Method and apparatus for managing radio connection state in wireless communication system

Abstract

A method for managing a radio connection is disclosed. The disclosed method comprises the steps of: transmitting a pre-allocated context; and transitioning from an RRC connected state to a pre-active state while maintaining the pre-allocated context. The pre-allocated context includes configuration information for resuming a HARQ operation, time alignment-related information, and security context information, and when connection resumption is performed in the pre-active state, whether to perform fast resumption without random access may be determined on the basis of a result of determining validity of the pre-allocated context.

Description

Method and device for managing wireless connection status in a wireless communication system

[0001] The present disclosure relates to a method and apparatus for managing a wireless connection state in a wireless communication system. The present disclosure provides a method for managing a wireless connection state that can minimize the Round Trip Delay (RTD) of a signal and reduce signal processing delay in a mobile communication system. The present disclosure discloses a method and apparatus for managing a wireless connection based on a pre-assigned context.

[0002] A communication system may include a core network, base stations (e.g., macro base stations, small base stations, relays, etc.), terminals, etc. Communication between a base station and a terminal may be performed based on various radio access technologies (RATs) (e.g., 4G communication technology, 5G communication technology, 6G communication technology, WLAN (wireless local area network) technology, WPAN (wireless personal area network) technology, etc.).

[0003] 3GPP has selected AI / ML as a 6G Study Item and is conducting research and discussions on it. AI / ML technology utilizes artificial intelligence and machine learning to intelligently manage network operations, enabling efficient operation, particularly in RAN (Radio Access Network). 3GPP has prioritized the introduction of AI / ML in 5G scenarios such as beam management, positioning, channel state prediction, and channel state compression, expecting improvements in system throughput, resource utilization, and coverage through this.

[0004] Mobile communication systems define multiple Radio Resource Control (RRC) states to improve wireless resource efficiency and reduce power consumption between terminals and base stations. For example, in 5G New Radio (NR) systems, RRC connected (RRC_CONNECTED), RRC idle (RRC_IDLE), and RRC inactive (RRC_INACTIVE) states are defined, and terminals can transition between these states depending on traffic characteristics and mobility conditions.

[0005] In the RRC_CONNECTED state, uplink and downlink resources between the terminal and the base station are dynamically scheduled, and Hybrid Automatic Repeat Request (HARQ) operations and Media Access Control (MAC) scheduling can be enabled. However, this state has the problem of high power consumption and continuous occupancy of wireless resources.

[0006] To address this, the RRC_INACTIVE state was introduced. In the RRC_INACTIVE state, power consumption can be reduced as user plane transmission is suspended while the terminal's security context and some connection information are maintained. If the terminal wishes to resume data transmission, it can return to the RRC_CONNECTED state by executing the RRC Resume procedure.

[0007] There are several limitations to the operation of conventionally defined RRC connection states.

[0008] According to conventional RRC connection state management methods, when a terminal resumes an RRC connection, it generally must perform a Random Access procedure, which can increase latency. In particular, since the 4-step Random Access procedure requires the exchange of multiple messages, a delay in resuming the connection may occur.

[0009] According to conventional RRC connection state management methods, MAC scheduling information, HARQ operation-related information, and uplink resource configuration information are not fully maintained in the RRC_INACTIVE state; therefore, a process to reconstruct this information may be required when the connection is resumed. As a result, data transmission cannot be resumed immediately, and additional control signal exchange may be required.

[0010] According to conventional RRC connection state management methods, in systems supporting beam-based transmission, a terminal may experience a beam failure, and if beam recovery is not performed properly, the random connection procedure must be executed again. In the RRC_INACTIVE state, these beam management procedures are not sufficiently reflected, which may result in delays in resuming the connection.

[0011] Furthermore, for terminals with low mobility, such as fixed terminals, industrial IoT terminals, or terminals operating within a limited area, there is a problem in that the existing RRC_INACTIVE structure does not fully utilize these characteristics, even though serving cell and timing alignment information is likely to be maintained for a long time.

[0012] In particular, even though beam information, serving cell information, time alignment information, MAC scheduling information, HARQ operation configuration information, uplink control channel resource information, pre-configured uplink resource information, logical channel priority information, and scheduling-related configuration information used by the terminal in the previous connection state are valid, existing technologies do not provide a structure to systematically verify this and adaptively select a random connection procedure.

[0013] In the existing RRC_INACTIVE-based connection resumption procedure, the base station verifies the validity of the terminal context only after the terminal transmits an RRC Resume request message; therefore, additional delays may occur during the resumption process. Accordingly, there is a need for a technology capable of reducing connection resumption delays by maintaining an enhanced prior context and adaptively controlling the levels of the connection resumption procedure and the random access procedure based on the validity of that context.

[0014] According to at least one embodiment, a wireless connection management method and device are provided that can reduce the delay occurring in the resumption of a wireless connection of a terminal and increase the efficiency of wireless resource utilization.

[0015] A wireless connection management method is disclosed, which is performed by a terminal including a communication unit and a processor. The disclosed method includes the steps of: transmitting a pre-allocated context; and transitioning from an RRC connection state to a pre-active state while maintaining the pre-allocated context. The pre-allocated context includes configuration information for resuming HARQ operation, time alignment related information, and security context information. When a connection resumption is performed in the pre-active state, whether to perform a fast resumption with random access omitted may be determined based on a result of judging the validity of the pre-allocated context.

[0016] According to at least one embodiment, by utilizing serving cell information, Timing Advance (TA) information, TA drift-related information, HARQ configuration information, MAC scheduling information, uplink resource configuration information, etc. included in the pre-allocation context, connection resumption can be performed while omitting or minimizing the Random Access procedure. Accordingly, the round-trip delay time occurring when resuming the connection can be reduced.

[0017] According to at least one embodiment, by enabling the base station to determine the validity of a pre-allocated context in advance and instruct a Fast Resume, the RRC connection resumption request and context verification procedure of the terminal can be shortened or omitted. In particular, if the context verification procedure between the base station and the AMF can be omitted, signaling delay with the core network can be reduced.

[0018] According to at least one embodiment, by using PUCCH in a terminal-led resumption procedure to transmit a pre-allocated context indicator and a Scheduling Request (SR) together, uplink resource allocation can be requested without random access via PRACH. Accordingly, unnecessary control signal overhead can be reduced and the connection resumption procedure can be simplified.

[0019] According to at least one embodiment, by including configuration information for resuming HARQ operation and MAC scheduling information in the pre-allocation context, data transmission and reception can be immediately resumed after connection resumption. This reduces additional delays and overhead caused by HARQ reset, scheduling reconfiguration, etc.

[0020] According to at least one embodiment, beam-related information is included in a pre-allocation context in a pre-active mode, and by enabling the terminal to perform beam monitoring and beam failure recovery, rapid beam recovery can be performed without relying on a random connection procedure when a beam failure occurs. Accordingly, beam failure recovery delay can be reduced and the stability of the wireless link can be improved.

[0021] According to at least one embodiment, by selecting an appropriate procedure among random connection omission, 2-step random connection, and 4-step random connection depending on the validity level of the pre-allocation context, it is possible to simultaneously achieve latency minimization and connection reliability.

[0022] According to at least one embodiment, when combined with AI / ML-based mobility prediction or location prediction technology, the movement pattern of a terminal can be predicted in advance to optimize whether to maintain a pre-allocated context. In particular, by actively utilizing a pre-allocated context-based resumption method in environments such as low-mobility environments, indoor environments, and smart factories, low-latency characteristics and power efficiency can be simultaneously improved.

[0023] According to at least one embodiment, by improving the inefficiency of existing connection resumption procedures and providing an optimized connection resumption structure in low-mobility or predictable environments, the effects of reduced latency, reduced control overhead, improved power efficiency, and increased wireless resource utilization efficiency can be achieved simultaneously.

[0024] FIG. 1 is a drawing showing a wireless communication system (100) according to an exemplary embodiment.

[0025] FIG. 2 is a block diagram illustrating the configuration of a communication node (200) that constitutes a communication system.

[0026] Figure 3 is a diagram illustrating an exemplary 5G network architecture.

[0027] Figure 4 is a flowchart exemplifying the transition of a terminal from an RRC inactive state (RRC Inactive) to an RRC connected state (RRC Connected).

[0028] FIG. 5 is a flowchart illustrating a procedure for resuming connection after transitioning to a pre-activation mode of a terminal according to an exemplary embodiment.

[0029] FIG. 6 is a flowchart exemplifying the resumption of an RRC connection by a base station in a pre-activated state by a terminal.

[0030] Figure 7 shows a modified embodiment of the rapid resumption procedure described in Figure 6.

[0031] FIG. 8 is a flowchart illustrating a terminal-led connection resumption procedure according to one embodiment of the present invention.

[0032] FIG. 9 is a flowchart illustrating an example of a terminal-led connection resumption procedure.

[0033] FIG. 10 is a flowchart illustrating an example of a connection resumption procedure that can be performed when the validity level of the pre-allocation context is low.

[0034] FIG. 11 is a flowchart illustrating an embodiment in which a terminal can perform beam monitoring and beam failure recovery in pre-active mode.

[0035] A wireless connection management method is disclosed, which is performed by a terminal including a communication unit and a processor. The disclosed method includes the steps of: transmitting a pre-allocated context; and transitioning from an RRC connection state to a pre-active state while maintaining the pre-allocated context. The pre-allocated context includes configuration information for resuming HARQ operation, time alignment related information, and security context information. When a connection resumption is performed in the pre-active state, whether to perform a fast resumption with random access omitted may be determined based on a result of judging the validity of the pre-allocated context.

[0036] The above-mentioned pre-allocation context may include serving cell information, beam-related information, scheduling requests, and resource configuration information for PUCCH transmission.

[0037] The above method may include the steps of: receiving a fast resumption indicator from a base station indicating whether to use fast resumption; performing a fast resumption with random access omitted based on the fast resumption indicator; and utilizing configuration information and time alignment related information for HARQ operation resumption included in the pre-allocated context in the resumed connection after the fast resumption is completed.

[0038] The above-mentioned fast resume indicator is transmitted by being included in downlink control information, and the downlink control information may include at least one of uplink resource indicator information or pre-configured resource allocation (configured grant) activation information.

[0039] The above method may further include the step of requesting a base station for a quick resumption with random access omitted by transmitting a pre-allocation context indicator that indicates whether the terminal possesses a pre-allocation context when it is determined that an RRC connection resumption is necessary in the above pre-active state.

[0040] In the step of requesting a base station for a fast resumption with the random access omitted, the terminal may transmit a scheduling request and the pre-allocated context indicator together.

[0041] The above method may include the step of receiving a request for identification information regarding the pre-assigned context from a base station; and the step of transmitting an RRC connection resumption request including a pre-assigned context identifier.

[0042] An RRC connection resumption request may further include an information element indicating whether to request an uplink acknowledgment without random access and an information element indicating whether the serving cell has not changed.

[0043] The weather station method may include a step of performing a connection resumption procedure accompanied by random access when it receives a rejection message for a quick resumption with random access omitted from the station.

[0044] The above-mentioned pre-allocation context includes beam-related information, and the method may include the steps of: performing beam monitoring in the pre-active mode; detecting a beam failure; and performing beam recovery by omitting random access using the beam-related information.

[0045] A wireless connection management method is disclosed, which is performed by a base station including a communication unit and a processor. The disclosed method includes the steps of receiving a pre-allocated context; and determining the validity of the pre-allocated context. When a connection resumption is performed in the pre-active state, whether to perform a fast resumption with random access omitted may be determined based on whether the validity of the pre-allocated context satisfies a preset condition.

[0046] The above pre-allocation context may include configuration information for resuming HARQ operation, time alignment related information, serving cell related information, and security context information.

[0047] The validity of the above-mentioned pre-allocation context can be determined based on at least one of whether the serving cell is identical, whether the amount of timing advance variation satisfies a preset range, the mobility level of the terminal, and the validity of the configuration information for resuming HARQ operation.

[0048] The above method may include the step of transmitting a fast reschedule indicator instructing the use of fast reschedule when it is determined that the validity of the above-mentioned pre-allocation context satisfies a preset condition; and the step of using configuration information for HARQ operation reschedule and time alignment related information included in the above-mentioned pre-allocation context in the resumed connection after the fast reschedule with random access omitted is completed.

[0049] The above method may include the step of requesting a resumption procedure including random access to the terminal when it is determined that the validity of the above-mentioned pre-allocation context does not satisfy a preset condition.

[0050] The above method may include the step of receiving a pre-allocation context indicator from a terminal that indicates whether the terminal possesses a pre-allocation context.

[0051] The above method may include the step of transmitting a request for identification information regarding the pre-assigned context; and the step of receiving an RRC connection resumption request including a pre-assigned context identifier from the terminal.

[0052] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0053] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0054] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0055] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0056] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0057] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding of the present invention, the same reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0058] Table 1 shows the abbreviations used in the present disclosure.

[0059] 약어전체 이름AI / MLArtificial Intelligence / Machine Learning3GPP3rd Generation Partnership ProjectACKAcknowledgementAFApplication FunctionAIArtificial IntelligenceAMFAccess and Mobility Management FunctionAUSFAuthentication Server FunctionBWPBandwidth PartC-RNTICell RNTICSIChannel State InformationCSI-RSChannel State Information Reference SignalCLICross link InterferenceCEControl ElementDCIDownlink Control InformationIEInformation elementMACMedium Access ControlMLMachine LearningNSSFNetwork Slicing Selection FunctionNEFNetwork Exposure FunctionNRFNF Repository FunctionPCFPolicy Control FunctionPDCCHPhysical Downlink Control ChannelPDSCHPhysical Downlink Shared ChannelPDUProtocol Data UnitPRACHPhysical Random Access ChannelPT-RSPhase Tracking Reference SignalPUCCHPhysical Uplink Control ChannelPUSCHPhysical Uplink Shared ChannelRARandom AccessRACHRandom Access ChannelRANRadio Access NetworkRBResource BlockRRCRadio Resource ControlRSRPReference Signal Received PowerRSRQReference Signal ReceivedQualityRSSIReceived Signal Strength IndicatorSBFDSub-Band Full DuplexSISelf InterferenceSIBSystem information blockUEUser EquipmentDLDownlinkULUplinkRARRandom Access ResponseRRMRadio Resource ManagementRRCRadio Resource ControlRSRPReference Signal Received PowerQoSQuality of ServiceDRBData Radio BearerDAPSDual Active Protocol StackTDDTime Division DuplexingFDDFrequency Division DuplexingSSBSS BlockCQIChannel Quality IndicatorPMIPrecoding Matrix IndicatorLILayer IndicatorLCMLife Cycle ManagementRIRank IndicatorHARQHybrid Automatic Repeat reQuestQCLQuasi coLocation

[0060] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. In order to facilitate overall understanding in describing the present invention, the same reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted. In this specification, "Pre-Active mode" refers to an operational state configured to maintain a certain range of wireless connection status information in order to quickly resume the connection while the wireless connection between the terminal and the base station is not completely disconnected.

[0061] The above-mentioned pre-activation mode may be implemented as a separate operational state distinct from the RRC connected state (RRC_CONNECTED), RRC idle state (RRC_IDLE), and RRC inactive state (RRC_INACTIVE) defined in existing mobile communication systems. However, it is not limited thereto, and the above-mentioned pre-activation mode may be implemented as an extension, modification, or subdivision of an existingly defined mode or state.

[0062] For example, according to one embodiment, the pre-active mode may be a modified inactive state configured to additionally maintain enhanced wireless connection state information as an extension of the RRC inactive state. According to another embodiment, the pre-active mode may be a light connected state that facilitates connection resumption while reducing power consumption by lightening the RRC connection state. According to yet another embodiment, the pre-active mode may be a type of power saving mode in which user plane data transmission is restricted or suspended, but some physical layer and MAC layer information for wireless resource access is maintained.

[0063] Accordingly, the pre-active mode in this specification is not limited by the state names or number of states defined in specific standards, and should be understood as a concept that comprehensively refers to a state that maintains pre-assigned context information to enable the terminal to more efficiently perform a return to an existing connection state.

[0064] In this specification, 'Pre-Allocated Context' may be a set of wireless connection-related state information that is stored or maintained in advance so that the terminal can reuse it when the wireless connection is resumed.

[0065] The pre-assigned context is not limited to basic connection information maintained in the existing RRC inactive state, and may include an extended range of physical layer and MAC layer information to reduce connection resumption delay. The pre-assigned context may be stored in the terminal and / or base station, and the validity of all or part of the context may be verified upon connection resumption. Additionally, the pre-assigned context may be set by the network, or maintained or updated according to the terminal's internal policy.

[0066] Accordingly, the pre-assigned context in this specification is not limited to the terminal context defined in a specific standard, and should be understood as a concept encompassing extended state information to accelerate the resumption of wireless connection.

[0067] Pre-active mode may be a state in which an enhanced pre-allocation context is maintained to enable the terminal to rapidly resume connection without maintaining a full connection state. In pre-active mode, user plane data transmission may be restricted or interrupted, but key state information related to wireless access, such as beam information, serving cell information, time alignment information, MAC scheduling information, HARQ operation-related information, and uplink resource configuration information, may be maintained. The terminal and / or base station may verify the validity of the pre-allocation context upon resuming connection. Depending on the validity level of the pre-allocation context, whether to perform a random access procedure or the steps to perform it may be adaptively determined.

[0068] FIG. 1 is a drawing showing a wireless communication system (100) according to an exemplary embodiment.

[0069] Referring to FIG. 1, a wireless communication system (100) may be composed of a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3, 120-4). Here, a communication node refers to a node capable of transmitting and receiving signals in the wireless communication system (100), and each of the plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3, 120-4) may support at least one communication protocol. For example, each of the multiple communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3, 120-4) can support cellular communication (e.g., LTE (long term evolution), LTE-A (advanced), 5G NR, 5G-Advanced, etc. as defined in the 3GPP (3rd generation partnership project) standard), 6G.

[0070] For example, each of the multiple communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3, 120-4) can support a CDMA (code division multiple access) based communication protocol, a WCDMA (wideband CDMA) based communication protocol, a TDMA (time division multiple access) based communication protocol, a FDMA (frequency division multiple access) based communication protocol, an OFDM (orthogonal frequency division multiplexing) based communication protocol, an OFDMA (orthogonal frequency division multiple access) based communication protocol, a SC (single carrier)-FDMA based communication protocol, a NOMA (non-orthogonal multiple access) based communication protocol, a SDMA (space division multiple access) based communication protocol, a SBFD (sub-band full duplex), AI / ML, etc.

[0071] A plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3, 120-4) may include a plurality of base stations (110-1, 110-2, 110-3) and a plurality of terminals (120-1, 120-2, 120-3, 120-4). Each of the base stations (110-1, 110-2, 110-3) may form a cell. The cell may include a small cell, a macro cell, a pico cell, a femto cell, etc., but the embodiments are not limited thereto. For example, the first terminal (120-1) and the second terminal (120-2) may be in the coverage of the first base station (110-1), the third terminal (120-3) may be in the coverage of the second base station (110-2), and the fourth terminal (120-4) may be in the coverage of the third base station (110-3).

[0072] Multiple base stations (110-1, 110-2, 110-3) may be referred to as gNodeB (gNB), NodeB, evolved NodeB, BTS (base transceiver station), radio base station, radio transceiver, access point, access node, roadside unit (RSU), RRH (radio remote head), TP (transmission point), TRP (transmission and reception point), relay node, etc. Multiple base stations (110-1, 110-2, 110-3) may form a Radio Access Network (RAN). The Radio Access Network may be connected to a core network.

[0073] Each of the multiple terminals (120-1, 120-2, 120-3, 120-4) may be referred to as a terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, etc.

[0074] The communication protocol support ranges of each of the multiple base stations (110-1, 110-2, 110-3) may differ from one another. For example, some of the multiple base stations (110-1, 110-2, 110-3) may support AI / ML functions while others do not. Similarly, the communication protocol support ranges of each of the terminals (120-1, 120-2, 120-3, 120-4) may also differ from one another. For example, some of the multiple terminals (120-1, 120-2, 120-3, 120-4) may support AI / ML functions while others do not.

[0075] FIG. 2 is a block diagram illustrating the configuration of a communication node (200) that constitutes a communication system. At least some of the communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3) shown in FIG. 1 may correspond to the communication node (200) shown in FIG. 2.

[0076] Referring to FIG. 2, the communication node (200) may include at least one processor (210), a memory (220), and a transceiver (230) that is connected to a network to perform communication. Additionally, the communication node (200) may further include an input interface device (240), an output interface device (250), a storage device (260), etc. Each component included in the communication node (200) may be connected by a bus (270) to communicate with one another.

[0077] The processor (210) can execute a program command stored in at least one of the memory (220) and the storage device (260). The processor (210) may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory (220) and the storage device (260) may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (220) may be composed of at least one of read-only memory (ROM) and random access memory (RAM).

[0078] Figure 3 is a diagram illustrating an exemplary 5G network architecture.

[0079] Referring to FIG. 3, the 5G network architecture may include an NSSF providing a network slicing control solution, an NEF providing a network function opening solution, an NRF providing an NF interoperability control solution within the 5G network, a PCF providing a data packet flow policy control solution, a UDM providing a user information and policy management solution, an AMF providing a network access and mobility management solution, an SMF providing a terminal / network session management solution, a UPF providing a solution for user packet routing and terminal connectivity between base stations, a radio access network (RAN), and a user terminal (UE).

[0080] N1 reference point is defined to transmit signaling between the UE and the AMF, N2 is defined as the reference point to connect the RAN access node and the AMF, and N3 is defined as the reference point to connect the RAN access node and the UPF.

[0081] 3GPP is currently conducting 6G research, and the 6G network architecture plans to integrate AI-native design, advanced sensing, and ultra-low latency communication based on the existing 5G structure. In 6G, the N4 interface between the User Plane Function (UPF) and Session Management Function (SMF) and the N3 interface between the RAN and UPF will be optimized, and AI / ML-based dynamic resource management and network slicing will be enhanced. Furthermore, 6G is highly likely to support industrial use cases (e.g., autonomous driving, holographic communication) by introducing new Network Functions (NFs) and interfaces.

[0082] For convenience, the first terminal (120-1) of FIG. 1 will be referred to as the 'terminal' and the first base station (110-1) as the 'base station' below.

[0083] Figure 4 is a flowchart exemplifying the transition of a terminal from an RRC inactive state (RRC Inactive) to an RRC connected state (RRC Connected).

[0084] Referring to FIG. 4, an example of a procedure in which a terminal (120-1) performs an RRC connection resumption (RRC Resume) in a conventional RRC inactive state (RRC_INACTIVE) can be illustrated.

[0085] In step S12, the terminal (120-1) may transmit an RRC Resume Request if the need to resume the RRC connection arises. The need to resume the RRC connection may arise, for example, when uplink data transmission is required by the terminal (120-1), when paging indicating the arrival of downlink data is received, when an internal timer expires, when NAS procedure execution is required, or when a security context update is required.

[0086] The terminal (120-1) may attempt to resume the connection upon the occurrence of such an event. The RRC Resume Request message may include a Resume Identity, a resume cause, terminal identification information, security context-related information, and serving cell-related information. In conventional 5G standards, Timing Advance information, HARQ operation status, MAC scheduling status, etc., may not be fully maintained, and such information may be reset during the resume process.

[0087] In step S14, the base station (110-1) can verify the validity of the terminal context based on the RRC Resume Request received from the terminal (120-1). The base station (110-1) can check whether the Resume Identity matches, the validity of the stored security context, whether the terminal (120-1) exists within the same serving cell or the same RAN Notification Area, etc.

[0088] In step S16, the base station (110-1) may request the upper core network node, AMF (130), to verify the terminal context as needed. This may be a procedure to verify the validity of the NAS security context or mobility-related information of the terminal (120-1). The AMF (130) may verify the validity of the security context, the registration status of the terminal, the session information of the terminal, etc.

[0089] In step S18, the AMF (130) may respond to the base station (110-1) with the result of verifying the validity of the terminal context, and accordingly, the base station (110-1) may determine whether to allow the terminal (120-1) to resume the connection.

[0090] In step S20, the base station (110-1) can determine whether to perform random access. For example, the base station (110-1) can determine whether to perform random access based on the validity of the time alignment information (Timing Advance) of the terminal (120-1), whether the serving cell has changed, the physical layer synchronization state, the stability of the beam state, and the completeness of the stored wireless context. Since uplink resources and physical layer information may not be sufficiently maintained in the conventional RRC inactive state, a random access procedure may be performed in most cases.

[0091] When a random access procedure is performed, for example, at step S22, the terminal (120-1) can transmit a random access preamble via PRACH, and at step S24, the base station (110-1) can transmit a Random Access Response (RAR). Subsequently, at step S26, the terminal (120-1) can transmit Msg3 via the uplink shared channel (PUSCH), and at step S28, the base station (110-1) can complete the identification and resource allocation of the terminal (120-1) by transmitting a contention resolution message. Through this four-step random access procedure, the terminal (120-1) can reset uplink resources and identification information.

[0092] Finally, at step S30, the terminal (120-1) can transmit an RRC Resume Complete message, and accordingly, the terminal (120-1) can be switched to an RRC connection state (RRC_CONNECTED).

[0093] The following limitations may exist in the conventional RRC inactive state-based connection resumption procedure. First, when resuming the connection, the MAC scheduling information, HARQ operation status, and time alignment information of the terminal (120-1) may be reset, so additional control signal exchange may be required, and a delay may occur as a result. Second, since a random connection procedure may be performed in most cases, multiple stages of message exchange may be required, and the connection resumption delay may increase. Third, physical layer and MAC layer overhead may occur due to the re-initialization of time alignment and HARQ status. Fourth, in the case of a terminal (120-1) with low mobility, even though serving cell and time alignment information may still be valid, the conventional structure may not actively utilize them, resulting in inefficiency where unnecessary random connection procedures are performed.

[0094] In order to provide low-latency based data services to fixed IoT terminals or terminals such as IoT terminals moving within a limited area and robots with mobility capabilities in low-mobility environments, Ultra-Reliable Low Latency Communication (URLC) technology can be applied in current 5G systems.

[0095] URLLC technology may include various physical and MAC layer optimization techniques to support ultra-low latency and high-reliability transmission. However, such URLLC technology may have the following disadvantages.

[0096] First, regarding limitations from the terminal side, Predictive Beamforming can be utilized in a URLLC environment, which may increase the computational complexity of the terminal. In particular, since the terminal may need to continuously perform calculations to predict channel states, there is a possibility that the computational burden will increase. Additionally, Fast Beam Recovery may be required in a URLLC environment, and to achieve this, the terminal may need to perform continuous Channel State Information (CSI) reporting. This continuous reporting procedure can increase the terminal's power consumption and control signal overhead. URLLC terminals may use very short DRX cycles or disable DRX to ensure low-latency characteristics, which may lead to increased power consumption. To apply techniques such as Uplink Grant-Free Scheduling (UL Grant-Free Scheduling) and Predictive HARQ, the terminal may need to continuously monitor network conditions, which can increase the burden of continuous monitoring on the terminal side.

[0097] The following burdens may also arise from a network perspective. First, URLLC can utilize Predictive Scheduling to minimize scheduling delays, which may increase the computational burden on the network at the MAC and PHY layers.

[0098] Second, since URLLC must support fast HARQ retransmission, optimization may be required to process HARQ feedback immediately, which may increase the complexity of the HARQ process.

[0099] Third, URLLC terminals can be given high priority in the network for ultra-low latency, and consequently, more resources may be allocated compared to eMBB terminals. This can increase overhead in terms of overall network resource management.

[0100] Fourth, in a URLLC environment, the network may need to continuously perform Beam Refinement and Beam Switching to respond to rapidly changing channel conditions, which can increase the burden on network resources.

[0101] Therefore, while URLLC technology can support ultra-low latency communication, it may entail excessive computational burden and resource overhead in low-mobility terminal environments, and these characteristics may not always make it an efficient solution for all terminal types.

[0102] Meanwhile, in current 5G NR systems, it may be difficult to accurately predict the mobility of a terminal in advance, and consequently, it may be difficult to determine in real time whether the terminal is moving or whether there is a possibility of changing the serving cell. As a result, it may be difficult for the network to decide in advance whether to perform a Handover or an RRC Resume procedure for the terminal.

[0103]

[0104] With the future introduction of AI / ML (Artificial Intelligence / Machine Learning)-based mobility prediction technology, it is expected that the movement speed, direction of movement, and the likelihood of a serving cell change can be predicted in advance by analyzing the movement patterns of the terminal. In this case, the network can determine a connection resumption strategy in advance based on the terminal's movement characteristics.

[0105] If AI / ML-based prediction results determine that the terminal is moving at high speed, the network may decide to perform a Handover procedure in advance. Conversely, if the terminal is predicted to be moving at low speed or moving only within a limited area, a strategy may be set to keep the terminal in an RRC-disabled state and resume RRC when necessary. Additionally, if the terminal is predicted to be highly likely to move in a specific direction, the network may pre-configure a Target gNB or prepare adjacent cell information in advance.

[0106] It is expected that the application of AI / ML-based Positioning Enhancement technology will enable more accurate prediction of whether a terminal will change serving cells in the future. Particularly in indoor or low-mobility environments, where the terminal's movement patterns are likely to remain relatively constant, AI / ML-based location prediction can be used to determine in advance the probability that the terminal will continue to stay in the same serving cell.

[0107] The network can optimize to maintain the Pre-Allocated Context for a longer period when it is highly likely that the terminal will remain in the same serving cell. Conversely, if it is determined that the terminal is likely to change serving cells, the network can discard the Pre-Allocated Context and adjust to perform a connection resumption procedure based, for example, CFRA (Contention-Free Random Access).

[0108]

[0109] Particularly in indoor environments such as smart factories, offices, and shopping malls, terminal movement patterns can be relatively repetitive or predictable; therefore, strategies to maintain pre-allocated context can be operated more efficiently by utilizing AI / ML-based positioning. For example, if a terminal repeatedly resumes connection at the same location or within the same serving cell, the network can be configured to maintain the pre-allocated context for a longer period, thereby enabling connection resumption that skips or minimizes the random connection procedure.

[0110] Therefore, when AI / ML-based movement prediction and location prediction technologies are applied, the network can reflect the terminal's movement patterns in real time to more precisely control the pre-allocated context-based connection resumption strategy, and the pre-active mode-based connection resumption method of the present invention can be a more efficient solution, especially in indoor environments or environments with low mobility.

[0111] FIG. 5 is a flowchart illustrating a connection resumption procedure after transitioning to a pre-active mode of a terminal (120-1) according to an exemplary embodiment. FIG. 4 illustrates an example of a connection resumption procedure based on a pre-active mode.

[0112] Referring to FIG. 5, at step S100, the terminal (120-1) can be switched to a pre-active mode. The switching to the pre-active mode can be performed, for example, during the transition process in the RRC connection state.

[0113] The transition to the above pre-active mode may be triggered by various conditions, and may be triggered by the terminal (120-1) or by the base station (110-1). For example, the transition to the pre-active mode on the terminal (120-1) side may be made in the following situations.

[0114] - When the mobility of the terminal (120-1) is determined to be low

[0115] - When the terminal repeatedly performs connection resumption within a specific serving cell area

[0116] - Cases where battery conservation is required while rapid connection resumption is necessary

[0117] - Cases where uplink data transmission frequency is low but occurs intermittently

[0118] - When the terminal operates in an indoor environment or a limited movement area

[0119]

[0120] Meanwhile, the pre-activation mode switching can also be performed under the initiative of the base station (110-1). For example, the base station (110-1) may trigger the switching to the pre-activation mode in the following situations.

[0121] - When the base station (110-1) analyzes the movement pattern of the terminal (120-1) and determines that the mobility is low

[0122] - When the terminal (120-1) corresponds to a specific service type (e.g., IoT, smart factory terminal, etc.)

[0123] - When it is necessary to keep specific terminals in a lightweight connection state to optimize network load

[0124] - Cases where AI / ML-based movement prediction results predict that the terminal will remain in the same serving cell for an extended period

[0125] The terminal (120-1) can transmit a pre-allocated context to the base station (110-1).

[0126] The base station (110-1) may instruct the terminal (120-1) to switch to a pre-active mode via a control message. Additionally, the switch to a pre-active mode may be performed directly from an existing RRC connection state, or in conjunction with an RRC inactive state, and may not be limited to a specific standard state definition.

[0127] In the process of switching to a pre-active mode, the terminal (120-1) may create or update a pre-allocated context and transmit it to the base station (110-1). The pre-allocated context may include terminal context information maintained in the existing RRC inactive state, and additionally may include extended wireless access-related information.

[0128] For example, a pre-allocation context may include at least one of the information disclosed below.

[0129] - Serving cell identification information,

[0130] - Beam identification information (Beam ID) and beam-related configuration information,

[0131] - Timing Advance (TA) information and information related to Timing Advance Variation (TA drift),

[0132] - Security context information,

[0133] - MAC scheduling information,

[0134] - Configuration information for resuming HARQ operation,

[0135] - SR / PUCCH resource configuration information,

[0136] - Configured Grant or Uplink Resource Configuration Information,

[0137] - Logical channel priority information,

[0138] - Scheduling-related configuration information.

[0139] For example, MAC scheduling information may include at least one of a C-RNTI or scheduling identifier, buffer status reporting (BSR) related configuration information, scheduling request (SR) related setting information, uplink resource allocation history or recent scheduling pattern information, and semi-persistent scheduling information.

[0140] If MAC scheduling information is maintained as part of the pre-allocation context, scheduling can be resumed without resetting the MAC layer to its initial state upon connection resumption, thereby reducing additional control signal exchange.

[0141] Timing Advance information may be a value for aligning the uplink transmission timing between the terminal and the base station. Generally, a RACH procedure may be performed to reset the timing alignment. The pre-allocation context may include information related to TA drift as well as the current TA value.

[0142] For example, TA drift-related information may include at least one of recent TA fluctuation trends, TA correction prediction values ​​based on movement speed, TA error tolerance range over time, and TA valid time range information.

[0143] When TA drift information is included in the pre-allocation context, the terminal (120-1) can transmit the uplink by applying a corrected TA based on the existing TA value, and the base station (110-1) can determine whether the time alignment is within the allowable range without an additional random access procedure.

[0144] Configuration information for resuming HARQ operation may be information that allows the HARQ process to be executed continuously without initializing it upon resuming the connection. For example, configuration information for resuming HARQ operation may include at least one of the number and identifier of HARQ processes, status information of each HARQ process, information related to the most recent transmitted block, the status of the New Data Indicator (NDI), HARQ timer configuration information, and configuration information related to ACK / NACK feedback.

[0145] The terminal (120-1) and / or base station (110-1) can immediately resume data transmission and reception based on the existing state without reconfiguring the HARQ process from the beginning after the connection is resumed.

[0146] The pre-allocation context may include at least one of SR / PUCCH resource configuration information, Configured Grant or uplink resource configuration information, and scheduling-related configuration information. Accordingly, the terminal (120-1) can transmit control information or data necessary for resuming the connection through a pre-configured uplink resource without performing a random access procedure during the connection resumption process.

[0147] In step S110, the base station (110-1) may store a pre-allocated context received from the terminal (120-1). Based on the pre-allocated context, the base station (110-1) may verify the validity of the context when a request to resume the connection is received later. In particular, if it is determined that the validity level of the pre-allocated context is high, the base station (110-1) may skip additional synchronization procedures or random connection procedures and immediately approve the resumption of the connection.

[0148] In step S120, the terminal (120-1) may be in a pre-active mode state. Unlike the RRC connection state, in the pre-active mode, user plane data transmission may not be performed, or only a very small portion may be transmitted. For example, HARQ operations may not be enabled in the pre-active mode. Additionally, continuous uplink data transmission or full scheduling procedures may not be performed. The terminal (120-1) may monitor the downlink control channel (PDCCH) as needed and perform beam state maintenance, time alignment state maintenance, or updates of serving cell-related information. Thus, the pre-active mode may be a state that is lighter than a full connection state, but maintains an extended context than the existing RRC inactive state.

[0149] In step S130, the resumption of the connection may be triggered. According to one embodiment of the present invention, the resumption of the connection may be triggered not only by the terminal (120-1) but also by the base station (110-1). For example, the terminal (120-1) may attempt to request the resumption of the connection via PUCCH or PUSCH when uplink data transmission is required. On the other hand, the base station (110-1) may transmit a control signal instructing the terminal (120-1) to resume the connection quickly via PDCCH, in which case the resumption of the connection may be performed under the initiative of the network (base station).

[0150] In step S140, the terminal (120-1) can transmit a connection resumption request by utilizing the stored pre-allocated context. At this time, the terminal (120-1) can transmit a connection resumption request message based on the identification information and wireless configuration information included in the pre-allocated context.

[0151] In step S150, the base station (110-1) may verify the validity of the pre-allocated context based on a connection resumption request received from the terminal (120-1). In the verification process, the validity of serving cell information, time alignment information, beam information, and security context may be determined. However, if the connection resumption is triggered by the base station (110-1), the pre-allocated context verification step may be omitted, and the connection resumption may be approved immediately based on the validity of the context.

[0152] Finally, at step S160, the base station (110-1) can send a connection resumption approval message to the terminal (120-1). If the random connection procedure is omitted, the HARQ configuration information, time alignment information, and MAC scheduling information included in the pre-allocation context can be maintained and utilized, and accordingly, data transmission and reception can be initiated quickly without additional resetting. That is, the connection resumption delay can be minimized by maintaining the state of the physical layer and the MAC layer continuously.

[0153] As another example, if the validity level of the pre-allocation context is low, the base station (110-1) may not immediately approve resumption and may request the terminal (120-1) to initiate a 2-step random access or 4-step random access procedure.

[0154] FIG. 6 is a flowchart exemplarily illustrating the resumption of an RRC connection by a terminal (120-1) in a pre-activated state by a base station (110-1). Referring to FIG. 6, a Fast Resume procedure in which random access is omitted (or at least part of the random access procedure is omitted) may be performed under the initiative of the base station (110-1).

[0155] Steps S200 and S210 may be similar to steps S100 and S110 described in FIG. 4. That is, the terminal (120-1) may be switched to a pre-active mode and may transmit a pre-assigned context to the base station (110-1). The base station (110-1) may store the pre-assigned context.

[0156] In step S220, the base station (110-1) may determine whether to trigger the resumption of the connection in a network-driven manner. For example, the base station (110-1) may decide to trigger the resumption of the connection in a network-driven manner in at least one of the following cases: when downlink data transmission is required; when it is determined that the mobility of the terminal (120-1) is low based on a report from AI / ML; and when it is determined that it is necessary to minimize delay due to the nature of the service.

[0157] The base station (110-1) can verify the validity of the stored pre-allocation context in advance. For example, the base station (110-1) can determine at least one of the following.

[0158] - Whether the terminal (120-1) exists in the same serving cell as at the time of the prior allocation context setup

[0159] - Whether the time alignment drift (TA drift) is within the set threshold

[0160] - Whether the freshness of the security context or RAN context is valid

[0161] - Whether the terminal satisfies the low mobility criterion

[0162]

[0163] If the above judgment result determines that the validity level of the pre-allocation context is high, the base station (110-1) may decide to perform a Fast Resume that does not perform random access. On the other hand, if the validity level of the pre-allocation context is determined to be partially satisfied or low, the base station (110-1) may decide that a 2-step random access procedure or a 4-step random access procedure is required.

[0164] In step S230, the base station (110-1) can transmit Downlink Control Information (DCI) through the Downlink Control Channel (PDCCH). The base station (110-1) may include an indicator in the DCI that indicates whether to use a fast resume procedure based on a judgment regarding the validity level of the pre-allocated context. The DCI may include a Fast Resume Indicator. The Fast Resume Indicator may indicate to the terminal (120-1) whether to perform a fast resume procedure with random access omitted. For example, the Fast Resume Indicator may consist of 1 bit to indicate whether to perform a fast resume procedure. As another example, the Fast Resume Indicator may consist of multiple bits to indicate any one of performing a fast resume procedure, performing a 4-step random access, or performing a 2-step random access.

[0165] The above DCI may further include uplink resource indication information (UL resource indication) or Configured Grant activation information.

[0166] In one embodiment, the DCI may simultaneously include a command to initiate a connection resumption procedure along with an instruction to use Fast Resume. In another embodiment, the instruction to use Fast Resume may be transmitted first through the DCI, and then the command to initiate connection resumption may be transmitted through a separate message (e.g., Resume Command).

[0167] In the above embodiment, an example in which a fast resume indicator is transmitted via DCI has been described, but it is not limited thereto. The fast resume indicator may also be transmitted via various control signals, RRC messages, MAC control elements, or other radio resource control signals through a downlink control channel. Additionally, the fast resume initiation command and resource indicator information may be transmitted together in a single message or separated into multiple messages.

[0168] In another embodiment, if the base station (110-1) determines that a random access procedure is required, the DCI may include an indicator that does not perform a quick resume. In this case, a standard RRC Resume procedure may be performed in a subsequent step, and, for example, a 2-step or 4-step random access procedure may be performed.

[0169] In step S240, the terminal (120-1) can check the received DCI. The terminal (120-1) can check the fast resumption indicator included in the DCI and prepare to resume the connection based on the stored pre-assigned context.

[0170] Subsequently, at step S250, the terminal (120-1) may transmit an RRC connection resumption request. The connection resumption request may be transmitted by utilizing identification information and configuration information included in the pre-allocated context without performing a random connection procedure.

[0171] In step S260, the base station (110-1) may immediately approve the resumption of the connection without performing a separate additional verification procedure for the pre-allocated context. This may be because the validity of the context has already been pre-verified in step S220. By omitting the additional verification procedure for the pre-allocated context, signaling overhead and delay may be reduced.

[0172] Finally, in step S270, the base station (110-1) can allocate wireless resources while maintaining HARQ-related configuration information, MAC scheduling information, etc., stored in the pre-allocation context, and accordingly, data transmission and reception with the terminal (120-1) can be initiated immediately. In this case, the state of the physical layer and the MAC layer can be maintained without being re-initialized, so the delay in resuming the connection can be minimized.

[0173] FIG. 7 shows a modified embodiment of the rapid resumption procedure described in FIG. 6. Steps S200, S210, S220, S230, S240, and S270 in FIG. 7 may be identical or substantially similar to each step described in FIG. 6.

[0174] Referring to FIG. 7, the operation after the terminal (120-1) checks the quick resumption indicator may be configured differently from FIG. 6. Specifically, in FIG. 6, the terminal (120-1) may transmit an RRC connection resumption request message after checking the quick resumption indicator. In the embodiment of FIG. 7, the transmission of the RRC connection resumption request message may be omitted when the terminal (120-1) checks the quick resumption indicator.

[0175] The terminal (120-1) can send an RRC connection resumption confirmation message (RRC Resume Confirm) immediately at step S256 without sending a separate RRC Resume Request message. This may be because the base station (110-1) has already verified the validity of the pre-allocated context in advance at step S220 and explicitly instructed a quick resumption.

[0176] If the step of transmitting the RRC connection resumption request message is omitted, the number of control message exchanges can be reduced, thereby decreasing signaling overhead. Additionally, as the number of steps in the connection resumption procedure is reduced, the resumption delay time can be further shortened.

[0177] Subsequently, at step S270, the base station (110-1) can allocate wireless resources while maintaining HARQ-related configuration information, MAC scheduling information, etc., stored in the pre-allocation context, and data transmission and reception with the terminal (120-1) can be initiated immediately. In this case, since the physical layer and MAC layer states can be continuously maintained, the resetting procedure during the connection resumption process can be minimized.

[0178] The embodiment according to FIG. 7 can provide a more simplified and faster resume procedure, and may have additional effects, particularly in terms of reducing signaling overhead and minimizing latency. Furthermore, according to the embodiments of FIG. 6 and FIG. 7, since the base station (110-1) can verify the validity of the pre-allocated context in advance or determine it independently within the network, the additional context verification procedure with the upper core network node (e.g., AMF) that can be performed in the conventional RRC Resume procedure may be omitted. The message round-trip time (RTT) between the base station (110-1) and the core network may be reduced, and the overall connection resume latency may be further shortened.

[0179] FIG. 8 is a flowchart illustrating a terminal (120-1)-led connection resumption procedure according to one embodiment of the present invention.

[0180] Referring to FIG. 8, steps S300 and S310 may be substantially the same as steps S200 and S210 described in FIG. 6 and 7. That is, the terminal (120-1) may be switched to a pre-active mode, transmit a pre-assigned context to the base station (110-1), and the base station (110-1) may store it.

[0181] In step S320, the terminal (120-1) may decide to resume the connection while in a pre-active mode. For example, the terminal (120-1) may decide to resume the connection when uplink data transmission is required, when an internal timer expires, when a periodic data reporting time arrives, when preparation for receiving downlink data is required, or when a connection resumption is requested at the application layer, etc.

[0182] The terminal (120-1) that has decided to resume the connection can check whether it possesses a pre-allocated context. Additionally, the terminal (120-1) can independently determine the validity of the pre-allocated context it possesses. For example, the terminal (120-1) can determine the validity of the pre-allocated context by considering at least one of the following.

[0183] - Whether the current serving cell is the same as the serving cell stored in the pre-allocation context

[0184] - Whether the time alignment value and TA drift are within the allowable threshold

[0185] - Whether the validity period range of the security context is maintained

[0186] - Whether the validity period of the pre-allocated context has not expired

[0187]

[0188] If the terminal (120-1) determines that a pre-allocated context can be used based on the above determination result, it may transmit a pre-allocated context indicator via PUCCH without performing random access (or omitting at least some of the random access procedure).

[0189] The above pre-allocation context indicator may be, for example, 1 bit information and may indicate that the terminal (120-1) has a pre-allocation context.

[0190] Additionally, the PUCCH may include a scheduling request (SR). That is, the terminal (120-1) can transmit the SR along with a pre-allocated context indicator, thereby requesting uplink resource allocation without random access.

[0191] Optionally, the PUCCH may additionally include terminal identifier information or a pre-assigned context identifier.

[0192] In step S330, the base station (110-1) can receive the PUCCH. The base station (110-1) can identify which terminal (120-1) the PUCCH was transmitted from based on the PUCCH resource location, C-RNTI, or identifier information included in the PUCCH.

[0193] The base station (110-1) can search for a pre-allocated context corresponding to the terminal (120-1) and verify its validity. For example, if multiple pre-allocated contexts are stored or if context synchronization is required after the base station (110-1) is restarted, the base station (110-1) can request a pre-allocated context identifier from the terminal (120-1).

[0194] Information regarding the above-mentioned pre-assigned context identifier may be shared in advance between the terminal (120-1) and the base station (110-1). For example, the above-mentioned pre-assigned context identifier may be included in a signaling message in which the base station (110-1) instructs the terminal (120-1) to enter a pre-active mode.

[0195] When the validation of the pre-allocation context is completed at step S380, the base station (110-1) may approve the resumption of the RRC connection. The base station (110-1) may transmit a resumption approval message, and at this time, may transmit uplink resource allocation information (UL Grant) together.

[0196] According to the above procedure, the terminal (120-1) can initiate connection resumption via a PUCCH-based control signal without performing a random connection procedure, so signaling overhead and resumption delay time can be reduced.

[0197] FIG. 8 illustrates a case where the random access procedure is omitted as an example, but the embodiment is not limited thereto. For example, at step S330, the base station (110-1) may determine that the validity of the pre-allocated context is insufficient. For example, the base station (110-1) may determine, by comparing the pre-allocated context stored by the terminal (120-1) with the current network state, whether the serving cell has changed, whether the TA drift has exceeded an allowable threshold, whether the freshness of the security context has expired, or whether the beam information is no longer valid.

[0198] In such a case, the base station (110-1) may not approve Fast Resume and may send a message to the terminal (120-1) indicating that a random access procedure needs to be performed. The message may include, for example, a RACH request indicator, and the terminal (120-1) may accordingly perform a 2-step random access procedure or a 4-step random access procedure.

[0199] In addition, the above RACH request instruction may be transmitted through downlink control signals, RRC messages, or MAC control elements, and may not be limited to a specific protocol layer.

[0200] Accordingly, the terminal-led connection resumption procedure according to the present embodiment can adaptively switch to either a fast resumption or a resumption procedure accompanied by random access, depending on the validity level of the pre-allocated context.

[0201]

[0202] FIG. 9 is a flowchart illustrating an example of a terminal (120-1)-led connection resumption procedure.

[0203] Steps S300, S310, S320, and S330 in FIG. 9 may be identical or substantially similar to steps S300, S310, S320, and S330 described in FIG. 8.

[0204] That is, the terminal (120-1) can determine to resume the connection in pre-active mode and can transmit a PUCCH including a Pre-Allocated Context Indicator.

[0205] However, in the embodiment of FIG. 9, the PUCCH transmitted at step S320 may include a pre-allocated context indicator, but may not include a pre-allocated context identifier (preAllocatedContextID). That is, in the initial stage, the terminal (120-1) may only indicate whether a pre-allocated context exists.

[0206] In step S340, after receiving the PUCCH, the base station (110-1) can transmit an uplink grant (UL Grant) via a downlink control signal (e.g., DCI).

[0207] In specific situations, such as when multiple pre-allocated contexts are used or when the base station (110-1) is restarted, the base station (110-1) may include a request for identification information regarding the pre-allocated contexts and / or a request for additional information for resuming the connection in the DCI. That is, the base station (110-1) may instruct the terminal (120-1) to transmit the pre-allocated context identifier and / or additional resumption-related information.

[0208] In step S350, the terminal (120-1) may transmit an RRC connection resumption request via PUSCH based on the UL Grant. The RRC connection resumption request may include a pre-allocated context identifier (preAllocatedContextID). Additionally, the terminal (120-1) may transmit additional information elements (IE) related to the connection resumption.

[0209] For example, the above RRC connection resumption request may include the IEs shown in Table 2. The names of the IEs are merely exemplary and a person skilled in the art can easily change the names of the IEs.

[0210] Field Name Description preAllocatedContextID: Unique identifier of the Pre-Allocated Context held by the UE (The network validates existing information and determines resumability based on this unique identifier) ulGrantRequest: Indicates whether the UE is requesting a UL Grant immediately without random access (If TRUE, UL Grant can be assigned immediately) servingCellValidation: Indicates that the current serving cell has not changed (If TRUE, the network can maintain the existing TA and Scheduling) resumeIdentity: Short for the UE's resume request I-RNTI value resumeMAC-I: MAC-I value for the UE's authentication resumeCause: The reason the UE is requesting an RRC resume (UL Data Arrival, Paging Response, etc.)

[0211] preAllocatedContextID: This may be an identifier for identifying a pre-allocated context held by the terminal (120-1). The base station (110-1) may search for the stored context based on the ID and determine its validity. ulGrantRequest: This may indicate whether the terminal (120-1) requests immediate uplink resource allocation without a random access procedure.

[0212] servingCellValidation: This may be a field indicating that the terminal (120-1) has not changed the current serving cell. For example, if set to TRUE, the base station (110-1) may maintain existing time alignment (TA) and scheduling information.

[0213] resumeIdentity: This may be a Short Identity value for the Resume request of the terminal (120-1).

[0214] resumeMAC-I: This may be a MAC-I value for terminal authentication and can be used for security context verification.

[0215] resumeCause: This may indicate the reason why the terminal (120-1) requests the resumption of the connection. For example, it may be the arrival of uplink data, a paging response, etc.

[0216] The terminal (120-1) transmits only minimal information during the initial PUCCH phase and can subsequently transmit more detailed information regarding connection resumption through PUSCH.

[0217] In step S360, the base station (110-1) can search for the corresponding pre-allocated context based on the pre-allocated context identifier received from the terminal (120-1). The base station (110-1) can verify the validity of the context, and this verification may be performed at the local RAN level. For example, it can check whether the serving cell matches, whether the TA drift is within the allowed range, the freshness of the security context, etc.

[0218] If necessary, the base station (110-1) may request validation of the NAS context or security context through communication with the AMF. That is, in this embodiment, both a RAN-only verification structure and a RAN+AMF verification structure may be possible.

[0219] If the validity of the pre-allocation context is verified in step S380, the base station (110-1) may approve the resumption of the RRC connection. The base station (110-1) may transmit a resumption approval message, which may include uplink resource allocation information.

[0220] In step S390, the terminal (120-1) can transmit a resumption completion message, and accordingly, the terminal (120-1) can switch to an RRC connection state.

[0221] According to the embodiment of FIGS. 8 and 9, the terminal (120-1) and the base station (110-1) can perform a connection resumption procedure by utilizing a pre-stored pre-allocation context. The pre-allocation context may include Timing Advance information, TA drift related information, HARQ process configuration information, MAC scheduling related information, SR / PUCCH resource configuration information, Configured Grant information, etc.

[0222] Accordingly, if the above information is valid, the connection may be resumed without performing a random connection procedure (e.g., sending a PRACH preamble and performing a 4-step or 2-step RACH).

[0223] In particular, by utilizing existing TA and TA drift information, uplink transmission can be performed without additional time alignment procedures, and by maintaining existing HARQ process configuration information, data transmission and reception can be initiated immediately without resetting the HARQ process, and uplink resources can be used without obtaining a separate random access-based UL Grant by utilizing stored MAC scheduling information and Configured Grant information.

[0224] As a result, the preamble transmission, contention resolution, timing resynchronization, and HARQ / scheduling reconfiguration processes associated with the random access procedure can be omitted or minimized, thereby significantly reducing signaling overhead and connection resumption latency.

[0225] In addition, since the base station (110-1) verifies the pre-allocated context locally, an additional context verification procedure with the AMF can be omitted, and as a result, the core network interlock delay can also be reduced. In particular, for terminals with low mobility or terminals that repeatedly perform connection resumption in the same serving cell, the pre-allocated context-based connection resumption method can be applied very advantageously in IoT, smart factories, indoor robot environments, etc., which require ultra-low latency characteristics.

[0226] FIG. 10 is a flowchart illustrating an example of a connection resumption procedure that can be performed when the validity level of the pre-assigned context is low. Steps S300 to S360 of FIG. 10 may be substantially the same as steps S300 to S360 described in FIG. 9, and a redundant description thereof may be omitted.

[0227] In step S360, the base station (110-1) can verify the validity of the pre-allocation context. The validity verification can be performed by considering, for example, the following factors.

[0228] - Whether the current serving cell is the same as the serving cell at the time the pre-allocation context was saved

[0229] - Whether the TA value and TA drift are within preset thresholds

[0230] - Whether the freshness and integrity of the security context are maintained

[0231] - Validity of HARQ configuration information and MAC scheduling information

[0232] - Whether the terminal's mobility level satisfies the pre-active mode maintenance condition

[0233] - The base station (110-1) can determine the validity level of the pre-allocation context based on the above verification result.

[0234] In the embodiment of FIG. 10, if it is determined that the validity level of the pre-allocation context is low in step S360, the base station (110-1) may not approve Fast Resume.

[0235] For example, it may not be appropriate to perform resumption based on a pre-allocated context when the serving cell has changed, when the TA drift has exceeded a threshold, when HARQ or scheduling-related information is no longer valid, or when the security context has expired. In this case, the base station (110-1) may send a resumption refusal message or a message requesting the terminal (120-1) to perform a random access procedure at step S391.

[0236] The above message may include, for example, one of the following.

[0237] - An indicator indicating that pre-allocated context-based resumption is not possible

[0238] - Instruction to perform 2-step random connection procedure

[0239] - Instruction to perform the 4-step random connection procedure

[0240] - Information about specific PRACH resources or CFRA resources

[0241] Accordingly, the terminal (120-1) can proceed with resuming the connection by performing a general random connection procedure instead of resuming based on a pre-allocated context.

[0242] According to the embodiment of FIG. 10, when the validity of the pre-allocation context is not sufficiently secured, the stability of the wireless link can be secured by re-establishing the connection through a random connection procedure without performing an excessively fast resumption.

[0243] FIG. 11 is a flowchart illustrating an embodiment in which a terminal (120-1) can perform beam monitoring and beam failure recovery in a pre-active mode.

[0244] Here, "beam failure" may refer to a state where stable communication through the currently used beam is difficult due to beam quality degradation, failure to receive reference signals, consecutive block errors, RLM (Radio Link Monitoring) failure, etc.

[0245] Steps S400 and S410 may be substantially the same as steps S300 and S310 of FIGS. 8 and 9. In this step, the terminal (120-1) switches to a pre-active mode and can create and store a pre-assignment context. The base station (110-1) can also store the pre-assignment context.

[0246] The pre-allocation context may further include beam-related information. For example, the beam-related information of the pre-allocation context may include at least one of the currently used beam ID, beam index or beam group information, beam timing information, information related to beam power or beam intensity, beam quality metrics, a list of candidate beams, and historical information of recently successfully used beams. The beam-related information can be utilized for rapid recovery in the event of a subsequent beam failure.

[0247] In step S420, the terminal (120-1) can check the status of the beam currently in use by monitoring the CSI-RS or other reference signals in the pre-active mode. In the pre-active mode, unlike the RRC connection state, continuous data transmission and reception may not be performed, but limited beam monitoring may be maintained.

[0248] In step S430, the terminal (120-1) can detect a beam failure if it does not satisfy the set criteria. For example, if a number of consecutive CSI-RS reception failures, RLM timer expiration, or a state below a signal strength threshold persists, the terminal (120-1) can determine that the current beam is no longer valid.

[0249] When a beam failure is detected, in step S440, the terminal (120-1) can determine whether beam-related information included in the pre-allocation context is available for use. For example, the terminal (120-1) can determine whether the pre-allocated beam-related information is available for use by considering whether candidate beam information is stored in the pre-allocation context, whether the stored beam information corresponds to the same serving cell, whether the beam timing information is valid, whether the TA drift is within an acceptable range, etc.

[0250] If it is determined that the pre-allocated beam information can be utilized, the terminal (120-1) may proceed to step S450. Conversely, if it is difficult to utilize the pre-allocated beam information, beam recovery may be performed by performing a general random access.

[0251] In step S450, the terminal (120-1) can utilize beam-related information included in the pre-allocation context to search for a new beam or recover an existing beam. In this process, random access can be omitted or minimized, thereby reducing the Round Trip Delay (RTD).

[0252] According to the embodiment of FIG. 11, in the pre-activation mode, the terminal (120-1) stores beam-related information in a pre-allocated context, thereby enabling rapid beam recovery without relying on random access even when a beam failure occurs.

[0253] With reference to FIGS. 1 to 11, a method and apparatus for managing a wireless connection status in a wireless communication system according to an exemplary embodiment have been described above.

[0254] According to at least one embodiment, by utilizing serving cell information, Timing Advance (TA) information, TA drift-related information, HARQ configuration information, MAC scheduling information, uplink resource configuration information, etc. included in the pre-allocation context, connection resumption can be performed while omitting or minimizing the Random Access procedure. Accordingly, the round-trip delay time occurring when resuming the connection can be reduced.

[0255] According to at least one embodiment, by enabling the base station to determine the validity of a pre-allocated context in advance and instruct a Fast Resume, the RRC connection resumption request and context verification procedure of the terminal can be shortened or omitted. In particular, if the context verification procedure between the base station and the AMF can be omitted, signaling delay with the core network can be reduced.

[0256] According to at least one embodiment, by using PUCCH in a terminal-led resumption procedure to transmit a pre-allocated context indicator and a Scheduling Request (SR) together, uplink resource allocation can be requested without random access via PRACH. Accordingly, unnecessary control signal overhead can be reduced and the connection resumption procedure can be simplified.

[0257] According to at least one embodiment, by including configuration information for resuming HARQ operation and MAC scheduling information in the pre-allocation context, data transmission and reception can be immediately resumed after connection resumption. This reduces additional delays and overhead caused by HARQ reset, scheduling reconfiguration, etc.

[0258] According to at least one embodiment, beam-related information is included in a pre-allocation context in a pre-active mode, and by enabling the terminal to perform beam monitoring and beam failure recovery, rapid beam recovery can be performed without relying on a random connection procedure when a beam failure occurs. Accordingly, beam failure recovery delay can be reduced and the stability of the wireless link can be improved.

[0259] According to at least one embodiment, by selecting an appropriate procedure among random connection omission, 2-step random connection, and 4-step random connection depending on the validity level of the pre-allocation context, it is possible to simultaneously achieve latency minimization and connection reliability.

[0260] According to at least one embodiment, when combined with AI / ML-based mobility prediction or location prediction technology, the movement pattern of a terminal can be predicted in advance to optimize whether to maintain a pre-allocated context. In particular, by actively utilizing a pre-allocated context-based resumption method in environments such as low-mobility environments, indoor environments, and smart factories, low-latency characteristics and power efficiency can be simultaneously improved.

[0261] According to at least one embodiment, by improving the inefficiency of existing connection resumption procedures and providing an optimized connection resumption structure in low-mobility or predictable environments, the effects of reduced latency, reduced control overhead, improved power efficiency, and increased wireless resource utilization efficiency can be achieved simultaneously.

[0262] Based on the foregoing description of various embodiments of this disclosure, a person skilled in the art will clearly understand that the methods and / or processes of the present invention and the steps thereof may be realized in hardware, software, or any combination of hardware and software suitable for a particular use case. The hardware may include a general-purpose computer and / or a dedicated computing device or a specific computing device or a particular form or component of a specific computing device. The processes may be realized by one or more processors having internal and / or external memory, such as a microprocessor, a controller, such as a microcontroller, an embedded microcontroller, a microcomputer, an arithmetic logic unit (ALU), a digital signal processor, such as a programmable digital signal processor, or other programmable device. In addition, or as an alternative, the above processes may be carried out by an application-specific integrated circuit (ASIC), a programmable gate array, such as a field programmable gate array (FPGA), a programmable logic unit (PLU), or a programmable array logic (PAL), or any other device capable of executing and responding to instructions, any other device or combination of devices that may be configured to process electronic signals. The processing unit may execute an operating system (OS) and one or more software applications executed on said operating system. Additionally, the processing unit may access, store, manipulate, process, and generate data in response to the execution of the software.For ease of understanding, the processing unit may be described as being used as a single unit, but a person of ordinary skill in the art will understand that the processing unit may include multiple processing elements and / or multiple types of processing elements. For example, the processing unit may include multiple processors or one processor and one controller. In addition, other processing configurations, such as parallel processors, are also possible.

[0263] Software may include computer programs, code, instructions, or a combination of one or more of these, and may configure a processing unit to operate as desired or command the processing unit independently or collectively. Software and / or data may be permanently or temporarily embodied in any type of machine, component, physical device, virtual equipment, computer storage medium or device, or transmitted signal wave in order to be interpreted by the processing unit or to provide instructions or data to the processing unit. Software may be distributed over networked computer systems and may be stored or executed in a distributed manner. Software and data may be stored on one or more machine-readable recording media.

[0264] Furthermore, parts contributing to the objects of the technical solution of the present invention or to the prior art may be implemented in the form of program instructions that can be executed through various computer components and recorded on a machine-readable medium. The machine-readable medium may include program instructions, data files, data structures, etc., either alone or in combination. The program instructions recorded on the machine-readable recording medium may be those specifically designed and configured for the embodiments, or they may be those known and available to a person skilled in the art of computer software. Examples of machine-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs, DVDs, and Blu-rays; magneto-optical media such as floptical disks; and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include machine code, bytecode, as well as high-level language code that can be executed by a computer using an interpreter, etc., which can be created using a structured programming language such as C, an object-oriented programming language such as C++, or high-level or low-level programming languages ​​(assembly language, hardware description languages, and database programming languages ​​and technologies), which can be stored and compiled or interpreted to be executed on a machine capable of executing any of the aforementioned devices, as well as a processor, a processor architecture, or a heterogeneous combination of different hardware and software combinations.

[0265] Accordingly, in one embodiment according to the present invention, when the methods and combinations thereof described above are performed by one or more computing devices, the methods and combinations thereof may be implemented as executable code that performs each step. In another embodiment, the methods may be implemented as systems that perform the steps, and the methods may be distributed in various ways across devices, or all functions may be integrated into a single dedicated, standalone device or other hardware. In yet another embodiment, the means for performing the steps associated with the processes described above may include any of the hardware and / or software described above. All such sequential combinations and combinations are intended to fall within the scope of this disclosure.

[0266] For example, the above-described hardware device may be configured to operate as one or more software modules to perform the operation of the embodiment, and vice versa. The hardware device may include a processor such as an MPU, CPU, GPU, or TPU that is combined with memory such as ROM / RAM for storing program instructions and configured to execute instructions stored in said memory, and may include a communication unit capable of exchanging signals with an external device. Additionally, the hardware device may include a keyboard, mouse, or other external input device for receiving instructions written by developers.

[0267] Although the present invention has been described above with specific details such as specific components, limited embodiments, and drawings, this is provided only to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments, and a person skilled in the art to which the invention belongs can make various modifications and variations from this description.

[0268] Accordingly, the scope of the present invention is not limited to the embodiments described above, and all modifications equivalent to or equivalent to the claims attached to this disclosure, as well as the claims attached to this disclosure, shall be considered to be within the scope of the scope of the concept of the present invention. For example, appropriate results may be achieved even if the described techniques are performed in a different order than the described method, and / or the components of the described system, structure, device, circuit, etc. are combined or assembled in a form different from the described method, or are replaced or substituted by other components or equivalents.

[0269] Such equivalent or equivalent modifications may include, for example, logically equivalent methods capable of producing the same result as carrying out the method according to the present invention; the true meaning and scope of the present invention shall not be limited by the examples described above, but shall be understood in the broadest sense permissible by law.

Claims

A wireless connection management method performed by a terminal including a communication unit and a processor, Step of transferring a pre-allocated context; and It includes the step of transitioning from an RRC connected state to a pre-active state while maintaining the above-mentioned pre-allocation context, The above pre-allocation context includes configuration information for resuming HARQ operation, time alignment related information, and security context information, and A wireless connection management method in which, when connection resumption is performed in the above-mentioned prior active state, whether to perform a fast resumption with random access omitted is determined based on the result of judging the validity of the above-mentioned prior allocation context. In Article 1, A wireless connection management method in which the above-mentioned pre-allocation context includes at least one of serving cell information, beam-related information, MAC scheduling information, scheduling request, and resource configuration information for PUCCH transmission. In Article 1, A step of receiving a fast resumption indicator from a base station that indicates whether to use fast resumption; A step of performing a fast resume with random access omitted based on the above fast resume indicator, and A wireless connection management method comprising the step of utilizing configuration information and time alignment related information for resuming HARQ operations included in the aforementioned pre-allocation context in the resumed connection after rapid resumption is completed. In Paragraph 3, The above-mentioned fast resume indicator is included in the downlink control information and transmitted, A wireless connection management method comprising at least one of uplink resource instruction information or pre-configured resource allocation (configured grant) activation information, wherein the downlink control information above includes. In Article 1, A wireless connection management method further comprising the step of requesting a base station for fast resumption with random access omitted by transmitting a pre-allocation context indicator indicating whether the terminal possesses a pre-allocation context when it is determined that RRC connection resumption is necessary in the above pre-active state. In Article 4, A wireless connection management method that transmits a scheduling request and a pre-allocated context indicator together in the step of requesting a base station for fast resumption with the above random access omitted. In Article 5, A step of receiving a request for identification information regarding the pre-allocation context from a base station; and A wireless connection management method comprising the step of transmitting an RRC connection resumption request including a pre-assigned context identifier. In Article 7, A wireless connection management method comprising an information element indicating whether an RRC connection resumption request requests an uplink acknowledgment without random access, and an information element indicating whether the serving cell has not changed. In Article 1, A wireless connection management method comprising the step of performing a connection resumption procedure accompanied by random access when a rejection message for fast resumption with random access omitted is received from a base station. In Article 1, The above pre-allocation context includes beam-related information, and A step of performing beam monitoring in the above pre-active mode; Step of detecting beam failure; and A wireless connection management method comprising the step of omitting random access and performing beam recovery using the above beam-related information. A wireless connection management method performed by a base station including a communication unit and a processor, Step of receiving a pre-allocation context; and It includes a step of determining the validity of the above-mentioned prior allocation context, A wireless connection management method in which, when connection resumption is performed in the above-mentioned prior active state, whether to perform a fast resumption with random access omitted is determined based on whether the validity of the above-mentioned prior allocation context satisfies a preset condition. In Article 11, A wireless connection management method in which the above-mentioned pre-allocation context includes configuration information for resuming HARQ operation, time alignment related information, MAC scheduling information, serving cell related information, and security context information. In Article 12, A wireless connection management method in which the validity of the above-mentioned pre-allocation context is determined based on at least one of whether the serving cell is identical, whether the amount of timing advance variation satisfies a preset range, the mobility level of the terminal, and the validity of configuration information for resuming HARQ operation. In Article 11, If it is determined that the validity of the above-mentioned pre-allocation context satisfies a preset condition, the step of transmitting a fast resumption indicator instructing the use of fast resumption; and A wireless connection management method comprising the step of utilizing configuration information and time alignment related information for HARQ operation resumption included in the pre-allocation context in the resumed connection after a fast resumption with random access omitted is completed. In Article 11, A wireless connection management method comprising the step of requesting a terminal to resume a procedure including random access when it is determined that the validity of the above-mentioned prior allocation context does not satisfy a preset condition. In Article 11, A wireless connection management method comprising the step of receiving a pre-allocation context indicator from a terminal that indicates whether the terminal possesses a pre-allocation context. In Article 16, A step of transmitting a request for identification information regarding the above-mentioned prior allocation context; and A wireless connection management method comprising the step of receiving an RRC connection resumption request including a pre-assigned context identifier from the terminal.

Images