast / broadcast scheduling may be performed in the MAC entity for point-to-multipoint transmission in another branch / path / RLC bearer of the MBS radio bearer. The RLC entity of the multicast / broadcast branch / path / RLC bearer may be configured in association with a logical channel identifier.

[0167] The RLC entity of the unicast branch / path / RLC bearer and the RLC entity of the multicast / broadcast point-to-multipoint branch / path / RLC bearer can be associated with a common PDCP entity. Alternatively, the RLC entity of the unicast branch / path / RLC bearer and the RLC entity of the multicast / broadcast point-to-multipoint branch / path / RLC bearer can be associated with different PDCP entities that are synchronized with each other.

[0168] The radio bearer for the unicast branch / path associated with the MBS radio bearer may be configured as a downlink dedicated radio bearer. Therefore, for L2 configuration information such as MAC configuration information, RLC configuration information, PDCP configuration information, and SDAP configuration information included in the unicast branch / path, only downlink dedicated configuration information may be included and configured. Alternatively, the radio bearer for the unicast branch / path associated with the MBS radio bearer may be configured as a normal radio bearer including a downlink / uplink.

[0169] exist Fig.13In the present invention, a radio bearer for a unicast branch / path associated with an MBS radio bearer may represent a radio bearer including such a branch / path / RLC bearer, which transmits data included in an MBS service / session by unicast / point-to-point through unicast scheduling in a MAC entity. As an example, a radio bearer for a unicast branch / path associated with an MBS radio bearer may represent a data radio bearer including a PDCP-RLC-MAC (unicast scheduling) entity. As another example, a radio bearer for a unicast branch / path associated with an MBS radio bearer may represent an RLC bearer including an RLC-MAC (unicast scheduling) entity.

[0170] An MBS session can include one or more multicast / broadcast flows. MBS flows can be identified by MBS QoS flow identifiers. NR supports QoS processing in radio bearer units. NR can use SDAP to map MBS QoS flows received from the core network to MBS radio bearers and send them to support MBS session data transmission.

[0171] As an example, one MBS QoS flow belonging to one MBS session may be mapped to one MBS radio bearer. As another example, one or more MBS QoS flows belonging to one MBS session may be mapped to one MBS radio bearer. As another example, one or more MBS QoS flows belonging to one or more MBS sessions may be mapped to one or more MBS radio bearers. As another example, one or more MBS QoS flows belonging to one or more MBS sessions may be mapped to one MBS radio bearer.

[0172] However, if all the above cases are supported, the related specifications and operations may be very complicated. In each case, the methods described below can be used individually or in combination.

[0173] Embodiment in which each MBS QoS flow sends data separately

[0174] For convenience of description, it is assumed in the following description that MBS session-A includes MBS QoS flow-1 and MBS QoS flow-2, and MBS session-B includes MBS QoS flow-3, MBS QoS flow-4, and MBS QoS flow-5.

[0175] If MBS QoS flow-1 belonging to MBS session-A and MBS QoS flow-3 belonging to MBS session-B have similar traffic characteristics (e.g., the same QCI / 5QI), it may be effective to multiplex the data belonging to the QoS flows and align them for transmission. In this case, if different MBS QoS flows included in different MBS sessions are multiplexed and transmitted through one multicast traffic channel, the UE needs to separate the different MBS QoS flows received through the multicast traffic channel and deliver them to a higher layer through the corresponding MBS session.

[0176] Data belonging to multiple MBS sessions can be transmitted over one transport channel using one radio network temporary identifier (RNTI). For ease of description, the RNTI used for this purpose is represented as the first G-RNTI. This is done only for ease of description and may be replaced by another term. The UE may use a first G-RNTI to identify (multiple / arbitrary) MBS session data transmissions sent over the MBS traffic channel. The first G-RNTI (or the MBS session data addressed by the first G-RNTI) may be transmitted on the DL-SCH. Alternatively, the first G-RNTI (or the MBS session data addressed by the first G-RNTI) may be transmitted on a transport channel for MBS session data transmission different from the DL-SCH. A transport channel different from the DL-SCH may be newly defined. The (time / frequency) radio resource configuration of the newly defined transport channel may be indicated to the UE by the base station. For ease of description, the newly defined transport channel is represented as the MBCH transport channel. This is done only for ease of description and may be replaced by another term.

[0177] The MBS QoS flows belonging to each MBS session can be associated with a logical channel identifier. For example, in the above embodiment, MBS QoS flow-1 and MBS QoS flow-3 having similar traffic characteristics (e.g., the same QCI / 5QI) can be configured to have the same downlink LCID value. MBS QoS flow-2, MBS QoS flow-4, and MBS QoS flow-5 can be configured to have different downlink LCID values. For example, the LCID of MBS QoS flow-1 can be set to 420, the LCID of MBS QoS flow-2 can be set to 321, the LCID of MBS QoS flow-3 can be set to 320, the LCID of MBS QoS flow-4 can be set to 322, and the LCID of MBS QoS flow-5 can be set to 323.

[0178] The above-mentioned MBS traffic logical channel can be distinguished according to the traffic characteristics (e.g., QCI / 5QI) of the MBS session data (associated with the traffic characteristics of the MBS session data). The logical channel identifier can be indicated to the UE by the base station through at least one of an RRC dedicated message (e.g., RRC reconfiguration), an RRC common message (e.g., SIB), and an NR MBS control channel (MCCH).

[0179] However, the LCID information field for DL-SCH is 6-bit long, so that a value allocable to a logical channel for MBS session data may be insufficient.

[0180] Fig.14 is a diagram showing a logical channel identifier value according to one embodiment.

[0181] Reference Fig.14 , 0 is used as the LCID value of DL-SCH, 1-32 is used as the logical channel identifier of the radio bearer, and 33 or 34 is used to use the extended logical channel ID. Since LCID is also used to distinguish various MAC CEs, only 12 values ​​(35-46) are currently reserved among the 6-bit values ​​(0 to 63).

[0182] As described above, an MBS session can be used for multiple applications. Therefore, in order to provide multiple MBS sessions in one cell, multiple G-RNTIs need to be provided to distinguish multiple MBS sessions. Alternatively, multiple MBS radio bearers associated with multiple MBS sessions need to be provided. Alternatively, multiple logical channel identifiers need to be provided to distinguish multiple MBS radio bearers. In order to distinguish and send MBS data, the following embodiments may be used individually or in combination.

[0183] As an example, as described above, an MBCH transport channel different from the DL-SCH may be defined so that a 6-bit in the corresponding transport channel may be used to allocate a logical channel identifier. For example, in a range of separate LCID values ​​that are independently different from the existing LCID value of the DL-SCH (LCID value 0-63 code points / index of the existing DL-SCH or LCID value 1-32 of the unicast radio bearer (SRB, DRB) in the existing DL-SCH), 6 bits (or n bits, where n is any natural number equal to or less than 6) are used to distinguish the MBS traffic logical channel associated with the MBS radio bearer to send / receive data.

[0184] As another example, a logical channel identifier may be set using a 1-octet or 2-octet extended LCID (eLCID) value on the DL-SCH.

[0185] Fig.15is a view exemplarily showing a MAC subheader format including an extended LCID field according to one embodiment.

[0186] Reference Fig.15 , the MAC subheader may be configured in format 1500, which includes an extended LCID as one octet extended from an existing LCID. Alternatively, the MAC subheader may be configured in format 1510, which includes an extended LCID as two octets extended from an existing LCID.

[0187] The extended LCID is a type of LCID used to address the shortage of LCIDs used to identify the MAC SDU or MAC CE in the MAC header / subheader. Fig.15 In the MAC subheader format shown, the eLCID field can have 8 bits (one octet) or 16 bits (two octets).

[0188] Fig.16 is a view showing allocation information of an extended LCID value according to each octet length for a DL-SCH according to one embodiment.

[0189] Reference Fig.16 , since some values ​​of the 1-octet eLCID table 1610 are reserved, the reserved values ​​can be used. Alternatively, when the 2-octet eLCID table 1600 is used, any value can be set and used.

[0190] Therefore, the base station may use an extended LCID for a logical channel identifier associated with an MBS radio bearer. For example, when the base station uses an extended LCID (eLCID), any value in the 2-octet eLCID may be specified and allocated, or a reserved value (code point: 0-244 / index: 64-308) in the 1-octet eLCID may be specified and allocated.

[0191] As another example, the base station may use a fixed (one) LCID value (on DL-SCH / MBCH). For example, among the 6-bit values ​​(0 to 63) of the LCID used for DL-SCH, one or more values ​​among the currently reserved 35-46 values ​​may be specified / fixed and used. In the existing DL-SCH, the LCID value may be used in a separate LCID space (35-46) that is independently different from the LCID space (1-32) of the unicast radio bearer (SRB, DRB). In other words, the logical channel identifier associated with the MBS radio bearer may be assigned a value different from the logical channel identifier assigned to the unicast radio bearer for DL-SCH.

[0192] By way of example, Fig.13 For the MBS radio bearers shown, a logical channel identifier may be used to distinguish between the RLC entities of the unicast branch / path / RLC bearer and the RLC entities of the multicast branch / path / RLC bearer.

[0193] MBS session data transmission is provided only on the downlink. Therefore, although a fixed value is used, there is no problem when the base station distinguishes QoS and performs scheduling and priority processing according to the QoS flow characteristics. The UE can transfer MBS session data (MAC PDU) addressed and received by the G-RNTI from the MAC of the UE to the associated RLC entity. The RLC entity refers to the RLC entity configured in association with the MBS radio bearer. To this end, the RLC entity can be configured in association with the G-RNTI.

[0194] As another example, MBS session data may be sent on DL-SCH using a new MAC subheader that is different from the existing MAC subheader. Alternatively, MBS session data may be sent using a specific value specified in any field included in the existing MAC subheader. The corresponding MAC subheader may include one or more of the following fields: MBS QoS flow identifier, MBS service / session identification information, MBS radio bearer identification information, logical channel identification information, length, G-RNTI, and information indicating the transmission / reception of data using an MBS traffic logical channel associated with an MBS radio bearer (using a separate LCID space (value) different from the LCID space (value) of DL-SCH to distinguish them). Alternatively, the MAC subheader may include code information obtained by mapping / encoding any of the above information.

[0195] Therefore, data can be sent / received using the MBS traffic logical channels associated with the MBS radio bearer (using separate LCID values ​​that are independently different from the existing LCID values ​​of the DL-SCH to distinguish them). Information for indicating the sending / receiving of data using the MBS traffic logical channels associated with the MBS radio bearer (using separate LCID values ​​that are independently different from the LCID values ​​of the DL-SCH to distinguish them) may include the following information: it is used to indicate that the LCID field used in the MAC subheader is used to identify the logical channel instance of the MBS service (MBS MAC SDU). Alternatively, information for indicating the sending / receiving of data using the distinguished MBS traffic logical channels associated with the MBS radio bearer may include the following information: it is used to indicate that the MAC SDU includes the MBS MAC SDU.

[0196] The UE can control to use the MAC subheader for data (MAC PDU) received through the first G-RNTI on the DL-SCH. The MAC subheader can specify a specific fixed value in the LCID field and use the fixed value. Therefore, the UE can recognize that the MAC SDU is an MBS MAC SDU and process the data.

[0197] As described above, one of the currently reserved values ​​(35-46) in the 6-bit value (0-63) can be specified as the LCID. Alternatively, as one of the fields included in the MAC subheader, a specific value can be specified and used to distinguish it. As another example, a new MAC subheader different from the MAC subheader included in the existing DL-SCH can be defined and sent on the MBCH. The new MAC subheader may include one or more of the following fields: MBS QoS flow identifier, MBS session identification information, MBS radio bearer identification information, logical channel identification information, length, G-RNTI, and information for indicating the transmission / reception of data using an MBS traffic logical channel associated with an MBS radio bearer (using a separate LCID space value that is independent / different from the LCID space of the DL-SCH to distinguish them). Alternatively, the new MAC subheader may include code information obtained by mapping / encoding any of the above information.

[0198] MBS session data transmission is provided only on the downlink. The UE can distinguish the MBS session data based on the information included in the MAC subheader of the received MAC PDU and send it to a higher layer. For example, the corresponding data can be sent separately on any sub-L2 (MAC / RLC / PDCP / SDAP) by the association between two of the following information: MBSQoS flow identifier, MBS session identification information, MBS radio bearer identification information, logical channel identification information, length, G-RNTI, and information for indicating the transmission / reception of data using the MBS traffic logical channel associated with the MBS radio bearer (using a separate LCID space value independent / different from the LCID space of the DL-SCH to distinguish them).

[0199] The base station may include the corresponding information in an RRC dedicated message (e.g., RRC reconfiguration), an RRC common message (e.g., SIB), and an NR MBS control channel (MCCH), and transmit it. In other words, the above information about the new MAC subheader may correspond to the combination of Fig.10 and Fig.11 Describes the configuration information.

[0200] As another example, the logical channel identifier may be set to use a 1-octet / 2-octet extended LCID (eLCID) on the DL-SCH. As another example, the base station may use a different RNTI for each MBS QoS flow to distinguish and send data belonging to an MBS session. The base station may indicate corresponding information to the UE through at least one of an RRC dedicated message (e.g., RRC reconfiguration), an RRC common message (e.g., SIB), and an NR MBS control channel (MCCH).

[0201] As another example, the UE (or the MAC entity of the UE) (focusing on the corresponding MBS session) may monitor the PDCCH for the first G-RNTI. When receiving a downlink assignment (or downlink control information) on the PDCCH for the first G-RNTI, the UE attempts to decode the received data. If the data that the UE (or the MAC entity of the UE) attempts to decode is successfully decoded, the UE may transmit the decoded MAC PDU to a disassembly and demultiplexing entity. The UE (or the MAC entity of the UE, or the disassembly and demultiplexing entity of the UE) may transmit the MAC PDU to an RLC entity associated with the corresponding G-RNTI and LCID. The RLC entity may transmit it to the associated PDCP entity. If it is not associated with a PDCP entity but with an SDAP entity, the RLC entity may transmit it directly to the SDAP entity.

[0202] As another example, the SDAP entity can distinguish and transmit different MBS QoS flows in the received data. To this end, an information field for identifying the MBS QoS flow can be defined and included in the SDAP header. In addition, related operations can also be defined in the newly defined field. The information for identifying the MBS QoS flow can be configured to have a 6-bit value (0-63) in the PDU session, similar to the QoS flow identifier. As another example, the information for identifying the MBS QoS flow can be configured to have a value greater than 6 bits (e.g., 7 bits, 8 bits... One of the 16 bits). Since the UE specifically uses the QoS flow identifier in the PDU session, 6 bits may be sufficient to identify the corresponding QoS flow. However, since the MBS session may be set / configured specifically for the core network entity (SMF / AMF) / base station / cell, 6 bits may be insufficient.

[0203] As another example, the SDAP entity can distinguish and transmit different MBS QoS flows belonging to different MBS sessions in the received data. To this end, the traditional SDAP header (SDAP data PDU format including the SDAM header) can be added / modified / changed. As an example, information for identifying an MBS session can be added to the SDAP header (SDAP data PDU format including the SDAP header). As another example, one SDAP entity can be configured for multiple MBS sessions. As another example, for an MBS session, a dynamic MBS QoS flow identifier assigned by the core network (SMF / AMF) / base station can be used instead of the same value as 5QI. Any MBS QoS flow included in an MBS service / session provided in one core network / base station can be configured to have a different QoS flow identifier. MBS session identification information and MBS QoS flow identification information can be assigned in association with each other. As another example, information indicating that a dynamic MBS QoS flow identifier (instead of 5QI) allocated by the core network (SMF / AMF) / base station is to be used for the MBS session may be added to the SDAP header (SDAP data PDU format including the SDAP header).

[0204] As another example, the base station may include information indicating whether to use the SDAP header in at least one of an RRC dedicated message (e.g., RRC reconfiguration), an RRC common message (e.g., SIB), and an NR MBS control channel, and transmit it.

[0205] As another example, a value of 1-32 used as a logical channel identifier for an existing unicast radio bearer (SRB, DRB) on DL-SCH may be used as a logical channel identifier for an MBS radio bearer. As an example, an RLC entity on a multicast point-to-multipoint leg may be configured in association with a logical channel identifier having one of the values ​​1-32. Alternatively, an RLC entity on a unicast point-to-point leg may be configured in association with a logical channel identifier having one of the values ​​1-32.

[0206] The RLC entity on the multicast / broadcast point-to-multipoint branch and the RLC entity on the unicast point-to-point branch may have the same logical channel identifier. Even in this case, since the RNTI for addressing the PDSCH on the multicast point-to-multipoint branch and the unicast point-to-point branch are different, the MAC entity can recognize it and transmit it to the RLC entity. Alternatively, the RLC entity on the multicast point-to-multipoint branch and the RLC entity on the unicast point-to-point branch may have different logical channel identifiers. Although the RNTI for addressing the PDSCH on the multicast point-to-multipoint branch and the unicast point-to-multipoint branch are different, if the MAC (de)multiplexing entity takes this into account, it may be difficult to perform independent operations of each layer. Therefore, it may be preferable to configure different logical channel identifiers for them. Therefore, information for distinguishing them (e.g., G-RNTI) may be included in the MAC subheader. Therefore, the corresponding MBS session data may be transmitted to the RLC entity.

[0207] If the initial transmission / reception of point-to-multipoint (PTM) through the multicast point-to-multipoint branch fails, HARQ retransmission can be performed through the unicast point-to-point branch. The corresponding transport block / data can be sent / received through the unicast point-to-point branch through the HARQ process in which the initial transmission / reception of PTM fails. The PDSCH including the transport block / data can be addressed by the C-RNTI. The HARQ entity / process can transmit it to the (de)multiplexing entity, and the (de)multiplexing entity can transmit the MBS data received through the retransmission to the RLC entity on the multicast point-to-multipoint branch based on the information included in the MAC subheader (e.g., G-RNTI). Alternatively, the HARQ entity / process can transmit it to the (de)multiplexing entity, and the (de)multiplexing entity can transmit the MBS data received through the retransmission to the RLC entity on the unicast point-to-point branch.

[0208] Method for transmitting data separately for each MBS session

[0209] For convenience of description, the following description is made based on the above example. As described above, MBS Session-A includes MBS QoS Flow-1 and MBS QoS Flow-2, and MBS Session-B includes MBS QoS Flow-3, MBS QoS Flow-4, and MBS QoS Flow-5.

[0210] Although MBS QoS flow-1 belonging to MBS session-A and MBS QoS flow-3 belonging to MBS session-B have similar traffic characteristics (e.g., the same QCI / 5QI), if data belonging to the QoS flows are multiplexed and sent, the UE receiving the data (e.g., on MAC or any sub-L2) may need to receive the MBS QoS traffic service belonging to the MBS session that the UE is concerned about and discard / distinguish the data (received sub-PDU).

[0211] As an example, a base station may use one radio network temporary identifier (RNTI) to send data belonging to multiple MBS sessions through one transport channel. For ease of description, the RNTI used in this case is represented as a second G-RNTI. This is done only for ease of description, and it may be replaced by another term. A second G-RNTI may be used to identify (multiple / arbitrary) MBS session data transmissions sent through an MBS traffic channel. The second G-RNTI (or MBS session data addressed by the second G-RNTI) may be sent on the DL-SCH. Alternatively, the second G-RNTI (or MBS session data addressed by the second G-RNTI) may be transmitted on a transport channel different from the DL-SCH for MBS session data transmission. The corresponding transport channel may be newly defined in the NR. The (time / frequency) radio resource configuration for the transport channel may be indicated to the UE by the base station.

[0212] As another example, the base station may associate each MBS session with a radio network temporary identifier (RNTI) and transmit data belonging to the MBS session. For ease of description, the RNTI in this case is represented as a third G-RNTI. This is only for ease of description, and it may be replaced by another term.

[0213] A second G-RNTI / third G-RNTI may be used to identify (multiple / arbitrary) MBS session data transmissions sent over an MBS traffic channel. A second G-RNTI / third G-RNTI (or MBS session data addressed by a second G-RNTI / third G-RNTI) may be sent on a DL-SCH. Alternatively, a second G-RNTI / third G-RNTI (or MBS session data addressed by a second G-RNTI / third G-RNTI) may be transmitted on a transport channel other than the DL-SCH for MBS session data transmission. The corresponding transport channel may be newly defined on the NR. The (time / frequency) radio resource configuration for the transport channel may be indicated to the UE by the base station. For ease of description, it is referred to as the MBCH transport channel. This is done only for ease of description, and it may be replaced by another term. The base station may include corresponding information (e.g., MBS service / session identification information and third G-RNTI associated information, or MBS service / session identification information and logical channel identifier, MBS bearer identification information, third G-RNTI associated information, and inter-MBS QoS flow identifier related information) in at least one of an RRC dedicated message (e.g., RRC configuration), an RRC common message (e.g., SIB), and an NR MBS control channel, and send it.

[0214] As another example, the MBS QoS flow belonging to each MBS session may be associated with a logical channel identifier. MBS traffic logical channels are distinguished according to the traffic characteristics (e.g., QCI / 5QI) of the MBS session data, and the corresponding logical channel identifier may be indicated by the base station to the UE through at least one of an RRC dedicated message (e.g., RRC reconfiguration), an RRC common message (e.g., SIB), and an NR MBS control channel. The length of the LCID information field of the DL-SCH is 6 bits long, so that there are insufficient values ​​that can be allocated to the logical channel of the MBS session data. The following embodiments may be used alone or in combination.

[0215] As an example, as described above, an MBCH transport channel different from the DL-SCH can be defined so that 6 bits in the corresponding transport channel can be used to allocate a logical channel identifier. For example, in a separate LCID space that is independently different from the existing LCID space for DL-SCH (LCID space 0-63 code points / indexes for the existing DL-SCH or LCID space 1-32 code points / indexes for unicast radio bearers (SRB, DRB) in the existing DL-SCH), 6 bits (or n bits, where n is any natural number equal to or less than 6) are used to distinguish the MBS traffic logical channel associated with the MBS radio bearer to send / receive data.

[0216] As another example, a 1-octet / 2-octet extended LCID (eLCID) on DL-SCH may be used. Fig.16 When using extended LCID, any value in the 2-octet eLCID can be specified and used, or a reserved value in the 1-octet eLCID (code point: 0-244 / index: 64-308) can be specified and used.

[0217] As another example, a fixed (one) LCID value (on DL-SCH / MBCH) may be used. For example, in the 6-bit value (0 to 63) of the LCID for DL-SCH, one or more values ​​from the currently reserved 35-46 values ​​may be specified / fixed and used. In the existing DL-SCH, the LCID value may be used in a separate LCID value (35-46) that is independently different from the LCID value (1-32) of the unicast radio bearer (SRB, DRB).

[0218] By way of example, Fig.13 For the MBS radio bearer shown, a logical channel identifier may be used to distinguish between an RLC entity of a unicast branch / path / RLC bearer and an RLC entity of a multicast branch / path / RLC bearer for the MBS radio bearer.

[0219] MBS session data transmission is provided only on the downlink. Therefore, although a fixed value is used, there is no problem when the base station distinguishes QoS and performs scheduling and priority processing according to the QoS flow characteristics. The UE can transfer MBS data (MAC PDU) addressed and received by the G-RNTI from the MAC of the UE to the associated RLC entity. The RLC entity refers to the RLC entity configured in association with the MBS radio bearer. To this end, the RLC entity can be configured in association with the G-RNTI.

[0220] As another example, a new MAC subheader different from the existing MAC subheader can be defined and sent on the DL-SCH. Alternatively, a specific value can be specified and sent in any field included in the existing MAC subheader. The newly defined MAC subheader may include one or more of the following fields: MBS QoS flow identifier, MBS session identification information, MBS radio bearer identification information, logical channel identification information, length, G-RNTI, and information for indicating the transmission / reception of data using the MBS traffic logical channel associated with the MBS radio bearer (using a separate LCID space value that is independent / different from the LCID space of the DL-SCH to distinguish them). Alternatively, the MAC subheader may include code information obtained by mapping / encoding any of the above information.

[0221] The MAC subheader can be used for data (MAC PDU) received through the third G-RNTI (or second G-RNTI) on the DL-SCH. The MAC subheader can specify a specific fixed value in the LCID and use the fixed value. Therefore, the UE can recognize that the MAC SDU is an MBS MAC SDU and process the data. As the LCID, one of the currently reserved values ​​(35-46) in the 6-bit value (0-63) can be assigned. Alternatively, as one of the fields included in the MAC subheader, a specific value can be specified and used to distinguish it.

[0222] As another example, a new MAC subheader different from the MAC subheader included in the existing DL-SCH can be defined and sent on the MBCH. The corresponding MAC subheader may include one or more of the following fields: MBS QoS flow identifier, MBS session identification information, MBS radio bearer identification information, logical channel identification information, length, G-RNTI, and information for indicating the transmission / reception of data using an MBS traffic logical channel associated with the MBS radio bearer (using a separate LCID space value that is independent / different from the LCID space of the DL-SCH to distinguish them). Alternatively, the MAC subheader may include code information obtained by mapping / encoding any of the above information. MBS session data transmission is provided only on the downlink. The UE can distinguish the MBS session data based on the information included in the MAC subheader of the received MAC PDU and send it to a higher layer. For example, corresponding data can be distinguished and sent on any sub-L2 (MAC / RLC / PDCP / SDAP) by association between two of the following information: MBS QoS flow identifier, MBS session identification information, MBS radio bearer identification information, logical channel identification information, and G-RNTI. The base station can include the corresponding information in at least one of an RRC dedicated message (e.g., RRC reconfiguration), an RRC common message (e.g., SIB), and an NR MBS control channel (MCCH), and send it.

[0223] As another example, the base station may use 1-octet / 2-octet extended LCID (eLCID) on DL-SCH. As another example, the base station may use a different RNTI for each MBS QoS flow to send data belonging to an MBS session. The base station may include corresponding information in at least one of an RRC dedicated message (e.g., RRC reconfiguration), an RRC common message (e.g., SIB), and an NR MBS control channel (MCCH), and send it.

[0224] As another example, in the base station, for a (MAC) PDU associated with one piece of downlink control information, the MAC may multiplex only a logical channel having one MBS session (or one piece of MBS session identification information).

[0225] As another example, the UE (or the MAC entity of the UE) (focusing on the corresponding MBS session) may monitor the PDCCH for the second G-RNTI / third G-RNTI. When receiving a downlink assignment (or downlink control information) on the PDCCH for the second G-RNTI / third G-RNTI, the UE attempts to decode the received data. If the data that the UE (or the MAC entity of the UE) attempts to decode is successfully decoded, the UE may transmit the decoded MAC PDU to the decomposition and demultiplexing entity. The UE (or the MAC entity of the UE, or the decomposition and demultiplexing entity of the UE) may transmit the MAC PDU to the RLC entity associated with the corresponding LCID. The RLC entity may transmit it to the associated PDCP entity. If it is not associated with the PDCP entity but with the SDAP entity, the RLC entity may transmit it directly to the SDAP entity.

[0226] As another example, the SDAP entity can distinguish and transmit different MBS QoS flows in the received data. To this end, an information field for identifying the MBS QoS flow can be defined and included in the SDAP header. In addition, related operations can also be defined in the corresponding field. The information for identifying the MBS QoS flow can be configured to have a 6-bit value (0-63) in the PDU session like the QoS flow identifier. As another example, the information for identifying the MBS QoS flow can have a value greater than 6 bits (e.g., 7 bits, 8 bits... One of the values ​​of 16 bits). Since the QoS flow identifier is specific to UE use in the PDU session, 6 bits may be sufficient to identify the corresponding QoS flow. However, since the MBS session may be set / configured specifically for the core network entity (SMF / AMF) / base station / cell, 6 bits may be insufficient.

[0227] As another example, the SDAP entity can distinguish and transmit different MBS QoS flows belonging to different MBS sessions in the received data. To this end, the traditional SDAP header (SDAP data PDU format including the SDAM header) can be added / modified / changed. As an example, information for identifying the MBS session can be added to the SDAP header (SDAP data PDU format including the SDAP header). As another example, one SDAP entity can be configured for multiple MBS sessions. As another example, the SDAP entity can be configured separately for each MBS session. The MBS radio bearer can be configured for each MBS session by the SDAP entity. One SDAP entity can be configured for an individual MBS session. To this end, the base station can include MBS session identification information and MBS QoS flow identifier related information in the SDAP configuration information, and send the information through at least one of an RRC dedicated message (e.g., RRC reconfiguration), an RRC common message (e.g., SIB), and an NR MBS control channel.

[0228] As another example, for an MBS session, a dynamic MBS QoS flow identifier assigned by the core network (SMF / AMF) / base station may be used instead of the same value as 5QI. Any MBS QoS flow included in an MBS session provided in one core network / base station may be configured to have a different QoS flow identifier. The MBS session identification information and the MBS QoS flow identification information may be assigned in association with each other. As another example, information indicating that a dynamic MBS QoS flow identifier (instead of 5QI) assigned by the core network (SMF / AMF) / base station is to be used for an MBS session may be added to an SDAP header (SDAP data PDU format including an SDAP header).

[0229] As another example, the base station may transmit information indicating whether to use the SDAP header through at least one of an RRC dedicated message (eg, RRC reconfiguration), an RRC common message (eg, SIB), and an NR MBS control channel (MCCH).

[0230] Through the above operation, MBS session data can be processed separately in QoS flow units in the NR radio access network. The configuration of the UE and the base station capable of performing the above embodiment is described again below.

[0231] Fig.17 is a view showing a configuration of a UE according to one embodiment.

[0232] Reference Fig.17, a UE 1700 receiving multicast / broadcast service (MBS) data includes: a receiver 1730 that receives configuration information for receiving MBS session data from a base station; and a controller 1710 that configures an MBS radio bearer for receiving MBS session data based on the configuration information. The receiver 1730 may receive a MAC protocol data unit (PDU) in which two or more different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed.

[0233] As an example, the configuration information for receiving the MBS session data may be included in the RRC reconfiguration message and received by the UE 1700. As another example, the configuration information for receiving the MBS session data may be received through an MBS control channel (MCCH) message.

[0234] The configuration information for receiving MBS session data may include various information required for UE 1700 to receive MBS session data. For example, the configuration information for receiving MBS session data may include MBS radio bearer identifier information. The MBS radio bearer identifier information may include identification information for identifying a radio bearer used by the UE to receive MBS session data. In addition, the logical channel identifier associated with the MBS radio bearer may include identification information indicating one or more logical channels associated with the radio bearer used for the UE to receive MBS session data. The configuration information for receiving MBS session data may include both an MBS radio bearer identifier and a logical channel identifier associated with the MBS radio bearer.

[0235] As an example, the MBS radio bearer identifier may be configured in association with at least one of the MBS session identification information and the MBS QoS flow identification information. In other words, the MBS radio bearer identifier may be allocated in association with the MBS session identification information for identifying the MBS session. Alternatively, the MBS radio bearer identifier may be allocated in association with the QoS flow identification information indicating the MBS QoS flow. Alternatively, the MBS radio bearer identifier may be configured in association with both the MBS session identification information and the MBS QoS flow identification information.

[0236] The logical channel identifier associated with the MBS radio bearer may be assigned a different value than the logical channel identifier assigned to the unicast radio bearer for DL-SCH. For example, when the logical channel identifiers 1-32 are assigned to the unicast radio bearer for DL-SCH, the logical channel identifier associated with the MBS radio bearer may be assigned a value other than 1-32.

[0237] Alternatively, a logical channel identifier associated with an MBS radio bearer may be allocated using an extended logical channel ID (LCID). For example, a logical channel identifier associated with an MBS radio bearer may be allocated using a 1-octet or 2-octet extended LCID (eLCID) value on the DL-SCH.

[0238] Therefore, the logical channel identifier associated with the MBS radio bearer may be distinguished from the unicast radio bearer.

[0239] The controller 1710 configures an MBS radio bearer for receiving MBS session data in the UE by using an MBS radio bearer identifier and a logical channel identifier associated with the MBS radio bearer. As described above, the logical channel identifier associated with the MBS radio bearer may be assigned a value different from the logical channel identifier of the unicast radio bearer. Alternatively, the logical channel identifier associated with the MBS radio bearer may be assigned as an extended LCID code point / index.

[0240] In addition, the controller 1710 controls the overall operation of the UE 1700 according to an embodiment of efficiently and individually processing multicast / broadcast service data in the NR radio network required to perform the above-mentioned embodiments.

[0241] The transmitter 1720 and the receiver 1730 are used to send or receive signals, messages or data required to execute the above embodiments with the base station.

[0242] Fig.18 is a view showing a configuration of a base station according to one embodiment.

[0243] Reference Fig.18 , a base station 1800 that transmits multicast / broadcast service (MBS) data includes: a transmitter 1820 that transmits configuration information for receiving MBS session data of the UE to a UE; and a controller 1810 that configures an MBS radio bearer for transmitting the MBS session data based on the configuration information.

[0244] The transmitter 1820 may transmit a MAC protocol data unit (PDU) in which two or more different logical channels associated with the same group radio network temporary identifier (G-RNTI) are multiplexed.

[0245] As an example, the configuration information for receiving MBS session data may be included in an RRC reconfiguration message and transmitted to the UE. As another example, the configuration information for receiving MBS session data may be transmitted through an MBS control channel (MCCH) message.

[0246] The configuration information for receiving MBS session data may include various information required for the UE to receive the MBS session data. For example, the configuration information for receiving MBS session data may include MBS radio bearer identifier information. The MBS radio bearer identifier information may include identification information for identifying the radio bearer used by the UE to receive the MBS session data. In addition, the logical channel identifier associated with the MBS radio bearer may include identification information indicating one or more logical channels associated with the radio bearer used by the UE to receive the MBS session data. The configuration information for receiving MBS session data may include both the MBS radio bearer identifier and the logical channel identifier associated with the MBS radio bearer.

[0247] As an example, the MBS radio bearer identifier may be configured in association with at least one of the MBS session identification information and the MBS QoS flow identification information. In other words, the MBS radio bearer identifier may be allocated in association with the MBS session identification information for identifying the MBS session. Alternatively, the MBS radio bearer identifier may be allocated in association with the QoS flow identification information indicating the MBS QoS flow. Alternatively, the MBS radio bearer identifier may be configured in association with both the MBS session identification information and the MBS QoS flow identification information.

[0248] For example, the logical channel identifier associated with the MBS radio bearer may be assigned a different value than the logical channel identifier assigned to the unicast radio bearer for DL-SCH. For example, when the logical channel identifiers 1-32 are assigned to the unicast radio bearer for DL-SCH, the logical channel identifier associated with the MBS radio bearer may be assigned a value other than 1-32.

[0249] Alternatively, a logical channel identifier associated with an MBS radio bearer may be allocated using an extended logical channel ID (LCID). For example, a logical channel identifier associated with an MBS radio bearer may be allocated using a 1-octet or 2-octet extended LCID (eLCID) value on the DL-SCH.

[0250] The controller 1810 may configure an MBS radio bearer for sending MBS session data to the UE. When configuring the MBS radio bearer, the controller 1810 may use information included in the configuration information sent to the UE. Thus, the base station and the UE may configure the MBS radio bearer. The controller 1810 may control the MBS radio bearer to be configured first, generate the configuration information, and send it to the UE.

[0251] The base station may transmit a MAC PDU to the UE, in which a plurality of logical channels configured in association with one G-RNTI are multiplexed, thereby transmitting the MBS session data.

[0252] In addition, the controller 1810 controls the overall operation of the base station 1800 according to an embodiment of efficiently and individually processing multicast / broadcast service data in the NR radio network required to perform the above-mentioned embodiments.

[0253] The transmitter 1820 and the receiver 1830 are used to send or receive signals, messages or data required to execute the above embodiments with the UE.

[0254] The above-mentioned embodiments may be supported by standard documents disclosed in IEEE 802, 3GPP and 3GPP2 as radio access systems. In other words, steps, components and parts not described in the embodiments for the purpose of clarifying the technical spirit may be supported by the above-mentioned standard documents. In addition, all terms disclosed in the present disclosure may be described by the above-mentioned standard documents.

[0255] The above-mentioned embodiment can be implemented by various means. For example, the embodiment can be implemented by various means, such as hardware, firmware, software or a combination thereof.

[0256] When implemented in hardware, the method according to the present embodiment can be implemented by, for example, one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, or microprocessors.

[0257] When implemented in firmware or hardware, the method according to the present embodiment can be implemented in the form of a device, process or function that performs the above functions or operations. The software code can be stored in a memory unit and driven by a processor. The memory unit can be located inside or outside the processor to exchange data with the processor through various known means.

[0258] The above terms such as "system", "processor", "controller", "component", "module", "interface", "model" or "unit" described above may generally refer to computer-related entity hardware, a combination of hardware and software, software, or software being executed. For example, the above components may be, but are not limited to, processes driven by a processor, multiple processors, a controller, a control processor, an entity, an execution thread, a program and / or a computer. For example, an application being executed by a controller or a processor and the controller or the processor are both components. One or more components may reside within an executing process and / or thread, and the components may be located in one device (e.g., a system, a computing device, etc.) or distributed in two or more devices.

[0259] The above-described embodiments are merely examples, and those of ordinary skill in the art will appreciate that various changes may be made thereto without departing from the scope of the present invention. Therefore, the embodiments set forth herein are provided for illustrative purposes, rather than to limit the scope of the present invention, and it should be understood that the scope of the present invention is not limited by the embodiments. The scope of the present invention should be interpreted by the appended claims, and all technical spirits within their equivalents should be interpreted as belonging to the scope of the present invention.

[0260] Cross-references to related applications

[0261] This patent application claims the benefit of priority under 35 USC 119(a) to Korean Patent Application Nos. 10-2020-0091116 and 10-2021-0094216 filed in the Korean Intellectual Property Office on July 22, 2020 and July 19, 2021, respectively, the disclosures of which are incorporated herein by reference in their entirety. This patent application claims the benefit of priority to other applications to be filed in other countries, the disclosures of which are also incorporated herein by reference in their entirety.

Claims

1. A method for receiving multicast / broadcast service (MBS) data by a UE, the method comprising: receiving, from a base station, configuration information for receiving MBS session data; configuring an MBS radio bearer for receiving the MBS session data based on the configuration information; as well as receiving the MBS session data using a logical channel identifier associated with the MBS radio bearer, wherein the configuration information for receiving MBS session data comprises an MBS radio bearer identifier associated with the MBS radio bearer and the logical channel identifier, and The MBS radio bearer identifier is configured in association with at least one of MBS session identification information and MBS QoS flow identification information. 2 . The method according to claim 1 , wherein the configuration information for receiving MBS session data is received through an RRC reconfiguration message or an MBS control channel (MCCH) message.

3. The method of claim 1, wherein the logical channel identifier associated with an MBS radio bearer is allocated using a 2-octet extended logical channel ID (LCID).

4. The method of claim 1, wherein a logical channel for processing the MBS session data is individually identified based on a G-RNTI indicated through an MBS control channel (MCCH) and the logical channel identifier associated with an MBS radio bearer. 5 . The method of claim 1 , wherein two or more MBS session data are received using the same Group Radio Network Temporary Identifier (G-RNTI) or different G-RNTIs.

6. A method for transmitting multicast / broadcast service (MBS) data by a base station, the method comprising: Sending, to a UE, configuration information for receiving MBS session data by the UE; configuring an MBS radio bearer for sending the MBS session data based on the configuration information; as well as sending the MBS session data using a logical channel identifier associated with the MBS radio bearer, wherein the configuration information for receiving MBS session data comprises an MBS radio bearer identifier associated with the MBS radio bearer and the logical channel identifier, and The MBS radio bearer identifier is configured in association with at least one of MBS session identification information and MBS QoS flow identification information. 7 . The method according to claim 6 , wherein the configuration information for receiving MBS session data is transmitted through an RRC reconfiguration message or an MBS Control Channel (MCCH) message.

8. The method of claim 6, wherein the logical channel identifier associated with an MBS radio bearer is allocated using a 2-octet extended logical channel ID (LCID).

9. The method of claim 6, wherein a logical channel for processing the MBS session data is individually identified based on a G-RNTI indicated through an MBS control channel (MCCH) and the logical channel identifier associated with an MBS radio bearer.

10. A UE for receiving multicast / broadcast service (MBS) data, the UE comprising: a receiver, which receives configuration information for receiving MBS session data from a base station; as well as a controller configured to configure an MBS radio bearer for receiving the MBS session data based on the configuration information, wherein the receiver receives the MBS session data using a logical channel identifier associated with the MBS radio bearer, wherein the configuration information for receiving MBS session data comprises an MBS radio bearer identifier associated with the MBS radio bearer and the logical channel identifier, and The MBS radio bearer identifier is configured in association with at least one of MBS session identification information and MBS QoS flow identification information. 11 . The UE according to claim 10 , wherein the configuration information for receiving MBS session data is received through an RRC reconfiguration message or an MBS Control Channel (MCCH) message.

12. The UE according to claim 10, wherein the configuration information for receiving MBS session data comprises an MBS radio bearer identifier associated with the MBS radio bearer and the logical channel identifier, and The MBS radio bearer identifier is configured in association with at least one of MBS session identification information and MBS QoS flow identification information.

13. A base station for sending multicast / broadcast service (MBS) data, the base station comprising: a transmitter, configured to send configuration information for receiving MBS session data by the UE to the UE; and a controller configured, based on the configuration information, to configure an MBS radio bearer for transmitting the MBS session data, wherein the transmitter sends the MBS session data using a logical channel identifier associated with the MBS radio bearer, wherein the configuration information for receiving MBS session data comprises an MBS radio bearer identifier associated with the MBS radio bearer and the logical channel identifier, and The MBS radio bearer identifier is configured in association with at least one of MBS session identification information and MBS QoS flow identification information.

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