State transition to non-connected state

Abstract

The present disclosure is related to state transition to non-connected state in wireless communications. According to an embodiment of the present disclosure, a method performed by a user equipment (UE) configured to operate in a wireless communication system comprises: establishing a connection with a network and entering a connected state; receiving a configuration for a data inactivity timer from the network; starting the data inactivity timer based on performing at least one of a transmission or a reception; and after the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.

Description

STATE TRANSITION TO NON-CONNECTED STATE

[0001] The present disclosure is related to state transition to non-connected state in wireless communications.

[0002] 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.

[0003] Work has started in International Telecommunication Union (ITU) and 3GPP to develop requirements and specifications for New Radio (NR) systems. 3GPP has to identify and develop the technology components needed for successfully standardizing the new RAT timely satisfying both the urgent market needs, and the more long-term requirements set forth by the ITU Radio communication sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process. Further, the NR should be able to use any spectrum band ranging at least up to 100 GHz that may be made available for wireless communications even in a more distant future.

[0004] The NR targets a single technical framework addressing all usage scenarios, requirements and deployment scenarios including enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), Ultra-Reliable and Low Latency Communications (URLLC), etc. The NR shall be inherently forward compatible.

[0005] In wireless communications, a user equipment (UE) operates under the control of a base station. The radio resource control (RRC) protocol governs the configuration, maintenance, and / or release of radio bearers and related procedures that support data transmission and mobility.

[0006] The RRC layer supports several UE states, each defining a specific level of connectivity and activity. These states may include a connected state (e.g., RRC_CONNECTED) and non-connected states (e.g., RRC_INACTIVE, RRC_IDLE). Efficient state management is critical for optimizing network resource usage and minimizing power consumption of the UE.

[0007] An aspect of the present disclosure is to provide method and apparatus for state transition to non-connected state in a wireless communication system.

[0008] According to an embodiment of the present disclosure, a method performed by a user equipment (UE) configured to operate in a wireless communication system comprises: establishing a connection with a network and entering a connected state; receiving a configuration for a data inactivity timer from the network; starting the data inactivity timer based on performing at least one of a transmission or a reception; and after the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.

[0009] According to an embodiment of the present disclosure, a method performed by a network node configured to operate in a wireless communication system comprises: establishing a connection with a user equipment (UE) based on which the UE enters a connected state; and transmitting, to the UE, a configuration for a data inactivity timer, wherein the UE is configured to perform operations comprising: starting the data inactivity timer based on performing at least one of a transmission or a reception; and after the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.

[0010] According to various embodiments, apparatuses to implement the above methods are provided.

[0011] The present disclosure may have various advantageous effects.

[0012] For example, even in the case that the UE with a valid suspend configuration allowing RRC state transition to RRC inactive state, the UE can decide to transit to RRC idle state upon expiry of the data inactivity timer if there is a potential link problem on the serving cell. This UE behaviour can avoid a connection failure in the near future during re-initiation of RRC connection by discarding the dedicated UE context that caused the potential link problem on the last serving cell.

[0013] Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and / or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

[0014] FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

[0015] FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

[0016] FIG. 3 shows an example of UE to which implementations of the present disclosure is applied.

[0017] FIGs. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0018] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0019] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

[0020] FIG. 8 shows an example of UE state machine and state transition.

[0021] FIG. 9 shows an example of a method performed by a UE for a state transition to non-connected state according to an embodiment of the present disclosure.

[0022] FIG. 10 shows an example of a signal flow between a UE and a network node for a state transition to non-connected state according to an embodiment of the present disclosure.

[0023] FIG. 11 shows an example of a method for state transition based on link status and suspend configuration according to an embodiment of the present disclosure.

[0024] The following techniques, apparatuses, and systems may be applied to a variety of wireless multiple access systems. Examples of the multiple access systems include a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, a Single Carrier Frequency Division Multiple Access (SC-FDMA) system, and a Multi Carrier Frequency Division Multiple Access (MC-FDMA) system. CDMA may be embodied through radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be embodied through radio technology such as Global System for Mobile communications (GSM), General Packet Radio Service (GPRS), or Enhanced Data rates for GSM Evolution (EDGE). OFDMA may be embodied through radio technology such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is a part of a Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in downlink (DL) and SC-FDMA in uplink (UL). Evolution of 3GPP LTE includes LTE-Advanced (LTE-A), LTE-A Pro, and / or 5G New Radio (NR).

[0025] For convenience of description, implementations of the present disclosure are mainly described in regards to a 3GPP based wireless communication system. However, the technical features of the present disclosure are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to a 3GPP based wireless communication system, aspects of the present disclosure that are not limited to 3GPP based wireless communication system are applicable to other mobile communication systems.

[0026] For terms and technologies which are not specifically described among the terms of and technologies employed in the present disclosure, the wireless communication standard documents published before the present disclosure may be referenced.

[0027] In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, "A or B" in the present disclosure may be interpreted as "A and / or B". For example, "A, B or C" in the present disclosure may mean "only A", "only B", "only C", or "any combination of A, B and C".

[0028] In the present disclosure, slash ( / ) or comma (,) may mean "and / or". For example, "A / B" may mean "A and / or B". Accordingly, "A / B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B or C".

[0029] In the present disclosure, "at least one of A and B" may mean "only A", "only B" or "both A and B". In addition, the expression "at least one of A or B" or "at least one of A and / or B" in the present disclosure may be interpreted as same as "at least one of A and B".

[0030] In addition, in the present disclosure, "at least one of A, B and C" may mean "only A", "only B", "only C", or "any combination of A, B and C". In addition, "at least one of A, B or C" or "at least one of A, B and / or C" may mean "at least one of A, B and C".

[0031] Also, parentheses used in the present disclosure may mean "for example". In detail, when it is shown as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information". In other words, "control information" in the present disclosure is not limited to "PDCCH", and "PDCCH" may be proposed as an example of "control information". In addition, even when shown as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information".

[0032] Technical features that are separately described in one drawing in the present disclosure may be implemented separately or simultaneously.

[0033] Although not limited thereto, various descriptions, functions, procedures, suggestions, methods and / or operational flowcharts of the present disclosure disclosed herein can be applied to various fields requiring wireless communication and / or connection (e.g., 5G) between devices.

[0034] Hereinafter, the present disclosure will be described in more detail with reference to drawings. The same reference numerals in the following drawings and / or descriptions may refer to the same and / or corresponding hardware blocks, software blocks, and / or functional blocks unless otherwise indicated.

[0035] FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

[0036] The 5G usage scenarios shown in FIG. 1 are only exemplary, and the technical features of the present disclosure can be applied to other 5G usage scenarios which are not shown in FIG. 1.

[0037] Three main requirement categories for 5G include (1) a category of enhanced Mobile BroadBand (eMBB), (2) a category of massive Machine Type Communication (mMTC), and (3) a category of Ultra-Reliable and Low Latency Communications (URLLC).

[0038] Referring to FIG. 1, the communication system 1 includes wireless devices 100a to 100f, Base Stations (BSs) 200, and a network 300. Although FIG. 1 illustrates a 5G network as an example of the network of the communication system 1, the implementations of the present disclosure are not limited to the 5G system, and can be applied to the future communication system beyond the 5G system.

[0039] The BSs 200 and the network 300 may be implemented as wireless devices and a specific wireless device may operate as a BS / network node with respect to other wireless devices.

[0040] The wireless devices 100a to 100f represent devices performing communication using Radio Access Technology (RAT) (e.g., 5G NR or LTE) and may be referred to as communication / radio / 5G devices. The wireless devices 100a to 100f may include, without being limited to, a robot 100a, vehicles 100b-1 and 100b-2, an eXtended Reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an Internet-of-Things (IoT) device 100f, and an Artificial Intelligence (AI) device / server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. The vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR) / Virtual Reality (VR) / Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter.

[0041] In the present disclosure, the wireless devices 100a to 100f may be called User Equipments (UEs). A UE may include, for example, a cellular phone, a smartphone, a laptop computer, a digital broadcast terminal, a Personal Digital Assistant (PDA), a Portable Multimedia Player (PMP), a navigation system, a slate Personal Computer (PC), a tablet PC, an ultrabook, a vehicle, a vehicle having an autonomous traveling function, a connected car, an UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a FinTech device (or a financial device), a security device, a weather / environment device, a device related to a 5G service, or a device related to a fourth industrial revolution field.

[0042] The wireless devices 100a to 100f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100a to 100f and the wireless devices 100a to 100f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and a beyond-5G network. Although the wireless devices 100a to 100f may communicate with each other through the BSs 200 / network 300, the wireless devices 100a to 100f may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs 200 / network 300. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., Vehicle-to-Vehicle (V2V) / Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0043] Wireless communication / connections 150a, 150b and 150c may be established between the wireless devices 100a to 100f and / or between wireless device 100a to 100f and BS 200 and / or between BSs 200. Herein, the wireless communication / connections may be established through various RATs (e.g., 5G NR) such as uplink / downlink communication 150a, sidelink communication (or Device-to-Device (D2D) communication) 150b, inter-base station communication 150c (e.g., relay, Integrated Access and Backhaul (IAB)), etc. The wireless devices 100a to 100f and the BSs 200 / the wireless devices 100a to 100f may transmit / receive radio signals to / from each other through the wireless communication / connections 150a, 150b and 150c. For example, the wireless communication / connections 150a, 150b and 150c may transmit / receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, and resource mapping / de-mapping), and resource allocating processes, for transmitting / receiving radio signals, may be performed based on the various proposals of the present disclosure.

[0044] NR supports multiples numerologies (and / or multiple Sub-Carrier Spacings (SCS)) to support various 5G services. For example, if SCS is 15 kHz, wide area can be supported in traditional cellular bands, and if SCS is 30 kHz / 60 kHz, dense-urban, lower latency, and wider carrier bandwidth can be supported. If SCS is 60 kHz or higher, bandwidths greater than 24.25 GHz can be supported to overcome phase noise.

[0045] The NR frequency band may be defined as two types of frequency range, i.e., Frequency Range 1 (FR1) and Frequency Range 2 (FR2). The numerical value of the frequency range may be changed. For example, the frequency ranges of the two types (FR1 and FR2) may be as shown in Table 1 below. For ease of explanation, in the frequency ranges used in the NR system, FR1 may mean "sub 6 GHz range", FR2 may mean "above 6 GHz range," and may be referred to as millimeter Wave (mmW).

[0046] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0047] As mentioned above, the numerical value of the frequency range of the NR system may be changed. For example, FR1 may include a frequency band of 410MHz to 7125MHz as shown in Table 2 below. That is, FR1 may include a frequency band of 6GHz (or 5850, 5900, 5925 MHz, etc.) or more. For example, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more included in FR1 may include an unlicensed band. Unlicensed bands may be used for a variety of purposes, for example for communication for vehicles (e.g., autonomous driving).

[0048] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0049] Here, the radio communication technologies implemented in the wireless devices in the present disclosure may include NarrowBand IoT (NB-IoT) technology for low-power communication as well as LTE, NR and 6G. For example, NB-IoT technology may be an example of Low Power Wide Area Network (LPWAN) technology, may be implemented in specifications such as LTE Cat NB1 and / or LTE Cat NB2, and may not be limited to the above-mentioned names. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may communicate based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and be called by various names such as enhanced MTC (eMTC). For example, LTE-M technology may be implemented in at least one of the various specifications, such as 1) LTE Cat 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and may not be limited to the above-mentioned names. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may include at least one of ZigBee, Bluetooth, and / or LPWAN which take into account low-power communication, and may not be limited to the above-mentioned names. For example, ZigBee technology may generate Personal Area Networks (PANs) associated with small / low-power digital communication based on various specifications such as IEEE 802.15.4 and may be called various names.FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

[0050] In FIG. 2, The first wireless device 100 and / or the second wireless device 200 may be implemented in various forms according to use cases / services. For example, {the first wireless device 100 and the second wireless device 200} may correspond to at least one of {the wireless device 100a to 100f and the BS 200}, {the wireless device 100a to 100f and the wireless device 100a to 100f} and / or {the BS 200 and the BS 200} of FIG. 1. The first wireless device 100 and / or the second wireless device 200 may be configured by various elements, devices / parts, and / or modules.

[0051] The first wireless device 100 may include at least one transceiver, such as a transceiver 106, at least one processing chip, such as a processing chip 101, and / or one or more antennas 108.

[0052] The processing chip 101 may include at least one processor, such a processor 102, and at least one memory, such as a memory 104. Additional and / or alternatively, the memory 104 may be placed outside of the processing chip 101.

[0053] The processor 102 may control the memory 104 and / or the transceiver 106 and may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts described in the present disclosure. For example, the processor 102 may process information within the memory 104 to generate first information / signals and then transmit radio signals including the first information / signals through the transceiver 106. The processor 102 may receive radio signals including second information / signals through the transceiver 106 and then store information obtained by processing the second information / signals in the memory 104.

[0054] The memory 104 may be operably connectable to the processor 102. The memory 104 may store various types of information and / or instructions. The memory 104 may store a firmware and / or a software code 105 which implements codes, commands, and / or a set of commands that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 105 may implement instructions that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 105 may control the processor 102 to perform one or more protocols. For example, the firmware and / or the software code 105 may control the processor 102 to perform one or more layers of the radio interface protocol.

[0055] Herein, the processor 102 and the memory 104 may be a part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). The transceiver 106 may be connected to the processor 102 and transmit and / or receive radio signals through one or more antennas 108. Each of the transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be interchangeably used with Radio Frequency (RF) unit(s). In the present disclosure, the first wireless device 100 may represent a communication modem / circuit / chip.

[0056] The second wireless device 200 may include at least one transceiver, such as a transceiver 206, at least one processing chip, such as a processing chip 201, and / or one or more antennas 208.

[0057] The processing chip 201 may include at least one processor, such a processor 202, and at least one memory, such as a memory 204. Additional and / or alternatively, the memory 204 may be placed outside of the processing chip 201.

[0058] The processor 202 may control the memory 204 and / or the transceiver 206 and may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts described in the present disclosure. For example, the processor 202 may process information within the memory 204 to generate third information / signals and then transmit radio signals including the third information / signals through the transceiver 206. The processor 202 may receive radio signals including fourth information / signals through the transceiver 106 and then store information obtained by processing the fourth information / signals in the memory 204.

[0059] The memory 204 may be operably connectable to the processor 202. The memory 204 may store various types of information and / or instructions. The memory 204 may store a firmware and / or a software code 205 which implements codes, commands, and / or a set of commands that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 205 may implement instructions that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 205 may control the processor 202 to perform one or more protocols. For example, the firmware and / or the software code 205 may control the processor 202 to perform one or more layers of the radio interface protocol.

[0060] Herein, the processor 202 and the memory 204 may be a part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). The transceiver 206 may be connected to the processor 202 and transmit and / or receive radio signals through one or more antennas 208. Each of the transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be interchangeably used with RF unit. In the present disclosure, the second wireless device 200 may represent a communication modem / circuit / chip.

[0061] Hereinafter, hardware elements of the wireless devices 100 and 200 will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or more processors 102 and 202. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as Physical (PHY) layer, Media Access Control (MAC) layer, Radio Link Control (RLC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Resource Control (RRC) layer, and Service Data Adaptation Protocol (SDAP) layer). The one or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs), one or more Service Data Unit (SDUs), messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive the signals (e.g., baseband signals) from the one or more transceivers 106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure.

[0062] The one or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors 102 and 202. For example, the one or more processors 102 and 202 may be configured by a set of a communication control processor, an Application Processor (AP), an Electronic Control Unit (ECU), a Central Processing Unit (CPU), a Graphic Processing Unit (GPU), and a memory control processor.

[0063] The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and / or commands. The one or more memories 104 and 204 may be configured by Random Access Memory (RAM), Dynamic RAM (DRAM), Read-Only Memory (ROM), electrically Erasable Programmable Read-Only Memory (EPROM), flash memory, volatile memory, non-volatile memory, hard drive, register, cash memory, computer-readable storage medium, and / or combinations thereof. The one or more memories 104 and 204 may be located at the interior and / or exterior of the one or more processors 102 and 202. The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 through various technologies such as wired or wireless connection.

[0064] The one or more transceivers 106 and 206 may transmit user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, to one or more other devices. The one or more transceivers 106 and 206 may receive user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, from one or more other devices. For example, the one or more transceivers 106 and 206 may be connected to the one or more processors 102 and 202 and transmit and receive radio signals. For example, the one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may transmit user data, control information, or radio signals to one or more other devices. The one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may receive user data, control information, or radio signals from one or more other devices.

[0065] The one or more transceivers 106 and 206 may be connected to the one or more antennas 108 and 208. Additionally and / or alternatively, the one or more transceivers 106 and 206 may include one or more antennas 108 and 208. The one or more transceivers 106 and 206 may be adapted to transmit and receive user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, through the one or more antennas 108 and 208. In the present disclosure, the one or more antennas 108 and 208 may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

[0066] The one or more transceivers 106 and 206 may convert received user data, control information, radio signals / channels, etc., from RF band signals into baseband signals in order to process received user data, control information, radio signals / channels, etc., using the one or more processors 102 and 202. The one or more transceivers 106 and 206 may convert the user data, control information, radio signals / channels, etc., processed using the one or more processors 102 and 202 from the base band signals into the RF band signals. To this end, the one or more transceivers 106 and 206 may include (analog) oscillators and / or filters. For example, the one or more transceivers 106 and 206 can up-convert OFDM baseband signals to OFDM signals by their (analog) oscillators and / or filters under the control of the one or more processors 102 and 202 and transmit the up-converted OFDM signals at the carrier frequency. The one or more transceivers 106 and 206 may receive OFDM signals at a carrier frequency and down-convert the OFDM signals into OFDM baseband signals by their (analog) oscillators and / or filters under the control of the one or more processors 102 and 202.

[0067] Although not shown in FIG. 2, the wireless devices 100 and 200 may further include additional components. The additional components 140 may be variously configured according to types of the wireless devices 100 and 200. For example, the additional components 140 may include at least one of a power unit / battery, an Input / Output (I / O) device (e.g., audio I / O port, video I / O port), a driving device, and a computing device. The additional components 140 may be coupled to the one or more processors 102 and 202 via various technologies, such as a wired or wireless connection.

[0068] In the implementations of the present disclosure, a UE may operate as a transmitting device in Uplink (UL) and as a receiving device in Downlink (DL). In the implementations of the present disclosure, a BS may operate as a receiving device in UL and as a transmitting device in DL. Hereinafter, for convenience of description, it is mainly assumed that the first wireless device 100 acts as the UE, and the second wireless device 200 acts as the BS. For example, the processor(s) 102 connected to, mounted on or launched in the first wireless device 100 may be adapted to perform the UE behavior according to an implementation of the present disclosure or control the transceiver(s) 106 to perform the UE behavior according to an implementation of the present disclosure. The processor(s) 202 connected to, mounted on or launched in the second wireless device 200 may be adapted to perform the BS behavior according to an implementation of the present disclosure or control the transceiver(s) 206 to perform the BS behavior according to an implementation of the present disclosure.

[0069] In the present disclosure, a BS is also referred to as a node B (NB), an eNode B (eNB), or a gNB.

[0070] FIG. 3 shows an example of UE to which implementations of the present disclosure is applied.

[0071] Referring to FIG. 3, a UE 100 may correspond to the first wireless device 100 of FIG. 2.

[0072] A UE 100 includes a processor 102, a memory 104, a transceiver 106, one or more antennas 108, a power management module 141, a battery 142, a display 143, a keypad 144, a Subscriber Identification Module (SIM) card 145, a speaker 146, and a microphone 147.

[0073] The processor 102 may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The processor 102 may be adapted to control one or more other components of the UE 100 to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. Layers of the radio interface protocol may be implemented in the processor 102. The processor 102 may include ASIC, other chipset, logic circuit and / or data processing device. The processor 102 may be an application processor. The processor 102 may include at least one of DSP, CPU, GPU, a modem (modulator and demodulator). An example of the processor 102 may be found in SNAPDRAGONTMseries of processors made by Qualcomm®, EXYNOSTMseries of processors made by Samsung®, A series of processors made by Apple®, HELIOTMseries of processors made by MediaTek®, ATOMTMseries of processors made by Intel®or a corresponding next generation processor.

[0074] The memory 104 is operatively coupled with the processor 102 and stores a variety of information to operate the processor 102. The memory 104 may include ROM, RAM, flash memory, memory card, storage medium and / or other storage device. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The modules can be stored in the memory 104 and executed by the processor 102. The memory 104 can be implemented within the processor 102 or external to the processor 102 in which case those can be communicatively coupled to the processor 102 via various means as is known in the art.

[0075] The transceiver 106 is operatively coupled with the processor 102, and transmits and / or receives a radio signal. The transceiver 106 includes a transmitter and a receiver. The transceiver 106 may include baseband circuitry to process radio frequency signals. The transceiver 106 controls the one or more antennas 108 to transmit and / or receive a radio signal.

[0076] The power management module 141 manages power for the processor 102 and / or the transceiver 106. The battery 142 supplies power to the power management module 141.

[0077] The display 143 outputs results processed by the processor 102. The keypad 144 receives inputs to be used by the processor 102. The keypad 144 may be shown on the display 143.

[0078] The SIM card 145 is an　integrated circuit　that is intended to　securely store the　International Mobile Subscriber Identity　(IMSI) number and its related　key, which are used to identify and authenticate subscribers on　mobile telephony　devices (such as　mobile phones　and　computers). It is also possible to store contact information on many SIM cards.

[0079] The speaker 146 outputs sound-related results processed by the processor 102. The microphone 147 receives sound-related inputs to be used by the processor 102.

[0080] FIGs. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0081] In particular, FIG. 4 illustrates an example of a radio interface user plane protocol stack between a UE and a BS and FIG. 5 illustrates an example of a radio interface control plane protocol stack between a UE and a BS. The control plane refers to a path through which control messages used to manage call by a UE and a network are transported. The user plane refers to a path through which data generated in an application layer, for example, voice data or Internet packet data are transported. Referring to FIG. 4, the user plane protocol stack may be divided into Layer 1 (L1, for example PHY layer) and Layer 2 (L2, for example MAC / RLC / PDCP layer). Referring to FIG. 5, the control plane protocol stack may be divided into Layer 1 (L1, for example PHY layer), Layer 2 (L2, for example MAC / RLC / PDCP layer), Layer 3 (L3, for example an RRC layer), and a non-access stratum (NAS) layer. Layer 1, Layer 2 and Layer 3 are referred to as an access stratum (AS).

[0082] In the 3GPP LTE system, the Layer 2 is split into the following sublayers: MAC, RLC, and PDCP. In the 3GPP NR system, the Layer 2 is split into the following sublayers: MAC, RLC, PDCP and SDAP. The PHY layer offers to the MAC sublayer transport channels, the MAC sublayer offers to the RLC sublayer logical channels, the RLC sublayer offers to the PDCP sublayer RLC channels, the PDCP sublayer offers to the SDAP sublayer radio bearers. The SDAP sublayer offers to 5G core network quality of service (QoS) flows.

[0083] In the 3GPP NR system, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing / de-multiplexing of MAC SDUs belonging to one or different logical channels into / from transport blocks (TB) delivered to / from the physical layer on transport channels; scheduling information reporting; error correction through hybrid automatic repeat request (HARQ) (one HARQ entity per cell in case of carrier aggregation (CA)); priority handling between UEs by means of dynamic scheduling; priority handling between logical channels of one UE by means of logical channel prioritization; padding. A single MAC entity may support multiple numerologies, transmission timings and cells. Mapping restrictions in logical channel prioritization control which numerology(ies), cell(s), and transmission timing(s) a logical channel can use.

[0084] Different kinds of data transfer services are offered by MAC. To accommodate different kinds of data transfer services, multiple types of logical channels are defined, i.e., each supporting transfer of a particular type of information. Each logical channel type is defined by what type of information is transferred. Logical channels are classified into two groups: control channels and traffic channels. Control channels are used for the transfer of control plane information only, and traffic channels are used for the transfer of user plane information only. Broadcast control channel (BCCH) is a downlink logical channel for broadcasting system control information, paging control channel (PCCH) is a downlink logical channel that transfers paging information, system information change notifications and indications of ongoing public warning service (PWS) broadcasts, common control channel (CCCH) is a logical channel for transmitting control information between UEs and network and used for UEs having no RRC connection with the network, and dedicated control channel (DCCH) is a point-to-point bi-directional logical channel that transmits dedicated control information between a UE and the network and used by UEs having an RRC connection. Dedicated traffic channel (DTCH) is a point-to-point logical channel, dedicated to one UE, for the transfer of user information. A DTCH can exist in both uplink and downlink. In downlink, the following connections between logical channels and transport channels exist: BCCH can be mapped to broadcast channel (BCH); BCCH can be mapped to downlink shared channel (DL-SCH); PCCH can be mapped to paging channel (PCH); CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH. In uplink, the following connections between logical channels and transport channels exist: CCCH can be mapped to uplink shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

[0085] The RLC sublayer supports three transmission modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged node (AM). The RLC configuration is per logical channel with no dependency on numerologies and / or transmission durations. In the 3GPP NR system, the main services and functions of the RLC sublayer depend on the transmission mode and include: transfer of upper layer PDUs; sequence numbering independent of the one in PDCP (UM and AM); error correction through ARQ (AM only); segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs; reassembly of SDU (AM and UM); duplicate detection (AM only); RLC SDU discard (AM and UM); RLC re-establishment; protocol error detection (AM only).

[0086] In the 3GPP NR system, the main services and functions of the PDCP sublayer for the user plane include: sequence numbering; header compression and decompression using robust header compression (ROHC); transfer of user data; reordering and duplicate detection; in-order delivery; PDCP PDU routing (in case of split bearers); retransmission of PDCP SDUs; ciphering, deciphering and integrity protection; PDCP SDU discard; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; duplication of PDCP PDUs and duplicate discard indication to lower layers. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; ciphering, deciphering and integrity protection; transfer of control plane data; reordering and duplicate detection; in-order delivery; duplication of PDCP PDUs and duplicate discard indication to lower layers.

[0087] In the 3GPP NR system, the main services and functions of SDAP include: mapping between a QoS flow and a data radio bearer; marking QoS flow ID (QFI) in both DL and UL packets. A single protocol entity of SDAP is configured for each individual PDU session.

[0088] In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcast of system information related to AS and NAS; paging initiated by 5GC or NG-RAN; establishment, maintenance and release of an RRC connection between the UE and NG-RAN; security functions including key management; establishment, configuration, maintenance and release of signaling radio bearers (SRBs) and data radio bearers (DRBs); mobility functions (including: handover and context transfer, UE cell selection and reselection and control of cell selection and reselection, inter-RAT mobility); QoS management functions; UE measurement reporting and control of the reporting; detection of and recovery from radio link failure; NAS message transfer to / from NAS from / to UE.

[0089] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0090] The frame structure shown in FIG. 6 is purely exemplary and the number of subframes, the number of slots, and / or the number of symbols in a frame may be variously changed. In the 3GPP based wireless communication system, OFDM numerologies (e.g., subcarrier spacing (SCS), transmission time interval (TTI) duration) may be differently configured between a plurality of cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells aggregated for the cell, an (absolute time) duration of a time resource (e.g., a subframe, a slot, or a TTI) including the same number of symbols may be different among the aggregated cells. Herein, symbols may include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbols).

[0091] Referring to FIG. 6, downlink and uplink transmissions are organized into frames. Each frame has Tf= 10ms duration. Each frame is divided into two half-frames, where each of the half-frames has 5ms duration. Each half-frame consists of 5 subframes, where the duration Tsfper subframe is 1ms. Each subframe is divided into slots and the number of slots in a subframe depends on a subcarrier spacing. Each slot includes 14 or 12 OFDM symbols based on a cyclic prefix (CP). In a normal CP, each slot includes 14 OFDM symbols and, in an extended CP, each slot includes 12 OFDM symbols. The numerology is based on exponentially scalable subcarrier spacing f = 2u*15 kHz.

[0092] Table 3 shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frameNframe,uslot, and the number of slots per subframe Nsubframe,uslotfor the normal CP, according to the subcarrier spacing f = 2u*15 kHz.

[0093] uNslotsymbNframe,uslotNsubframe,uslot01410111420221440431480841416016

[0094] Table 4 shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frameNframe,uslot, and the number of slots per subframe Nsubframe,uslotfor the extended CP, according to the subcarrier spacing f = 2u*15 kHz.

[0095] uNslotsymbNframe,uslotNsubframe,uslot212404

[0096] A slot includes plural symbols (e.g., 14 or 12 symbols) in the time domain. For each numerology (e.g., subcarrier spacing) and carrier, a resource grid ofNsize,ugrid,x*NRBscsubcarriers andNsubframe,usymbOFDM symbols is defined, starting at common resource block (CRB)Nstart,ugridindicated by higher-layer signaling (e.g., RRC signaling), whereNsize,ugrid,xis the number of resource blocks (RBs) in the resource grid and the subscript x is DL for downlink and UL for uplink.NRBscis the number of subcarriers per RB. In the 3GPP based wireless communication system,NRBscis 12 generally. There is one resource grid for a given antenna portp, subcarrier spacing configurationu, and transmission direction (DL or UL). The carrier bandwidthNsize,ugridfor subcarrier spacing configurationuis given by the higher-layer parameter (e.g., RRC parameter). Each element in the resource grid for the antenna portpand the subcarrier spacing configurationuis referred to as a resource element (RE) and one complex symbol may be mapped to each RE. Each RE in the resource grid is uniquely identified by an indexkin the frequency domain and an indexlrepresenting a symbol location relative to a reference point in the time domain. In the 3GPP based wireless communication system, an RB is defined by 12 consecutive subcarriers in the frequency domain. As shown in FIG. 6, as SCS doubles, the slot length and symbol length are halved. For example, when SCS is 15kHz, the slot length is 1ms, which is the same as the subframe length. When SCS is 30kHz, the slot length is 0.5ms (=500us), and the symbol length is half of that when the SCS is 15kHz. When SCS is 60kHz, the slot length is 0.25ms (=250us), and the symbol length is half of that when the SCS is 30kHz. When SCS is 120kHz, the slot length is 0.125ms (=125us), and the symbol length is half of that when the SCS is 60kHz. When SCS is 240kHz, the slot length is 0.0625ms (=62.5us), and the symbol length is half of that when the SCS is 120kHz.

[0097] In the 3GPP NR system, RBs are classified into CRBs and physical resource blocks (PRBs). CRBs are numbered from 0 and upwards in the frequency domain for subcarrier spacing configurationu. The center of subcarrier 0 of CRB 0 for subcarrier spacing configurationucoincides with 'point A' which serves as a common reference point for resource block grids. In the 3GPP NR system, PRBs are defined within a bandwidth part (BWP) and numbered from 0 toNsizeBWP,i-1, where i is the number of the bandwidth part. The relation between the physical resource block nPRBin the bandwidth part i and the common resource block nCRBis as follows: nPRB= nCRB+NsizeBWP,i, whereNsizeBWP,iis the common resource block where bandwidth part starts relative to CRB 0. The BWP includes a plurality of consecutive RBs. A carrier may include a maximum of N (e.g., 5) BWPs. A UE may be configured with one or more BWPs on a given component carrier. Only one BWP among BWPs configured to the UE can active at a time. The active BWP defines the UE's operating bandwidth within the cell's operating bandwidth.

[0098] In the present disclosure, the term "cell" may refer to a geographic area to which one or more nodes provide a communication system, or refer to radio resources. A "cell" as a geographic area may be understood as coverage within which a node can provide service using a carrier and a "cell" as radio resources (e.g., time-frequency resources) is associated with bandwidth which is a frequency range configured by the carrier. The "cell" associated with the radio resources is defined by a combination of downlink resources and uplink resources, for example, a combination of a DL component carrier (CC) and a UL CC. The cell may be configured by downlink resources only, or may be configured by downlink resources and uplink resources. Since DL coverage, which is a range within which the node is capable of transmitting a valid signal, and UL coverage, which is a range within which the node is capable of receiving the valid signal from the UE, depends upon a carrier carrying the signal, the coverage of the node may be associated with coverage of the "cell" of radio resources used by the node. Accordingly, the term "cell" may be used to represent service coverage of the node sometimes, radio resources at other times, or a range that signals using the radio resources can reach with valid strength at other times.

[0099] In CA, two or more CCs are aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA is supported for both contiguous and non-contiguous CCs. When CA is configured, the UE only has one RRC connection with the network. At RRC connection establishment / re-establishment / handover, one serving cell provides the NAS mobility information, and at RRC connection re-establishment / handover, one serving cell provides the security input. This cell is referred to as the primary cell (PCell). The PCell is a cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on UE capabilities, secondary cells (SCells) can be configured to form together with the PCell a set of serving cells. An SCell is a cell providing additional radio resources on top of special cell (SpCell). The configured set of serving cells for a UE therefore always consists of one PCell and one or more SCells. For dual connectivity (DC) operation, the term SpCell refers to the PCell of the master cell group (MCG) or the primary SCell (PSCell) of the secondary cell group (SCG). An SpCell supports PUCCH transmission and contention-based random access, and is always activated. The MCG is a group of serving cells associated with a master node, comprised of the SpCell (PCell) and optionally one or more SCells. The SCG is the subset of serving cells associated with a secondary node, comprised of the PSCell and zero or more SCells, for a UE configured with DC. For a UE in RRC_CONNECTED not configured with CA / DC, there is only one serving cell comprised of the PCell. For a UE in RRC_CONNECTED configured with CA / DC, the term "serving cells" is used to denote the set of cells comprised of the SpCell(s) and all SCells. In DC, two MAC entities are configured in a UE: one for the MCG and one for the SCG.

[0100] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

[0101] Referring to FIG. 7, "RB" denotes a radio bearer, and "H" denotes a header. Radio bearers are categorized into two groups: DRBs for user plane data and SRBs for control plane data. The MAC PDU is transmitted / received using radio resources through the PHY layer to / from an external device. The MAC PDU arrives to the PHY layer in the form of a transport block.

[0102] In the PHY layer, the uplink transport channels UL-SCH and random access channel (RACH) are mapped to their physical channels physical uplink shared channel (PUSCH) and physical random access channel (PRACH), respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to physical downlink shared channel (PDSCH), physical broadcast channel (PBCH) and PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to physical uplink control channel (PUCCH), and downlink control information (DCI) is mapped to physical downlink control channel (PDCCH). A MAC PDU related to UL-SCH is transmitted by a UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCH is transmitted by a BS via a PDSCH based on a DL assignment.

[0103] Hereinafter, UE states and state transitions are described.

[0104] A UE is either in RRC_CONNECTED state (or, connected state) or in RRC_INACTIVE state (or, inactive state) when an RRC connection has been established. If this is not the case, i.e., no RRC connection is established, the UE is in RRC_IDLE state (or, idle state).

[0105] The RRC_CONNECTED state is defined as an RRC state in which a UE maintains an active RRC connection with the network via a network.

[0106] When the UE is in the RRC_CONNECTED state, the RRC connection has been established between the UE and the network, thereby enabling the exchange of control and user plane data. In this state, the UE is contextually known to the network and can actively transmit and receive data.

[0107] The RRC_CONNECTED state is characterized by the following attributes:

[0108] - Dedicated radio resources are allocated to the UE for uplink and downlink transmissions;

[0109] - The UE maintains an active connection with the Access Stratum (AS), including the maintenance of physical channels and logical channel mappings;

[0110] - The UE may perform handover procedures as triggered by mobility events, based on measurements and reporting to the serving base station;

[0111] - The UE is capable of receiving RRC signaling messages, such as measurement control, mobility commands, security control, and configuration updates;

[0112] - Security procedures, including encryption and integrity protection, are applied to both signaling and user data; and / or

[0113] - The UE may perform discontinuous reception (DRX) to conserve battery power while still monitoring for control messages.

[0114] Additionally, in the RRC_CONNECTED state, the network maintains full AS and NAS context for the UE, allowing it to perform coordinated actions, such as bearer setup / modification / release and Quality of Service (QoS) enforcement.

[0115] Transition to the RRC_CONNECTED state typically occurs from the RRC_IDLE or RRC_INACTIVE state upon initiation of a connection establishment procedure, such as for mobile-originated data transmission or mobile-terminated data reception.

[0116] The RRC_CONNECTED state remains active until the RRC connection is explicitly released or transitioned to a lower activity state, such as RRC_IDLE or RRC_INACTIVE, by the network based on inactivity or mobility management procedures.

[0117] The RRC_IDLE state is defined as an RRC state in which the UE does not maintain an RRC connection with the network. Instead, the UE performs necessary monitoring and mobility-related procedures while in a power-efficient and resource-unallocated mode.

[0118] In the RRC_IDLE state, the UE is not contextually known to the radio access network (RAN) on a per-cell basis but remains known to the core network through stored Non-Access Stratum (NAS) context. The UE camps on a selected cell and may change cells autonomously without notification to the network.

[0119] Key characteristics of the RRC_IDLE state include:

[0120] - The UE performs cell selection and reselection autonomously based on broadcast system information and radio measurements;

[0121] - The UE monitors paging messages from the network for mobile-terminated services using Discontinuous Reception (DRX) cycles to minimize power consumption;

[0122] - No dedicated radio resources are assigned to the UE, and no RRC signaling connection exists with the network;

[0123] - The UE is required to periodically acquire system information to maintain synchronization and support mobility decisions; and / or

[0124] - The UE initiates the RRC connection establishment procedure when it needs to perform data transmission or reception (i.e., mobile-originated or mobile-terminated services).

[0125] In the RRC_IDLE state, the UE is responsible for maintaining its own mobility within a Public Land Mobile Network (PLMN) and tracking area. The UE updates the core network by initiating NAS-level Tracking Area Update (TAU) procedures when necessary, such as upon entering a new tracking area not registered with the core network.

[0126] The RRC_IDLE state provides a low-energy, scalable configuration suitable for UEs that are not actively engaged in data communication but must remain reachable by the network.

[0127] Transition from the RRC_IDLE state to RRC_CONNECTED or RRC_INACTIVE is initiated by the UE or the network depending on service requirements, including uplink data availability or paging reception, respectively.

[0128] The RRC_INACTIVE state is defined as an RRC state that enables a UE to remain in a lightweight connected mode, allowing for rapid transition to the RRC_CONNECTED state while minimizing signaling overhead and power consumption.

[0129] In the RRC_INACTIVE state, the UE retains an RRC context with the network (i.e., the gNB), yet no active radio bearer is maintained. The UE is not required to perform RRC connection re-establishment for state transitions to RRC_CONNECTED, thereby enabling reduced latency and overhead for mobile-terminated and mobile-originated services.

[0130] Key characteristics of the RRC_INACTIVE state include:

[0131] - The UE is known to the network, and its Access Stratum (AS) context is preserved in both the UE and the serving gNB;

[0132] - The UE performs paging monitoring using a configured RAN-based paging mechanism with Discontinuous Reception (DRX) to conserve battery power;

[0133] - The UE performs cell reselection within a predefined Registration Area without notifying the network, unless a change of registration area occurs;

[0134] - System information acquisition may be performed on-demand as necessary during mobility or upon specific triggers; and / or

[0135] - The UE can rapidly transition to the RRC_CONNECTED state using the Resume procedure, eliminating the need for full RRC connection re-establishment.

[0136] The RRC_INACTIVE state is particularly optimized for scenarios involving frequent transitions between idle and connected behaviors, such as Internet of Things (IoT) devices, delay-tolerant applications, and UEs exhibiting intermittent activity patterns.

[0137] When in the RRC_INACTIVE state, the UE is reachable by the network via RAN-based paging and can resume the RRC connection with significantly reduced signaling latency compared to RRC_IDLE.

[0138] Transition to the RRC_INACTIVE state may occur upon network initiation (e.g., RRC Release message withsuspendConfig) or via UE-initiated procedures, depending on policy, configuration, or inactivity conditions. Transition out of the RRC_INACTIVE state occurs when the UE resumes the connection, transitions to RRC_IDLE (e.g., upon exceeding the registration timer), or performs a registration area update.

[0139] FIG. 8 shows an example of UE state machine and state transition.

[0140] Referring to FIG. 8, state transitions between RRC states including RRC_CONNECTED, RRC_INACTIVE and RRC_IDLE may occur under some conditions.

[0141] A transition from RRC_IDLE to RRC_CONNECTED may be initiated by the UE to send uplink data, or in response to paging, via RRC Connection Establishment.

[0142] A transition from RRC_CONNECTED to RRC_INACTIVE may be initiated by the network using an RRC Release message comprising a suspend configuration (i.e.,suspendConfiginformation element (IE)), allowing the UE to retain RRC context and enabling quick resume. A transition from RRC_CONNECTED to RRC_INACTIVE may also be initiated upon expiry of a data inactivity timer (i.e.,dataInactivityTimer) when the UE is provided with a suspend configuration before thedataInactivityTimerexpires.

[0143] A transition from RRC_CONNECTED to RRC_IDLE may be triggered by an RRC Release without context suspension, typically due to mobility across registration areas, network-directed release, or upon expiry of thedataInactivityTimer.

[0144] A transition from RRC_INACTIVE to RRC_CONNECTED may be triggered by uplink data availability at the UE or a paging reception, via RRC Resume.

[0145] A transition from RRC_INACTIVE to RRC_IDLE may be initiated when the UE exits the configured registration area, when the UE receives RRC Release message, or upon expiry of thedataInactivityTimer.

[0146] The UE may be configured by RRC with a Data inactivity monitoring functionality, when in RRC_CONNECTED. RRC controls Data inactivity operation by configuring the timerdataInactivityTimer.

[0147] WhendataInactivityTimeris configured, the UE shall:

[0148] 1> if any MAC entity receives a MAC SDU for DTCH logical channel, DCCH logical channel, or CCCH logical channel, or multicast MTCH logical channel; or

[0149] 1> if any MAC entity transmits a MAC SDU for DTCH logical channel, or DCCH logical channel:

[0150] 2> start or restartdataInactivityTimer.

[0151] 1> if thedataInactivityTimerexpires:

[0152] 2> indicate the expiry of thedataInactivityTimerto upper layers.

[0153] Upon the expiry ofDataInactivityTimerwhile in RRC_CONNECTED, the UE shall:

[0154] 1> perform the actions upon going to RRC_IDLE, with release cause 'RRC connection failure'.

[0155] ThesuspendConfigindicates configuration for the RRC_INACTIVE state. The network does not configuresuspendConfigwhen the network redirect the UE to an inter-RAT carrier frequency or if the UE is configured with a DAPS bearer. ThesuspendConfigis provided to allow the UE to transition to RRC inactive state instead of RRC idle state when the UE release the RRC connection. ThesuspendConfigincludes information for the UE to perform RAN area update and RAN paging after entering RRC inactive state (e.g., RAN notification area information, RAN area update timer), as well as security information for RRC resume procedure (e.g., full I-RNTI, short I-RNTI, and next hop chaining count).

[0156] The RAN notification area information (i.e.,ran-NotificationAreaInfo) specifies the set of cells or areas in which a UE is expected to remain while in the RRC_INACTIVE state. It is primarily used to support efficient paging and mobility management in the RRC_INACTIVE state.

[0157] The RAN area update timer (i.e.,t380) specifies the interval at which a UE in the RRC_INACTIVE state performs a periodic RAN-based Notification Area Update (RNAU).

[0158] The full inactive - radio network temporary identifier (I-RNTI) (i.e.,fullI-RNTI) and short I-RNTI (i.e.,shortI-RNTI) uniquely identifies a UE in RRC_INACTIVE state. They are used when a UE resumes its RRC connection by sending anRRCResumeRequestmessage to the network.

[0159] The next hop chaining count (i.e.,nextHopChainingCount) is used to track the derivation of new Next Hop (NH) keys as part of the key hierarchy and chaining mechanism during mobility or RRC state transitions. It ensures that both the UE and base station are synchronized with respect to key generation, particularly when the UE moves between cells or base stations.

[0160] Hereinafter, radio link failure (RLF) and / or RLF timer (e.g., T310) is described.

[0161] The RLF timer may be used by a UE to detect and handle RLF. The RLF timer may be used to determine whether a radio link between the UE and the serving cell has become unreliable and / or lost entirely.

[0162] The RLF timer may be started by the UE when the radio link is detected as poor, based on consecutive out-of-sync indications from radio link monitoring (RLM). For example, the UE may start the RLF timer when the UE receives a predefined number (e.g., N310) of consecutive out-of-sync indications, meaning that the signal quality is below a certain threshold. The UE receiving the predefined number of consecutive out-of-sync indications may imply that the radio link is likely failing, so T310 is started as a waiting period to see if it improves.

[0163] While the RLF timer is running, the UE may continue to monitor the downlink signal(s). When the UE receives a sufficient number (e.g., N311) of in-sync indications before T310 expires, the UE may stop the RLF timer, and consider the radio link recovered.

[0164] If the RLF timer expires before the UE detects recovery (i.e., sufficient in-sync indications), then the UE may declare an RLF. For example, when the UE declares RLF, the UE may trigger RRC re-establishment procedure, and / or cell reselection (e.g., entering idle mode and searching for a new cell).

[0165] Hereinafter, random access preamble transmission and / or preamble transmission counter (e.g.,PREAMBLE_TRANSMISSION_COUNTER) is described.

[0166] A random access preamble (or, shortly preamble) a known signal transmitted by the UE on a physical random access channel (PRACH) to initiate a random access attempt. Transmission of the random access preamble may indicate to the base station that the UE wants to establish a connection.

[0167] During the random access procedure, the UE may maintain a preamble transmission counter. The preamble transmission counter may keep track of how many times the UE has transmitted a random access preamble (or, PRACH preamble) in an attempt to access the network. The preamble transmission counter is used to count the number of PRACH preamble transmissions made by the UE during a single random access procedure and / or determine whether the UE should declare the attempt as failed, based on a configured maximum number of attempts. This is especially relevant in contention-based random access, where multiple UEs might choose the same preamble and interfere with each other.

[0168] Upon initiating the random access procedure, the UE may transmit a random access preamble and wait for a random access response (RAR) from the base station. If no valid RAR is received within the RAR window, the UE may increment the preamble transmission counter and retry the random access preamble transmission with the same or a different preamble. The UE may continue this process until: a valid RAR is received; or the preamble transmission counter reaches the maximum limit (e.g.,preambleTransMax), at which point the UE declares the random access procedure has failed.

[0169] Meanwhile, a data inactivity timer may be used to allow UE to transition from RRC connected state to RRC idle state without receiving an RRC release message from a network. This means that even if the UE does not receive an RRC release message due to link problems on the current serving cell, the UE can release the RRC connection when there are no further data transmissions between the network and the UE before declaration of a radio link failure.

[0170] When the data inactivity timer expires, the UE can transition to RRC inactive state from RRC connected state instead of transitioning to RRC idle state if the network provides a suspend configuration before the data inactivity timer expires.

[0171] The problem is that, even if the UE has a valid suspend configuration allowing the UE to transition to the RRC inactive state, the UE may still suffer from link problems on the serving cell. These link problems can be caused by incorrect reconfiguration from the network and / or out-of-sync situations. If the UE transitions to the RRC inactive state while maintaining the dedicated UE context configured by the network's reconfiguration, the UE may face the same link problems when initiating the RRC resume procedure based on this context in the near future to establish the RRC connection again.

[0172] Therefore, there needs to be a way that a UE can avoid a connection failure in the near future during re-initiation of RRC connection considering the data inactivity timer function.

[0173] FIG. 9 shows an example of a method performed by a UE for a state transition to non-connected state according to an embodiment of the present disclosure.

[0174] Referring to FIG. 9, in step S901, the UE may establish a connection with a network and entering a connected state.

[0175] In step S903, the UE may receive a configuration for a data inactivity timer from the network.

[0176] In step S905, the UE may start the data inactivity timer based on performing at least one of a transmission or a reception.

[0177] In step S907, after the data inactivity timer expires, the UE may transit from the connected state to the inactive state based on no link problem being detected / expected from a link status of the serving cell.

[0178] According to various embodiments, the UE may receive a suspend configuration during the connected statue. A state may be transited from the connected state to the inactive state based on the suspend configuration.

[0179] According to various embodiments, the UE may determine whether a link problem is detected / expected from the link status of the serving cell, upon an expiry of the data inactivity timer while the suspend configuration is available.

[0180] According to various embodiments, the UE may transit from the connected state to the inactive state based on no link problem being detected / expected from the link status of the serving cell, after the data inactivity timer expires while the suspend configuration is available.

[0181] According to various embodiments, the UE may transit from the connected state to an idle state based on the link problem being detected / expected from the link status of the serving cell, after the data inactivity timer expires while the suspend configuration is available.

[0182] According to various embodiments, the UE may determine whether the link problem is detected / expected from the link status of the serving cell based on at least one of conditions. The conditions comprise: a condition that a value of an elapsed time of a radio link failure (RLF) timer and a configured value of the RLF timer is greater than a ratio threshold; and a condition that a condition that a value of a preamble transmission counter is above a count threshold.

[0183] According to various embodiments, the link problem may be determined to be detected / expected based on at least one of the conditions being met. No link problem may be determined to be detected / expected based on all of the conditions being not met.

[0184] According to various embodiments, the UE may receive one or more configurations for at least one of the conditions, the ratio threshold, or the count threshold.

[0185] According to various embodiments, the suspend configuration may be received via a radio resource control (RRC) message other than an RRC release message.

[0186] According to various embodiments, the RRC message may comprise an RRC reconfiguration message.

[0187] According to various embodiments, the UE may set a release cause other than a cause of a radio resource control (RRC) connection failure based on transiting from the connected state to the inactive state. The release cause may inform that a state is transited to the inactive state based on an expiry of the data inactivity timer.

[0188] According to various embodiments, the UE may transmit, to a network, information for a state transition from the connected state to the inactive state before transiting from the connected state to the inactive state.

[0189] FIG. 10 shows an example of a signal flow between a UE and a network node for a state transition to non-connected state according to an embodiment of the present disclosure.

[0190] Referring to FIG. 10, in step S1001, the network node may establish a connection with the UE based on which the UE enters a connected state.

[0191] In step S1003, the network node may transmit, to the UE, a configuration for a data inactivity timer,

[0192] In step S1005, the UE may start the data inactivity timer based on performing at least one of a transmission or a reception.

[0193] In step S1007, after the data inactivity timer expires, the UE may transit from the connected state to the inactive state based on no link problem being detected / expected from a link status of the serving cell.

[0194] Hereinafter, detailed implementations regarding state transition to non-connected state are described.

[0195] According to implementations of the present disclosure, upon expiry of a data inactivity timer, the UE may determine whether a transition from RRC connected state to RRC inactive state is allowed based on configuration related to RRC inactive state (i.e., suspend configuration) and link status on the serving cell. If the UE has received the configuration related to RRC inactive state before the expiry of the data inactivity timer and if there is no potential link problem on the serving cell, the UE may transit to RRC inactive state instead of transiting to RRC idle state upon the expiry of the data inactivity timer.

[0196] FIG. 11 shows an example of a method for state transition based on link status and suspend configuration according to an embodiment of the present disclosure.

[0197] Referring to FIG. 11, in step S1101, the UE may receive a configuration for a data inactivity timer. The data inactivity timer may be configured via a dedicated RRC message (e.g., RRC reconfiguration) from the network.

[0198] In step S1103, after receiving the dedicated RRC message / configuration, the UE may start / restart the data inactivity timer whenever any data scheduling begins.

[0199] If the data inactivity timer expires, the UE may assume that there is no longer any data to exchange with the network and release the RRC connection.

[0200] In step S1105, the UE may determine whether there is a potential link problem and there is valid suspend configuration.

[0201] Upon expiry of the data inactivity timer, the UE may check if the following conditions are met (i.e., determine whether a link problem is expected from the link status of the serving cell). If at least one of the conditions is met, the UE may determine that there is a potential link problem on the serving cell (i.e., link problem is expected from the link status of the serving cell). Below conditions are optionally configured by the network i.e., the network may configure at least one of the below conditions and / or may configure all of the below conditions together:

[0202] 1) When the data inactivity timer expires, timer related to declare radio link failure (e.g., RLF timer / T310) is running, and a ratio between a value of the elapsed time of the RLF timer and the configured value of the RLF timer is greater than a time threshold value (or, ratio threshold) received from the network. The time threshold may have value from 0 to 100 (or, 0 to 1) so as to function as a threshold for the ratio between a value of the elapsed time of the RLF timer and the configured value of the RLF timer; and / or

[0203] 2) When the data inactivity timer expires, the value to retry random access attempt (i.e., the preamble transmission counter / PREAMBLE_TRANSMISSION_COUNTER) on MCG MAC is above a count value (or, count threshold) received from the network. For example, if the count value is received, the UE may check whether the preamble transmission counter is equal to or greater than the count value.

[0204] The time threshold value and the count value may be configured via a dedicated RRC message (e.g., RRC reconfiguration) from the network. The network may configure these values together with the data inactivity timer.

[0205] In step S1107, when there is no potential link problem and there is valid suspend configuration, the UE may transit to RRC_INACTIVE.

[0206] For example, when the UE decides that the serving cell has no potential link problem based on the above conditions 1) and / or 2), the UE may check whether the UE has a valid configuration related to RRC inactive state (i.e., valid suspend configuration). If the UE has the valid configuration related to RRC inactive state, and if the UE considers that the serving cell has no potential link problem, the UE may perform a transition from RRC connected state to RRC inactive state. When transiting RRC state to RRC inactive state, the UE may set the release cause by a new cause (i.e., not set by the RRC connection failure cause) to indicate that the UE enters RRC inactive state upon expiry of the data inactivity timer.

[0207] In step S1109, when there is potential link problem, or when there is no potential link problem but there is no valid suspend configuration, the UE may transit to RRC_IDLE.

[0208] For example, if the UE has the valid configuration related to RRC inactive state, but if the UE considers that the serving cell has a potential link problem, the UE may perform a transition from RRC connected state to RRC idle state regardless of whether the UE has a valid configuration related to RRC inactive state. For this case, the UE may set the release cause by existing cause (i.e., RRC connection failure).

[0209] Before leaving RRC connected state, i.e., releasing / suspending RRC connection, the UE may indicate that the UE transits from RRC connected state to RRC inactive state via RRC signaling. Even in the case that UE transits RRC state from RRC connected state to RRC idle state, the UE may indicate that the UE transits from RRC connected state to RRC idle state via RRC signaling. Upon expiry of the data inactivity timer, the data inactivity timer doesn't restart by indicating the RRC state transition.

[0210] The configuration related to RRC inactive state (e.g., suspend configuration) may be provided via a dedicated RRC message (e.g., RRC reconfiguration) from the network. The configuration related to RRC inactive state may be provided to allow the UE to transition to RRC inactive state instead of RRC idle state when the UE release the RRC connection. The configuration related to RRC inactive state may include information for the UE to perform RAN area update and / or RAN paging after entering RRC inactive state (e.g., RAN notification area information, RAN area update timer), as well as security information for RRC resume procedure (e.g., full inactive-radio network temporary identifier (I-RNTI), short I-RNTI, and / or next hop chaining count).

[0211] When sending request to resume RRC connection from RRC inactive state, the UE may include an identity to indicate which configuration related to RRC inactive state is currently being used if the network has provided the identity before expiry of the data inactivity timer.

[0212] According to various embodiments, UE may receive a data inactivity timer configuration from a network. The data inactivity configuration may include a threshold value related to a radio link failure declaration. Upon expiry of the data inactivity timer, the UE may check whether a suspend configuration has been received and check whether a ratio between a value of the elapsed time of the RLF timer and the configured value of the RLF timer is greater than the threshold value. The UE may transit from RRC connected state to RRC inactivate state based on the suspend configuration when the suspend configuration has been received and the ratio between the value of the elapsed time of the RLF timer and the configured value of the RLF timer is not greater than the threshold value.

[0213] Furthermore, the method in perspective of the communication device / UE described in the present disclosure (e.g., in FIG. 9) may be performed by the first wireless device 100 shown in FIG. 2 and / or the UE 100 shown in FIG. 3.

[0214] More specifically, the communication device / UE comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations.

[0215] The operations comprise: establishing a connection with a network and entering a connected state; receiving a configuration for a data inactivity timer from the network; starting the data inactivity timer based on performing at least one of a transmission or a reception; and after the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.

[0216] Furthermore, the method in perspective of the communication device / UE described in the present disclosure (e.g., in FIG. 9) may be performed by a software code 105 stored in the memory 104 included in the first wireless device 100 shown in FIG. 2.

[0217] More specifically, at least one computer readable medium (CRM) stores instructions that, based on being executed by at least one processor, perform operations comprising: establishing a connection with a network and entering a connected state; receiving a configuration for a data inactivity timer from the network; starting the data inactivity timer based on performing at least one of a transmission or a reception; and after the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.

[0218] Furthermore, the method in perspective of the communication device / UE described in the present disclosure (e.g., in FIG. 9) may be performed by control of the processor 102 included in the first wireless device 100 shown in FIG. 2 and / or by control of the processor 102 included in the UE 100 shown in FIG. 3.

[0219] More specifically, an apparatus configured to / adapted to operate in a wireless communication system (e.g., communication device / UE) comprises at least processor, and at least one computer memory operably connectable to the at least one processor. The at least one processor is configured to / adapted to perform operations comprising: establishing a connection with a network and entering a connected state; receiving a configuration for a data inactivity timer from the network; starting the data inactivity timer based on performing at least one of a transmission or a reception; and after the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.

[0220] Furthermore, the method in perspective of a network node described in the present disclosure (e.g., in FIG. 10) may be performed by the second wireless device 200 shown in FIG. 2. The network node may be related to a serving cell.

[0221] More specifically, the network node comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations.

[0222] The operations comprise: establishing a connection with a user equipment (UE) based on which the UE enters a connected state; and transmitting, to the UE, a configuration for a data inactivity timer, wherein the UE is configured to perform operations comprising: starting the data inactivity timer based on performing at least one of a transmission or a reception; and after the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.

[0223] The present disclosure may have various advantageous effects.

[0224] For example, even in the case that the UE with a valid suspend configuration allowing RRC state transition to RRC inactive state, the UE can decide to transit to RRC idle state upon expiry of the data inactivity timer if there is a potential link problem on the serving cell. This UE behaviour can avoid a connection failure in the near future during re-initiation of RRC connection by discarding the dedicated UE context that caused the potential link problem on the last serving cell.

[0225] Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and / or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

[0226] Claims in the present disclosure can be combined in a various way. For instance, technical features in method claims of the present disclosure can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method. Other implementations are within the scope of the following claims.

Claims

1.A method comprising:establishing a connection with a network and entering a connected state;receiving a configuration for a data inactivity timer from the network;starting the data inactivity timer based on performing at least one of a transmission or a reception; andafter the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.2.The method of claim 1, further comprising receiving a suspend configuration during the connected statue,wherein a state is transited from the connected state to the inactive state based on the suspend configuration.3.The method of claim 2, further comprising determining whether a link problem is detected from the link status of the serving cell, upon an expiry of the data inactivity timer while the suspend configuration is available.4.The method of claim 3, wherein the transiting from the connected state to the inactive state comprises transiting from the connected state to the inactive state based on no link problem being detected from the link status of the serving cell, after the data inactivity timer expires while the suspend configuration is available.5.The method of claim 3, further comprising transiting from the connected state to an idle state based on the link problem being detected from the link status of the serving cell, after the data inactivity timer expires while the suspend configuration is available.6.The method of claim 3, wherein the determining of whether the link problem is detected from the link status of the serving cell comprises determining whether the link problem is detected from the link status of the serving cell based on at least one of conditions,wherein the conditions comprise:a condition that a value of an elapsed time of a radio link failure (RLF) timer and a configured value of the RLF timer is greater than a ratio threshold; anda condition that a condition that a value of a preamble transmission counter is above a count threshold.7.The method of claim 6, wherein the link problem is determined to be detected based on at least one of the conditions being met, andwherein no link problem is determined to be detected based on all of the conditions being not met.8.The method of claim 6, further comprising receiving one or more configurations for at least one of the conditions, the ratio threshold, or the count threshold.9.The method of claim 2, wherein the suspend configuration is received via a radio resource control (RRC) message other than an RRC release message.10.The method of claim 9, wherein the RRC message comprises an RRC reconfiguration message.11.The method of claim 1, further comprising setting a release cause other than a cause of a radio resource control (RRC) connection failure based on transiting from the connected state to the inactive state, andwherein the release cause informs that a state is transited to the inactive state based on an expiry of the data inactivity timer.12.The method of claim 1, further comprising transmitting, to the network, information for a state transition from the connected state to the inactive state before transiting from the connected state to the inactive state.13.The method of claims 1, wherein the method is performed by a user equipment (UE) in communication with at least one of a mobile device, a network, or autonomous vehicles.14.A user equipment (UE) comprising:at least one transceiver;at least one processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:establishing a connection with a network and entering a connected state;receiving a configuration for a data inactivity timer from the network;starting the data inactivity timer based on performing at least one of a transmission or a reception; andafter the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.15.An apparatus comprising:at least processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:establishing a connection with a network and entering a connected state;receiving a configuration for a data inactivity timer from the network;starting the data inactivity timer based on performing at least one of a transmission or a reception; andafter the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.16.A non-transitory computer readable medium (CRM) having stored thereon a program code implementing instructions that, based on being executed by at least one processor, perform operations comprising:establishing a connection with a network and entering a connected state;receiving a configuration for a data inactivity timer from the network;starting the data inactivity timer based on performing at least one of a transmission or a reception; andafter the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.17.A method comprising:establishing a connection with a user equipment (UE) based on which the UE enters a connected state; andtransmitting, to the UE, a configuration for a data inactivity timer,wherein the UE is configured to perform operations comprising:starting the data inactivity timer based on performing at least one of a transmission or a reception; andafter the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.18.A network node comprising:at least one transceiver;at least one processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:establishing a connection with a user equipment (UE) based on which the UE enters a connected state; andtransmitting, to the UE, a configuration for a data inactivity timer,wherein the UE is configured to perform operations comprising:starting the data inactivity timer based on performing at least one of a transmission or a reception; andafter the data inactivity timer expires, transiting from the connected state to the inactive state based on no link problem being detected from a link status of the serving cell.

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