MBS Secure Communication Method and Equipment in Wireless Communication Systems

Abstract

A method and apparatus are provided for secure multicast and broadcast service (MBS) communication in a wireless communication system. A method for operating a terminal in a wireless communication system includes receiving configuration information from a base station to be applied to MBS data, and receiving the MBS data based on the configuration information, wherein the configuration information is used to configure initial values ​​for state variables corresponding to the MBS data.

Description

Technical Field

[0001] The present invention relates to a wireless communication system, and more specifically, to a method and apparatus for secure multicast and broadcast service (MBS) communication in a wireless communication system. Background Technology

[0002] To meet the growing demand for wireless data services following the commercialization of fourth-generation (4G) communication systems, efforts are underway to develop fifth-generation (5G) or pre-5G communication systems. For this purpose, 5G or pre-5G communication systems are referred to as "beyond 4G networks" or "post-LTE" systems. To achieve high data rates, implementation of 5G communication systems in ultra-high frequency (UHF) or millimeter-wave (mmWave) bands (e.g., the 60 GHz (80 GHz) band) is being considered. To reduce path loss and increase transmission distance of radio waves in the UHF band used for 5G communication systems, various technologies are being investigated, such as beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO. To improve system networks used in 5G communication systems, various technologies have been developed, such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), and receive interference cancellation. Furthermore, for 5G communication systems, advanced coding and modulation (ACM) technologies have been developed, such as hybrid frequency shift keying (FSK), quadrature amplitude modulation (QAM) (FQAM), and sliding window superposition coding (SWSC), as well as advanced access technologies such as filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse coded multiple access (SCMA).

[0003] The Internet has evolved from a human-based network of connections where humans create and consume information to the Internet of Things (IoT), where distributed elements, such as objects, exchange information to process it. The Internet of Everything (IoE) technology has emerged, where IoT technology combines with technologies for processing big data, such as those for connecting to cloud servers. To realize IoT, various technological components are needed, such as sensing technologies, wired / wireless communication and network infrastructure, service interface technologies, and security technologies. In recent years, technologies related to sensor networks for connecting objects, machine-to-machine (M2M) communication, and machine-type communication (MTC) have been researched. In the IoT environment, intelligent Internet technology (IT) services can be provided to collect and analyze data from connected objects, thereby creating new value in human life. Due to the convergence and integration of existing information technology (IT) with various industries, IT can be applied to a wide range of fields, such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services.

[0004] Various attempts are underway to apply 5G communication systems to IoT networks. For example, technologies related to sensor networks, M2M communication, and MTC are being implemented using 5G communication technologies including beamforming, MIMO, and array antennas. Cloud RAN, as an application of the aforementioned big data processing technologies, can be seen as an example of the convergence of 5G communication and IoT technologies.

[0005] Since various services can be provided based on the above characteristics and the development of wireless communication systems, there is a particular need for methods to seamlessly provide services related to multicast and broadcast. Summary of the Invention

[0006] [Technical Issues]

[0007] The described embodiments provide an apparatus and method for effectively supporting services in a mobile communication system.

[0008] [Solution to the problem]

[0009] According to an embodiment of this disclosure, an operation method of a terminal in a wireless communication system includes: receiving configuration information from a base station to be applied to multicast and broadcast service (MBS) data; and receiving the MBS data based on the configuration information, wherein the configuration information is used to configure initial values ​​of state variables corresponding to the MBS data.

[0010] Receiving configuration information from a base station can include receiving configuration information while MBS data is being broadcast or multicast from the base station.

[0011] Configuration information may include at least one of the following: RX_DELIV value, RX_NEXT value, COUNT value, or superframe number (HFN) value.

[0012] The operation method may also include identifying the HFN value of the first received MBS data packet in the MBS data based on the RX_DELIV value or the RX_NEXT value.

[0013] The operation method may also include identifying the COUNT value of the first received MBS data packet in the MBS data based on the HFN value.

[0014] According to an embodiment of this disclosure, an operation method of a base station in a wireless communication system includes: broadcasting or multicasting multicast and broadcast service (MBS) data to a terminal, and sending configuration information to the terminal, the configuration information being applied to a first MBS data packet received by the terminal in the MBS data, wherein the configuration information is used to configure an initial value for a state variable corresponding to the first MBS data packet.

[0015] Configuration information may include at least one of the following: RX_DELIV value, RX_NEXT value, COUNT value, or superframe number (HFN) value.

[0016] The initial value can be determined by the HFN value, which is identified based on the RX_DELIV or RX_NEXT values.

[0017] The initial value can be determined by the COUNT value identified based on the HFN value.

[0018] According to embodiments of the present disclosure, a terminal in a wireless communication system includes a transceiver and at least one processor connected to the transceiver, wherein the at least one processor is configured to receive configuration information from a base station that will be applied to multicast and broadcast service (MBS) data, and to receive the MBS data based on the configuration information, wherein the configuration information is used to configure initial values ​​for state variables corresponding to the MBS data.

[0019] The at least one processor may be configured to receive the configuration information while the MBS data is being broadcast or multicast from the base station.

[0020] Configuration information may include at least one of the following: RX_DELIV value, RX_NEXT value, COUNT value, or superframe number (HFN) value.

[0021] The at least one processor may be configured to identify the HFN value of the first received MBS data packet in the MBS data based on the RX_DELIV value or the RX_NEXT value.

[0022] The at least one processor may be configured to identify the COUNT value of the first received MBS data packet in the MBS data based on the HFN value.

[0023] According to embodiments of this disclosure, a base station in a wireless communication system includes a transceiver and at least one processor connected to the transceiver, wherein the at least one processor is configured to broadcast or multicast service and broadcast service (MBS) data to a terminal and send configuration information to the terminal for a first MBS data packet received by the terminal in the MBS data, wherein the configuration information is used to configure an initial value for a state variable corresponding to the first MBS data packet. Attached Figure Description

[0024] Figure 1 This is a diagram illustrating an operational method of MBS communication according to an embodiment of the present disclosure.

[0025] Figure 2 This is a diagram illustrating the operation of a terminal receiving data for MBS communication from the middle of transmitting data according to an embodiment of the present disclosure.

[0026] Figure 3 This is a diagram illustrating how to configure RX_DELIV and RX_NEXT as state variables of the PDCP layer.

[0027] Figure 4 This is a diagram illustrating the operation of a terminal receiving data for MBS communication from the middle of transmitting data according to an embodiment of the present disclosure.

[0028] Figure 5 A method for configuring initial values ​​of state variables for a terminal performing MBS communication by a base station according to an embodiment of the present disclosure is shown.

[0029] Figure 6 A method for configuring initial values ​​of state variables for a terminal performing MBS communication by a base station according to an embodiment of the present disclosure is shown.

[0030] Figure 7 A method is shown for a base station to configure the HFN value of a state variable for a terminal performing MBS communication according to an embodiment of the present disclosure.

[0031] Figure 8 A method for configuring reference count values ​​for a terminal performing MBS communication by a base station according to an embodiment of the present disclosure is shown.

[0032] Figure 9 A method for configuring initial values ​​of state variables for a terminal performing MBS communication by a base station according to an embodiment of the present disclosure is shown.

[0033] Figure 10This is a flowchart illustrating a method by which a base station performs secure MBS communication with a terminal according to an embodiment of the present disclosure.

[0034] Figure 11 This is a flowchart illustrating a method by which a base station performs secure MBS communication with a terminal according to an embodiment of the present disclosure.

[0035] Figure 12 This is a diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0036] Figure 13 This is a diagram illustrating the structure of a terminal according to an embodiment of the present disclosure. Detailed Implementation

[0037] The operating principles of this disclosure will be described in detail below with reference to the accompanying drawings. Detailed descriptions of well-known functions or configurations will be omitted in the following description of this disclosure, as they would unnecessarily obscure the subject matter of this disclosure. Furthermore, the terminology described below may be defined in consideration of the functions in this disclosure and may vary depending on the intent or practice of the user or operator. Therefore, its definition should be based on the entire contents of this specification.

[0038] For the same reason, some parts in the accompanying drawings may be exaggerated, omitted, or shown schematically. Furthermore, the dimensions of each part may not perfectly reflect its actual size. In the drawings, identical or corresponding elements may be given the same reference numerals.

[0039] The advantages and features of this disclosure, as well as its implementation methods, will become apparent from the embodiments described in detail below with reference to the accompanying drawings. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments described below; rather, these embodiments are provided to complete this disclosure and to fully convey the scope of this disclosure to those skilled in the art, and this disclosure will be defined only by the scope of the claims. Throughout the specification, the same reference numerals may denote the same elements.

[0040] It should be understood that each block of a process flowchart and combinations thereof can be executed by computer program instructions. Because these computer program instructions can be mounted on a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions, which execute via the processor of the computer or other programmable data processing equipment, can generate means for performing the functions described in the flowchart blocks. Because these computer program instructions can be stored in a computer-executable or computer-readable storage device and directed to the computer or other programmable data processing equipment to implement the functions in a particular manner, the instructions stored in the computer-executable or computer-readable storage device can also produce an article of writing containing instruction means for performing the functions described in one or more flowchart blocks. Because the computer program instructions can also be mounted on a computer or other programmable data processing equipment, the execution of a series of operations on the computer or other programmable data processing equipment to generate a computer-implemented process, and the execution of the instructions of the computer or other programmable data processing equipment, can also provide operations for performing the functions described in one or more flowchart blocks.

[0041] Furthermore, each box can represent a portion of a module, segment, or code that includes one or more executable instructions for performing one or more specified logical functions. It should also be noted that the functions mentioned in a box may appear in a different order in some alternative implementation examples. For example, two boxes shown consecutively may actually be executed substantially simultaneously, or sometimes in reverse order depending on their respective functions.

[0042] In this context, the term "unit" as used in this embodiment can refer to a software component or a hardware component, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), and a "unit" can perform certain functions. However, a "unit" is not limited to software or hardware. A "unit" can be configured to reside in addressable storage media or can be configured to operate one or more processors. Thus, as an example, a "unit" can include components such as software components, object-oriented software components, class components, and task components, and can include processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided by components and "units" can be associated with a small number of components and "units," or can be further divided into additional components and "units." Furthermore, components and "units" can be implemented as one or more central processing units (CPUs) in an operating device or secure multimedia card. Additionally, in this embodiment, a "unit" can include one or more processors.

[0043] In the following description of this disclosure, detailed descriptions of well-known functions or configurations will be omitted as they would unnecessarily obscure the subject matter of this disclosure. Embodiments of this disclosure will be described below with reference to the accompanying drawings.

[0044] In the following description, for ease of description, terms used to identify access nodes, terms relating to network entities, terms relating to messages, terms relating to interfaces between network entities, terms relating to various identification information, etc., are used. Therefore, this disclosure is not limited to the terms used below, and other terms relating to objects with equivalent technical meanings may be used.

[0045] In the following text, a base station may be an agent that performs terminal resource allocation, and may be at least one of a gNode B, eNode B, Node B, base station (BS), radio access unit, base station controller, or node on a network. Examples of terminals may include user equipment (UE), mobile station (MS), cellular phone, smartphone, computer, or multimedia system capable of performing communication functions. Furthermore, the term "terminal" may refer to other wireless communication devices besides mobile phones, NB-IoT devices, and sensors. However, base stations and terminals are not limited to these.

[0046] In the following description, for ease of description, this disclosure uses terms and names defined in the 3GPP Long Term Evolution (3GPP LTE) standard and / or 3GPP New Radio (NR). However, this disclosure is not limited to those terms and names and can be applied equivalently to systems according to other standards. In this disclosure, for ease of description, eNB and gNB may be used interchangeably. That is, a base station described as eNB may represent gNB.

[0047] Specifically, this disclosure applies to 3GPP NR (5G mobile communication standard). Furthermore, this disclosure applies to smart services based on 5G communication technology and IoT technology (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail businesses, security and security-related services). In this disclosure, for ease of description, eNB and gNB can be used interchangeably. That is, a base station described as eNB can represent a gNB. Additionally, the term "terminal" can refer to other wireless communication devices besides mobile phones, NB-IoT devices, and sensors.

[0048] Wireless communication systems that provide voice-based services are evolving into broadband wireless communication systems that provide high-speed and high-quality packet data services according to communication standards such as High-Speed ​​Packet Access (HSPA), Long Term Evolution (LTE) or Evolved Universal Terrestrial Radio Access (E-UTRA), 3GPP's LTE Advanced (LTE-A) and LTE-Pro, 3GPP2's High Rate Packet Data (HRPD) and Ultra Mobile Broadband (UMB), and the Institute of Electrical and Electronics Engineers (IEEE) 802.16e.

[0049] As a representative example of a broadband wireless communication system, the LTE system employs Orthogonal Frequency Division Multiplexing (OFDM) for the downlink (DL) and Single-Carrier Frequency Division Multiple Access (SC-FDMA) for the uplink (UL). The uplink can refer to the radio link used to transmit data or control signals from a terminal (e.g., a User Equipment (UE) or Mobile Station (MS)) to a base station (e.g., an eNode B (eNB) or Base Station (BS)), and the downlink can refer to the radio link used to transmit data or control signals from the base station to the terminal. These multiple access schemes distinguish the data or control information of different users by allocating non-overlapping time-frequency resources to their data or control information, thus achieving orthogonality between them.

[0050] As a post-LTE system, 5G systems may need to support services that can simultaneously meet a variety of needs, as they may have to freely reflect the diverse requirements of users, service providers, and others. Services considered for 5G systems may include enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC).

[0051] According to embodiments, eMBB can be designed to provide data rates better than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, from the base station's perspective, eMBB should be able to provide a peak data rate of 20Gbps in the downlink and a peak data rate of 10Gbps in the uplink. Furthermore, 5G communication systems may need to provide increased user-perceived data rates to the terminal while providing peak data rates. To meet this requirement, 5G communication systems may need to improve various transmit / receive technologies, including more improved multiple-input multiple-output (MIMO) transmission technologies. Additionally, 5G communication systems can meet the required data rates by using up to 20MHz of transmission bandwidth in the 2GHz band currently used in LTE, while using frequency bandwidths wider than 20MHz in the 3GHz to 6GHz or 6GHz and above bands.

[0052] Meanwhile, mMTC is considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To effectively deliver IoT, mMTC may need to support access to a large number of terminals within a cell, improved terminal coverage, improved battery life, and reduced terminal costs. Because IoT connects to various sensors and devices to provide communication capabilities, it should be able to support a large number of terminals within a cell (e.g., 1,000,000 terminals / km). 2 Furthermore, because mMTC-enabled terminals may be located in shadow areas not covered by the cell (such as the basement of a building), they may require wider coverage than other services provided by 5G communication systems due to the nature of the service. Since it is difficult to frequently replace the terminal's battery, mMTC-enabled terminals should be configured as low-cost terminals and may require a very long battery life of approximately 10 to 15 years.

[0053] Finally, URLLC can be used as a cellular-based wireless communication service for mission-critical purposes, such as robot or machine remote control, industrial automation, drones, telemedicine, emergency alarms, etc. Therefore, communication provided by URLLC may need to offer very low latency (ultra-low latency) and very high reliability (ultra-high reliability). For example, services supporting URLLC should meet an air interface latency of less than 0.5 milliseconds and can simultaneously have 10 -5 Or a smaller packet error rate requirement. Therefore, for services supporting URLLC, 5G systems should provide smaller transmission time intervals (TTIs) than other services, and can also have design requirements for allocating wide resources in the frequency band to ensure the reliability of the communication link.

[0054] In 5G communication systems, the three services eMBB, URLLC, and mMTC can be multiplexed and transmitted within a single system. In this case, different transmit / receive technologies and parameters can be used between services to meet their varying requirements. However, mMTC, URLLC, and eMBB are merely examples of different service types, and the service types applied in this disclosure are not limited to these.

[0055] Furthermore, although embodiments of this disclosure will be described below using LTE, LTE-A, LTE Pro, or 5G (or NR, next-generation mobile communications) as examples, embodiments of this disclosure can also be applied to other communication systems with similar technical backgrounds or channel configurations. Moreover, embodiments of this disclosure can be applied to other communication systems with modifications without departing from the scope of this disclosure as judged by those skilled in the art.

[0056] In the following description, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0057] Figure 1 This is a diagram illustrating an operational method of MBS communication according to an embodiment of the present disclosure. Multicast and Broadcast Service (MBS) communication can refer to a method in which a transmitting device in a mobile communication system communicates with several receiving devices. Here, the transmitting device may be a base station, and each receiving device may be a terminal. However, the present disclosure is not limited thereto, and the transmitting device may be a terminal.

[0058] Figure 1 An example of MBS communication is shown, where base station (gNB) 110 is the transmitting device, and terminals 120, 130, 140, and 150 are receiving devices. MBS communication can be a broadcast to multiple unspecified receiving devices, or it can be a multicast to multiple specific receiving devices. When communication is performed in a multicast manner, the base station can configure only specific terminals to receive the corresponding multicast packets. For this purpose, a set of terminals can be configured to perform specific multicast communication, and... Figure 1 In this embodiment, it is referred to as multicast group 160.

[0059] Terminals 120, 130, and 140 in multicast group 160 can receive data assigned to the G-RNTI by being assigned the same Group Radio Network Temporary Identifier (G-RNTI) from base station 110. Figure 1 In this embodiment, it is assumed that terminals 1120, 2130, and 3140 are configured as a multicast group 160 and are assigned a G-RNTI to receive data from base station 110 via multicast. Because terminal 4150 is not included in the multicast group, terminal 4150 may not be assigned a G-RNTI, and therefore terminal 4150 may not receive the data received by terminals 1120, 2130, and 3140 from the base station.

[0060] One or more multicast groups can be configured within the coverage area of ​​base station 110, and each multicast group can be identified by a G-RNTI. One or more G-RNTIs can be assigned from base station 110 to a terminal. The terminal can receive multicast data not only in connected mode (RRCCONNECTED MODE), but also in idle mode (RRC IDLE MODE) or inactive mode (RRC INACTIVE MODE) by using the G-RNTI value assigned in connected mode. The G-RNTI can be configured in the terminal by being included in at least one of RRC reconfiguration, RRC establishment, and RRC reconstruction messages that the terminal can receive in connected mode. However, this disclosure is not limited to this, and the G-RNTI can be sent from the base station by including the G-RNTI as a G-RNTI value that the terminal can receive in a System Information Block (SIB). A terminal configured with a G-RNTI value according to one or more of the above methods can apply the G-RNTI value after it has been configured.

[0061] Figure 2 This diagram illustrates the operation of a terminal receiving data for MBS communication from the middle of data transmission according to an embodiment of the present disclosure. MBS communication can be a communication method in which multiple terminals receive the same data from base station 200. Whether a terminal will receive data for a specific MBS communication can be determined based on whether the terminal is interested in the MBS communication data. However, all terminals may not receive MBS communication data simultaneously. For example, by establishing an RRC connection with base station 200 later than other terminals receiving information about MBS communication from base station 200, terminal 210 may receive information about MBS communication later than other terminals. In this case, the reception time of terminal 210 regarding data for MBS communication can be delayed. That is, there may be a situation where terminal 210 starts receiving data sent from base station 200 for MBS communication from the middle, rather than starting to receive data from the beginning. As another example, due to the mobility of terminal 210, terminal 210 can perform a handover to a base station other than base station 200. In this scenario, within the coverage of base station 200, since the desired reception time for MBS communication data by terminal 210 can occur after handover, terminal 210 can begin receiving data from a time different from when another terminal receives data for MBS communication from base station 200. For example, refer to... Figure 2The base station 200, which transmits data for MBS communication, may transmit data associated with a specific MBS communication, and the terminal 210, which attempts to receive data for MBS communication, may not receive data transmitted by the base station from the beginning for various reasons. Alternatively, the terminal 210 may perform data reception for MBS communication after obtaining reception information for MBS communication. This may mean that packets can be received (220) from the middle of the sequence number in the Packet Data Convergence Protocol (PDCP) layer. Receiving packets from the middle of the sequence number may mean that the existing unicast transmit / receive process of configuring the initial value of the sequence number to 0 can be avoided. In particular, when security functions such as encryption and integrity protection should be performed, the COUNT value corresponding to the combination of the sequence number value and the superframe number (HFN) value should match the packets transmitted between the base station 200 as the transmitting device and the terminal 210 as the receiving device. This disclosure proposes a method for configuring the HFN value and COUNT value of packets between the base station and the terminal to perform security functions in MBS communication.

[0062] Figure 3 This diagram illustrates the configuration of RX_DELIV and RX_NEXT as state variables in the PDCP layer. PDCP layer receive operations can be performed by updating the values ​​of state variables representing the COUNT values ​​of packets. The main state variables used in this case can include RX_DELIV and RX_NEXT. RX_DELIV can represent the COUNT value of the packet with the smallest COUNT value among packets that have not yet been sent to the upper layers of the PDCP layer but are still waiting to be received in the PDCP layer. RX_NEXT can be the COUNT value of a packet expected to be received in the next PDCP layer, and can be configured to be obtained by adding 1 to the maximum COUNT value among the COUNT values ​​of packets received up to now.

[0063] Figure 3 An example of configuring RX_DELIV and RX_NEXT is shown. Assuming in... Figure 3At the current time, packets corresponding to COUNT values ​​35, 36, and 40 have already been received. However, suppose no packets corresponding to COUNT values ​​37, 38, 39, 41, 42, and higher have been received. In this case, the PDCP layer can sequentially send the received packets to the upper layer up to COUNT 36. However, to wait for packets corresponding to COUNT values ​​37, 38, and 39 (which are unreceived packets with COUNT values ​​less than 40), packets corresponding to the received COUNT value 40 can be queued in the PDCP receive buffer and not sent to the upper layer. In this case, RX_NEXT 320 can be configured as 41, which is obtained by adding 1 to the COUNT value of the packets received so far. This is likely because packets corresponding to COUNT value 41 are expected to arrive at the next PDCP layer. Furthermore, 37, which has the smallest COUNT value among the packets not yet received, can be configured as RX_DELIV 310. The difference between the RX_DELIV and RX_NEXT values ​​can indicate that there is currently a packet stored in the PDCP receive buffer, and that the PDCP layer is waiting for a packet with a COUNT value smaller than the stored packet. Figure 3 This illustrates a scenario where the PDCP layer should wait for the reception of packets corresponding to COUNT values ​​37, 38, and 39, because packets corresponding to COUNT 40 have arrived, but packets corresponding to COUNT 37, 38, and 39 have not yet arrived. For this purpose, the PDCP layer can start a reordering timer, configure the RX_NEXT value as the RX_REORD state variable, and wait for the reception of packets with values ​​less than or equal to the RX_REORD value during the reordering timer period. When a terminal performs data reception for MBS communication, it may be necessary to determine which RX_DELIV and RX_NEXT values ​​to use when initiating MBS communication. For example, the terminal may need to determine which RX_DELIV and RX_NEXT values ​​to use to prevent unwanted packet loss or to prevent increased latency due to packet reordering.

[0064] Figure 4This diagram illustrates the operation of a terminal receiving data for MBS communication from the middle of data transmission according to an embodiment of the present disclosure. MBS communication can be a communication method in which multiple terminals receive the same data from base station 400. Whether a terminal will receive data for a specific MBS communication can be determined based on whether the terminal is interested in the MBS communication data. However, all terminals may not receive MBS communication data simultaneously. For example, by establishing an RRC connection with base station 400 later than other terminals receiving information about MBS communication from base station 400, terminal 410 may receive information about MBS communication later than other terminals. In this case, the reception time of terminal 410 regarding data for MBS communication can be delayed. That is, there may be a situation where terminal 410 starts receiving data for MBS communication transmitted from base station 400 from the middle without starting to receive data from the beginning. As another example, due to the mobility of terminal 410, terminal 410 may perform a handover to a base station other than base station 400. In this scenario, within the coverage of base station 400, since the desired reception time for data used for MBS communication by terminal 410 can occur after handover, terminal 410 can begin receiving data from a time different from when another terminal receives data for MBS communication from base station 400. For example, refer to... Figure 4 The base station 400, which transmits data for MBS communication, may transmit data about a specific MBS communication, and the terminal 410, which attempts to receive data for MBS communication, may not receive data transmitted by the base station from the beginning for various reasons. Alternatively, the terminal 410 may perform data reception for MBS communication after obtaining reception information for MBS communication. This may mean that packets (420) can be received from the middle of the sequence number in the Packet Data Convergence Protocol (PDCP) layer. Receiving packets from the middle of the sequence number may mean that the existing unicast transmit / receive process of configuring the initial value of the sequence number to 0 can be avoided. In particular, when security functions such as encryption and integrity protection should be performed, the COUNT value corresponding to the combination of the sequence number value and the superframe number (HFN) value should match the packets transmitted between the base station 400 as the transmitting device and the terminal 410 as the receiving device.

[0065] According to embodiments of this disclosure, in order to match the aforementioned COUNT value, before terminal 410 receives data for MBS communication, base station 400 may notify terminal 410 of an initial state variable value or a variable value 430 that can be used to derive the initial state variable value. For example, the initial state variable value may be at least one of the RX_DELIV and RX_NEXT values ​​that should be configured and used by terminal 410. Alternatively, in order for terminal 410 to derive the RX_DELIV or RX_NEXT value, base station 400 may notify terminal 410 of the HFN value of the first received packet that terminal 410 receives for MBS communication as an initial variable value. Initial state variables or variable values ​​that can be used to derive initial state variable values ​​may be configured for each PDCP entity, and the PDCP entity may be a radio bearer that can provide MBS service or perform point-to-multipoint (PTM) transmission. A radio bearer capable of providing MBS service or performing PTM transmission may be referred to as a PTM data radio bearer (DRB). However, in another embodiment, it can be referred to by another name, such as MBS DRB, MBS RB, or MBS Radio Bearer (MRB). Terminal 410 can perform the process of receiving packets from the intermediate sequence number from base station 400 by using the received initial state variable value or variable value 430 that can be used to derive the initial state variable value. According to embodiments of this disclosure, in order to receive data from base station 400 for MBS communication, terminal 410 can send a message to base station 400 requesting MBS service. For example, the message requesting MBS service may include MBS service request information and / or a list of MBS services of interest. When base station 400 receives the message requesting MBS service from terminal 410, base station 400 can send a message to terminal 410 configuring MBS service. The message configuring MBS service may include MBS service configuration information for receiving data by terminal 410 for MBS communication. The MBS service configuration information may include the aforementioned initial state variable value or variable value 430 that can be used to derive the initial state variable value. Furthermore, the message configuring MBS service may be sent via unicast. Terminal 410 can perform secure MBS communication with base station 400 by applying MBS service configuration information received from base station 400 to terminal 410.

[0066] According to embodiments of this disclosure, reference can be made to Figure 3The process described herein is used to execute the procedure by which terminal 410 receives packets from base station 400 from the middle of the sequence number using an initial state variable value or a variable value 430 that can be used to derive the initial state variable value. For example, terminal 410, having already obtained the initial state variable value, can start a reordering timer in the PDCP layer of terminal 410, configure the obtained RX_NEXT value as the RX_REORD state variable, and can wait for the reception of packets less than or equal to the RX_REORD value during the reordering timer period. As described above, terminal 410 can prevent unwanted packet loss and prevent increased latency due to packet reordering by using an initial state variable value configured by base station 400 for MBS service or a variable value 430 that can be used to derive the initial state variable value.

[0067] Figure 5 A method for configuring initial values ​​of state variables for a terminal performing MBS communication by a base station according to an embodiment of the present disclosure is illustrated. When terminal 520 intends to receive data for MBS communication or to change the configuration regarding the data being received for MBS communication, base station 510 may send configuration information regarding MBS communication to terminal 520 to allow terminal 520 to apply the configuration information regarding MBS communication. However, in some cases, terminal 520 receiving data for MBS communication may receive data from the middle of a sequence number. Therefore, by allowing base station 510 to send initial values ​​of state variables to be used by terminal 520 for receiving data for MBS communication, it may be necessary to prevent unwanted packet loss and increase in latency due to packet reordering when terminal 520 sends / receives data from the middle of a packet sequence. According to reference... Figure 5 The methods described in the embodiments of this disclosure can prevent packet loss and increased latency.

[0068] refer to Figure 5 In embodiments of this disclosure, during operation 530, base station 510 may configure terminal 520 using the initial values ​​of RX_DELIV and RX_NEXT of the PDCP layer, which are used by terminal 520 to receive data for MBS communication. Since RX_DELIV and RX_NEXT are both state variables of the COUNT value, they may have an HFN portion and a sequence number portion. According to embodiments of this disclosure, the transmitted initial value of RX_DELIV may be equal to or less than the initial value of RX_NEXT. However, the difference between the RX_DELIV value and the RX_NEXT value may not be greater than (or may not be greater than) the length of the PDCP receive window. For example, when the length of the receive window is 2^(number of bits in the sequence number size - 1), the RX_DELIV and RX_NEXT values ​​may not be greater than (or may not be less than) the length of the receive window.

[0069] In embodiments of this disclosure, base station 510 may send all COUNT values ​​related to the RX_DELIV value to terminal 520, and configure only the difference between RX_DELIV and the RX_NEXT value. For example, when the initial value of RX_DELIV has a COUNT value of 15 and the difference with RX_NEXT is 3, RX_NEXT may be configured as a value of 18 obtained by adding 3 to 15. Alternatively, base station 510 may send all COUNT values ​​related to the RX_NEXT value to terminal 520, and configure only the difference between RX_DELIV and RX_NEXT. For example, when the initial value of RX_NEXT has a COUNT value of 18 and the difference with RX_NEXT is 3, RX_DELIV may be configured as a value of 15 obtained by subtracting 3 from 18.

[0070] According to embodiments of this disclosure, initial values ​​for RX_DELIV and RX_NEXT can be configured for each Point-to-Multipoint Data Radio Bearer (PTM DRB) that performs MBS communication. Furthermore, when no initial RX_DELIV and RX_NEXT values ​​are configured for a specific PTM DRB, the terminal 520 can configure the initial values ​​of RX_DELIV and RX_NEXT to 0 for that specific PTM DRB. In another embodiment, when no initial RX_DELIV and RX_NEXT values ​​are configured for a specific PTM DRB, the terminal 520 can configure the initial value of RX_NEXT as the remainder after dividing the value obtained by adding the sequence number of the first received packet in the PTM DRB to 1 by the total sequence number size (2^(number of bits in the sequence number size)). Furthermore, the initial value of RX_DELIV can be configured as the remainder after dividing the value obtained by subtracting half the size of the PDCP receive window from the sequence number of the first received packet by the total sequence number size (2^(number of bits in the sequence number size)). In operation 540, terminal 520 may apply the RX_DELIV and RX_NEXT values ​​received in operation 530 (or, in the case where the PTM DRB has not configured the initial RX_DELIV and RX_NEXT values, the values ​​are 0) to subsequently receive data for MBS communication. Afterward, terminal 520 may send a configuration completion report message to base station 510, indicating that the initial values ​​of RX_DELIV and RX_NEXT have been accurately received and will be applied to terminal 520.

[0071] Figure 6A method for configuring initial values ​​of state variables for a terminal performing MBS communication by a base station according to an embodiment of the present disclosure is illustrated. When terminal 620 intends to receive data for MBS communication or change the configuration regarding the data being received for MBS communication, base station 610 may send configuration information regarding MBS communication to terminal 620 to allow terminal 620 to apply the configuration information. However, in some cases, terminal 620 receiving data for MBS communication may receive data from the middle of a sequence number. Therefore, by allowing base station 610 to send initial values ​​of state variables to be used by terminal 620 for receiving data for MBS communication, it may be necessary to prevent unwanted packet loss and increase latency due to packet reordering when terminal 620 sends / receives data from the middle of a packet sequence. Reference Figure 6 The method described according to embodiments of this disclosure can prevent packet loss and increased latency.

[0072] refer to Figure 6 In embodiments of this disclosure, during operation 630, base station 610 can configure terminal 620 using the initial value of RX_DELIV of the PDCP layer, which is used by terminal 620 to receive data for MBS communication. Because RX_DELIV is a state variable of the COUNT value, it can have an HFN portion and a sequence number portion. Furthermore, the initial value of RX_NEXT can be configured to be the same as RX_DELIV.

[0073] According to embodiments of this disclosure, an initial value for RX_DELIV can be configured for each Point-to-Multipoint Data Radio Bearer (PTM DRB) that performs MBS communication. Furthermore, when no initial RX_DELIV value is configured for a particular PTM DRB, the terminal 620 can configure the initial value of RX_DELIV to 0. In another embodiment, when no initial RX_DELIV and RX_NEXT values ​​are configured for a particular PTM DRB, the terminal 620 can configure the initial value of RX_NEXT as the remainder after dividing the value obtained by adding the sequence number of the first received packet in the PTM DRB to 1 by the total sequence number size (2^(number of bits in the sequence number size)). Furthermore, the initial value of RX_DELIV can be configured as the remainder after dividing the value obtained by subtracting half the size of the PDCP receive window from the sequence number of the first received packet by the total sequence number size (2^(number of bits in the sequence number size)). In operation 640, terminal 620 may apply the RX_DELIV and RX_NEXT values ​​received in operation 630 (or, in the case where the PTM DRB has not configured the initial RX_DELIV and RX_NEXT values, the value is 0) to subsequently receive data for MBS communication. Afterward, terminal 620 may send a configuration completion report message to base station 610, indicating that the initial value of RX_DELIV has been accurately received and will be applied to terminal 620.

[0074] Figure 7 A method for configuring the HFN value of a state variable for a terminal performing MBS communication by a base station according to an embodiment of the present disclosure is illustrated. When terminal 720 intends to receive data for MBS communication or to change the configuration regarding the data being received for MBS communication, base station 710 may send configuration information regarding MBS communication to terminal 720 to allow terminal 720 to apply the configuration information regarding MBS communication. However, in some cases, terminal 720 receiving data for MBS communication may receive data from the middle of a sequence number. Therefore, by allowing base station 710 to send initial values ​​of state variables to be used by terminal 720 for receiving data for MBS communication, it may be necessary to prevent unwanted packet loss and increase latency due to packet reordering when terminal 720 sends / receives data from the middle of a packet sequence.

[0075] Furthermore, when applying encryption or integrity protection to transmitted / received data, the base station 710 and terminal 720 may need to use the same HFN value for encrypting each packet. (According to reference...) Figure 7 The methods described in the embodiments of this disclosure can prevent packet loss and increased latency, while simultaneously performing data encryption and integrity protection.

[0076] refer to Figure 7 In embodiments of this disclosure, during operation 730, base station 710 can configure terminal 720 using the initial value of the HFN of the PDCP layer used by terminal 720 to receive data for MBS communication. By applying the received HFN value, terminal 720 can determine the HFN value and initial values ​​of state variables (e.g., RX_DELIV or RX_NEXT) for the first packet of data received by terminal 720 for MBS communication. The initial value of the HFN can be configured for each Point-to-Multipoint Data Radio Bearer (PTM DRB) that performs MBS communication. Furthermore, when no initial HFN value is configured for a particular PTM DRB, the terminal can configure the initial value of the HFN to 0 for that particular PTM DRB. In another embodiment, when the initial RX_DELIV and RX_NEXT values ​​are not configured for a specific PTM DRB, the terminal 720 can configure the initial value of RX_NEXT as the remainder after dividing the value obtained by adding 1 to the sequence number of the first received packet in the PTM DRB by the total sequence number size (2^(number of bits in the sequence number size)). Furthermore, the initial value of RX_DELIV can be configured as the remainder after dividing the value obtained by subtracting half the size of the PDCP receive window from the sequence number of the first received packet by the total sequence number size (2^(number of bits in the sequence number size)).

[0077] According to an embodiment of the present invention, in operation 730, the initial value of the HFN received by terminal 720 may be data used for MBS communication through terminal 720, and may be the HFN value of the first PDCPPDU (or PDCP SDU) received in the radio bearer performing MBS communication. Terminal 720 can obtain the COUNT value of the first received packet by combining the sequence number and the HFN value included in the header of the first received packet.

[0078] According to embodiments of this disclosure, the initial value of the HFN received by the terminal 720 in operation 730 may include the HFN value of the initial value of RX_DELIV. The sequence number portion of the initial value of RX_DELIV may be data used for MBS communication via the terminal 720, and may be derived from the sequence number of the first packet received in the radio bearer performing the MBS communication. The terminal 720 can obtain the COUNT value of the initial value of RX_DELIV by combining the derived sequence number portion of the initial value of RX_DELIV and the HFN value received in operation 730. The sequence number portion of RX_DELIV may be the remainder after dividing the value obtained by subtracting a predetermined constant from the sequence number of the first received packet by 2^(number of bits in the sequence number size). Here, the predetermined constant may be half the size of the reordering window.

[0079] According to embodiments of this disclosure, the initial value of the HFN received by the terminal 720 in operation 730 may include the HFN value of the initial value of RX_NEXT. The sequence number portion of the initial value of RX_NEXT may be data used for MBS communication performed by the terminal 720, and may be derived from the sequence number of the first packet received in the radio bearer performing the MBS communication. The terminal 720 can obtain the COUNT value of the initial value of RX_NEXT by combining the derived sequence number portion of the initial value of RX_NEXT and the HFN value received in operation 730.

[0080] In operation 740, terminal 720 can apply the HFN value received in operation 730 to subsequently receive data for MBS communication. Afterward, terminal 720 can send a configuration completion report message to base station 710, indicating that the initial HFN value configuration has been accurately received and will be applied to terminal 720.

[0081] Figure 8 A method for configuring reference count values ​​for a terminal performing MBS communication by a base station according to an embodiment of the present disclosure is illustrated. When terminal 820 intends to receive data for MBS communication or to change the configuration regarding the data being received for MBS communication, base station 810 may send configuration information regarding MBS communication to terminal 820 to allow terminal 820 to apply the configuration information regarding MBS communication. However, in some cases, terminal 820 receiving data for MBS communication may receive data from the middle of a sequence number. Therefore, by allowing base station 810 to send initial values ​​of state variables to be used by terminal 820 for receiving data for MBS communication, it may be necessary to prevent unwanted packet loss and increase latency due to packet reordering when terminal 820 sends / receives data from the middle of a packet sequence.

[0082] Furthermore, when applying encryption or integrity protection to transmitted / received data, the base station 810 and terminal 820 may need to use the same HFN value for encrypting each packet. (According to reference...) Figure 8 The methods described in the embodiments of this disclosure can prevent packet loss and increased latency, while simultaneously performing data encryption and integrity protection.

[0083] refer to Figure 8 In embodiments of this disclosure, during operation 830, base station 810 may configure terminal 820 using a reference COUNT value of the PDCP layer used by terminal 820 to receive data for MBS communication. By using the reference COUNT value configured by base station 810, terminal 820 can determine which HFN value to apply to which received packet. A reference COUNT value can be configured for each Point-to-Multipoint Data Radio Bearer (PTM DRB) that performs MBS communication. Furthermore, when no reference COUNT value is configured for a particular PTM DRB, the terminal may configure the initial value of HFN to 0 for that particular PTM DRB. In another embodiment, when no initial RX_DELIV and RX_NEXT values ​​are configured for a particular PTM DRB, terminal 820 may configure the initial value of RX_NEXT as the remainder after dividing the value obtained by adding the sequence number of the first received packet in the PTM DRB to 1 by the total sequence number size (2^(number of bits in the sequence number size)). In addition, the initial value of RX_DELIV can be configured as the remainder after dividing the value obtained by subtracting half the size of the PDCP receive window from the sequence number of the first received packet by the total sequence number size (2^(number of bits in the sequence number size)).

[0084] The reference COUNT can include a reference sequence number and its HFN value. For example, when the reference COUNT is 32 bits in size and the reference sequence number is 18 bits in size, the HFN value of the reference sequence number can be 14 bits in size, obtained by subtracting 18 from 32. Furthermore, for example, the HFN can be 14 most significant bits (MSB), and the sequence number can be 18 least significant bits (LSB). Additionally, for example, the COUNT value can be "(2^(number of bits in the sequence number)) * HFN + sequence number". The reference COUNT value can be a value indicating which HFN value should be applied to which sequence number when the terminal 820 receives data for MBS communication.

[0085] In operation 830, the reference COUNT value received by terminal 820 can be data used for MBS communication performed by terminal 820, and can also be used to determine the HFN value of the first PDCP PDU (or PDCPSDU) received in the radio bearer performing MBS communication. For example, when the sequence number value of the first PDCP PDU (or PDCP SDU) received in the radio bearer performing MBS communication as data performed by terminal 820 is x, the COUNT value with the closest distance to the reference COUNT among the COUNT values ​​with sequence number x can be applied as the COUNT value of the PDCP PDU (or PDCP SDU). Terminal 820 can obtain the HFN value from the COUNT value of the aforementioned first received PDCP PDU (or PDCP SDU).

[0086] For example, when the absolute value of the value obtained by subtracting the sequence number of the first received PDCP PDU (or PDCP SDU) from the reference sequence number is greater than or equal to 0 and less than the reordering window size, the terminal 820 can configure the HFN value of the first received PDCP PDU (or PDCP SDU) to be the same as the reference HFN value. Otherwise, when the absolute value of the value obtained by subtracting the reference sequence number from the sequence number of the first received PDCP PDU (or PDCP SDU) is greater than the reordering window size, the terminal 820 can configure the HFN value of the first received PDCP PDU (or PDCP SDU) to be the value obtained by subtracting 1 from the reference HFN value. Otherwise, when the absolute value of the value obtained by subtracting the sequence number of the first received PDCP PDU (or PDCP SDU) from the reference sequence number is greater than the reordering window size, the terminal 820 can configure the HFN value of the first received PDCP PDU (or PDCP SDU) to be the value obtained by adding 1 to the reference HFN value. When the difference between <the sequence number of the first received PDCP PDU (or PDCP SDU)> and <the reference sequence number> equals the reordering window size, terminal 820 can apply a specific HFN value or apply a predetermined value.

[0087] The reference COUNT value received by the terminal 820 in operation 830 can be used to determine the initial HFN value of RX_DELIV. The sequence number value of RX_DELIV can be data for MBS communication performed by the terminal 820, and can be determined by the sequence number value of the first received PDCP PDU (or PDCP SDU). In addition, when the determined sequence number value of RX_DELIV is x, the COUNT value having the closest distance to the reference COUNT among the COUNT values having the sequence number x value can be applied as the COUNT value of RX_DELIV. The terminal 820 can obtain the HFN value from the applied COUNT value of RX_DELIV.

[0088] For example, when the absolute value of the value obtained by subtracting the <sequence number of RX_DELIV> from the <reference sequence number> is greater than or equal to 0 and less than the reordering window size, the terminal 820 can configure the HFN value of RX_DELIV to be the same as the value of the reference HFN. Otherwise, when the value obtained by subtracting the <reference sequence number> from the <sequence number of RX_DELIV> is greater than the reordering window size, the terminal 820 can configure the HFN value of RX_DELIV to be the value obtained by subtracting 1 from the reference HFN value. Otherwise, when the value obtained by subtracting the <sequence number of RX_DELIV> from the <reference sequence number> is greater than the reordering window size, the terminal 820 can configure the HFN value of RX_DELIV to be the value obtained by adding 1 to the reference HFN value. When the difference between the <sequence number of RX_DELIV> and the <reference sequence number> is equal to the reordering window size, the terminal 820 can apply a specific HFN value or apply a predetermined value.

[0089] The reference COUNT value received by the terminal 820 in operation 830 can be used to determine the initial HFN value of RX_NEXT. The sequence number value of RX_NEXT can be data for MBS communication performed by the terminal 820, and can be determined by the sequence number value of the first received PDCP PDU (or PDCP SDU). In addition, when the determined sequence number value of RX_NEXT is x, the COUNT value having the closest distance to the reference COUNT among the COUNT values having the sequence number x value can be applied as the COUNT value of RX_NEXT. The terminal 820 can obtain the HFN value from the applied COUNT value of RX_NEXT.

[0090] For example, when the absolute value of the value obtained by subtracting the sequence number of <RX_NEXT> from the <reference sequence number> is greater than or equal to 0 and less than the reordering window size, the terminal 820 may configure the HFN value of RX_NEXT to be the same as the value of the reference HFN. Otherwise, when the value obtained by subtracting the <reference sequence number> from the <sequence number of RX_NEXT> is greater than the reordering window size, the terminal 820 may configure the HFN value of RX_NEXT to be the value obtained by subtracting 1 from the reference HFN value. Otherwise, when the value obtained by subtracting the <reference sequence number> from the <sequence number of RX_NEXT> is greater than the reordering window size, the terminal 820 may configure the HFN value of RX_NEXT to be the value obtained by adding 1 to the reference HFN value. When the difference between the <sequence number RX_NEXT> and the <reference sequence number> is equal to the reordering window size, the terminal 820 may apply a specific HFN value or apply a predetermined value.

[0091] As Figure 8 shown, the terminal 820 may obtain an initial HFN value by applying the reference count value received in operation 830, and may receive data for MBS communication later by using the obtained initial HFN value. Thereafter, the terminal 820 may send a configuration completion report message to the base station 810, which indicates that the configuration of the reference count value has been accurately received and that the received reference count value (or the initial HFN value obtained by using the reference count value) will be applied.

[0092] Figure 9 shows a method for a base station to configure an initial value of a status variable for a terminal performing MBS communication according to an embodiment of the present disclosure. When the terminal 920 intends to receive data for MBS communication or change the configuration regarding the data for MBS communication being received, the base station 910 may send configuration information regarding MBS communication to the terminal 920 to allow the terminal 920 to apply the configuration information regarding MBS communication. However, in some cases, the terminal 920 receiving data for MBS communication may receive data from the middle of the sequence number. Therefore, by allowing the base station 910 to send the initial value of the status variable to be used by the terminal 920 to receive data for MBS communication, it may be necessary to prevent unexpected packet loss and prevent an increase in the delay time due to packet reordering when the terminal 920 sends / receives data from the middle of the packet. Referring to Figure 9 the method according to an embodiment of the present disclosure described can prevent packet loss and an increase in the delay time.

[0093] Referring to Figure 9In embodiments of this disclosure, during operation 930, base station 910 can configure terminal 920 using the initial value of RX_NEXT of the PDCP layer used by terminal 920 to receive data from MBS communication. Because RX_NEXT is a state variable of the COUNT value, it can have an HFN portion and a sequence number portion. Furthermore, terminal 920 can configure the initial value of RX_DELIV to be the same as the value of RX_NEXT.

[0094] According to embodiments of this disclosure, an initial value for RX_NEXT can be configured for each Point-to-Multipoint Data Radio Bearer (PTM DRB) that performs MBS communication. When no initial RX_NEXT value is configured for a particular PTM DRB, the terminal 920 can configure the initial value of RX_NEXT to 0 for that particular PTM DRB. In another embodiment, when no initial RX_DELIV and RX_NEXT values ​​are configured for a particular PTM DRB, the terminal 920 can configure the initial value of RX_NEXT as the remainder after dividing the value obtained by adding the sequence number of the first received packet in the PTM DRB to 1 by the total sequence number size (2^(number of bits in the sequence number size)). Furthermore, the initial value of RX_DELIV can be configured as the remainder after dividing the value obtained by subtracting half the size of the PDCP receive window from the sequence number of the first received packet by the total sequence number size (2^(number of bits in the sequence number size)). In operation 940, terminal 920 can apply the RX_DELIV and RX_NEXT values ​​received in operation 930 to subsequently receive data for MBS communication. Afterward, terminal 920 can send a configuration completion report message to base station 910, indicating that the initial value of RX_NEXT has been accurately received and will be applied to terminal 920.

[0095] Figure 10 This is a flowchart illustrating a method by which a base station performs secure MBS communication with a terminal according to an embodiment of the present disclosure.

[0096] Reference Figure 10 In operation 1010, the base station may send an initial value to the terminal for secure MBS data transmission. The initial value may include at least one of the following: RX_DELIV value, RX_NEXT value, superframe number (HFN) value, or reference COUNT value. Furthermore, the base station may send the initial value to the terminal while simultaneously multicasting or broadcasting secure MBS data to multiple terminals.

[0097] In Operation 1020, the base station can send secure MBS data to the terminal based on the initial value sent to the terminal.

[0098] Figure 11This is a flowchart illustrating a method by which a terminal performs secure MBS communication with a base station according to an embodiment of the present disclosure.

[0099] Reference Figure 11 In operation 1110, the terminal can receive an initial value from the base station for secure MBS data transmission. The initial value may include at least one of the following: an RX_DELIV value, an RX_NEXT value, a superframe number (HFN) value, or a reference COUNT value. Furthermore, the base station can send the initial value to the terminal while simultaneously multicasting or broadcasting secure MBS data to multiple terminals. Additionally, when the base station multicasts or broadcasts secure MBS data to multiple terminals, the terminal can receive the initial value from the base station.

[0100] In operation 1120, the terminal can configure the initial values ​​received from the base station.

[0101] In operation 1130, the terminal can receive secure MBS data from the base station based on the configured initial values.

[0102] Figure 12 This is a diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0103] refer to Figure 12 The base station may include a transceiver 1210, a controller 1220, and a memory 1230. In this disclosure, the controller 1220 may be defined as a circuit, an application-specific integrated circuit (ASIC), or at least one processor. The transceiver 1210, controller 1220, and memory 1230 of the base station can operate according to the communication method described above. However, the components of the base station are not limited thereto. For example, the base station may include more or fewer components than those described above. Furthermore, the transceiver 1210, controller 1220, and memory 1230 may be implemented as a single chip.

[0104] Transceiver 1210 can exchange signals with other network entities. For example, transceiver 1210 can send system information to a terminal and can send synchronization signals or reference signals to it. Transceiver 1210 can be collectively referred to as a receiver and transmitter of a base station and can exchange signals with a terminal or network entity. The signals exchanged with the terminal or network entity may include control information and data. For this purpose, transceiver 1210 may include, for example, an RF transmitter for up-conversion and amplification of the transmitted signal and an RF receiver for low-noise amplification and down-conversion of the received signal. However, this is only one embodiment of transceiver 1210, and the components of transceiver 1210 are not limited to RF transmitters and RF receivers.

[0105] Furthermore, transceiver 1210 can receive signals on a radio channel and output the signals to controller 1220, and can also transmit signals output from controller 1220 on a radio channel.

[0106] According to embodiments of this disclosure, controller 1220 can control the overall operation of the base station. For example, controller 1220 can control the signal flow between various blocks to perform operations according to the flowchart above. Controller 1220 can receive control signals and data signals through transceiver 1210 and process the received control signals and data signals. Furthermore, controller 1220 can transmit the processed control signals and data signals through transceiver 1210. Additionally, controller 1220 can configure downlink control information (DCI) including allocation information regarding the Physical Downlink Shared Channel (PDSCH) and control each component of the base station to transmit DCI. Controller 1220 may include one or more controllers and may include one or more processors. Controller 1220 can control the components of the base station by executing a program stored in memory 1230.

[0107] The memory 1230 can store at least one of the information transmitted / received by the transceiver 1210 and the information generated by the controller 1220. The memory 1230 can be defined as a "memory". The memory 1230 can store programs and data required for base station operation. Furthermore, the memory 1230 can store control information or data included in signals acquired by the base station. The memory 1230 can include storage media or combinations of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. Additionally, the memory 1230 may not be provided separately and may be included in the controller 1220.

[0108] Figure 13 This is a diagram illustrating the structure of a terminal according to an embodiment of the present disclosure.

[0109] refer to Figure 13 The terminal may include a transceiver 1310, a controller 1320, and a memory 1330. In this disclosure, the controller 1320 may be defined as a circuit, an application-specific integrated circuit (ASIC), or at least one processor. The transceiver 1310, controller 1320, and memory 1330 of the terminal can operate according to the communication method described above. However, the components of the terminal are not limited thereto. For example, the terminal may include more or fewer components than described above. Furthermore, the transceiver 1310, controller 1320, and memory 1330 may be implemented as a single chip.

[0110] Transceiver 1310 can exchange signals with other network entities. For example, transceiver 1310 can receive system information from a base station and can receive synchronization signals or reference signals from it. Transceiver 1310 can be collectively referred to as a receiver and transmitter of a terminal and can exchange signals with network entities, base stations, or other terminals. Furthermore, the signals exchanged with network entities, base stations, or other terminals may include control information and data. For this purpose, transceiver 1310 may include, for example, an RF transmitter for up-conversion and amplification of transmitted signals and an RF receiver for low-noise amplification and down-conversion of received signals. However, this is merely an embodiment of transceiver 1310, and the components of transceiver 1310 are not limited to RF transmitters and RF receivers.

[0111] In addition, transceiver 1310 can receive signals on a radio channel and output the signals to controller 1320, and can also transmit signals output from controller 1320 on a radio channel.

[0112] According to embodiments of this disclosure, controller 1320 can control the overall operation of the terminal. For example, controller 1320 can control the signal flow between various blocks to perform operations according to the flowchart above. Controller 1320 can receive and process control signals and data signals via transceiver 1310. Furthermore, controller 1320 can transmit processed control signals and data signals via transceiver 1310. Additionally, controller 1320 can control terminal components to receive DCI including two layers to simultaneously receive multiple PDSCHs. Controller 1320 may include one or more controllers and may include one or more processors. Controller 1320 can control terminal components by executing a program stored in memory 1330.

[0113] The memory 1330 can store at least one of the information transmitted / received by the transceiver 1310 and the information generated by the controller 1320. The memory 1330 can be defined as "memory".

[0114] It should be understood that the embodiments described herein are to be considered merely descriptive and not for limiting purposes. That is, those skilled in the art will understand that various changes in form and detail may be made to the embodiments of this disclosure without departing from the scope of this disclosure. Furthermore, the above embodiments may be combined as necessary. For example, a base station and a terminal may operate according to a combination of a portion of one embodiment and a portion of another embodiment of this disclosure. Moreover, the embodiments of this disclosure can also be applied to other communication systems, and other modifications based on the technical spirit of the embodiments can be implemented.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: Receive configuration information about the multicast and broadcast service MBS from the base station, the configuration information about MBS including the initial value of RX_DELIV; as well as The received initial value of RX_DELIV is applied to the RX_DELIV of the radio bearer for MBS. Here, RX_DELIV is a Packet Data Convergence Protocol (PDCP) state variable, and RX_DELIV indicates the count value of the first packet that has not been delivered to the upper layer.

2. The method according to claim 1, further comprising: Apply 0 to RX_DELIV for radio bearers serving unicast services.

3. The method according to claim 1, in, The RX_DELIV includes the superframe number HFN and the sequence number SN.

4. The method according to claim 1, further comprising sending a configuration completion message to the base station, the configuration completion message indicating that the initial value of RX_DELIV has been applied.

5. A user equipment (UE) for a wireless communication system, the UE comprising: transceiver; as well as At least one processor, which is coupled to the transceiver and configured to: Receive configuration information about Multicast and Broadcast Services (MBS) from the base station, including the initial value of RX_DELIV; and The received initial value of RX_DELIV is applied to the RX_DELIV of the radio bearer for MBS. Here, RX_DELIV is a Packet Data Convergence Protocol (PDCP) state variable, and RX_DELIV indicates the count value of the first packet that has not been delivered to the upper layer.

6. The UE according to claim 5, wherein, The at least one processor is also configured to apply 0 to RX_DELIV for the radio bearer for unicast services.

7. The UE according to claim 5, in, The RX_DELIV includes the superframe number HFN and the sequence number SN.

8. The UE according to claim 5, wherein, The at least one processor is further configured to send a configuration completion message to the base station, the configuration completion message indicating that the initial value of RX_DELIV has been applied.

9. A method performed by a base station in a wireless communication system, the method comprising: The configuration information regarding Multicast and Broadcast Services (MBS) is sent to the User Equipment (UE), wherein the MBS configuration information includes the initial value of RX_DELIV. The transmission of the initial value of RX_DELIV causes the UE to apply the transmitted initial value of RX_DELIV to the RX_DELIV of the radio bearer for MBS, and Here, RX_DELIV is a Packet Data Convergence Protocol (PDCP) state variable, and RX_DELIV indicates the count value of the first packet that has not been delivered to the upper layer.

10. The method according to claim 9, in, 0 is applied to RX_DELIV for radio bearers of unicast services.

11. The method according to claim 9, in, The RX_DELIV includes the superframe number HFN and the sequence number SN.

12. A base station for a wireless communication system, the base station comprising: transceiver; as well as At least one processor, coupled to the transceiver and configured to send configuration information about the Multicast and Broadcast Service (MBS) to the user equipment, wherein the MBS configuration information includes an initial value for RX_DELIV. The transmission of the initial value of RX_DELIV causes the UE to apply the transmitted initial value of RX_DELIV to the RX_DELIV of the radio bearer for MBS, and Here, RX_DELIV is a Packet Data Convergence Protocol (PDCP) state variable, and RX_DELIV indicates the count value of the first packet that has not been delivered to the upper layer.

13. The base station according to claim 12, in, 0 is applied to RX_DELIV for radio bearers of unicast services.

14. The base station according to claim 12, in, The RX_DELIV includes the superframe number HFN and the sequence number SN.

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