Radio terminal, radio access network node, and methods therefor

Abstract

This radio terminal transmits, to a network, a status confirmation report indicating an activation state of cell discontinuous transmission (DTX) or an activation state of cell discontinuous reception (DRX), which is perceived by the radio terminal, or both thereof. This can contribute, for example, to the solution of a problem related to inconsistency in understanding of an activation state of cell DTX or cell DRX between a network and a radio terminal.

Description

Wireless terminal, radio access network node, and methods thereof

[0001] The present disclosure relates to wireless communication networks, and more particularly to various techniques that directly or indirectly contribute to improving network energy saving.

[0002] The 3rd Generation Partnership Project (3GPP®) Release 15 and later releases specify 5G New Radio (NR) User Equipment (UE) power saving schemes. These UE power saving schemes include discontinuous reception (DRX) performed by a UE in Radio Resource Control (RRC)_CONNECTED mode. This DRX performed by a UE in RRC_CONNECTED mode is referred to herein as connected mode DRX (CDRX) to distinguish it from cell discontinuous transmission (DTX) and cell DRX, which are described below.

[0003] Currently, 3GPP is discussing network energy saving for 3GPP Release 18 (see, for example, non-patent documents 1-7). Network energy saving is abbreviated as NES. As described in non-patent documents 1 and 2, there are various techniques for improving network energy saving, including cell DTX and DRX. In one example, the network may provide a mechanism to notify UEs in a cell whether the cell is in an inactive state. During cell DTX or cell DRX, i.e., while the cell is in an inactive state, the cell may not transmit or receive, or may maintain only limited transmission or reception. For example, the cell does not need to transmit or receive some periodic signals and channels, such as cell common channels and signals and UE-specific signals and channels.

[0004] Hereinafter, the term "cell DTX / DRX" may be used to refer to either or both of cell DTX and cell DRX. Although the definition of the term cell DTX / DRX is unclear at present, the terms "cell DTX on duration," "cell DTX off duration," "cell DRX on duration," and "cell DRX off duration" are used in this specification to refer to cell DTX / DRX. The cell DTX / DRX on duration refers to the duration, time, or period during which a cell is active and capable of transmitting and receiving all necessary cell common channels and signals and UE-specific signals and channels. In contrast, the cell DTX / DRX off duration refers to the duration, time, or period during which a cell is inactive for NES and does not transmit or receive, or can maintain only limited transmission or reception. The cell DTX / DRX on duration may also be referred to as the cell DTX / DRX on time or on period, or the cell DTX / DRX active time, period, or duration. The cell DTX / DRX off duration may also be referred to as a cell DTX / DRX off time or off period, or a cell DTX / DRX inactive or non-active time, period, or duration.

[0005] Chapter 6.1.4 of Non-Patent Document 2 states that the cell DTX / DRX mode can be activated and deactivated via dynamic Layer 1 or Layer 2 (L1 / L2) signaling and UE-specific (specific or dedicated) RRC signaling. For activation and deactivation of the cell DTX / DRX mode, both UE-specific L1 / L2 signaling and common L1 / L2 signaling can be considered. Furthermore, Chapter 6.1.4 of Non-Patent Document 2 states that it is beneficial to align UE CDRX with cell DTX and align DRX among multiple UEs.

[0006] Chapter 2.3 of 3GPP TS 31.2(1) describes the alignment between cell DTX and UE CDRX as follows: When cell DTX is activated, the UE must adopt a UE CDRX that is aligned with the cell DTX. For UE power efficiency, it is necessary to ensure that the cell DTX active period completely overlaps with the UE CDRX on duration. Aligning the UE CDRX with a specific cell DTX does not mean that the UE CDRX on / off pattern will be exactly the same as that of the cell DTX. The aligned UE CDRX on / off pattern can have a different on duration, periodicity, or starting offset from that of the cell DTX, and the UE CDRX on duration can still fall within the cell DTX active period. The offset, periodicity, or on duration of the aligned CDRX should be determined by the network implementation. The periodicity of the UE CRX configuration in a cell should be the same as or a multiple of the cell DTX periodicity of the serving cell, and the UE CDRX on duration cannot exceed the cell DTX on duration.

[0007] In addition, Chapter 2.3 of NRTL 3 describes the following about changing or updating the UE CDRX configuration: When cell DTX is activated, the UE needs to adopt an aligned CDRX that is different from the current CDRX pattern. Also, when cell DTX is deactivated, the aligned CDRX may be released and a new CDRX may be configured for the UE. The existing mechanism reconfigures the UE's CDRX via a UE-specific RRC message. This is not dynamic enough and may cause high signaling overhead when cell DTX is activated / deactivated. RAN2 should discuss how to efficiently change the UE's CDRX when cell DTX is activated / deactivated without increasing signaling overhead.

[0008] Chapter 2.2 of Non-Patent Document 4 describes the alignment of cell DTX and UE CDRX as follows: To maximize energy saving, it is necessary to strive to align the on-duration of the UE and the network. One option to achieve this is to reconfigure UE CDRX parameters, such as drx-LongCycleStartOffset, to align the UE CDRX cycle and start offset with those of the cell DTX / DRX. However, this requires a long time for the RRC reconfiguration parameters to take effect. Furthermore, when traffic load increases, the gNB needs to reconfigure these parameters to distribute the UE's active time. Another option is to use dynamic signaling. The alignment of UE CDRX can be performed in conjunction with the L1 activation and deactivation of cell DTX / DRX. Specifically, when the gNB decides to start cell DTX / DRX, it sends a dynamic indication to the UE informing it of the activation of cell DTX / DRX. Following this dynamic activation, all UEs update their CDRX parameters, such as the CDRX cycle and start offset, to common values ​​configured by the network. Alternatively, these common parameters share the same value as the cell DTX / DRX, for example, all UEs use the same offset and cycle for CDRX as the cell DTX / DRX, while the DRX on duration timer can share the same value as the cell DTX / DRX or can be a different value from that of the cell DTX / DRX.

[0009] Non-Patent Document 5 proposes a method for implicitly activating an additional CDRX configuration in response to activation of cell DTX. In this method, for consistency between UE CDRX and cell DTX, a gNB can configure an additional CDRX configuration in a UE along with cell DTX / DRX parameters. This additional CDRX configuration is implicitly activated upon activation of cell DTX. The additional CDRX configuration includes optional CDRX parameters that the UE uses when cell DTX is activated.

[0010] Appendix B of Non-Patent Document 6 states that one of the agreements reached at the 121st meeting of the 3GPP Technical Specification Group (TSG) Radio Access Network (RAN) Working Group #2 (WG2) (RAN2) is that the cell DRX / DTX pattern configuration is common to Release 18 UEs in a cell.

[0011] Appendix B of Non-Patent Document 6 describes the agreements reached at the 3GPP RAN2 121bis meeting, including the following: Periodic cell DTX / DRX configuration is explicitly signaled to UEs. Periodic cell DTX / DRX patterns are configured by UE-specific RRC signaling. Cell DTX / DRX configuration includes at least periodicity, start slot or offset, and duration. As a baseline, cell DTX / DRX is implicitly activated or deactivated by RRC signaling. That is, cell DTX / DRX is activated as soon as it is configured by RRC, and is deactivated when the RRC configuration is released.

[0012] Appendix A of Non-Patent Document 6 describes that, as one of the agreements reached at the 113th meeting of 3GPP TSG WG #1 (WG1) (RAN1), group-wide L1 signaling using the Physical Downlink Control Channel (PDCCH) without hybrid automatic repeat request (HARQ) feedback is supported for cell DTX / DRX activation and deactivation.

[0013] Appendix B of Non-Patent Document 6 and Chapter 7.3.2 of Non-Patent Document 7 describe the agreements made at the 3GPP RAN2 123rd Meeting, including the following: The gNB must ensure that there is at least a partial overlap between the UE's CDRX on time and the cell's DTX / DRX on time. It is up to the network implementation to ensure this alignment. The understanding is that alignment means that the cell's DTX / DRX and CDRX periodicities are multiples of each other. As a baseline, the existing CDRX reconfiguration (i.e., reconfiguration of the CDRX setting via RRC signaling) can be used to change the UE's CDRX setting when the cell DTX is activated or deactivated.

[0014] Chapter 7.3.2 of Non-Patent Document 7 lists comments from several companies on the above proposal of Non-Patent Document 5. One of these comments is that activation / deactivation is unreliable.

[0015] Huawei, "New WID: Network energy savings for NR", RP-223540, 3GPP TSG RAN Meeting #98-e, December 12 - 16, 2022 3GPP TR 38.864 V18.1.0 (2023-03) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on network energy savings for NR (Release 18)", March 2023 Huawei, HiSilicon, "Discussion on cell DTX and DRX", R2-2302797, 3GPP TSG-RAN WG2 Meeting #121-bis-e, Online, April 17 - 26, 2023 CMCC, "Discussion on cell DTX / DRX", R2-2303792, 3GPP TSG-RAN WG2 Meeting #121-bis-e, Online, April 17 - 26, 2023 vivo, Fraunhofer IIS, Huawei, HiSilicon, LG Electronics Inc., MediaTek Inc., NEC, Xiaomi, "UE C-DRX configuration used upon cell DTX activation", R2-2308738, 3GPP TSG-RAN WG2 Meeting #123, Toulouse, France, August 21-25, 2023Intel Corporation, "Discussion summary #2 for enhancements on cell DTX / DRX mechanism", R1-2308352, 3GPP TSG-RAN WG1 Meeting #114, Toulouse, France, August 21-25, 2023InterDigital, "Report from Session on NES, UAV, Rel-15-17 UP, Rel-17 Small Data, IIoT / URLLC, and RACH partitioning", R2-2308963, 3GPP TSG-RAN WG2 Meeting #123, Toulouse, France, August 21-25, 2023.

[0016] As mentioned above, Chapter 7.3.2 of Non-Patent Document 7 mentions that there was a comment that activation / deactivation is unreliable regarding the above proposal of Non-Patent Document 5. This comment is presumed to mean that cell DTX / DRX activation and deactivation via L1 signaling without HARQ feedback may not be received correctly by the UE, and the network may not be aware of this.

[0017] When a UE fails to successfully receive group-wide L1 signaling for cell DTX / DRX activation or deactivation, a situation may occur in which the cell DTX / DRX activation state perceived by the UE does not match the correct state intended or configured by the network (e.g., gNB or RAN node). Here, the cell DTX / DRX activation state refers to whether the cell DTX / DRX is activated or deactivated. This situation in which the network and the UE have different or inconsistent understandings of the cell DTX / DRX activation state is referred to herein as an inconsistency or mismatch in understanding of the cell DTX / DRX activation state.

[0018] The inventors have studied cell DTX / DRX and found various problems. One of the problems that the inventors have found is to provide an improvement that contributes to enabling a network to detect an inconsistency in understanding of the activation status of cell DTX / DRX between any UE in a cell. Another of the problems that the inventors have found is to provide an improvement that contributes to enabling a network to resolve an inconsistency in understanding of the activation status of cell DTX / DRX between any UE in a cell when the network can detect it in some way.

[0019] One of the objectives that the embodiments disclosed in this specification aim to achieve is to provide an apparatus, a method, and a program that contribute to solving at least one of the problems, including the problems described above. It should be noted that this objective is only one of the objectives that the embodiments disclosed in this specification aim to achieve. Other objectives or objectives and novel features will become apparent from the description of this specification or the accompanying drawings.

[0020] In a first aspect, the wireless terminal is configured to transmit a status check report to the network indicating a cell DTX activation state or a cell DRX activation state or both as perceived by the wireless terminal.

[0021] In a second aspect, a method performed by a wireless terminal includes transmitting a status check report to the network indicating a cell DTX activation status or a cell DRX activation status or both recognized by the wireless terminal.

[0022] In a third aspect, the radio access network node is configured to receive a status check report from the radio terminal indicating a cell DTX activation state or a cell DRX activation state or both as recognized by the radio terminal.

[0023] In a fourth aspect, a method performed by a radio access network node includes receiving a status check report from a radio terminal indicating a cell DTX activation state or a cell DRX activation state or both as recognized by the radio terminal.

[0024] In a fifth aspect, the radio access network node is configured to, in response to detecting a situation in which a radio terminal is suspected of misrecognizing the activation state of a cell DTX or a cell DRX, perform an operation to correct the activation state of the cell DTX or the cell DRX as recognized by the radio terminal.

[0025] In a sixth aspect, a method performed by a radio access network node comprises, in response to detecting a situation in which a radio terminal is suspected of misrecognizing an activation state of a cell DTX or a cell DRX, performing an operation to correct an activation state of the cell DTX or the cell DRX as recognized by the radio terminal.

[0026] In a seventh aspect, a program includes a set of instructions (software code) that, when loaded into a computer, causes the computer to perform the operations or methods of a radio terminal or radio access network node described in the above aspects.

[0027] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems including the above-described problem.

[0028]

[0023] Figure 1 illustrates an example configuration of a wireless communication system according to one or more embodiments.

[0024] Figure 2 illustrates a CDRX cycle.

[0025] Figure 3 illustrates an example of a plurality of CDRX-related timers.

[0026] Figure 4 illustrates an example of a cell DTX pattern.

[0027] Figure 5 illustrates a cell DRX pattern.

[0028] Figure 6 illustrates an example relationship between cell DTX on duration and CDRX on duration.

[0029] Figure 7 illustrates an example of signaling between a UE and a RAN node according to one or more embodiments.

[0029] Figure 8 illustrates an example of signaling between a UE and a RAN node according to one or more embodiments.

[0030] Figure 9 illustrates an example of a format for a Cell DTX / DRX Status Check Medium Access Control (MAC) Control Element (CE) according to one or more embodiments.

[0031] Figure 10 illustrates an example of a format for a Cell DTX / DRX Status Check MAC CE according to one or more embodiments.

[0032] Figure 11 illustrates a flowchart of an example of a UE operation according to one or more embodiments.

[0033] Figure 12 illustrates an example of signaling between a UE and a RAN node according to one or more embodiments.

[0034] Figure 13 illustrates an example of a UE operation according to one or more embodiments.

[0035] Figure 14 illustrates an example of a UE operation according to one or more embodiments. 1A-1C are a flowchart illustrating an example of the operation of a RAN node in accordance with one or more embodiments; 1B are a flowchart illustrating an example of the operation of a RAN node in accordance with one or more embodiments; 1C are a block diagram illustrating an example configuration of a UE in accordance with one or more embodiments; and 1D are a block diagram illustrating an example configuration of a RAN node in accordance with one or more embodiments.

[0029] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0030] The multiple embodiments described below may be used independently, or two or more embodiments may be combined as appropriate. These multiple embodiments may have different novel features. Therefore, these multiple embodiments may contribute to achieving different objectives or solving different problems, and may contribute to achieving different effects.

[0031] Each drawing is merely an example for describing one or more embodiments. Each drawing may not relate to only one particular embodiment, but may also relate to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0032] The following embodiments are described primarily for the 3GPP fifth generation mobile communication system (5G system), but may also be applied to other wireless communication systems that support technologies similar to 3GPP cell DTX and cell DRX.

[0033] As used herein, depending on the context, "if" may be interpreted to mean "when," "while," "at or around the time," "after," "upon," "in response to determining," "in accordance with a determination," or "in response to detecting." These expressions may be interpreted to have the same meaning, depending on the context.

[0034] First, the configuration and operation of multiple network elements common to multiple embodiments will be described. Fig. 1 shows an example configuration of a wireless communication system related to multiple embodiments. Each element (network function) shown in Fig. 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0035] In the example of FIG. 1 , the wireless communication system includes multiple UEs 1 and a Radio Access Network (RAN) node 2. Hereinafter, when describing matters common to the multiple UEs 1, reference will be made to the UE 1 unless otherwise specified. The UE 1 may be referred to by other terms, such as a wireless terminal, a mobile terminal, a mobile station, or a wireless transmit receive unit (WTRU). The RAN node 2 may be referred to by other terms, such as a network, a base station, or a radio station. The UE 1 has at least one radio transceiver and communicates with the RAN node 2. The RAN node 2 manages, operates, or provides a cell 21 and communicates with the multiple UEs 1 within the cell 21 using cellular communication technology (i.e., NR Radio Access Technology). These communications include downlink and uplink transmissions. Downlink transmissions include cell-specific synchronization signals, cell-specific and UE-specific reference signals, broadcast channels (e.g., Physical Broadcast Channel (PBCH)), control channels (e.g., PDCCH), and data transmission channels (e.g., Physical Downlink Shared Channel (PDSCH)). Uplink transmissions include reference signals, random access channels (e.g., Physical RACH (PRACH)), control channels (e.g., Physical Uplink Control Channel (PUCCH)), and data transmission channels (e.g., Physical Uplink Shared Channel (PUSCH)).

[0036] The RAN node 2 may provide multiple cells including cell 21, and the UE 1 may be simultaneously connected to multiple cells provided by the RAN node 2. In other words, the UE 1 may perform carrier aggregation (CA) between multiple cells provided by the RAN node 2. In addition, the UE 1 may be simultaneously connected to the RAN node 2 and other RAN nodes for dual connectivity (DC).

[0037] The RAN node 2 may be a Next Generation Radio Access Network (NG-RAN) node. The NG-RAN node may be a gNB or an ng-eNB. The ng-eNB provides Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (E-UTRA) user plane and control plane protocol termination for UEs and connects to the 5G Core Network (5GC) via an NG interface. The RAN node 2 may be a Central Unit (e.g., gNB-CU) in a cloud RAN (C-RAN) deployment, or a combination of a CU and one or more Distributed Units (e.g., gNB-DUs). The C-RAN is also referred to as a CU / DU split. Furthermore, a CU may include a Control Plane (CP) Unit (e.g., gNB-CU-CP) and one or more User Plane (UP) Units (e.g., gNB-CU-UP). Thus, the RAN node 2 may be a CU-CP or a combination of a CU-CP and a CU-UP. The CU may be a logical node that hosts the Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols of the gNB (or the RRC and PDCP protocols of the gNB). The DU may be a logical node that hosts the Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers of the gNB.

[0038] The UE 1 and the RAN node 2 support connected mode DRX (CDRX). When CDRX is configured, the UE 1 does not need to continuously monitor the PDCCH. CDRX is characterized by an on-duration, an inactivity timer, a retransmission timer, a DRX cycle, and an active time. The on-duration is the duration that the UE 1 waits to receive PDCCHs after waking up. If the UE 1 successfully decodes a PDCCH, the UE 1 stays awake and starts the inactivity timer. The inactivity timer is the duration that the UE 1 waits to decode the (next) PDCCH from the last successful PDCCH decode. If the UE 1 fails to decode the PDCCH before the inactivity timer expires, the UE 1 can return to sleep. The retransmission timer is the duration that the UE 1 must stay awake to receive retransmissions. The DRX cycle specifies the periodic repetition of on durations followed by possible periods of inactivity. Active time is the total time that UE 1 monitors the PDCCH. Active time includes the on duration within the DRX cycle, the time that UE 1 performs continuous reception while the inactivity timer has not expired, and the time that UE 1 performs continuous reception while waiting for a retransmission opportunity.

[0039] CDRX is controlled by RRC. CDRX-related parameters provided to the UE by the network via the RRC configuration (DRX-Config) include the following: drx-onDurationTimer, drx-SlotOffset, drx-InactivityTimer, drx-RetransmissionTimerDL (per Downlink (DL) HARQ process except for the broadcast process), drx-RetransmissionTimerUL (per Uplink (UL) HARQ process), drx-LongCycleStartOffset, drx-ShortCycle (optional), drx-ShortCycleTimer (optional), drx-HARQ-RTT-TimerDL (per DL HARQ process except for the broadcast process), and drx-HARQ-RTT-TimerUL (per UL HARQ process). Multiple serving cells of the MAC entity of UE 1 may be configured by RRC with two CDRX groups with different CDRX parameters. As already explained, the term "CDRX group" is used in this specification instead of the term "DRX group" used in the 3GPP specifications. When two CDRX groups are configured, each serving cell is uniquely assigned to one of the two groups. The CDRX parameters configured individually for each CDRX group are drx-onDurationTimer and drx-InactivityTimer. On the other hand, the CDRX parameters common to multiple CDRX groups are drx-SlotOffset, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, drx-LongCycleStartOffset, drx-ShortCycle (optional), drx-ShortCycleTimer (optional), drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerUL.

[0040] drx-onDurationTimer is a timer that measures the CDRX on duration. drx-onDurationTimer specifies the time to decode the PDCCH at the beginning of each DRX cycle (DRX ON) before entering power saving mode (CDRX OFF).

[0041] The drx-SlotOffset specifies the delay before starting the drx-onDurationTimer, i.e., the drx-SlotOffset defines the start of the CDRX on duration (or drx-onDurationTimer) relative to the start of the subframe.

[0042] The drx-InactivityTimer defines the duration after a PDCCH occasion that a PDCCH indicates a new uplink UL, downlink, or sidelink transmission for the MAC entity, in other words, the drx-InactivityTimer indicates the duration that UE 1 waits to decode the (next) PDCCH since the previous successful PDCCH decoding.

[0043] The drx-RetransmissionTimerDL indicates the maximum duration for receiving a downlink retransmission, in other words, the drx-RetransmissionTimerDL indicates the duration for which the UE 1 must be awake to receive a downlink retransmission.

[0044] drx-RetransmissionTimerUL indicates the maximum duration until a grant for uplink retransmission (uplink grant) is received, in other words, drx-RetransmissionTimerUL indicates the duration that UE 1 must be awake to receive a grant for uplink retransmission.

[0045] drx-LongCycleStartOffset indicates the long DRX cycle (drx-LongCycle) and the start offset (drx-StartOffset), which defines the subframe in which the long DRX cycle and the short DRX cycle start.

[0046] drx-ShortCycle (optional) indicates the short DRX cycle.

[0047] drx-ShortCycleTimer (optional) indicates the duration for which the UE 1 follows the short DRX cycle. The drx-ShortCycleTimer indicates the timer value as a multiple of the short DRX cycle (drx-ShortCycle), and the timer value can range from 1 to 16, i.e., 1 to 16 short DRX cycles.

[0048] The drx-HARQ-RTT-TimerDL indicates the minimum duration or interval after which a DL allocation for a HARQ retransmission is expected by the MAC entity. In other words, the drx-HARQ-RTT-TimerDL defines the minimum time after UE 1 sends a hybrid automatic repeat request (HARQ) negative acknowledge (NACK) on the uplink until UE 1 can expect a downlink retransmission.

[0049] The drx-HARQ-RTT-TimerUL indicates the minimum duration or interval until a grant for uplink retransmission is expected by the MAC entity, in other words, the drx-HARQ-RTT-TimerUL defines the minimum time from when UE 1 makes a PUSCH transmission until UE 1 can expect downlink reception of a grant for retransmission.

[0050] If CDRX is configured, the active time for serving cells in one CDRX group includes, among other time periods: - while the drx-onDurationTimer or drx-InactivityTimer configured for the CDRX group is running; or - while the drx-RetransmissionTimerDL or drx-RetransmissionTimerUL is running for any serving cell in the CDRX group; or - while a scheduling request has been sent and is pending on the PUCCH; or - while no PDCCH indicating a new transmission addressed to the C-RNTI of the MAC entity has been received after successful reception of a random access response to a random access preamble not selected by the MAC entity.

[0051] The network, specifically the RAN node 2, provides the RRC configuration related to CDRX (i.e., DRX-Config) to the UE 1 by a UE-specific or dedicated RRC message, specifically an RRCReconfiguration message. The DRX-Config is included in the MAC-CellGroupConfig within the CellGroupConfig carried by the RRCReconfiguration message.

[0052] Figure 2 shows an example of a CDRX cycle. As shown in Figure 2, one CDRX cycle 201 includes an on duration 202 at the beginning of the cycle. The on duration 202 is one of the CDRX active periods of UE 1. After the on duration 202 is a CDRX opportunity 203. During the CDRX opportunity 203, UE 1 can enter sleep mode if neither the inactivity timer (drx-InactivityTimer) nor the retransmission timers (drx-RetransmissionTimerDL, drx-RetransmissionTimerUL) are running.

[0053] Figure 3 shows the relationship between several CDRX-related timers and the CDRX active time for UE 1's downlink reception. If UE 1 receives a PDCCH indicating a new downlink (DL) transmission while the on-duration timer (drx-onDurationTimer) 301 is running, UE 1 starts or restarts the inactivity timer (drx-InactivityTimer) 302. The MAC entity of UE 1 starts or restarts the inactivity timer (drx-InactivityTimer) 302 at the first symbol after the end of PDCCH reception. If UE 1 fails to receive the PDSCH, UE 1 sends a HARQ NACK and starts the HARQ round trip time (RTT) timer (drx-HARQ-RTT-TimerDL) 303 for the corresponding HARQ process. The MAC entity of UE 1 starts the HARQ RTT timer (drx-HARQ-RTT-TimerDL) 303 for the corresponding HARQ process at the first symbol after the end of the transmission carrying the HARQ feedback (NACK). After the expiration of the HARQ RTT timer (drx-HARQ-RTT-TimerDL) 303, UE 1 immediately starts the retransmission timer (drx-RetransmissionTimerDL) 304 for the corresponding HARQ process. The MAC entity of UE 1 starts the retransmission timer (drx-RetransmissionTimerDL) 304 at the first symbol after the expiration of the HARQ RTT timer (drx-HARQ-RTT-TimerDL) 303. In the example of Fig. 3, the CDRX active time includes a time period 321 during which the on-duration timer (drx-onDurationTimer) 301 and the inactivity timer (drx-InactivityTimer) 302 are running, and a time period 322 during which the retransmission timer (drx-RetransmissionTimerDL) 304 is running. During the CDRX active time, the UE 1 needs to monitor the PDCCH.

[0054] Figure 4 shows the relationship between several CDRX-related timers and the CDRX active time for UE 1's uplink transmission. If UE 1 receives a PDCCH indicating a grant for a new uplink (UL) transmission while the on-duration timer (drx-onDurationTimer) 401 is running, UE 1 starts or restarts the inactivity timer (drx-InactivityTimer) 402. The MAC entity of UE 1 starts or restarts the inactivity timer (drx-InactivityTimer) 402 at the first symbol after the end of PDCCH reception. After a PUSCH transmission, UE 1 starts the HARQ RTT timer (drx-HARQ-RTT-TimerUL) 403 for the corresponding HARQ process. The MAC entity of UE 1 starts the HARQ RTT timer (drx-HARQ-RTT-TimerUL) 403 at the first symbol after the end of the first PUSCH transmission. After the HARQ RTT timer (drx-HARQ-RTT-TimerUL) 403 expires, UE 1 immediately starts the retransmission timer (drx-RetransmissionTimerUL) 404 for the corresponding HARQ process. The MAC entity of UE 1 starts the retransmission timer (drx-RetransmissionTimerUL) 404 at the first symbol after the expiration of the HARQ RTT timer (drx-HARQ-RTT-TimerUL) 403. In the example of Figure 4, the CDRX active time includes a time period 421 during which the on duration timer (drx-onDurationTimer) 401 and the inactivity timer (drx-InactivityTimer) 402 are running, and a time period 422 during which the retransmission timer (drx-RetransmissionTimerUL) 404 is running. During the CDRX active time, UE 1 needs to monitor the PDCCH.

[0055] Furthermore, UE 1 and RAN node 2 support cell DTX and cell DRX. As previously mentioned, the terms "cell DTX on duration," "cell DTX off duration," "cell DRX on duration," and "cell DRX off duration" are used herein in reference to cell DTX / DRX. Cell DTX / DRX on duration refers to the duration, time, or period during which a cell is active and capable of transmitting and receiving all necessary cell common channels and signals and UE-specific signals and channels. In contrast, cell DTX / DRX off duration refers to the duration, time, or period during which a cell is inactive for NES and either does not transmit or receive or can maintain only limited transmission or reception. Cell DTX / DRX on duration may also be referred to as cell DTX / DRX on time or on period, or cell DTX / DRX active time, period, or duration. The cell DTX / DRX off duration may also be referred to as a cell DTX / DRX off time or off period, or a cell DTX / DRX inactive or non-active time, period, or duration.

[0056] If cell DTX of cell 21 is activated, then during the cell DTX off duration, the RAN node 2 may not perform downlink transmission in cell 21 or may maintain only limited downlink transmission. Similarly, if cell DRX of cell 21 is activated, then during the cell DRX off duration, the RAN node 2 may not perform uplink reception in cell 21 or may maintain only limited uplink reception. In a first example, during the cell DTX / DRX off duration, the RAN node 2 is expected to turn off all transmission or reception of data traffic and reference signals in cell 21. In a second example, during the cell DTX / DRX off duration, the RAN node 2 is expected to turn off only transmission or reception of data traffic in cell 21. That is, the RAN node 2 continues to transmit or receive reference signals. In a third example, during the cell DTX / DRX off duration, the RAN node 2 is expected to turn off dynamic data transmission or reception in cell 21. That is, the RAN node 2 is expected to still transmit or receive on periodic resources such as SPS, CG PUSCH, SR, RACH, and SRS. In a fourth example, during the cell DTX off duration, the RAN node 2 is expected to transmit only reference signals (e.g. CSI-RS for measurements) in the cell 21.

[0057] The cell DTX mode and the cell DRX mode can be configured and operated separately (e.g., one RRC configuration set for the downlink and another for the uplink). The cell DTX and cell DRX can also be configured and operated together. For each cell DTX / DRX configuration, parameters can be configured, including at least the periodicity or cycle, the start offset, and the on-duration. The start offset defines the starting point (e.g., subframe or slot) of the cell DTX / DRX cycle. The RAN node 2 may provide the cell DTX / DRX configuration information to the UE 1 via cell-specific (or cell-common) or UE-specific RRC signaling. The cell-specific RRC signaling may be system information (e.g., SIB). The UE-specific RRC signaling may be an RRC Reconfiguration message. When system information is used to send the cell DTX / DRX configuration information, the cell DTX / DRX configuration information may be updated using a system information modification procedure.

[0058] Cell DTX and cell DRX may be activated or deactivated separately or together. Activation of cell DTX / DRX may be performed using Layer 1, Layer 2, or Layer 3 (L1 / L2 / L3) signaling. The RAN node 2 may send L1 / L2 / L3 signaling indicating activation of cell DTX / DRX. This indication may be referred to as an NES mode indication, an NES activation indication, etc. L1 / L2 / L3 signaling may be UE-specific, UE group-specific (i.e., UE group-wide), or cell-specific (i.e., cell-wide).

[0059] More specifically, cell DTX / DRX may be implicitly activated and deactivated. That is, cell DTX / DRX may be immediately activated when configured by UE-specific RRC signaling, or may be deactivated when the RRC configuration is released. In addition, cell DTX / DRX may be dynamically activated and deactivated by L1 / L2 signaling. Dynamic L1 / L2 signaling may be UE-specific or UE-group-wide.

[0060] The RAN node 2 may configure multiple sets of cell DTX configurations for the UE 1 via RRC signaling and may activate one set of cell DTX configurations to be applied using L1 / L2 signaling. Similarly, the RAN node 2 may configure multiple sets of cell DRX configurations for the UE 1 via RRC signaling and may activate one set of cell DRX configurations to be applied using L1 / L2 signaling.

[0061] The UE-specific L1 signaling may be in a DCI format with Cyclic Redundancy Check (CRC) bits scrambled by a UE-specific RNTI (e.g., C-RNTI). In other words, the UE-specific L1 signaling may be a PDCCH carrying CRC bits scrambled by a UE-specific RNTI.

[0062] The UE group-common L1 signaling may be in a DCI format with CRC bits scrambled by a UE group-specific RNTI. In other words, the UE group-common L1 signaling may be a PDCCH carrying CRC bits scrambled by a UE group-specific RNTI. The UE group may be a group to which only NES-capable UEs in the cell 21 belong, and may exclude legacy UEs that are not NES-capable. The UE group-specific RNTI may be a newly defined RNTI for cell DTX / DRX.

[0063] The cell-common L1 signaling may be in a DCI format with CRC bits scrambled by a cell-specific RNTI. In other words, the cell-common L1 signaling may be a PDCCH carrying CRC bits scrambled by a cell-specific RNTI. The cell-specific or cell-common RNTI may be a System Information RNTI (SI-RNTI) or a Paging RNTI (P-RNTI), or may be a newly defined RNTI for cell DTX / DRX. Specifically, the cell-common L1 signaling may be a DCI including a short message indicating a change in system information, or a PDCCH carrying the DCI and CRC bits scrambled by the P-RNTI. The DCI may indicate a short message indicating cell DTX / DRX activation or NES mode indication in addition to the short message indicating the change in system information.

[0064] The UE-specific L2 signaling may be a Medium Access Control (MAC) Control Element (CE) transmitted on a PDSCH scheduled by a DCI format with CRC bits scrambled by a UE-specific RNTI. The UE group-common L2 signaling may be a MAC CE transmitted on a PDSCH scheduled by a DCI format with CRC bits scrambled by a UE group-specific RNTI. The cell-specific L2 signaling may be a MAC CE transmitted on a PDSCH scheduled by a DCI format with CRC bits scrambled by a cell-specific RNTI.

[0065] The cell-common L3 signaling may be system information (e.g., SIB), and the UE-specific L3 signaling may be a UE-dedicated RRC message, specifically, an RRC Reconfiguration message.

[0066] The cell DTX / DRX on-duration may be extended. The cell DTX on-duration and the cell DRX on-duration may be extended separately or together. If the RAN node 2 wishes to extend the cell DTX on-duration, the cell DRX on-duration, or both, it may send L1 / L2 signaling to the UE 1 to trigger the on-duration extension. This L1 / L2 signaling may be cell-specific (or cell-general), UE group-specific, or UE-specific. Examples of L1 / L2 signaling for extending the cell DTX / DRX on-duration are similar to those described for the L1 / L2 signaling for cell DTX / DRX activation. An extension of the cell DTX / DRX on-duration within a cell DTX / DRX cycle is accompanied by a shortening of the cell DTX / DRX off-duration within that cycle.

[0067] Figure 5 shows an example of a cell DTX cycle. In the example of Figure 5, one cell DTX cycle 501 includes an on duration 502 at the beginning of the cycle. The on duration 502 is followed by an off duration 503. Figure 6 shows an example of a cell DRX cycle. In the example of Figure 6, one cell DRX cycle 601 includes an on duration 602 at the beginning of the cycle. The on duration 602 is followed by an off duration 603.

[0068] Figure 7 shows an example of the relationship between the cell DTX on duration and the UE CDRX on duration. In the example of Figure 7, the CDRX configured for UE-A, UE-B, UE-C, and UE-D have the same CDRX cycle length and the same CDRX on duration length, but different start offsets. The length of the CDRX cycle common to UE-A, UE-B, UE-C, and UE-D is half the length of the cell DTX cycle.

[0069] UE-A's CDRX on duration 720 falls within either cell DTX on duration 710 every two cycles. Similarly, UE-B's CDRX on duration 730 falls within either cell DTX on duration 710 every two cycles. Therefore, it may be said that the CDRX patterns of UE-A and UE-B are well aligned with the cell DTX pattern. However, depending on the network implementation, UE-A and UE-B's CDRX configurations may be updated to remove CDRX on durations 720 and 730 that fall outside the cell DTX on duration 710, for example, in response to cell DTX activation.

[0070] The UE-C's CDRX on duration 740 partially overlaps with one of the cell DTX on durations 710 every two cycles. Therefore, the UE-C's CDRX pattern may be said to be somewhat aligned with the cell DTX pattern. Alternatively, the UE-C's CDRX pattern may be said to be not fully aligned with the cell DTX pattern. Depending on the network implementation, the UE-C's CDRX configuration may be updated, for example, in response to cell DTX activation, so that the UE-C's CDRX on duration 740 falls completely within the cell DTX on duration 710 every two cycles. This can be achieved, for example, by changing the start offset of the UE-C's CDRX cycle.

[0071] On the other hand, UE-D's CDRX on duration 750 does not overlap, even partially, with the cell DTX on duration 710. Therefore, UE-D's CDRX pattern is not aligned with the cell DTX pattern. Depending on the network implementation, UE-D's CDRX configuration may be updated, e.g., in response to cell DTX activation, so that UE-D's CDRX on duration 750 falls completely within the cell DTX on duration 710 every two cycles. This can be achieved, for example, by changing the start offset of UE-D's CDRX cycle.

[0072] To achieve consistency between the UE CDRX and the cell DTX, the RAN node 2 can use, for example, the following two methods. In the first method, the RAN node 2 uses the existing CDRX reconfiguration (i.e., reconfiguration of the CDRX configuration via RRC signaling) to change the UE's CDRX configuration. For example, when the RAN node 2 configures the cell DTX configuration or parameters (e.g., periodicity, start offset, and on-duration) for the UE 1 via a UE-specific RRC message (e.g., RRCReconfiguration), the RAN node 2 may also send an updated CDRX configuration to the UE 1 to align the CDRX pattern with the cell DTX pattern. The UE 1 applies the updated CDRX configuration regardless of whether the cell DTX is activated or deactivated, unless a new updated CDRX configuration is provided in the RRC message. In other words, the UE 1 does not implicitly switch or change the CDRX configuration or pattern depending on the activation or deactivation of the cell DTX.

[0073] In the second method, the UE 1 implicitly switches or changes the CDRX configuration or pattern depending on the activation and deactivation of the cell DTX. For example, the UE 1 may implicitly enable an additional CDRX configuration depending on the activation of the cell DTX and implicitly disable the additional CDRX configuration depending on the deactivation of the cell DTX. The RAN node 2 may configure the UE 1 with the additional CDRX configuration along with the cell DTX / DRX parameters. This additional CDRX configuration is implicitly enabled upon activation of the cell DTX. The additional CDRX configuration includes optional CDRX parameters (e.g., start offset, or DRX cycle and start offset) that the UE 1 uses when the cell DTX is activated. The additional CDRX configuration may be a full configuration or a delta configuration. The full configuration includes all the configurations for defining the CDRX pattern when the cell DTX is activated. In contrast, the delta configuration includes only the differences from the normal CDRX configuration that is applied when the cell DTX is deactivated. The delta configuration may include only a subset of information elements or items that the normal CDRX configuration (full configuration) has that are applied when the cell DTX is deactivated. Specifically, the delta configuration may include only the configuration of one or more CDRX parameters (e.g., start offset, or DRX cycle and start offset) that need to be changed while the cell DTX is activated.

[0074] 8 shows an example of the first method described above. In step 801, RAN node 2 sends an RRC message (e.g., RRCReconfiguration) including a first CDRX configuration to UE 1. At this point, the cell DTX configuration has not yet been provided to UE 1, and therefore the cell DTX is not activated. In step 802, UE 1 applies the received first CDRX configuration. UE 1 performs CDRX operation according to the first CDRX configuration. The first CDRX configuration defines, for example, an on-duration, an inactivity timer, a retransmission timer, a DRX cycle, and a start offset.

[0075] In step 803, to start cell DTX, RAN node 2 sends an RRC message (e.g., RRCReconfiguration) including a cell DTX configuration to UE 1. At this time, RAN node 2 sends a second CDRX configuration to UE 1 to align UE 1's CDRX pattern with the cell DTX pattern. The cell DTX configuration and the second CDRX configuration may be sent in the same RRC message or in different RRC messages. In step 804, UE 1 applies the received cell DTX configuration and implicitly activates cell DTX. In step 805, UE 1 discards the first CDRX configuration, applies the second CDRX configuration, and performs CDRX operation according to the second CDRX configuration.

[0076] In step 806, RAN node 2 transmits L1 signaling to UE 1 for deactivating cell DRX. This L1 signaling may be group-wide signaling, i.e., common to a group of UEs including UE 1. In accordance with the L1 signaling, UE 1 deactivates cell DTX in step 807. Note that UE 1 continues CDRX operation according to the second CDRX configuration. UE 1 applies the second CDRX configuration regardless of cell DTX activation and deactivation, unless a new updated CDRX configuration (e.g., the first CDRX configuration) is provided in an RRC message. In other words, UE 1 does not implicitly switch or change its CDRX configuration or pattern depending on cell DTX activation and deactivation.

[0077] In step 808, RAN node 2 sends L1 signaling for activating cell DRX to UE 1. This L1 signaling may be group-wide signaling, i.e., common to a group of UEs including UE 1. According to the L1 signaling, UE 1 activates cell DTX in step 808. UE 1 continues CDRX operation according to the second CDRX configuration.

[0078] On the other hand, Figure 9 shows an example of the second method described above. In step 901, RAN node 2 sends an RRC message (e.g., RRCReconfiguration) including a CDRX configuration (normal CDRX configuration) to UE 1. At this point, the cell DTX configuration has not yet been provided to UE 1, and therefore the cell DTX is not activated. In step 902, UE 1 applies the received CDRX configuration. UE 1 performs CDRX operation according to the received CDRX configuration. This CDRX configuration defines, for example, the on-duration, inactivity timer, retransmission timer, DRX cycle, and start offset.

[0079] In step 903, to start cell DTX, RAN node 2 sends an RRC message (e.g., RRCReconfiguration) including a cell DTX configuration to UE 1. At this time, RAN node 2 sends an additional CDRX configuration to UE 1 to align UE 1's CDRX pattern with the cell DTX pattern. This additional CDRX configuration is implicitly enabled when cell DTX is activated. The additional CDRX configuration includes optional CDRX parameters (e.g., start offset, or DRX cycle and start offset) that the UE uses when cell DTX is activated. UE 1 does not discard the normal CDRX configuration received in step 901, but stores the additional CDRX configuration in addition to the normal CDRX configuration. In step 904, UE 1 applies the received cell DTX configuration and implicitly activates cell DTX. In step 905, UE 1 switches from the normal CDRX configuration to the additional CDRX configuration and performs CDRX operation according to the additional CDRX configuration.

[0080] In step 906, RAN node 2 transmits L1 signaling for deactivating cell DRX to UE 1. This L1 signaling may be group-wide signaling, i.e., common to a group of UEs including UE 1. According to the L1 signaling, UE 1 deactivates cell DTX in step 907. Furthermore, UE 1 implicitly switches to a normal CDRX configuration in response to the deactivation of cell DTX, and performs CDRX operation according to the normal CDRX configuration.

[0081] In step 908, RAN node 2 transmits L1 signaling for activating cell DRX to UE 1. This L1 signaling may be group-wide signaling, i.e., common to a group of UEs including UE 1. According to the L1 signaling, UE 1 activates cell DTX in step 908. Furthermore, UE 1 implicitly switches to an additional CDRX configuration in response to the deactivation of cell DTX, and performs CDRX operation according to the additional CDRX configuration.

[0082] First Embodiment A configuration example of a wireless communication system according to this embodiment is similar to the configuration example described with reference to Fig. 1. This embodiment provides an improvement that contributes to enabling the network (e.g., RAN node 2) to detect when there is an inconsistency in understanding the cell DTX / DRX activation status between any UEs in the cell.

[0083] As already explained, an inconsistency or mismatch in the understanding of the cell DTX / DRX activation state refers to a situation in which the cell DTX / DRX activation state recognized by UE 1 does not match the correct state intended or configured by the network (e.g., RAN node 2). Here, the cell DTX / DRX activation state means whether the cell DTX / DRX is activated or deactivated. This inconsistency or mismatch may occur, for example, when UE 1 fails to properly receive UE group-wide L1 signaling for cell DTX / DRX activation or deactivation.

[0084] Consider a case where UE 1 mistakenly believes that cell DTX is activated when RAN node 2 deactivates it. In this case, UE 1 may monitor the PDCCH only on some occasions that overlap with the cell DTX on duration among the periodic CDRX on durations configured by RAN node 2. Furthermore, if UE 1 implicitly changes the CDRX pattern depending on the activation and deactivation of cell DTX, and if there is no overlap between the CDRX on duration when cell DTX is activated and the CDRX on duration when cell DTX is deactivated, UE 1 may not receive any PDCCH transmitted by RAN node 2. This may result in a situation where UE 1 cannot perform any uplink or downlink data transmission scheduled by RAN node 2.

[0085] Next, consider a case where UE 1 mistakenly believes that cell DTX is deactivated when RAN node 2 activates cell DTX. In this case, RAN node 2 may transmit PDCCH only on some occasions that overlap with the cell DTX on duration among the periodic CDRX on durations during which UE 1 attempts to receive PDCCH. Furthermore, if UE 1 implicitly changes its CDRX pattern depending on cell DTX activation and deactivation, and if there is no overlap between the CDRX on duration when cell DTX is activated and the CDRX on duration when cell DTX is deactivated, UE 1 may not receive any PDCCH transmitted by RAN node 2. This may result in a situation where UE 1 is unable to perform any uplink or downlink data transmission scheduled by RAN node 2.

[0086] If the RAN node 2 is able to detect that there is an inconsistency in understanding of the cell DTX / DRX activation state with any UE in the cell, the RAN node 2 may take action to, for example, resolve this inconsistency. Figure 10 shows an example of the operations of the UE 1 and the RAN node 2 that contribute to enabling the RAN node 2 to know that there is an inconsistency in understanding of the cell DTX / DRX activation state.

[0087] In step 1001, the UE 1 transmits a status check report to the network (e.g., RAN node 2) indicating the cell DTX activation state or the cell DRX activation state, or both, recognized (or detected) by the UE 1. Hereinafter, this status check report will be referred to as the cell DTX / DRX status check report. The cell DTX / DRX status check report indicates whether the cell DTX / DRX activation state recognized by the UE 1 is activated or deactivated.

[0088] As already explained, the RAN node 2 may configure multiple sets of cell DTX configurations for the UE 1 by RRC signaling and may activate one applicable cell DTX configuration set using group-common L1 signaling. Similarly, the RAN node 2 may configure multiple sets of cell DRX configurations for the UE 1 by RRC signaling and may activate one applicable cell DRX configuration set using group-common L1 signaling. In these cases, the cell DTX / DRX status check report of step 1001 may indicate multiple activation states, each corresponding to a respective one of the multiple cell DTX configurations. Similarly, the cell DTX / DRX status check report may indicate multiple activation states, each corresponding to a respective one of the multiple cell DRX configurations.

[0089] The cell DTX / DRX status check report in step 1001 may be transmitted via L1 or L2 signaling. The cell DTX / DRX status check report may be a MAC CE. Figures 11 and 12 show examples of the format of a MAC CE carrying a cell DTX / DRX status check report (hereinafter referred to as a cell DTX / DRX status check MAC CE). The cell DTX / DRX status check MAC CE 1100 in Figure 11 consists of one octet. "R" in Figure 11 is a reserved bit. The reserved bit is, for example, set to a value of 0. The MAC entity of UE 1 ignores the value of the reserved bit.

[0090] The "Cell DTX state" bit or field 1102 in Figure 11 indicates whether the activation state of the cell DTX recognized (or detected) by UE 1 is activated or deactivated. For example, if the "Cell DTX state" bit or field 1102 is set to 1, this may mean that the activation state of the cell DTX recognized (or detected) by UE 1 is activated. Conversely, if the "Cell DTX state" bit or field 1102 is set to 0, this may mean that the activation state of the cell DTX recognized (or detected) by UE 1 is deactivated.

[0091] The "Cell DRX state" bit or field 1103 in Figure 11 indicates whether the activation state of the cell DRX recognized (or detected) by UE 1 is activated or deactivated. For example, if the "Cell DRX state" bit or field 1103 is set to 1, this may mean that the activation state of the cell DRX recognized (or detected) by UE 1 is activated. Conversely, if the "Cell DRX state" bit or field 1103 is set to 0, this may mean that the activation state of the cell DRX recognized (or detected) by UE 1 is deactivated.

[0092] The cell DTX / DRX status confirmation MAC CE 1200 in FIG. 12 consists of two octets. The first octet of the cell DTX / DRX status confirmation MAC CE 1200 indicates the activation status of each of eight cell DTXs corresponding to a maximum of eight cell DTX settings. The second octet of the cell DTX / DRX status confirmation MAC CE 1200 indicates the activation status of each of eight cell DRXs corresponding to a maximum of eight cell DRX settings. The format of FIG. 12 is merely an example. For example, the MAC CE 1200 having two octets may indicate the activation status of each of 16 cell DTXs corresponding to a maximum of 16 cell DTX settings. The MAC CE 1200 having two octets may indicate the activation status of each of 16 cell DRXs corresponding to a maximum of 16 cell DRX settings. Alternatively, the MAC CE 1200 may be of variable size, with the number of octets determined depending on the number of cell DTX and DRX settings configured in the UE 1 .

[0093] By way of example and not limitation, the trigger for UE 1 to send a cell DTX / DRX status check report (e.g., MAC CE) may be any of the following: UE 1 may trigger the transmission of a cell DTX / DRX status check report in response to receiving signaling from the network (e.g., RAN node 2) indicating activation or deactivation of cell DTX or cell DRX. This allows RAN node 2 to verify whether UE 1 correctly understands (or detects) the activation status of cell DTX / DRX every time cell DTX / DRX activation or deactivation occurs.

[0094] In this case, the UE 1 may apply the cell DTX or cell DRX activation or deactivation indicated in the signaling after the cell DTX / DRX status check report is transmitted. If an additional CDRX configuration is used, the UE 1 may apply the cell DTX activation or deactivation indicated in the signaling after the cell DTX / DRX status check report is transmitted, and may also implicitly apply the associated CDRX configuration (i.e., normal CDRX configuration or additional CDRX configuration).

[0095] Similarly, after receiving the cell DTX / DRX status check report from the UE 1, the RAN node 2 may apply the cell DTX or cell DRX activation or deactivation indicated by the signaling to the UE 1. If an additional CDRX configuration is used, after receiving the cell DTX / DRX status check report from the UE 1, the RAN node 2 may apply the cell DTX activation or deactivation indicated by the signaling to the UE 1 and implicitly apply the associated CDRX configuration (i.e., the normal CDRX configuration or the additional CDRX configuration) to the UE 1. In other words, the RAN node 2 may manage the cell DTX / DRX application state (or activation state) for each of multiple UEs performing cell DTX / DRX operation within the cell 21.

[0096] Additionally or alternatively, the UE 1 may trigger the transmission of the cell DTX / DRX status confirmation report in response to detecting a situation in which the UE 1 is suspected of misunderstanding the cell DTX or cell DRX activation state. This enables the RAN node 2 to confirm whether the UE 1 correctly understands (or detects) the cell DTX / DRX activation state in response to the UE 1 detecting a suspected inconsistency or mismatch in its understanding of the cell DTX / DRX activation state. More specifically, the UE 1 may trigger the transmission of the cell DTX / DRX status confirmation report in response to detecting no PDCCH reception for a predetermined number of consecutive PDCCH monitoring occasions. The predetermined number may be configured in the UE 1 by the network (e.g., RAN node 2). The configuration of the predetermined number (e.g., maxNumConsecutiveNoPDCCH) may be provided to the UE 1 via an RRC message (e.g., RRCReconfiguration).

[0097] The operation of UE 1 and RAN node 2 described with reference to Figure 10 allows RAN node 2 to know when there is a mismatch in understanding of the cell DTX / DRX activation state between UE 1 and RAN node 2. In other words, this allows RAN node 2 to know when the cell DTX / DRX activation state as perceived by UE 1 does not match the correct state intended or configured by RAN node 2.

[0098] The cell DTX / DRX status confirmation report can trigger the network (e.g., RAN node 2) to detect whether UE 1 has misidentified the activation status of cell DTX or cell DRX. In other words, RAN node 2 may detect whether UE 1 has misidentified the activation status of cell DTX or cell DRX based on the cell DTX / DRX status confirmation report. RAN node 2 may detect whether UE 1 has misidentified the activation status of cell DTX or cell DRX based on receiving or not receiving the cell DTX / DRX status confirmation report from UE 1. RAN node 2 may perform an operation to correct the activation status of cell DTX or cell DRX recognized by UE 1 based on receiving or not receiving the cell DTX / DRX status confirmation report from UE 1. In response to detecting that UE 1 has misidentified the activation state of cell DTX or cell DRX based on receipt or non-receipt of a cell DTX / DRX status confirmation report from UE 1, RAN node 2 may perform an action to correct the activation state of cell DTX or cell DRX as perceived by UE 1.

[0099] To correct the activation state of cell DTX or cell DRX known by UE 1, RAN node 2 may retransmit L1 signaling for activating or deactivating cell DTX or cell DRX to UE 1 or to a UE group including UE 1. Alternatively, to correct the activation state of cell DTX or cell DRX known by UE 1, RAN node 2 may send an RRC message (e.g., RRCReconfiguration) to UE 1 containing cell DTX configuration or cell DRX configuration.

[0100] Second Embodiment A configuration example of a wireless communication system according to this embodiment is the same as the configuration example described with reference to Fig. 1. This embodiment provides a specific example of transmitting the cell DTX / DRX status confirmation report described in the first embodiment.

[0101] FIG. 13 shows an example of the operation of UE 1. In step 1301, UE 1 receives signaling from RAN node 2 indicating activation or deactivation of cell DTX / DRX. The signaling may be L1 signaling common to a UE group including UE 1. In step 1302, in response to receiving the signaling of step 1301, UE 1 triggers the transmission of a cell DTX / DRX status check report. If the signaling of step 1301 indicates activation or deactivation of cell DTX, the cell DTX / DRX status check report may indicate only the activation status of cell DTX, or may indicate both the activation status of cell DTX and the activation status of cell DRX. Similarly, if the signaling of step 1301 indicates activation or deactivation of cell DRX, the cell DTX / DRX status check report may indicate only the activation status of cell DRX, or may indicate both the activation status of cell DTX and the activation status of cell DRX.

[0102] The cell DTX / DRX status check report may be a cell DTX / DRX status check MAC CE. In this case, the MAC entity of UE 1 associated with cell 21 or a cell group including cell 21 triggers the transmission of the cell DTX / DRX status check MAC CE. Once the transmission of the cell DTX / DRX status check MAC CE is triggered, the MAC entity instructs a multiplexing and assembly procedure to generate a cell DTX / DRX status check MAC CE. The MAC entity multiplexes the generated MAC CE into a MAC Protocol Data Unit (PDU). The MAC entity passes the MAC PDU, uplink grant, and HARQ information to the HARQ process and instructs the HARQ process to trigger a new transmission.

[0103] UE 1 may perform step 1303 after step 1302. In step 1303, UE 1 applies the activation or deactivation of cell DTX / DRX indicated by the signaling in step 1301 after sending the cell DTX / DRX status confirmation report.

[0104] Figure 14 shows an example of the operation of UE 1 and RAN node 2. Steps 1401 to 1403 correspond to steps 1301 to 1303 in Figure 13. In step 1401, RAN node 2 transmits UE-specific or group-wide L1 signaling to UE 1 indicating cell DTX / DRX activation or deactivation. In step 1402, RAN node 2 receives a cell DTX / DRX status check report from UE 1. The cell DTX / DRX status check report is transmitted by UE 1 in response to receiving the L1 signaling of step 1401. In step 1403, UE 1 applies the cell DTX / DRX activation or deactivation indicated by the signaling of step 1401 after transmitting the cell DTX / DRX status check report.

[0105] In step 1404, after receiving the cell DTX / DRX status confirmation report from UE 1, RAN node 2 applies the cell DTX / DRX activation or deactivation indicated by the signaling in step 1401 to UE 1. For each of a plurality of UEs performing cell DTX / DRX operation within cell 21, RAN node 2 manages the application state (or activation state) of cell DTX / DRX for each UE.

[0106] The operation of UE 1 and RAN node 2 described with reference to Figures 13 and 14 enables RAN node 2 to know that there is a mismatch in understanding of the cell DTX / DRX activation state between UE 1 and RAN node 2. More specifically, this enables RAN node 2 to check whether UE 1 correctly understands (or detects) the cell DTX / DRX activation state after each cell DTX / DRX activation or deactivation.

[0107] Similar to the first embodiment, the RAN node 2 may perform an operation to correct the activation state of cell DTX or cell DRX recognized by the UE 1 based on the reception or non-reception of the cell DTX / DRX status confirmation report from the UE 1. To correct the activation state of cell DTX or cell DRX recognized by the UE 1, the RAN node 2 may retransmit L1 signaling for activation or deactivation of cell DTX or cell DRX to the UE 1 or to a UE group including the UE 1. Alternatively, to correct the activation state of cell DTX or cell DRX recognized by the UE 1, the RAN node 2 may send an RRC message (e.g., RRCReconfiguration) containing cell DTX configuration or cell DRX configuration to the UE 1.

[0108] <Third Embodiment> A configuration example of a wireless communication system according to this embodiment is the same as the configuration example described with reference to Fig. 1. This embodiment provides a specific example of transmitting the cell DTX / DRX status confirmation report described in the first embodiment.

[0109] Figure 15 shows an example of the operation of UE 1. In step 1501, UE 1 detects a situation in which UE 1 is suspected of misidentifying the cell DTX / DRX activation status. In response to this detection, in step 1502, UE 1 triggers the transmission of a cell DTX / DRX status confirmation report.

[0110] The cell DTX / DRX status check report may be a cell DTX / DRX status check MAC CE. In this case, the MAC entity of UE 1 associated with cell 21 or a cell group including cell 21 triggers the transmission of the cell DTX / DRX status check MAC CE. Once the transmission of the cell DTX / DRX status check MAC CE is triggered, the MAC entity instructs a multiplexing and assembly procedure to generate a cell DTX / DRX status check MAC CE. The MAC entity multiplexes the generated MAC CE into a MAC Protocol Data Unit (PDU). The MAC entity passes the MAC PDU, uplink grant, and HARQ information to the HARQ process and instructs the HARQ process to trigger a new transmission.

[0111] The operation of UE 1 described with reference to Figure 15 enables RAN node 2 to verify whether UE 1 correctly understands (or detects) the cell DTX / DRX activation state in response to UE 1 detecting a suspected inconsistency or mismatch in its understanding of the cell DTX / DRX activation state.

[0112] More specifically, UE 1 may determine a suspected inconsistency or mismatch in its understanding of the cell DTX / DRX activation status by detecting the absence of PDCCH reception for a predetermined number of consecutive PDCCH monitoring occasions. FIG. 16 illustrates an example of the operation of UE 1. In step 1601, UE 1 detects the absence of PDCCH reception for a predetermined number of consecutive PDCCH monitoring occasions. The predetermined number may be configured for UE 1 by the network (e.g., RAN node 2). The configuration of the predetermined number (e.g., maxNumConsecutiveNoPDCCH) may be provided to UE 1 via an RRC message (e.g., RRCReconfiguration). In response to this detection, in step 1602, UE 1 triggers the transmission of a cell DTX / DRX status confirmation report.

[0113] The MAC entity of UE 1 associated with cell 21 or a cell group including cell 21 may operate as follows: The MAC entity uses a counter or variable (e.g., numConsecutiveNoPDCCH) to count consecutive PDCCH monitoring occasions where no PDCCH is received. The MAC entity initializes or resets this counter or variable to zero in response to PDCCH reception or transmission of a cell DTX / DRX status check report. The MAC entity increments the counter or variable by one if there is no PDCCH reception. The MAC entity initializes or resets the counter to zero if there is PDCCH reception. When the counter or variable reaches a predetermined number (e.g., a configured maximum value), the MAC entity triggers transmission of a cell DTX / DRX status check report.

[0114] The operation of UE 1 described with reference to Figure 16 enables RAN node 2 to verify whether UE 1 correctly understands (or detects) the cell DTX / DRX activation status in response to UE 1 detecting no PDCCH reception in a predetermined number of consecutive PDCCH monitoring opportunities.

[0115] <Fourth embodiment> A configuration example of a wireless communication system according to this embodiment is the same as the configuration example described with reference to Fig. 1. This embodiment provides a specific example of the operation of the RAN node 2.

[0116] FIG. 17 illustrates an example of the operation of RAN node 2. In step 1701, RAN node 2 detects a situation in which UE 1 is suspected of misidentifying the activation status of cell DTX / DRX. In one example, RAN node 2 may detect whether UE 1 is misidentifying the activation status of cell DTX or cell DRX based on reception or non-reception of a cell DTX / DRX status confirmation report from UE 1. The cell DTX / DRX status confirmation report may be similar to that described in the first, second, or third embodiment. Additionally or alternatively, RAN node 2 may detect that UE 1 is suspected of misidentifying the activation status of cell DTX or cell DRX in response to detecting the absence of a response or feedback from UE 1 to a scheduled transmission. The scheduled transmission may be a PDSCH transmission in the downlink or a PUSCH transmission in the uplink. RAN node 2 may detect that UE 1 is suspected of misidentifying the activation status of cell DTX or cell DRX in response to detecting the absence of a response or feedback from UE 1 to a scheduled transmission for a predetermined number of consecutive transmissions.

[0117] In step 1702, in response to the detection in step 1701, RAN node 2 performs an operation to correct the cell DTX / DRX activation state recognized by UE 1. Specifically, RAN node 2 may retransmit L1 signaling for cell DTX or cell DRX activation or deactivation to UE 1 or to a UE group including UE 1. Alternatively, RAN node 2 may send an RRC message (e.g., RRCReconfiguration) to UE 1 containing cell DTX configuration or cell DRX configuration.

[0118] The operation of the RAN node 2 described with reference to Figure 17 enables the RAN node 2 to resolve any inconsistencies in understanding of the cell DTX / DRX activation state between the RAN node 2 and the UE 1 that it detects in any way.

[0119] Figure 18 shows an example of the operation of RAN node 2. In step 1801, RAN node 2 detects the absence of a response or feedback from UE 1 to a scheduled transmission. RAN node 2 may detect the absence of a response or feedback from UE 1 to a scheduled transmission for a predetermined number of consecutive times. The scheduled transmission may be a PDSCH transmission on the downlink or a PUSCH transmission on the uplink.

[0120] In step 1802, in response to the detection in step 1801, RAN node 2 performs an operation to correct the cell DTX / DRX activation state recognized by UE 1. Specifically, RAN node 2 may retransmit L1 signaling for cell DTX or cell DRX activation or deactivation to UE 1 or to a UE group including UE 1. Alternatively, RAN node 2 may send an RRC message (e.g., RRCReconfiguration) to UE 1 containing cell DTX configuration or cell DRX configuration.

[0121] The operation of the RAN node 2 described with reference to Figure 18 enables the RAN node 2 to resolve suspected inconsistencies or mismatches in its understanding of the cell DTX / DRX activation state in response to detecting a lack of response or feedback from the UE 1 to a scheduled transmission.

[0122] Next, exemplary configurations of the UE 1 and the RAN node 2 according to the above-described embodiments will be described. FIG. 19 is a block diagram showing an exemplary configuration of the UE 1. A radio frequency (RF) transceiver 1901 performs analog RF signal processing for communication with the RAN node 2. The RF transceiver 1901 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1901 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1901 is coupled to an antenna array 1902 and a baseband processor 1903. The RF transceiver 1901 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1903, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1902. The RF transceiver 1901 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1902 and provides the baseband receive signal to the baseband processor 1903. The RF transceiver 1901 may include an analog beamformer circuit for beamforming, which may include, for example, multiple phase shifters and multiple power amplifiers.

[0123] The baseband processor 1903 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communications. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management for Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0124] For example, the digital baseband signal processing by the baseband processor 1903 may include signal processing of a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. Also, the control plane processing by the baseband processor 1903 may include processing of a Non-Access Stratum (NAS) protocol, a Radio Resource Control (RRC) protocol, MAC Control Elements (CEs), and Downlink Control Information (DCIs).

[0125] The baseband processor 1903 may perform Multiple Input Multiple Output (MIMO) encoding and precoding for beamforming.

[0126] The baseband processor 1903 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1904, which will be described later.

[0127] The application processor 1904 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1904 may include multiple processors (multiple processor cores). The application processor 1904 executes a system software program (operating system (OS)) and various application programs (e.g., a calling application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1906 or other memories, thereby realizing various functions of the UE 1.

[0128] In some implementations, the baseband processor 1903 and the application processor 1904 may be integrated on a single chip, as indicated by the dashed line (1905) in Figure 19. In other words, the baseband processor 1903 and the application processor 1904 may be implemented as a single System on Chip (SoC) device 1905. An SoC device may also be called a system Large Scale Integration (LSI) or chipset.

[0129] The memory 1906 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1906 may include multiple physically independent memory devices. The volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The nonvolatile memory may be mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, a hard disk drive, or any combination thereof. For example, the memory 1906 may include an external memory device accessible from the baseband processor 1903, the application processor 1904, and the SoC 1905. The memory 1906 may also include an internal memory device integrated within the baseband processor 1903, the application processor 1904, or the SoC 1905. Furthermore, the memory 1906 may include memory within a Universal Integrated Circuit Card (UICC).

[0130] The memory 1906 may store one or more software modules (computer programs) 1907 containing instructions and data for processing by the UE 1. In some implementations, the baseband processor 1903 or the application processor 1904 may be configured to read and execute the software modules 1907 from the memory 1906 to perform the processing of the UE 1 described in one or more of the embodiments.

[0131] It should be noted that the control plane processing and operations performed by UE 1 described in the above embodiment can be realized by elements other than the RF transceiver 1901 and the antenna array 1902, namely, at least one of the baseband processor 1903 and the application processor 1904, and the memory 1906 storing the software module 1907.

[0132] FIG. 20 is a block diagram showing an example configuration of a RAN node 2. Referring to FIG. 20, the RAN node 2 includes a radio frequency (RF) transceiver 2001, a network interface 2003, a processor 2004, and a memory 2005. The RF transceiver 2001 performs analog RF signal processing for communication with UEs 1. The RF transceiver 2001 may include multiple transceivers. The RF transceiver 2001 is coupled to an antenna array 2002 and a processor 2004. The RF transceiver 2001 receives modulation symbol data from the processor 2004, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 2002. The RF transceiver 2001 also generates a baseband receive signal based on the receive RF signal received by the antenna array 2002 and provides the baseband receive signal to the processor 2004. The RF transceiver 2001 may include an analog beamformer circuit for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0133] The network interface 2003 is used to communicate with network nodes (e.g., other RAN nodes, and control and forwarding nodes of the core network), and may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0134] The processor 2004 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 2004 may include multiple processors. For example, the processor 2004 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. The processor 2004 may include a digital beamformer module for beamforming. The digital beamformer module may include a Multiple Input Multiple Output (MIMO) encoder and precoder.

[0135] The memory 2005 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, Static Random Access Memory (SRAM), Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 2005 may include storage located remotely from the processor 2004. In this case, the processor 2004 may access the memory 2005 via the network interface 2003 or another I / O interface.

[0136] The memory 2005 may store one or more software modules (computer programs) 2006 containing instructions and data for processing by the RAN node 2. In some implementations, the processor 2004 may be configured to read and execute the software modules 2006 from the memory 2005 to perform the processing of the RAN node 2 described in one or more of the embodiments.

[0137] In addition, if the RAN node 2 is a CU (e.g., gNB-CU) or a CU-CP (e.g., gNB-CU-CP), the RAN node 2 may not include the RF transceiver 2001 (and the antenna array 2002).

[0138] As described with reference to Figures 19 and 20, each of the processors included in the UE 1 and the RAN node 2 according to the above-described embodiments may execute one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs include instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disk (DVD), Blu-ray disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The programs may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0139] The above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0140] For example, some or all of the above embodiments may also be described as, but are not limited to, the following appendices. Some or all of the elements (e.g., configurations and functions) described in appendices directed to apparatuses (e.g., wireless terminals or RAN nodes) may naturally also be described as appendices directed to methods and programs. For example, some or all of the elements described in appendices 2-15, which are dependent on appendices 1, may also be described as appendices dependent on appendices 34 and 36, due to the same dependency relationship as appendices 2-15. Similarly, some or all of the elements described in appendices 17-33, which are dependent on appendices 16, may also be described as appendices dependent on appendices 35 and 37, due to the same dependency relationship as appendices 17-33. Similarly, some or all of the elements described in appendices 39-43, which are dependent on appendices 38, may also be described as appendices dependent on appendices 44 and 45, due to the same dependency relationship as appendices 39-43. Some or all of the elements described in any appendix may be applicable to a variety of hardware, software, recording means for recording software, systems, and methods.

[0141] (Supplementary Note 1) A radio terminal comprising means for transmitting, to a network, a status check report indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state or both recognized by the radio terminal. (Supplementary Note 2) The radio terminal according to Supplementary Note 1, wherein the status check report indicates whether the activation state of the cell DTX or the cell DRX recognized by the radio terminal is activated or deactivated. (Supplementary Note 3) The radio terminal according to Supplementary Note 1 or 2, wherein the status check report indicates a plurality of activation states, each corresponding to one of a plurality of cell DTX or DRX settings. (Supplementary Note 4) The radio terminal according to any one of Supplements 1 to 3, wherein the status check report is a Medium Access Control (MAC) Control Element (CE). (Supplementary Note 5) The radio terminal of any one of Supplements 1 to 4, wherein the transmitting means is adapted to trigger transmission of the status check report in response to receiving signaling from the network indicating activation or deactivation of the cell DTX or the cell DRX. (Supplementary Note 6) The radio terminal of Supplementary Note 5, further comprising: means for applying activation or deactivation of the cell DTX or the cell DRX indicated in the signaling after the status check report is transmitted. (Supplementary Note 7) The radio terminal of Supplementary Note 5, further comprising: means for applying activation or deactivation of the cell DTX or the cell DRX indicated in the signaling and for applying an associated connected mode discontinuous reception (CDRX) configuration after the status check report is transmitted. (Supplementary Note 8) The radio terminal of any one of Supplements 5 to 7, wherein the signaling is Layer 1 signaling that is common to a group of multiple radio terminals including the radio terminal and does not have hybrid automatic repeat request (HARQ) feedback.(Supplementary Note 9) The radio terminal according to any one of Supplements 1 to 4, wherein the transmitting means is adapted to trigger transmission of the state check report in response to detecting a situation in which the radio terminal is suspected of misrecognizing an activation state of the cell DTX or the cell DRX. (Supplementary Note 10) The radio terminal according to any one of Supplements 1 to 4, wherein the transmitting means is adapted to trigger transmission of the state check report in response to detecting no PDCCH reception in a predetermined number of consecutive Physical Downlink Control Channel (PDCCH) monitoring occasions. (Supplementary Note 11) The radio terminal according to Supplementary Note 10, further comprising: means for receiving a setting of the predetermined number from the network. (Supplementary Note 12) The radio terminal according to Supplementary Note 10 or 11, further comprising: means for initializing or resetting a counter for counting consecutive PDCCH monitoring occasions in which a PDCCH is not received in response to reception of a PDCCH or in response to transmission of the state check report. (Supplementary note 13) The radio terminal according to any one of Supplements 1 to 12, wherein the state check report causes the network to detect whether the radio terminal has misrecognized the activation state of the cell DTX or the cell DRX. (Supplementary note 14) The radio terminal according to any one of Supplements 1 to 13, wherein activation of the cell DTX involves implicit enabling of an additional connected mode discontinuous reception (CDRX) configuration by the radio terminal. (Supplementary note 15) The radio terminal according to Supplementary note 14, wherein deactivation of the cell DTX involves implicit disabling of the additional CDRX configuration by the radio terminal. (Supplementary note 16) A radio access network node comprising: means for receiving from the radio terminal a state check report indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state recognized by the radio terminal, or both.(Supplementary note 17) The radio access network node according to Supplementary note 16, wherein the state check report indicates whether an activation state of the cell DTX or the cell DRX recognized by the radio terminal is activated or deactivated. (Supplementary note 18) The radio access network node according to Supplementary note 16 or 17, wherein the state check report indicates a plurality of activation states, each corresponding to a respective one of a plurality of cell DTX or DRX settings. (Supplementary note 19) The radio access network node according to any one of Supplements 16 to 18, wherein the state check report is a Medium Access Control (MAC) Control Element (CE). (Supplementary note 20) The radio access network node according to any one of Supplements 16 to 19, comprising: means for transmitting signaling indicating activation or deactivation of the cell DTX or the cell DRX to the radio terminal or to a radio terminal group including the radio terminal, wherein the state check report is transmitted by the radio terminal in response to receiving the signaling from the radio access network node. (Supplementary note 21) The radio access network node according to Supplementary note 20, further comprising: means for applying, to the radio terminal, the activation or deactivation of the cell DTX or the cell DRX indicated in the signaling after the status check report is received. (Supplementary note 22) The radio access network node according to Supplementary note 20, further comprising: means for applying, to the radio terminal, the activation or deactivation of the cell DTX or the cell DRX indicated in the signaling after the status check report is received, and for applying an associated connected mode discontinuous reception (CDRX) configuration to the radio terminal. (Supplementary note 23) The radio access network node according to any one of Supplements 20 to 22, wherein the signaling is common to a group of multiple radio terminals including the radio terminal and is Layer 1 signaling without hybrid automatic repeat request (HARQ) feedback.(Supplementary Note 24) The radio access network node according to any one of Supplements 16 to 19, wherein the state check report is transmitted by the radio terminal in response to detecting a situation in which the radio terminal is suspected of misrecognizing an activation state of the cell DTX or the cell DRX. (Supplementary Note 25) The radio access network node according to any one of Supplements 16 to 19, wherein the state check report is transmitted by the radio terminal in response to detecting no Physical Downlink Control Channel (PDCCH) reception in a predetermined number of consecutive PDCCH monitoring occasions. (Supplementary Note 26) The radio access network node according to Supplementary Note 25, further comprising: means for providing the radio terminal with a setting of the predetermined number of times. (Supplementary Note 27) The radio access network node according to any one of Supplements 16 to 25, further comprising means for detecting whether the radio terminal has misrecognized an activation state of the cell DTX or the cell DRX, based on reception or non-reception of the state check report from the radio terminal. (Supplementary Note 28) The radio access network node according to any one of Supplements 16 to 25, further comprising: means for executing an operation to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal, based on reception or non-reception of the state check report from the radio terminal. (Supplementary Note 29) The radio access network node according to any one of Supplements 16 to 25, further comprising: means for executing an operation to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal, in response to detecting, based on reception or non-reception of the state check report from the radio terminal, that the radio terminal has erroneously recognized the activation state of the cell DTX or the cell DRX.(Supplementary Note 30) The radio access network node according to Supplementary Note 28 or 29, wherein the executing means is adapted to retransmit, to the radio terminal or to a radio terminal group including the radio terminal, signaling for activation or deactivation of the cell DTX or the cell DRX, in order to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal. (Supplementary Note 31) The radio access network node according to Supplementary Note 28 or 29, wherein the executing means is adapted to transmit, to the radio terminal, a Radio Resource Control (RRC) message including configuration of the cell DTX or the cell DRX, in order to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal. (Supplementary Note 32) The radio access network node according to any one of Supplements 16 to 31, wherein activation of the cell DTX involves implicit enabling of an additional connected mode discontinuous reception (CDRX) configuration by the radio terminal. (Supplementary note 33) The radio access network node according to Supplementary note 32, wherein the deactivation of the cell DTX involves an implicit deactivation of the additional CDRX configuration by the radio terminal. (Supplementary note 34) A method performed by a radio terminal, comprising transmitting to a network a status check report indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state or both recognized by the radio terminal. (Supplementary note 35) A method performed by a radio access network node, comprising receiving from the radio terminal a status check report indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state or both recognized by the radio terminal.(Supplementary Note 36) A program for causing a computer to perform a method for a radio terminal, the method comprising transmitting to a network a status check report indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state, or both, recognized by the radio terminal. (Supplementary Note 37) A program for causing a computer to perform a method for a radio access network node, the method comprising receiving from the radio terminal a status check report indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state, or both, recognized by the radio terminal. (Supplementary Note 38) A radio access network node, comprising: means for performing an operation to correct the activation state of the cell DTX or the cell DRX recognized by the radio terminal in response to detecting a situation in which the radio terminal is suspected of misrecognizing the activation state of the cell discontinuous transmission (DTX) or the cell discontinuous reception (DRX). (Supplementary Note 39) The radio access network node according to Supplementary Note 38, wherein the executing means is adapted to retransmit, to the radio terminal or to a radio terminal group including the radio terminal, signaling for activating or deactivating the cell DTX or the cell DRX, in order to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal. (Supplementary Note 40) The radio access network node according to Supplementary Note 38, wherein the executing means is adapted to transmit, to the radio terminal, a Radio Resource Control (RRC) message including configuration of the cell DTX or the cell DRX, in order to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal.(Supplementary Note 41) The radio access network node according to any one of Supplements 38 to 40, further comprising: means for detecting whether the radio terminal has erroneously recognized the activation state of the cell DTX or the cell DRX, based on reception or non-reception from the radio terminal of a state confirmation report indicating the activation state of the cell DTX or the activation state of the cell DRX recognized by the radio terminal, or both. (Supplementary Note 42) The radio access network node according to any one of Supplements 38 to 40, further comprising: means for detecting, in response to detecting no response or feedback from the radio terminal to a scheduled transmission, that the radio terminal is suspected of erroneously recognizing the activation state of the cell DTX or the cell DRX. (Supplementary Note 43) The radio access network node according to any one of Supplements 38 to 40, further comprising: means for detecting, in response to detecting no response or feedback from the radio terminal to a scheduled transmission for a predetermined number of consecutive times, that the radio terminal is suspected of erroneously recognizing the activation state of the cell DTX or the cell DRX. (Supplementary Note 44) A method performed by a radio access network node, comprising, in response to detecting a situation in which a radio terminal is suspected of misrecognizing an activation state of a cell discontinuous transmission (DTX) or a cell discontinuous reception (DRX), performing an operation to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal. (Supplementary Note 45) A program for causing a computer to perform a method for a radio access network node, the method comprising, in response to detecting a situation in which a radio terminal is suspected of misrecognizing an activation state of a cell discontinuous transmission (DTX) or a cell discontinuous reception (DRX), performing an operation to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal.

[0142] This application claims priority based on Japanese Patent Application No. 2023-156215, filed September 21, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0143] 1 UE 2 RAN node 21 cell 1903 baseband processor 1904 application processor 1906 memory 1907 modules 2004 processor 2005 memory 2006 modules

Claims

1. A wireless terminal comprising: means for transmitting a status check report to a network indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state or both recognized by the wireless terminal.

2. The wireless terminal according to claim 1, wherein the status check report indicates whether an activation state of the cell DTX or the cell DRX recognized by the wireless terminal is activated or deactivated.

3. The wireless terminal according to claim 1 or 2, wherein the status check report indicates a plurality of activation states, each corresponding to a respective one of a plurality of cell DTX or DRX settings.

4. The wireless terminal according to any one of claims 1 to 3, wherein the status check report is a Medium Access Control (MAC) Control Element (CE).

5. The wireless terminal according to any one of claims 1 to 4, wherein the transmitting means is adapted to trigger the transmission of the status check report in response to receiving signaling from the network indicating activation or deactivation of the cell DTX or the cell DRX.

6. A radio terminal according to any one of claims 1 to 4, wherein the transmitting means is adapted to trigger the transmission of the status confirmation report in response to detecting a situation in which the radio terminal is suspected of misrecognizing an activation state of the cell DTX or the cell DRX.

7. The wireless terminal according to any one of claims 1 to 4, wherein the transmitting means is adapted to trigger transmission of the status check report in response to detecting absence of Physical Downlink Control Channel (PDCCH) reception in a predetermined number of consecutive PDCCH monitoring occasions.

8. A radio terminal according to any one of claims 1 to 7, wherein the status check report causes the network to detect whether the radio terminal has misrecognized the activation state of the cell DTX or the cell DRX.

9. A radio terminal according to any one of claims 1 to 8, wherein the activation of the cell DTX involves an implicit enabling of an additional connected mode discontinuous reception (CDRX) setting by the radio terminal.

10. The wireless terminal according to claim 9, wherein deactivation of the cell DTX involves an implicit disabling of the additional CDRX configuration by the wireless terminal.

11. A radio access network node comprising: means for receiving from a radio terminal a status check report indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state or both as perceived by the radio terminal.

12. The radio access network node according to claim 11, wherein the status check report indicates whether an activation state of the cell DTX or the cell DRX recognized by the radio terminal is activated or deactivated.

13. A radio access network node according to claim 11 or 12, wherein the status check report indicates a plurality of activation states, each corresponding to a respective one of a plurality of cell DTX or DRX configurations.

14. A radio access network node according to any one of claims 11 to 13, wherein the status check report is a Medium Access Control (MAC) Control Element (CE).

15. A radio access network node according to any one of claims 11 to 14, comprising means for transmitting signaling indicating activation or deactivation of the cell DTX or the cell DRX to the radio terminal or to a radio terminal group including the radio terminal, and the status check report is transmitted by the radio terminal in response to receiving the signaling from the radio access network node.

16. A radio access network node according to any one of claims 11 to 14, wherein the status confirmation report is transmitted by the radio terminal in response to detecting a situation in which the radio terminal is suspected of misrecognizing an activation state of the cell DTX or the cell DRX.

17. A radio access network node according to any one of claims 11 to 14, wherein the status check report is transmitted by the radio terminal in response to detecting no Physical Downlink Control Channel (PDCCH) reception for a predetermined number of consecutive PDCCH monitoring occasions.

18. A radio access network node according to any one of claims 11 to 17, further comprising means for detecting whether the radio terminal erroneously recognizes the activation state of the cell DTX or the cell DRX based on reception or non-reception of the status confirmation report from the radio terminal.

19. A radio access network node according to any one of claims 11 to 17, further comprising means for performing an operation to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal based on reception or non-reception of the status check report from the radio terminal.

20. A radio access network node according to any one of claims 11 to 17, further comprising means for executing an operation to correct the activation state of the cell DTX or the cell DRX recognized by the radio terminal in response to detecting that the radio terminal erroneously recognizes the activation state of the cell DTX or the cell DRX based on reception or non-reception of the status confirmation report from the radio terminal.

21. A radio access network node according to any one of claims 11 to 20, wherein the activation of the cell DTX involves an implicit enabling of an additional connected mode discontinuous reception (CDRX) setting by the radio terminal.

22. A method performed by a wireless terminal, comprising: transmitting a status check report to a network indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state, or both, as perceived by the wireless terminal.

23. A method performed by a radio access network node, comprising receiving a status check report from a wireless terminal indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state or both as perceived by the wireless terminal.

24. A program for causing a computer to execute a method for a wireless terminal, the method comprising transmitting a status check report to a network indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state, or both, recognized by the wireless terminal.

25. A program for causing a computer to perform a method for a radio access network node, the method comprising receiving a status check report from a wireless terminal indicating a cell discontinuous transmission (DTX) activation state or a cell discontinuous reception (DRX) activation state or both as recognized by the wireless terminal.

26. A radio access network node comprising: means for performing, in response to detecting a situation in which a radio terminal is suspected of misrecognizing a cell discontinuous transmission (DTX) or cell discontinuous reception (DRX) activation state, to correct the cell DTX or cell DRX activation state recognized by the radio terminal.

27. A radio access network node according to claim 26, wherein the executing means is adapted to retransmit, to the radio terminal or to a radio terminal group including the radio terminal, signaling for activation or deactivation of the cell DTX or the cell DRX in order to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal.

28. A radio access network node according to claim 26, wherein the executing means is adapted to send a Radio Resource Control (RRC) message to the radio terminal comprising a configuration of the cell DTX or the cell DRX in order to correct an activation state of the cell DTX or the cell DRX as perceived by the radio terminal.

29. A method performed by a radio access network node, comprising, in response to detecting a situation in which a radio terminal is suspected of misperceiving a cell discontinuous transmission (DTX) or cell discontinuous reception (DRX) activation state, performing operations to correct the cell DTX or cell DRX activation state as perceived by the radio terminal.

30. A program for causing a computer to perform a method for a radio access network node, the method comprising: in response to detecting a situation in which a radio terminal is suspected of misrecognizing an activation state of a cell discontinuous transmission (DTX) or a cell discontinuous reception (DRX), performing an operation to correct an activation state of the cell DTX or the cell DRX recognized by the radio terminal.

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