User Equipment for Monitoring Downlink Control Channel - Patent application

Abstract

To provide a method, a device, and an article for monitoring a downlink control channel of an unlicensed radio cell for information intended in user equipment (UE).SOLUTION: In a communication system, an unlicensed radio cell operates in an unlicensed spectrum and is controlled by a base station. User equipment (UE) executes monitoring of a downlink control channel based on a first timer and a second timer operated in parallel. The first timer is used to limit the maximum time during which the downlink control channel is monitored by starting the first timer at the start of the monitoring and stopping the monitoring upon expiration of the first timer. The second timer is used to stop the monitoring earlier than the first timer according to a state of channel occupation performed by the base station in the unlicensed spectrum.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present disclosure relates to methods, apparatus and articles in communication systems, such as 3GPP communication systems. [Background technology]

[0002] Currently, the 3rd Generation Partnership Project (3GPP) is working on technical specifications for the next generation of cellular technology, also known as the fifth generation (5G).

[0003] One objective is to provide a single technical framework that addresses all usage scenarios, requirements and deployment scenarios (see, for example, section 6 of TR38.913 version 15.0.0), including at least enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communication (mMTC). For example, eMBB deployment scenarios may include indoor hotspots, dense urban, rural, urban macro and high speed, URLLC deployment scenarios may include industrial control systems, mobile healthcare (remote monitoring, diagnosis and treatment), real-time control of vehicles, wide area monitoring and control systems for smart grids, and mMTC deployment scenarios may include scenarios with a large number of devices with non-time critical data transmission, such as smart wearables and sensor networks. eMBB and URLLC services are similar in that they both require extremely high bandwidth, but differ in that URLLC services may preferably require ultra-low latency.

[0004] A second objective is to achieve forward compatibility: backward compatibility with Long Term Evolution (LTE, LTE-A) cellular systems is not required, facilitating the introduction of entirely new system designs and / or novel features. Summary of the Invention

[0005] One non-limiting illustrative embodiment facilitates providing an improved procedure for monitoring a downlink control channel.

[0006] In an embodiment, the disclosed technology features a user equipment having a processing circuitry operating during operation a function related to monitoring a downlink control channel of an unlicensed radio cell for information intended for a UE, the unlicensed radio cell operating in an unlicensed spectrum and controlled by a base station communicating with the user equipment. The processing circuitry and the receiver perform monitoring of the downlink control channel based on a first timer and a second timer operating in parallel. The first timer is used to limit a maximum time for which the downlink control channel is monitored by starting the first timer at the start of monitoring the downlink control channel and stopping monitoring of the downlink control channel upon expiration of the first timer. The second timer is used to stop monitoring of the downlink control channel earlier than the first timer depending on a channel occupancy status of the unlicensed spectrum of the radio cell by the base station.

[0007] It should be noted that the general or specific embodiments may be realized as a system, a method, an integrated circuit, a computer program, a storage medium, or any combination thereof.

[0008] Further benefits and advantages of the disclosed embodiments and different implementations will become apparent from the specification and drawings. Benefits and / or advantages may be obtained individually from various embodiments and features of the specification and drawings, which need not all be provided in order to obtain one or more of such benefits and / or advantages. [Brief description of the drawings]

[0009] In the following, exemplary embodiments are explained in more detail with reference to the attached drawings. [Figure 1] 1 illustrates an example architecture for a 3GPP NR system. [Diagram 2] 1 illustrates an example user and control plane architecture for LTE eNB, gNB and UE. [Diagram 3] 1 shows the DRX operation of a mobile terminal, in particular showing DRX opportunities and on-duration periods according to short and long DRX cycles. [Figure 4] 1 shows messages exchanged between an eNB and a UE when performing a contention-based RACH procedure. [Diagram 5] 1 shows messages exchanged between an eNB and a UE when performing a contention-free RACH procedure. [Figure 6] 1 illustrates an example LAA scenario with multiple licensed and unlicensed cells. [Figure 7] 1 shows a transmission operation for LAA transmission. [Figure 8] An example simplified configuration of a UE and a gNB is shown. [Figure 9] 1 illustrates a UE configuration according to an example implementation of an improved downlink control channel monitoring procedure. [Figure 10] 1 illustrates various functions operated in the UE, the parallel operation of two associated timers and downlink control channel monitoring. [Figure 11] FIG. 13 is a flow diagram of a UE operation according to an example implementation for an improved downlink control channel monitoring procedure. [Figure 12] FIG. 1 is a flow diagram of a UE operation according to a first exemplary implementation for an improved downlink control channel monitoring procedure. [Figure 13] 13 illustrates parallel operation of first and second timers and resulting PDCCH monitoring according to a first exemplary implementation of the improved downlink control channel monitoring procedure described in FIG. 12 . [Figure 14] FIG. 11 is a flow diagram of a UE operation according to a second exemplary implementation of an improved downlink control channel monitoring procedure. [Figure 15] 15 illustrates parallel operation of the first and second timers and the resulting PDCCH monitoring according to a second exemplary implementation of the improved downlink control channel monitoring procedure described in FIG. 14 . [Figure 16] 15 illustrates parallel operation of the first and second timers and the resulting PDCCH monitoring according to a second exemplary implementation of the improved downlink control channel monitoring procedure described in FIG. 14 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 5G NR system architecture and protocol stack 3GPP is working on the next release for the fifth generation of cellular technology, simply called 5G, which includes the development of New Radio Access Technology (NR) that will operate in frequencies up to the 100 GHz range. The first version of the 5G standard was completed at the end of 2017, allowing smartphones compliant with the 5G NR standard to proceed to trials and commercial deployment.

[0011] In particular, the overall system architecture assumes a Next Generation-Radio Access Network (NG-RAN) that includes gNBs and provides NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocol termination for UEs. The gNBs are interconnected with each other by an Xn interface. The gNBs are also connected to a Next Generation Core (NGC) by a Next Generation (NG) interface, and more specifically to an Access and Mobility Management Function (AMF) (e.g., a specific core entity that runs AMF) by an NG-C interface and to a User Plane Function (UPF) (e.g., a specific core entity that runs UPF) by an NG-U interface. The NG-RAN architecture is shown in FIG. 1 (see, for example, Section 4 of 3GPP TS38.300 v15.5.0).

[0012] Various different deployment scenarios can be supported (see, for example, 3GPP TR38.801 v14.0.0). For example, a decentralized deployment scenario is presented therein (see, for example, section 5.2 of TR38.801; a centralized deployment is shown in section 5.4), in which base stations supporting 5G NR can be deployed. FIG. 2 illustrates an example decentralized deployment scenario (see, for example, Figure 5.2-1 of TR38.801), further illustrating an LTE eNB with user equipment (UE) connected to both the gNB and the LTE eNB. The new eNB for NR 5G can be exemplarily referred to as a gNB. The eLTE eNB is an evolution of the eNB that supports connectivity with the Evolved Packet Core (EPC) and the Next Generation Core (NGC).

[0013] The NR user plane protocol stack (see, for example, section 4.4.1 of 3GPP TS38.300 v15.5.0) has a PDCP (Packet Data Convergence Protocol, see section 6.4 of TS38.300) sublayer, an RLC (Radio Link Control, see section 6.3 of TS38.300) sublayer, and a MAC (Medium Access Control, see section 6.2 of TS38.300) sublayer, which are terminated at the gNB on the network side. Furthermore, a new Access Stratum (AS) sublayer (SDAP, Service Data Adaptation Protocol) is introduced on top of the PDCP (see, for example, subclause 6.5 of 3GPP TS38.300). A control plane protocol stack is also specified for NR (see, for example, section 4.4.2 of TS38.300). An overview of Layer 2 functions is given in subclause 6 of TS38.300. The functions of the PDCP, RLC and MAC sublayers are listed in sections 6.4, 6.3 and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in subclause 7 of TS 38.300.

[0014] For example, the MAC layer handles logical channel multiplexing and scheduling and scheduling related functions, including handling of different numerologies.

[0015] For the physical layer, the MAC layer uses services in the form of transport channels. A transport channel can be defined by how and with what characteristics information is transmitted over the radio interface. A random access channel (RACH) is also defined as a transport channel that does not carry transport blocks but is handled by the MAC. One of the procedures supported by the MAC layer is the random access procedure.

[0016] The physical layer (PHY) is responsible for e.g. coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. It also handles mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmission of a particular transport channel, and each transport channel is mapped to a corresponding physical channel. One physical channel is the Physical Random Access Channel (PRACH), which is used for random access.

[0017] Use cases / deployment scenarios for NR may include enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC) and massive Machine Type Communication (mMTC) with diverse requirements on data rates, latency and coverage. For example, eMBB is expected to support peak data rates (20 Gbps for downlink and 10 Gbps for uplink) and user experienced data rates on the order of three times those offered by IMT-Advanced. On the other hand, in the case of URLLC, tighter requirements are set for ultra-low latency (0.5 ms for user plane latency UL and DL respectively) and high reliability (1-10 ms within 1 ms). -5 ). Finally, mMTC is preferably imposed on high connection density (1,000,000 devices / km in urban environments). 2 ), large coverage in harsh environments, and extremely long battery life (15 years) for low-cost devices.

[0018] Thus, OFDM numerology (e.g., subcarrier spacing, OFDM symbol duration, cyclic prefix (CP) duration, number of symbols per scheduling interval, etc.) suitable for one use case may not work well for another use case. For example, low latency services may preferably require a shorter symbol duration (and thus a larger subcarrier spacing) and / or fewer symbols per scheduling interval (a.k.a. TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP duration than scenarios with small delay spreads. To maintain similar CP overhead, the subcarrier spacing should be optimized accordingly. NR may support multiple values ​​of subcarrier spacing. Correspondingly, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, etc. are currently being considered. Symbol duration T u and the subcarrier spacing Δf is Δf=1 / T u Similar to LTE systems, the term "resource element" can be used to denote the smallest resource unit consisting of one subcarrier for the duration of one OFDM / SC-FDMA symbol.

[0019] In the new radio system 5G-NR, for each numerology and carrier, a resource grid of subcarriers and OFDM symbols is defined for the uplink and downlink, respectively. Each element in the resource grid is called a resource element and is specified based on a frequency index in the frequency domain and a symbol position in the time domain (see 3GPP TS38.211 v15.5.0).

[0020] Downlink control channel monitoring PDCCH DCI Many of the functions operated by the UE include, for example, monitoring a downlink control channel (e.g., for PDCCH, see section 5.2.3 of 3GPP TS38.300 v15.5.0) to receive specific control information or data directed to the UE.

[0021] A non-exhaustive list of these functions is given below. - Paging message monitoring function - System information acquisition function Notification monitoring operation for discontinuous reception (DRX) function - Inactivity monitoring for discontinuous reception (DRX) function · Receiving random access responses for random access functions - PDCP (Packet Data Convergence Protocol) layer reordering function

[0022] This description focuses on the above list of functions, however, the concepts and aspects for improving PDCCH monitoring described herein are also applicable to other functions related to PDCCH monitoring.

[0023] As mentioned above, PDCCH monitoring is performed by a UE to identify and receive information intended for the UE, such as control information and user traffic (e.g., DCI on the PDCCH and user data on the PDSCH that is signaled by the PDCCH).

[0024] The control information in the downlink (called Downlink Control Information (DCI)) has the same purpose in 5G NR as DCI in LTE, i.e. it is a special set of control information for scheduling, for example, a downlink data channel (e.g., PDSCH) or an uplink data channel (e.g., PUSCH). In 5G NR, there are several different DCI formats already specified (see section 7.3.1 of TS38.212 v15.5.0).

[0025] The PDCCH monitoring of each of these functions serves a specific purpose and is therefore initiated until completion. PDCCH monitoring is typically controlled based on a timer operated at least by the UE. The timer has the purpose of controlling the PDCCH monitoring, e.g., limiting the maximum time that the UE monitors the PDCCH. For example, the UE does not need to monitor the PDCCH indefinitely, but may stop monitoring after a certain time so that power can be saved. Correspondingly, a timer may be started when the UE starts PDCCH monitoring for the intended purpose. Then, when the timer expires, the UE may stop PDCCH monitoring for the intended purpose and has the opportunity to save power.

[0026] The functions listed above are described in more detail below.

[0027] Paging Procedure in 5G NR An exemplary implementation of a paging function in 5G NR for PDCCH monitoring according to the currently standardized version is described below in a simplified and abbreviated form.

[0028] 5G NR has two different paging procedures: a RAN-based paging procedure (e.g., based on RAN-based notification areas) and a core network-based paging procedure (see, e.g., 3GPP TS38.300 v15.5.0, TS38.304 v15.3.0 and TS38.331 v15.5.0, which refer to RAN paging and CN paging in several sections, such as section 9.2.5 "Paging" in TS38.300).

[0029] Paging allows the network to reach UEs in RRC_IDLE and RRC_INACTIVE states via paging messages, and to inform UEs in RRC_IDLE, RRC_INACTIVE and RRC_CONNECTED states of system information changes and ETWS / CMAS (Earthquake and Tsunami Warning System / Commercial Mobile Alert System) notifications via short messages. Both paging messages and short messages are addressed by the P-RNTI on the PDCCH, which is monitored by the UE. However, the actual paging message (e.g. by a paging record) is then sent on the PCCH (signaled by the PDCCH), while the short message can be sent directly via the PDCCH.

[0030] In RRC_IDLE, the UE monitors the paging channel of the CN initiated paging channel, while in RRC_INACTIVE, the UE also monitors the paging channel of the RAN initiated paging. The UE does not need to continuously monitor the paging channel, but a paging DRX is defined (see, e.g., 3GPP TS38.304 v15.3.0, sections 6.1 and 7.1) that only requires the UE in RRC_IDLE or RRC_INACTIVE to monitor the paging channel during one paging occasion (PO) per DRX period. The paging DRX period is configured by the network.

[0031] The POs of UEs for CN initiated paging and RAN initiated paging are based on the same UE ID, and both POs overlap. The number of different POs in a DRX period is configurable through system information, and the network may distribute UEs to their POs based on their IDs. A PO is a set of PDCCH monitoring opportunities and may consist of multiple time slots (e.g., subframes or OFDM symbols) in which paging DCI can be transmitted. One paging frame (PF) is one radio frame and may include one or more POs or the start point of a PO.

[0032] When in RRC_CONNECTED, the UE monitors the paging channel on any PO indicated in the system information for SI change notification and Public Warning System (PWS) notification. In case of Bandwidth Adaptation (BA) (see section 6.10 of TS38.300), a UE in RRC_CONNECTED monitors only the paging channel on active BWPs where a common search space is configured.

[0033] To summarise the above within the context of improved concepts and aspects for PDCCH monitoring as described below, to control PDCCH monitoring for the paging function, the UE may for example use a timer that counts the duration of a paging occasion, e.g., the timer is started at the beginning of a PO until it expires (with the length of the PO as the timer value).

[0034] When the UE receives a paging message, PDCCH monitoring can be stopped by the UE. Depending on the cause of the paging, the UE may continue to acquire system information or establish an RRC connection with the base station and receive traffic / instructions from the network, etc.

[0035] NR system information acquisition An exemplary implementation of a system information acquisition function in 5G NR for PDCCH monitoring according to the currently standardized version is described below in a simplified and abbreviated form.

[0036] In 5G NR, the system information (SI) is divided into a Master Information Block (MIB) and several System Information Blocks (SIBs) (see e.g. 3GPP TS38.331 v15.5.1 section 5.2, e.g. 3GPP TS38.300 v15.5.0 section 7.3, e.g. 3GPP TS38.213 section 13). The MIB is transmitted on the BCH and contains the parameters required to obtain SIB1 from the cell. SIB1 is transmitted periodically on the DL-SCH and contains information about availability and scheduling, such as mapping of SIBs to SI messages, periodicity, SI window size of other SIBs with an indication if one or more SIBs are only provided on demand, and the configuration required by the UE to perform the SI request in this case.

[0037] SIBs other than SIB1 are carried in System Information messages (SI messages) transmitted on the DL-SCH. SIBs with the same periodicity can be mapped to the same SI message. Each SI message is transmitted within a periodically occurring time-domain window (referred to as the SI window, which has the same length for all SI messages). Each SI message is associated with an SI window, and the SI windows of different SI messages do not overlap.

[0038] The UE applies the SI acquisition procedure to acquire access stratum (AS) and non-access stratum (NAS) information and applies to UEs in RRC_IDLE, RRC_INACTIVE and RRC_CONNECTED modes. For example, the UE may apply the SI acquisition procedure upon cell selection (e.g., power-on), cell reselection, return from out-of-coverage, after reconfiguration due to synchronization completion, after entering the network from another RAT (Radio Access Technology), after receiving a notification that the system information has changed, and when the UE does not have a valid version of the stored SIB. A modification period is used, i.e., updated SI is reported in the modification period following whether or not an SI change notification is sent.

[0039] The UE receives notification about the SI change using a short message sent with the P-RNTI over the DCI. A UE in RRC_IDLE or RRC_INACTIVE may monitor for SI change notification on its own paging occasions every DRX period (see above). A UE in RRC_CONNECTED monitors for SI change notification on any paging occasion at least once every modification period.

[0040] For SI message acquisition, one or more PDCCH monitoring occasions are determined, which may be the same as or different from those for PDCCH monitoring of SIB1. For example, the UE assumes that in an SI window, the PDCCH of the SI message is transmitted in at least one PDCCH monitoring occasion corresponding to each transmitted Synchronization Signal Block (SSB). The SIB1 configuration provides information about the search space and other PDCCH related parameters required by the UE to monitor the scheduling of SIB1.

[0041] To summarize the above within the context of improved concepts and aspects for PDCCH monitoring, as described below, the UE may utilize a timer to control the SI window length, and the UE may monitor the PDCCH until successful reception of an SI message or until the end of an SI window having a particular length. If an SI message is not received by the end of the SI window, the monitoring of the PDCCH may be repeated at the next SI window opportunity for the relevant SI message in the current modification period.

[0042] Discontinuous Reception (DRX) in LTE and 5G NR An exemplary implementation of a system information acquisition function in 5G NR for PDCCH monitoring according to the currently standardized version is described below in a simplified and abbreviated form.

[0043] To reduce battery consumption in the UE, a mechanism is used to minimize the time the UE spends monitoring the PDCCH, which is called the Discontinuous Reception (DRX) function. The DRX function can be configured for RRC_IDLE, in which case the UE uses a specific DRX value or a default DRX value (defaultPagingCycle). The default is broadcast in the system information and can have values ​​of 32, 64, 128, 256 radio frames. The UE needs to wake up at one paging occasion per DRX cycle, which is one subframe. The DRX function can also be configured for an "RRC_CONNECTED" UE, which does not need to constantly monitor the downlink control channel for downlink control information (or simply, the UE is said to monitor the PDCCH) (see 3GPP Technical Standard TS36.321 15.5.0, chapter 5.7).

[0044] The following parameters are available to define the behavior of a DRX UE: the On-Duration period during which the mobile node is active (i.e., DRX Active Time) and the period during which the mobile node is in DRX (i.e., not in DRX Active Time).

[0045] - On-duration : the duration of a downlink subframe during which the user equipment receives and monitors the PDCCH after waking up from DRX, i.e. more specifically, the duration of a subframe with PDCCH (also called PDCCH subframe). It should be noted here that the term "PDCCH" refers to PDCCH, EPDCCH (in the subframe when configured) or R-PDCCH for relay nodes where R-PDCCH is configured and not suspended. If the user equipment successfully decodes the PDCCH, the user equipment stays awake / active and starts the inactivity timer [1 to 200 subframes; 16 steps: 1 to 6, 10 to 60, 80, 100, 200]. - DRX inactivity timer : the duration in downlink subframes that the user equipment waits for a successful decoding of the PDCCH since the last successful decoding of the PDCCH. If the UE fails to decode the PDCCH in this period, it re-enters DRX. The user equipment restarts the inactivity timer following one successful decoding of the PDCCH for the first transmission only (i.e. not for a retransmission) [1 to 2560 subframes; 22 steps, 10 spare: 1 to 6, 8, 10 to 60, 80, 100 to 300, 500, 750, 1280, 1920, 2560]. - DRX Retransmission timer : Specifies the number of consecutive PDCCH subframes in which downlink retransmission is expected by the UE after the first available retransmission time. [1 to 33 subframes, 8 steps: 1, 2, 4, 6, 8, 16, 24, 33]. - DRX short cycle: specifies the periodic repetition of on-duration following possible inactivity periods for short DRX cycles. This parameter is optional [2 to 640 subframes; 16 steps: 2, 5, 8, 10, 16, 20, 32, 40, 64, 80, 128, 160, 256, 320, 512, 640]. - DRX short cycle timer : Specifies the number of consecutive frames that the UE will follow in a short DRX cycle after the DRX Inactivity Timer expires. This parameter is optional [1 to 16 subframes]. - Long DRX Cycle Start offset : specifies the subframe offset when the on-duration starts (determined by the formula specified in section 5.7 of TS 36.321) and the cyclic repetition of the on-duration followed by a possible inactivity period for the DRX long cycle [cycle length 10 to 2560 subframes; 16 steps: 10, 20, 30, 32, 40, 64, 80, 128, 160, 256, 320, 512, 640, 1024, 1280, 2048, 2560; offset is an integer between [0 and subframe length of the selected cycle]].

[0046] The total duration that the UE is awake is called the "active time" or DRX Active Time. The active time includes, for example, the on-duration of the DRX period, the time during which the UE performs continuous reception while the inactivity timer has not expired, and the time during which the UE performs continuous reception while waiting for a downlink retransmission after one HARQ RTT. Similarly, for the uplink, the UE is woken up (i.e., in the DRX Active Time) in a subframe in which an uplink retransmission grant can be received via the PDCCH, i.e., every 8 ms after the first uplink transmission until the maximum number of retransmissions is reached. Based on the above, the minimum Active Time is a fixed length equal to the on-duration, and the maximum is variable, for example, depending on the PDCCH activity.

[0047] A "DRX period" or "DRX off period" is a duration of a downlink subframe during which the UE can skip reception of the downlink channel for battery saving purposes, i.e., monitoring of the downlink channel is not required. The operation of DRX gives the mobile terminal the opportunity to repeatedly deactivate the radio circuitry (according to the currently active DRX period) in order to save power. Whether the UE actually stays in DRX (i.e., is not active) during the DRX period may be decided by the UE, e.g., the UE normally performs inter-frequency measurements that are not feasible during On-Duration periods and therefore need to be performed at other times, e.g., during DRX off times.

[0048] To meet the competing requirements, two DRX cycles (short and long) can be configured for each UE, and the short DRX cycle is optional, i.e., only the long DRX cycle can be used. The transition between the short DRX cycle, the long DRX cycle and the continuous reception is controlled by a timer or an explicit command from the eNodeB. In a sense, the short DRX cycle can be considered as a confirmation period in case a late packet arrives before the UE enters the long DRX cycle. If data arrives at the eNodeB while the UE is in the short DRX cycle, the data is scheduled for transmission at the next on-duration time, and the UE resumes continuous reception. On the other hand, if no data arrives at the eNodeB during the short DRX cycle, the UE assumes that the packet activity has timed out and enters the long DRX cycle.

[0049] During the active time, the UE monitors the PDCCH, reports the configured SRS (Sounding Reference Signal), and reports CQI (Channel Quality Information) / PMI (Precoding Matrix Indicator) / RI (Rank Indicator) / PTI (Precoder Type Indication) on the PUCCH. When the UE is not in the active time, the Type 0 triggered SRS and CQI / PMI / RI / PTI on the PUCCH may not be reported. If a CQI mask is configured in the UE, the reporting of CQI / PMI / RI / PTI on the PUCCH is limited to On-Duration subframes.

[0050] FIG. 3 discloses an example of DRX operation. The UE checks for a scheduling message (which may be referred to as a downlink / uplink assignment, for example, indicated by its C-RNTI (Cell Radio Network Temporary Identity) on the PDCCH) during the same "on-duration" period for the long and short DRX cycles. If a scheduling message is received during the "on-duration period", the UE starts an "inactivity timer" and continues to monitor the PDCCH in all subframes while the Inactivity Timer is running. During this period, the UE can be considered to be in "continuous reception mode". If a scheduling message is received while the Inactivity Timer is running, the UE restarts the Inactivity Timer, and when it expires, the UE transitions to the short DRX cycle and starts a "short DRX cycle timer" (assuming that a short DRX cycle is configured). When the short DRX cycle timer expires, the UE transitions to the long DRX cycle. A short DRX cycle may also be initiated by a DRX cycle, i.e. a DRX MAC Control Element that the eNB can send at any time to put the UE immediately into a short DRX cycle (if so configured) or a long DRX cycle (if the short DRX cycle is not configured).

[0051] The basic concepts of DRX described above for LTE also apply to the emerging 5G NR, with some differences. Standardization has advanced and specified DRX (see section 5.7 of 3GPP TS38.321 v15.5.0, titled "Discontinuous Reception (DRX)").

[0052] The following is stated in TS38.321:

[0053] RRC controls the DRX operation by setting the following parameters: -drx-onDurationTimer: Duration from the start of the DRX cycle -drx-SlotOffset: Delay before starting drx-onDurationTimer -drx-StartOffset: The subframe where the DRX cycle starts -drx-InactivityTimer: Duration after a PDCCH opportunity during which the PDCCH notifies the MAC entity of a new UL or DL ​​transmission -drx-RetransmissionTimerDL (per DL HARQ process): Maximum duration before a DL retransmission is received -drx-RetransmissionTimerUL (per UL HARQ process): Maximum duration before a grant for UL retransmission is received -drx-LongCycle: Long DRX cycle -drx-ShortCycle (optional): Short DRX cycle -drx-ShortCycleTimer (optional): duration for which the UE follows a short DRX cycle -drx-HARQ-RTT-TimerDL (per DL HARQ process): the minimum duration before a DL allocation for HARQ retransmission is expected by the MAC entity -drx-HARQ-RTT-TimerUL (per UL HARQ process): the minimum duration before a UL HARQ retransmission grant is expected by the MAC entity

[0054] When the DRX cycle is set, the active time includes the following periods of time: - the drx-onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL or ra-ContentionResolutionTimer (as described in subclause 5.1.5) is running, or - a scheduling request has been sent on the PUCCH and is pending (as described in subclause 5.4.4), or - 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 of a contention-based random access preamble not selected by the MAC entity (as described in subclause 5.1.4 of TS 38.321);

[0055] It should be noted that the term PDCCH may refer to, for example, a PDCCH with a common search space, a PDCCH with a UE-specific search space, or a Group Common PDCCH (GC-PDCCH) in 5G NR.

[0056] As is evident therefrom, DRX for 5G NR is also based on a long DRX cycle and a short DRX cycle, with the transition between them based on the Short DRX Cycle timer defining the On-Duration at the start of the DRX cycle, and the DRX inactivity timer determining the duration of continued reception after the UE has received the PDCCH after going into a sleep state. Thus, conceptually, the 5G-NR DRX mechanism works as shown in Figure 3.

[0057] To summarise the above within the context of improved concepts and aspects for PDCCH monitoring as described below, the UE monitors the PDCCH using timers to control the On-Duration time and the DRX-inactivity time, respectively, and the UE is required to continue monitoring the PDCCH for DRX operation while the corresponding timer is running.

[0058] Random Access Channel Procedures An exemplary implementation of a random access function in 5G NR for PDCCH monitoring according to the currently standardized version is described below in a simplified and abbreviated form.

[0059] Once a UE detects a cell, it may access the cell. This can be done using a random access procedure. The LTE RACH procedure is described in more detail below with reference to Figures 4 and 5. A mobile terminal in LTE can be scheduled for uplink transmission only if its uplink transmission is time synchronized. Thus, the random access channel (RACH) procedure plays an important role as an interface between an unsynchronized mobile terminal (UE) and the orthogonal transmission of uplink radio access. For example, random access in LTE is used to achieve uplink time synchronization for a user equipment that has not yet acquired or lost its uplink synchronization. Once the user equipment achieves uplink synchronization, the eNodeB can schedule uplink transmission resources for it. One scenario related to random access is that a user equipment in RRC_CONNECTED state handing over from its current cell to a new target cell performs a random access procedure to achieve uplink time synchronization in the target cell.

[0060] LTE offers two types of random access procedures that allow access to be either contention-based, meaning there is an inherent collision risk, or contention-free (non-contention-based) (see section 5.1 of 3GPP TS36.321 v15.5.0).

[0061] In the following, the LTE contention-based random access procedure is explained in more detail with respect to Fig. 4. The procedure consists of four "steps". First, a user equipment transmits a random access preamble on the Physical Random Access Preamble (PRACH) to the eNodeB (i.e., message 1 of the RACH procedure). After detecting the RACH preamble, the eNodeB transmits a Random Access Response (RAR) message on the Physical Downlink Shared Channel (PDSCH) addressed on the PDCCH with a (random access) RA-RNTI identifying the time-frequency slot in which the preamble was detected (message 2 of the RACH procedure). If multiple user equipments transmit the same RACH preamble on the same PRACH resource (this is also called collision), they will receive the same Random Access Response message. The RAR message may carry the detected RACH preamble, a Timing Alignment Command (TA command) for synchronization of subsequent uplink transmissions, an initial uplink resource allocation (grant) for the first scheduled transmission, and an allocation of a Temporary Cell Radio Network Temporary Identifier (T-CRNTI) that is used by the eNodeB to address the mobile for which a RACH preamble was detected until the RACH procedure is completed, since the "real" identity of the mobile at this point is not yet known by the eNodeB.

[0062] The user equipment monitors the PDCCH for reception of a random access response message within a predefined time window (e.g., called the RAR time window) configured by the eNodeB. In response to the RAR message received from the eNodeB, the user equipment transmits a first scheduled uplink transmission on the radio resources allocated by the grant in the random access response. This scheduled uplink transmission carries the actual random access procedure message, e.g., an RRC Connection Request, an RRC Resume Request, or a buffer status report.

[0063] Figure 5 shows a simplified 3GPP LTE contention-free random access procedure compared to the contention-based random access procedure. In a first step, the eNodeB provides the user equipment with a preamble to use for random access, so that there is no risk of collision, i.e. no risk of multiple user equipments transmitting the same preamble. The user equipment then transmits the preamble notified by the eNodeB in the uplink on the PRACH resource. Essentially, the contention-free random access procedure is terminated after successful reception of the random access response by the UE, since multiple UEs transmitting the same preamble are avoided in favor of contention-free random access.

[0064] Similar or identical RACH procedures as described in connection with Figures 4 and 5 are implemented for the new 5G radio technology (see section 5.1 of 38.321 v15.5.0).

[0065] Furthermore, 3GPP is also studying a two-step RACH procedure for 5G NR, in which message 1, which corresponds to messages 1 and 3 in the four-step RACH procedure, is transmitted first. The gNB then responds with message 2, which corresponds to messages 2 and 4 in the LTE RACH procedure. Due to the reduced message exchange, the delay of the two-step RACH procedure may be reduced compared to the four-step RACH procedure. The radio resources of the messages are optionally configured by the network.

[0066] To summarise the above within the context of improved concepts and aspects for PDCCH monitoring as described below, after transmitting a RACH preamble as the first step of the RACH procedure, the UE monitors the PDCCH utilizing a timer to control the random access response time window. When the timer expires and no RAR has been received, the UE does not need to continue PDCCH monitoring but may, for example, retransmit the RACH preamble. If the RAR is received within the RAR time window, the UE proceeds to the next step of the RACH procedure, for example the next step of transmitting a scheduled user data transmission.

[0067] PDCP Reordering An exemplary implementation of a PDCP reordering function in 5G NR for PDCCH monitoring according to the currently standardized version is described below in a simplified and abbreviated form (see sections 5.1.2, 5.2.1, 5.2.2, etc. of 3GPP TS38.323 v15.5.0).

[0068] PDCP (Packet Data Convergence Protocol) performs IP header compression, encryption, and integrity protection. It also handles retransmission, in-order delivery, and de-duplication in case of handover. In particular, PDCP is responsible for performing reordering to ensure in-order delivery of SDUs (Service Data Units) (also called packets) to higher layer protocols. Reordering basically involves buffering received SDUs and not forwarding them to higher layers until all lower numbered SDUs have been delivered. Counter values ​​are used to identify missing SDUs and request retransmission, as well as reordering received SDUs for delivery to higher layers.

[0069] A timer (e.g., called t-reordering) is available to control the reordering function of the PDCP layer. This timer is started when out-of-order delivery from the base station is detected and controls how long the UE waits for in-order delivery of data packets (SDUs) before proceeding further. While the t-reordering timer is running, the UE may monitor the PDCCH for in-order delivery of data packets (e.g., PDCP PDUs). If such a data packet is received, the UE transitions to PDCP operation, e.g., delivers in-order SDUs to upper layers, and stops the t-reordering timer until out-of-order delivery is next detected.

[0070] LAA (Licensed-Assisted Access) and enhanced LAA (eLAA) The reason for extending LTE to unlicensed bands is the ever-increasing demand for wireless broadband data in conjunction with limited licensed bands. Therefore, unlicensed spectrum is increasingly considered by cellular operators as a complementary tool to enhance their service offerings. The advantage of LTE in unlicensed bands compared to relying on other radio access technologies (RATs) such as Wi-Fi is that by complementing the LTE platform with unlicensed spectrum access, operators and vendors can leverage existing or planned investments in LTE / EPC hardware in radio and core networks.

[0071] However, it must be taken into account that unlicensed spectrum access can never match the quality of licensed spectrum access due to the inevitable coexistence with other radio access technologies (RATs) in the unlicensed spectrum, such as Wi-Fi. Therefore, LTE operation on unlicensed bands was, at least initially, considered as a complement to LTE on licensed spectrum, and not as a standalone operation on unlicensed spectrum. Based on this assumption, 3GPP established Licensed Assisted Access (LAA) for LTE operation on unlicensed bands in association with at least one licensed band. However, standalone operation of LTE on unlicensed spectrum, i.e. without being assisted by a licensed cell, is not excluded, and such standalone unlicensed operation is currently foreseen for 5G NR.

[0072] The overall LAA approach currently intended in 3GPP is to utilize as much as possible the already specified Rel-12 Carrier Aggregation (CA) framework, where the CA framework configuration as described above includes a so-called Primary Cell (Pcell) carrier and one or more Secondary Cell (SCell) carriers. CA generally supports both cell self-scheduling (scheduling information and user data are transmitted on the same component carrier) and cross-carrier scheduling between cells (scheduling information for PDCCH / EPDCCH and user data for PDSCH / PUSCH are transmitted on different component carriers).

[0073] The use of unlicensed bands has also become a focus for new 5G-NR developments. With the NR licensed design available as a baseline, the following development scenarios can be considered: Carrier aggregation between NR licensed cells (e.g., PCell) and NR unlicensed cells (e.g., SCell), similar to LTE LAA Dual connectivity (with LTE and NR), ENU-DC where the master eNB operates in licensed spectrum and the secondary gNB operates in unlicensed spectrum, NNU-DC where the master NB operates in licensed spectrum and the secondary gNB operates in unlicensed spectrum Standalone (SA): NR-U SA where a standalone NR PCell operates in unlicensed spectrum NR radio cells with downlink in unlicensed bands and UL in licensed bands

[0074] In NR, Listen-Before-Talk is performed on unlicensed carriers. In particular, the transmitting entity performs LBT and channel occupation is only possible after successful LBT CCA (Clear Channel Assessment).

[0075] A very simple scenario is shown in Figure 6 with a licensed PCell, a licensed SCell 1 and various unlicensed SCells 2, 3, 4 (shown exemplarily as small cells). The transmitting / receiving network nodes of the unlicensed SCells 2, 3, 4 can be remote radio heads managed by the eNB or can be nodes not managed by the eNB and attached to the network. For simplicity, the connection of these nodes to the eNB or the network is not explicitly shown in the figure. Furthermore, the unlicensed radio cell 5 shows a standalone scenario of an NR PCell operating in an unlicensed spectrum.

[0076] At some point before the data distribution phase 1320, the master AP also configures the upper layer data to be routed through itself instead of through the slave AP1. This may be done by temporarily updating the routing tables of network router devices that forward data payloads to the AP so that the master AP is recorded as the serving AP for the target STA.

[0077] One of the most important issues is coexistence with other systems, such as Wi-Fi (IEEE 802.11) systems, operating in these unlicensed bands. To support fair coexistence between other technologies, such as LTE, 5G NR, and Wi-Fi, as well as to ensure fairness between different operators in the same unlicensed band, channel access for the unlicensed bands must follow a set of specific regulatory rules that may depend in part on the geographic region and the specific frequency band (see, for example, version 13.0.0 of 3GPP Technical Report TR36.889). Depending on the region and band, regulatory requirements that must be considered when designing LAA and 5G NR procedures include Dynamic Frequency Selection (DFS), Transmit Power Control (TPC), Listen Before Talk (LBT), and discontinuous transmission with limited maximum transmission duration (also called channel occupation time, channel acquisition time, or similar expressions). A single global framework can be targeted, which basically means that all requirements for different regions and bands of 5 GHz can be considered for system design.

[0078] The Listen-Before-Talk (LBT) procedure is defined as a mechanism for a device to apply a Clear Channel Assessment (CCA) check before using a channel. According to an example implementation, CCA utilizes at least energy detection to determine whether a channel is occupied or clear, and to determine the presence or absence of other signals on the unlicensed channel. For example, European and Japanese regulations mandate the use of LBT in unlicensed bands. Apart from regulatory requirements, such carrier sensing via LBT is one method for fair sharing of unlicensed spectrum, and is therefore considered a key feature for fair and friendly operation in unlicensed spectrum in a single global solution framework.

[0079] In unlicensed spectrum, channel availability is not necessarily guaranteed. Also, certain regions, such as Europe and Japan, prohibit continuous transmission and impose constraints on the maximum duration of a transmission burst (maximum channel occupancy) in unlicensed spectrum. Therefore, discontinuous transmission with limited maximum transmission duration is a feature for LAA and 5G NR.

[0080] According to this European regulation on LBT, a device must perform a CCA (Clear Channel Assessment) before occupying an unlicensed radio channel by data transmission. In such a restricted exemplary scenario, a device is allowed to start transmitting on an unlicensed channel only after detecting the channel as free-based, for example based on energy detection. In particular, a device must observe the channel for a certain minimum time during CCA (e.g., for 20 μs in Europe, see clause 4.8.3 of ETSI 301 893). If the detected energy level exceeds the set CCA threshold (e.g., −73 dBm / MHz in Europe, see clause 4.8.3 of ETSI 301 893), the channel is considered occupied, and conversely, if the detected power level is below the set CCA threshold, the channel is considered free. If a channel is determined to be occupied, it shall not transmit on said channel during the next fixed frame period. If the channel is classified as free, the device is allowed to transmit immediately. To achieve fair resource sharing with other devices operating in the same band, the maximum transmission duration is limited.

[0081] CCA can be performed repeatedly, optionally with a back-off time in between.

[0082] Furthermore, the total time that a device has a transmission on a given carrier without re-evaluating the availability (i.e., LBT / CCA) of that carrier is defined as the channel occupancy time (see, for example, clause 4.8.3.1 of ETSI 301893). The channel occupancy time must be in the range of 1 ms to 10 ms, and the maximum channel occupancy time can be, for example, 4 ms as currently specified for Europe. Furthermore, there is a minimum idle time during which the UE is not allowed to transmit after a transmission on an unlicensed cell, which is at least 5% of the channel occupancy time. Towards the end of the idle period, the UE can perform a new CCA, and so on.

[0083] Additionally, CCA may not be required within a predetermined period of time, e.g., 16 microseconds, after receiving a signal by another entity as part of the shared COT, e.g., switching between DL and UL and between UL and DL within the shared gNB COT does not require LBT.

[0084] This transmission operation is shown diagrammatically in FIG. 7 (see, for example, ETSI EN 301.893).

[0085] Operation on an unlicensed radio cell therefore requires any transmitter to perform Listen-Before-Talk, as described above, which also applies to the transmission of the PDCCH by the base station and may therefore have an impact on PDCCH monitoring by the UE.

[0086] Many different functions performed by the UE (see examples above) involve monitoring the PDCCH and may therefore be affected by failure of the LBT of a gNB to acquire an unlicensed cell (which can be expressed as acquiring unlicensed spectrum of an unlicensed radio cell).

[0087] One possible solution to compensate for these LBT failures by the gNB side for scenarios where a radio cell is operated in an unlicensed spectrum is to extend the time for which the PDCCH is monitored, as compared to licensed radio cell operation, thereby increasing the chances that the gNB will successfully acquire the unlicensed spectrum and reach the UE, for example, to transmit the PDCCH and / or possibly the PDSCH.

[0088] For example, it may be possible to configure a longer SI window for NR unlicensed operation to add more opportunities for the gNB to transmit system information. Furthermore, a longer DRX-On-Duration can be configured to accommodate possible LBT failures. The reduced transmission opportunities for paging caused by LBT failures can be compensated by increasing the length of the paging occasions or by increasing the number of paging occasions. As a further example, the RAR window size can be extended, for example, to 20 ms. Configuring a longer PDCCH monitoring time window to compensate for LBT failures on the gNB side may be a simple solution that utilizes existing capabilities as much as possible and therefore has little impact on any of the 3GPP specifications.

[0089] However, simply setting a longer PDCCH monitoring duration (e.g., static / semi-static) may also result in higher UE power consumption, since the UE is required to monitor the PDCCH for a longer duration. This power drawback may occur especially when the channel is not busy. In particular, assuming that the unlicensed spectrum is not blocked by another entity, the gNB will soon have an opportunity to transmit the PDCCH (and possibly the PDSCH), but if the gNB is not yet serving the UE, the UE will monitor the PDCCH for a longer period without any benefit.

[0090] The inventors have therefore identified the possibility of improving the monitoring of the PDCCH for one or more of the above mentioned functions (e.g. DRX, paging, system information, random access, PDCP reordering) when operating in an unlicensed frequency spectrum. The present invention is also applicable to other functions relating to monitoring of the PDCCH, not explicitly mentioned above.

[0091] In the following, the UE, the base station and the procedures for fulfilling these requirements are mainly described for the new radio access technology envisaged for the 5G mobile communication system, but it can also be used in the LTE mobile communication system. Different implementations and variants are also described. The following disclosure is realized by the description and discoveries as described above, but may be based at least in part thereon, for example, and may be implemented in such a system.

[0092] In general, it should be noted that many assumptions are made herein to enable the principles underlying the present disclosure to be explained in a clear and understandable manner. However, these assumptions should be understood as merely examples made herein for illustrative purposes that should not limit the scope of the present disclosure. Those skilled in the art will recognize that the principles of the following disclosure, as developed in the claims, can be applied to different scenarios in ways not explicitly described herein.

[0093] Furthermore, some of the terms such as procedures, entities, layers, etc. used below are closely related to the terms used in the LTE / LTE-A system or current 3GPP 5G standardization, although the specific terms used in the context of new radio access technologies for the upcoming 3GPP 5G communication system have not yet been fully determined or may eventually be changed. Thus, the terms may be changed in the future without affecting the functionality of the embodiments. For this reason, those skilled in the art will recognize that the embodiments and their scope of protection should not be limited to the specific terms used illustratively herein due to the lack of newer or finally agreed upon terms, but should be more broadly understood with respect to the functions and concepts underlying the functions and principles of the present disclosure.

[0094] For example, a mobile station, mobile node, user terminal or user equipment (UE) is a physical entity (physical node) in a communication network. A node may have multiple functional entities. A functional entity represents a software or hardware module that implements and / or provides a given set of functions to other functional entities of the same or another node or network. A node may have one or more interfaces that attach the node to communication facilities or media over which the node may communicate. Similarly, a network entity may have logical interfaces that attach a functional entity to communication facilities or media over which it may communicate with other functional entities or corresponding nodes.

[0095] A "base station" or "radio base station" here refers to a physical entity in a communication network. Similar to a mobile station, a base station may have several functional entities. A functional entity refers to a software or hardware module that implements and / or provides a given set of functions to other functional entities of the same or another node or network. A physical entity performs several control tasks for communication devices, including one or more of scheduling and configuration. It should be noted that the functions of a base station and communication devices may be integrated in a single device. For example, a mobile terminal may also implement the functions of a base station for other terminals. The term used in LTE is eNB (or eNodeB), while the term currently used for 5G NR is gNB.

[0096] 8 shows a general simplified exemplary block diagram of a user equipment (also called communication device) and a scheduling device (here exemplarily assumed to be located in a base station such as, for example, an eNB (alternatively called ng-eNB) in eLTE or a gNB in ​​5G NR). The UE and the eNB / gNB communicate with each other via (radio) physical channels using their respective transceivers.

[0097] A communication device may have a transceiver and a processing circuit. The transceiver may then have and / or function as a receiver and a transmitter. The processing circuit may be one or more hardware such as one or more processors or any LSI. Between the transceiver and the processing circuit there are input / output points (or nodes) through which the processing circuit can control the transceiver during operation, i.e. control the receiver and / or transmitter and exchange receive / transmit data. The transceiver may include an RF (Radio Frequency) front-end as a transmitter and receiver, including one or more antennas, amplifiers, RF modulators / demodulators, etc. The processing circuit may realize control tasks such as controlling the transceiver to transmit user data and control data provided by the processing circuit and / or to receive user data and control data that are further processed by the processing circuit. The processing circuit may also be responsible for performing other processes such as judgments, decisions, calculations, measurements, etc. The transmitter may be responsible for performing the transmission process and other processes related thereto. The receiver may be responsible for performing the reception process and other processes related thereto such as monitoring the channel.

[0098] Improved monitoring of a downlink control channel (eg, PDCCH) is described below.

[0099] The solution provided below is mainly described in the context of a 5G NR unlicensed scenario, but is also applicable to unlicensed operation in LTE(A). As described above with reference to Fig. 6, the UE may be located in an unlicensed radio cell operated by a gNB (e.g., one of the unlicensed SCells in Fig. 6 or a standalone unlicensed radio cell). The UE is configured to perform a number of functions and also comprises functionality related to monitoring a downlink control channel transmitted by the gNB in ​​the unlicensed radio cell (utilizing the unlicensed frequency spectrum). That is, the downlink control channel is available by the gNB to transmit downlink control information (e.g., scheduling of downlink or uplink transmissions on corresponding downlink / uplink shared channels) and user data.

[0100] Fig. 9 shows a simplified exemplary UE configuration according to an exemplary solution for improved monitoring of a downlink control channel, which can be realized based on the overall UE configuration described above in connection with Fig. 8. The various components of the UE shown in the figure can be interconnected with each other with corresponding input / output nodes (not shown), for example, to exchange control data, user data and other signals. The UE may have further components, which are not shown for illustrative purposes. As will be apparent therefrom, the UE may include a functional operation circuit, a downlink control channel monitoring circuit, a circuit for parallel operation of first and second timers, and a channel occupancy status determination circuit.

[0101] Thus, in this case, as will become apparent from the following description, the processing circuitry can be exemplarily configured to at least partially perform one or more of the following: monitoring the downlink control channel and operating the first and second timers. The receiver can thus be exemplarily configured to at least partially perform one or more of the following: monitoring the downlink control channel and receiving information intended for the UE via the downlink control channel.

[0102] FIG. 10 is a schematic diagram of different functions operable by a UE. As can be seen, the UE is capable of operating a number of different functions #1 to #N, such as the functions mentioned above. For example, the functions #1 to #N are: - Paging message monitoring function - System information acquisition function Notification monitoring operation for DRX function - Non-activity monitoring for DRX function · Receiving random access responses for random access functions -PDCP layer reordering function

[0103] Each of the operating functions relates to monitoring the downlink control channel together with the parallel operation of first and second timers, each of which typically differs between the different functions, e.g., having different timer values ​​and different purposes, as will become clearer below.

[0104] The concepts and aspects for the improved downlink control channel monitoring procedure will be first described independent of the different features, focusing on common aspects that facilitate solving the problems of the prior art.

[0105] Fig. 11 is a sequence diagram for an exemplary UE operation according to this improved downlink control channel monitoring procedure. As can be seen, it is assumed that the UE performs functions related to monitoring the downlink control channels of unlicensed radio cells. The monitoring of the downlink control channels is performed based on a first timer and a second timer operated in parallel, which can be controlled by using two timers, for example, when the monitoring of the downlink control channels is stopped.

[0106] Correspondingly, the first timer is used to limit the maximum time that the downlink control channel is monitored by the UE. To this end, the first timer is started when the UE starts monitoring the downlink control channel due to the activated function, and monitoring is stopped at the latest when the first timer expires. This first timer is set and executed independently of the channel occupancy status of the unlicensed spectrum. In one optional embodiment, the first timer can be a timer used in the prior art to control the monitoring of the downlink control channel for the activated function (e.g., a paging opportunity timer for the paging function, an on-duration timer for the DRX function, a timer for a system information acquisition window, an inactivity timer for the DRX function, a timer for an RAR window, or a PDCP reordering timer). The timer value of the first timer is, for example, extensible to an unlicensed scenario compared to a licensed scenario (see above description of a simple solution and the resulting drawbacks).

[0107] On the other hand, the second timer is utilized to be able to stop monitoring the downlink control channel earlier than the first timer depending on the channel occupancy status of the unlicensed spectrum of the radio cell. In other words, the purpose of the second timer is to reduce the time for the UE to monitor the downlink control channel, if possible or appropriate, based on the channel occupancy status of the unlicensed spectrum by the gNB. For example, the channel occupancy status of the channel is taken into consideration as to how the second timer is utilized to stop monitoring, so that monitoring can be stopped earlier in cases where the gNB can occupy the channel but is nevertheless not transmitting information (e.g., control information or data) to the UE. This follows the consideration that the gNB is not prohibited from reaching the UE due to an LBT failure, but rather the gNB does not need or can not reach the UE for another reason (possibly unrelated to LBT). Thus, the second timer is to compensate for the LBT failure, and not for other reasons for which the gNB does not reach the UE, by allowing the UE to stop channel monitoring earlier than the first timer depending on the channel occupancy status.

[0108] This second timer is operated in parallel by the UE, e.g., one timer does not follow the other. The feature-specific monitoring of the downlink control channel can be stopped based on either the first timer or the second timer. Thus, the parallel operation of two timers for controlling when to stop monitoring allows the advantage of stopping monitoring as early as possible based on the second timer and the channel occupancy status, while ensuring a maximum monitoring time of the downlink control channel by using the first timer. Thus, the power used to monitor the downlink control channel can be reduced in some cases.

[0109] Correspondingly, monitoring of the downlink control channel for a particular function is based on a first timer when operating in a licensed radio cell, while monitoring of the downlink control channel for that function is based on the first and second timers when operating in an unlicensed radio cell.

[0110] One possible example implementation for achieving the second timer expiring earlier than the first timer is to set a smaller timer value for the second timer than the first timer. The smaller the second timer is compared to the first timer, the greater the power saving gain the UE can achieve. However, the gNB will have less time to reach the UE according to the function (e.g., paging the UE in time, etc.).

[0111] Returning to the flow diagram of Figure 11, the UE operates the first timer and the second timer in parallel to control the timing to stop monitoring the downlink control channel. As shown in Figure 11, the improved monitoring procedure involves determining the channel occupancy status of the unlicensed spectrum to stop monitoring using the second timer, while the first timer is operated independently of the channel occupancy status of the unlicensed spectrum. And the second timer is used to control whether it is appropriate to stop monitoring the downlink control channel earlier than the first timer. Whether monitoring is stopped earlier depends on the channel occupancy status of the unlicensed spectrum during monitoring of the downlink control channel.

[0112] As mentioned above, monitoring of the downlink control channel is performed as part of the function being operated and is therefore very specific to the function being operated. The function itself may already define some function-specific conditions for when to start and stop monitoring of the downlink control channel. For example, monitoring may also end upon receiving information intended for the UE, in line with the purpose of the function being operated.

[0113] For example, upon receiving a paging message, the paging function specific monitoring of the downlink control channel is also stopped. In other words, the paging function requires the UE to monitor the downlink control channel during a paging occasion in order to be able to receive the paging message. In this particular function, the monitoring of the downlink control channel is not only stopped based on the operation of the first and second timers, but also when the paging message is received. According to a different function, the downlink control channel is monitored for non-operation of the DRX function, where the monitoring of the downlink control channel is stopped based on the operation of the first and second timers, but the monitoring is continued (not stopped) if the information intended for the UE is actually received.

[0114] Generally, the improved downlink control channel monitoring as described above and below is based on the use of a second timer and provides for an additional termination of the PDCCH monitoring based on the channel occupancy status of the corresponding unlicensed spectrum of the unlicensed radio cell. The resulting advantage is that it reduces the time required for the UE to perform downlink control channel monitoring, thus providing the UE with the opportunity to omit monitoring and save power.

[0115] On the other hand, by terminating the function-specific monitoring of the downlink control channel early, the UE may be able to move on to the next step of the function earlier and thus reduce the delay of a particular procedure. For example, when considering a random access function, early termination of monitoring of the random access response may trigger an early retransmission of the RACH preamble. Another example is the PDCP reordering function, which may benefit from early termination of monitoring since a PDU status report can be sent earlier to the sender to request retransmission of missing out-of-order PDUs.

[0116] The improved monitoring of the downlink control channel described above relates to the determination of the channel occupancy status of the unlicensed spectrum of the unlicensed radio cell. The UE can determine this channel occupancy status in various ways. According to one exemplary embodiment, the base station periodically transmits a channel occupancy signal when acquiring / occupying the unlicensed spectrum, whereas it does not transmit a channel occupancy signal when not occupying the unlicensed spectrum. Thus, the UE can deduce the channel occupancy status at all times from the reception or non-reception of the channel occupancy signal. Optionally, the channel occupancy signal may include information about the expected length of the channel occupancy by the gNB. According to a different implementation, the channel occupancy signal is not transmitted periodically, but only upon the first acquisition of the unlicensed spectrum. However, the channel occupancy signal further includes information about the length of the channel occupancy to enable the UE to derive how long the channel occupancy will last. According to a further alternative, the gNB broadcasts a channel occupancy signal when starting the channel occupancy to indicate the start of the channel occupancy, and a further channel occupancy signal when terminating the channel occupancy to indicate the end of the channel occupancy.

[0117] According to current 3GPP discussions, a channel occupancy signal (also called COT notification) can be periodically transmitted by a gNB. Its content and notification method have not yet been agreed upon. However, Layer 1 (L1) of the UE may notify Layer 2 and Layer 3 (L2 and L3) of the UE of the COT status, for example, when the gNB occupies the unlicensed spectrum and, optionally (see alternatives above), when the gNB stops occupying the unlicensed spectrum.

[0118] One further exemplary assumption is that the timer value of the first timer is longer when the monitoring of the downlink control channel is operated in an unlicensed radio cell scenario than when it is operated in a licensed radio cell scenario. As mentioned above, one possible solution to compensate for LBT failure is to increase the length of the timer controlling the monitoring of the downlink control channel (e.g., PDCCH) when operating in an unlicensed radio cell. Correspondingly, the gNB configures the UE with a longer timer value when communicating with the UE via the unlicensed radio cell. And the second timer is realized as described above and below, in order to be able to reduce the extra power cost for long monitoring in the unlicensed radio cell if possible. When operating in a licensed radio cell, the second timer is not needed.

[0119] The first and second timers can be configured in different ways. For example, the first and second timers can be configured separately, for example, by the gNB. In this regard, the gNB transmits configuration information to the UE including separate notifications for configuring the first and second timers (e.g., two different timer values, the timer value of the second timer being smaller than the timer value of the first timer). This configuration information can be provided separately for each function to be performed, whereby the first and second timers can be configured separately for each function.

[0120] On the other hand, the first and second timers can be set together, one timer being set depending on the other timer, e.g., the second timer is determined based on the first timer. For example, configuration information is sent by the gNB to set the first timer (e.g., see the above-mentioned 3GPP function in the usual way as already done in prior art solutions). And the second timer is determined by the UE to be part of the first timer. For example, the unlicensed related first timer value is multiplied by a scaling factor (e.g., 0 to 1) to determine the timer value of the second timer.

[0121] The scaling factor (or a part of it) can then be configurable by the gNB, for example by means of a configuration message together with, for example, setting the unlicensed related first timer, or the scaling factor may be defined by the 3GPP specifications and thus hard-coded in the UE or in the UE's SIM card.

[0122] According to further example implementations, the same or different scaling factors may be utilized to determine a second timer based on the first timer for different functions operated in the UE.

[0123] According to a further exemplary implementation, when the gNB decides to correct the value of the scaling factor and sends a configuration message to the UE to change the value of the scaling factor, the UE may gradually apply the change over a period of time instead of changing the value of the scaling factor immediately upon receiving the configuration message.

[0124] According to a further exemplary implementation, the unlicensed-related second timer (utilized by the UE to monitor the downlink control channel for functionality when in an unlicensed radio cell) can be configured to be identical or similar to the licensed-related first timer utilized by the UE (to monitor the downlink control channel for functionality when in a licensed radio cell). In particular, the timer value of the unlicensed-related second timer can be identical or similar to the timer value of the licensed-related first timer. Reusing the configuration for the licensed-related first timer to configure the unlicensed-related second timer facilitates implementation and reduces impact on 3GPP specifications.

[0125] On the other hand, the first timer may be set when operating in an unlicensed radio cell (exemplarily referred to as an unlicensed-related first timer) depending on the first timer when operating in a licensed radio cell (exemplarily referred to as a licensed-related first timer). For example, the unlicensed-related first timer may simply be a multiple of the time of the licensed-related first timer. Alternatively, the unlicensed-related first timer may be given by the 3GPP specifications and thus may be, for example, hard-coded in the UE or in a SIM card of the UE.

[0126] In an example implementation specific to 3GPP, the configuration information can be sent by the gNB to the UE using RRC messages.

[0127] In the following, two different exemplary implementations of the above mentioned improved monitoring of the downlink control channel are described. A first implementation is described with reference to Figures 12 and 13. A second implementation is described with reference to Figures 14, 15 and 16. The first and second implementations mainly differ in how the second timer is operated depending on the channel occupancy status and its stopping as a result of the downlink control channel monitoring procedure.

[0128] According to a first alternative realization, the second timer is operated to accumulate the time that the downlink control channel is monitored while the gNB occupies the unlicensed spectrum. That is, while the first timer runs independently of the channel occupancy to time the time that the downlink control channel is monitored, the second timer runs when the gNB occupies the unlicensed spectrum and does not run when the gNB does not occupy the unlicensed spectrum. Thus, the second timer accumulates only the time that the gNB can actually reach the UE via the unlicensed radio cell (e.g., while ignoring other times when the unlicensed spectrum is already busy and occupied by other systems or other gNBs, regardless of whether the gNB cannot reach the UE due to LBT failure). Correspondingly, in this respect the second timer is similar to the first timer operating in the licensed radio cell.

[0129] FIG. 12 shows that monitoring of the downlink control channel is started as part of the function. Then, the start of the monitoring specific to the function triggers the operation of the second timer together with the start of the first timer. However, whether the second timer is started, restarted or stopped (for the first time) depends on the channel occupancy state. Thus, the UE determines the channel occupancy state of the unlicensed spectrum. It is exemplarily assumed that the gNB finally acquires the unlicensed spectrum (at the first time after the monitoring is started), in which case the second timer is started. The second timer continues to run for the duration of the channel occupancy time and is stopped when the unlicensed channel is no longer occupied by the gNB. The second timer can be restarted when the gNB occupies the unlicensed spectrum again. Thus, the second timer is run until it expires, in which case the monitoring of the downlink control channel is stopped. Optionally, the first timer may be stopped upon expiration of the second timer, since there is no need for the first timer to continue running, considering that monitoring of the downlink control channel has already been stopped based on the second timer (not shown in FIG. 12).

[0130] Figure 13 illustrates an improved downlink control channel monitoring procedure according to the alternative described above with reference to Figure 12 in an exemplary scenario. Figure 13 illustrates at the top when channel occupancy by the gNB (here called gNB COT) is monitored together with the downlink control channel (here PDCCH). In the middle of Figure 13, the operation of the first timer is illustrated, and at the bottom, the operation of the second timer is illustrated. The horizontal dashed lines indicate the timer value of each timer, where the timer value of the second timer is significantly lower than the timer value of the first timer. When the timer reaches the respective timer value (horizontal line), the timer expires.

[0131] As can be seen, the first timer is started simultaneously with the PDCCH monitoring and runs continuously independent of the gNB COT. On the other hand, the second timer is not started at the start of the PDCCH monitoring, but rather when the gNB acquires the unlicensed spectrum. The second timer runs until the end of the first gNB COT and is then restarted in the second gNB COT. In an exemplary scenario, it is assumed that the second timer expires by the end of the second gNB COT and the PDCCH monitoring is stopped (as shown in the top part of Figure 13).

[0132] Figure 13 is only an example and assumes certain timer values ​​and gNB COT lengths. In other scenarios, the second timer may expire earlier (e.g., during the first gNB COT) than in Figure 13, or may not even expire at all if the first timer is allowed to expire first (see "Stop PDCCH monitoring if first timer expires" in the top right of Figure 13).

[0133] FIG. 14 shows a flow chart of a second alternative implementation of the improved downlink control channel monitoring procedure. The second alternative implementation differs from the first implementation mainly in the way the second timer operates. In particular, the second timer is essentially started at the same time as the first timer, e.g., when PDCCH monitoring is started. Furthermore, the second timer, like the first timer, operates continuously independent of the gNB COT until it expires (or is stopped because the other timer expires first). When the second timer expires, the UE evaluates the channel occupancy status of the unlicensed spectrum (e.g., by determining the channel occupancy of the unlicensed spectrum by the gNB in ​​response to the expiration of the second timer). If the base station occupies the unlicensed spectrum, the UE continues to monitor the PDCCH until the end of the current COT as to whether the gNB (which acquired the unlicensed spectrum) transmits information to the UE. The monitoring is stopped at the end of the current gNB channel occupancy time. On the other hand, if the UE determines that the base station does not occupy the unlicensed spectrum, no specific action is required by the UE, which follows the operation of the first timer and continues monitoring the downlink control channel until the first timer expires (dashed box and arrow in Figure 14).

[0134] Correspondingly, a second timer is used to include a one-time check of the COT (upon expiry of the second timer) in order to stop monitoring earlier if the gNB determines that it currently occupies the unlicensed channel. In other words, if the UE determines that the gNB has acquired unlicensed spectrum but does not transmit information / data intended for the UE to the UE (the second timer expires during the COT but no data is received during monitoring), the UE considers that further monitoring of the PDCCH is not beneficial and monitoring is stopped once the gNB COT expires.

[0135] The second implementation according to Fig. 14 is simpler than the solution of Fig. 12 because the UE does not continuously determine the channel occupancy status and does not need to accumulate the COT length. Rather, the UE checks the COT status only once when the second timer expires. Furthermore, if the second timer expires during the gNB COT period, the monitoring time is shortened, and therefore power can be saved.

[0136] Figures 15 and 16 show an improved downlink control channel monitoring procedure according to the second alternative described above with reference to Figure 14 in two exemplary scenarios. Figures 15 and 16 are similar to Figure 13 in that they show at the top when the channel occupancy by the gNB (here called gNB COT) is monitored together with the downlink control channel (here PDCCH). In the middle of the figure, the operation of the first timer is shown, and at the bottom, the operation of the second timer is shown. The horizontal dashed lines show the timer value of each timer, where the timer value of the second timer is significantly lower than the timer value of the first timer. When the timers reach their respective timer value (horizontal line), they expire.

[0137] In Fig. 15, it is exemplarily assumed that the second timer expires during the gNB COT, while in Fig. 16, it is exemplarily assumed that the second timer expires outside the gNB COT. As is evident from Fig. 15, the expiration of the second timer causes the UE to check the COT state and determine that the gNB is currently occupying the unlicensed spectrum. The UE continues to monitor the downlink control channel until the end of the current (first in the exemplary scenario) COT, and then stops monitoring, thus allowing the UE to save power.

[0138] On the other hand, as is evident from Figure 16, expiry of the second timer causes the UE to check the COT state and determine that the gNB is not currently occupying the unlicensed spectrum, and therefore the UE continues to monitor the downlink control channel until expiry of the first timer.

[0139] Certain variations of the above-described improved monitoring procedures of Figures 11-16 are feasible in LTE and 5G NR environments, both now and as they are standardized in the future. In the above description, certain LTE and 5G NR functions have been presented that involve monitoring of downlink control channels (in particular the PDCCH) and therefore benefit from improved monitoring procedures. Some of the different functions and how the improved monitoring procedures can be implemented therein are described in detail below.

[0140] The PDCCH is monitored as part of the paging function so that the UE can receive paging messages sent by the base station. When implementing the improved PDCCH monitoring procedure in the paging function, the first timer can be a timer that counts the length of a paging occasion (see sections 6.1 and 7.1 of TS38.304 v15.3.0 and section 9.2.5 of TS38.300 v15.5.0). In one example implementation, the first timer value can be increased to cover an extended paging occasion (having a longer length) or to cover more than one paging occasion (e.g., the sum of the lengths of multiple POs) by operating in an unlicensed frequency spectrum of an unlicensed radio cell. And the second timer is a new timer for the paging function used when operating in an unlicensed radio cell. The timer value of the second timer can be, for example, a timer value corresponding to a paging occasion monitored by the UE when in a licensed scenario.

[0141] The paging functionality thus configured is operated by the UE. PDCCH monitoring is started at the start of a paging occasion, at which point (at least) a first PO timer is started by the UE. The second PO timer operates according to one of the various implementations described in connection with Figures 11 to 16. Correspondingly, the second timer is started after PO PDCCH monitoring has started, in particular at the start of the gNB COT, and accumulates the PDCCH monitoring time during the remaining gNB COT (and possibly further gNB COT) and triggers the UE to stop monitoring the PDCCH upon its expiry (see Figures 12 and 13). Alternatively, the second timer is started simultaneously with the first timer at the start of PDCCH monitoring (see Figs. 14-16), and upon its expiry, the UE is triggered to check the COT status to decide whether to continue monitoring until the end of the COT (if the gNB determines that it has now acquired unlicensed spectrum) or to continue monitoring the PDCCH until expiry of the first timer (e.g., end of paging occasion). Optionally, according to the current provisions of the paging functionality, the UE may enter the idle DRX OFF state upon expiry of the first and / or second timer.

[0142] If a paging message is received during PDCCH monitoring (PDCCH with P-RNTI is received and corresponding PDSCH is received), there is no need for the UE to continue monitoring the PDCCH for the paging function and the UE can stop monitoring the PDCCH until the next paging interval (if it is not required as part of another function). Furthermore, the two timers can be stopped.

[0143] The second PO timer allows the UE to stop PDCCH monitoring earlier (especially when the unlicensed channel is free and the gNB can acquire the unlicensed channel), thus allowing the UE to save significant power.

[0144] Furthermore, the PDCCH is monitored as part of the system information acquisition function to enable receiving system information. When implementing the improved PDCCH monitoring procedure in the system information acquisition function, the first timer can be a timer that counts the length of a system information window (see section 5.2 of TS38.331 v15.5.1, section 7.3 of TS38.300 v15.5.0, section 13 of TS38.213). In one exemplary implementation, the first timer value can be increased to cover an extended system information window (having a longer length) or to cover multiple SI windows (e.g., the sum of the lengths of multiple SI windows) for operation in an unlicensed frequency spectrum of an unlicensed radio cell. And the second timer is a new timer for the SI acquisition function utilized when operating in an unlicensed radio cell. The timer value of the second timer can be, for example, a timer value corresponding to the SI window monitored by the UE when in a licensed scenario.

[0145] The thus configured system information acquisition function is then operated by the UE. PDCCH monitoring is started at the start of the SI window, at which point (at least) the first SI window timer is started by the UE. The second SI window timer operates according to one of the various implementations described in connection with Figures 11-16. Correspondingly, the second SI window timer is started after the PDCCH monitoring of the SI window has started, in particular at the start of the gNB COT, and accumulates the PDCCH monitoring time during the remaining gNB COT (and possibly further gNB COT) and at its expiry triggers the UE to stop monitoring the PDCCH (see Figures 12 and 13). Alternatively, a second timer may be started simultaneously with the first timer at the start of PDCCH monitoring (see Figures 14-16), and upon its expiry, the UE may be triggered to check the COT status to determine whether to continue monitoring until the end of the COT (if the gNB determines that it has currently acquired unlicensed spectrum) or to continue monitoring the PDCCH until expiry of the first timer (e.g., the end of the SI window). Furthermore, if the SI message is not successfully received and the PDCCH monitoring is stopped, the UE may resume acquiring system information in the next SI period.

[0146] If a system information message is received while monitoring the PDCCH (e.g., a PDCCH with SI-RNTI and a corresponding PDSCH), the UE no longer needs to continue monitoring the PDCCH for the SI acquisition function, and the UE can stop monitoring the PDCCH until the next time new system information needs to be received (e.g., if it is not required as part of another function). Additionally, the two timers can be stopped.

[0147] Thus, the second SI window timer allows the UE to stop PDCCH monitoring earlier (especially when the unlicensed channel is free and the gNB can acquire the unlicensed channel), thus allowing the UE to significantly save power.

[0148] Furthermore, the PDCCH is monitored as part of the On-Duration period of the DRX function to check whether information addressed to the UE has been received and to determine whether to enter the DRX off state. When implementing the improved PDCCH monitoring procedure in the DRX function, the first timer can be a timer that counts the length of the On-Duration period (for the On-Duration timer, see section 5.7 of TS38.321 v15.5.0). In one example implementation, the first timer value can be increased to cover an extended On-Duration (with a longer length) for operation in an unlicensed frequency spectrum of an unlicensed radio cell. And the second timer is a new timer for On-Duration operation used when operating in an unlicensed radio cell. The timer value of the second timer can be, for example, a timer value corresponding to the On-Duration period monitored by the UE when in a licensed scenario.

[0149] The DRX On-Duration operation thus configured is then executed by the UE. PDCCH monitoring is started at the beginning of the DRX On-Duration period, at which point (at least) the first On-Duration timer is started by the UE. The second On-Duration timer is operated according to the various implementations described in connection with Figures 11 to 16. Correspondingly, the second On-Duration timer is started after the On-Duration PDCCH monitoring is started, in particular at the beginning of the gNB COT, and then accumulates the PDCCH monitoring during the remaining gNB COT (and possibly further gNB COT) and triggers the UE to stop the PDCCH monitoring upon its expiry (see Figures 12 and 13). Alternatively, the second On-Duration timer is started simultaneously with the first On-Duration timer at the start of PDCCH monitoring (see Figures 14-16), and upon its expiration, the UE is triggered to check the COT status to determine whether to continue monitoring until the end of the COT (if the gNB determines that it has currently acquired unlicensed spectrum) or whether to continue monitoring the PDCCH until the expiration of the first timer (e.g., the end of the On-Duration period). Furthermore, if no PDCCH is received for the UE and the PDCCH monitoring is stopped based on the first or second On-Duration timer, the UE may enter the DRX OFF state.

[0150] On the other hand, if a PDCCH for the UE is received while monitoring the PDCCH (e.g., a downlink or uplink grant), the UE does not need to continue monitoring the PDCCH based on the On-Duration configuration (e.g., the UE proceeds to process the downlink or uplink grant and then transitions to the next PDCCH monitoring phase). Furthermore, in accordance with current DRX provisions, the UE may monitor the PDCCH as part of the DRX Inactivity timer operation, as described in connection with the following functions.

[0151] Thus, the second On-Duration timer allows the UE to stop On-Duration PDCCH monitoring early (especially when the unlicensed channel is free and the gNB can acquire the unlicensed channel), thus allowing the UE to significantly save power.

[0152] Furthermore, the PDCCH is monitored as part of the inactivity timer of the DRX function to check whether information addressed to the UE has been received and whether the UE enters a DRX period (due to extended inactivity, see section 5.7 of TS38.321 v15.5.0). When implementing an improved PDCCH monitoring procedure in the DRX function, the first timer can be a DRX inactivity timer that counts the length of inactivity. In one exemplary implementation, the first timer value can be increased to cover the extended inactivity period (with a longer length) for operation in an unlicensed frequency spectrum of an unlicensed radio cell. And the second timer is a new timer for inactivity monitoring used when operating in an unlicensed radio cell. The timer value of the second timer can be, for example, a timer value corresponding to the inactivity timer that is set for the UE when in a licensed scenario.

[0153] The thus configured operation of the DRX Inactivity function is then executed by the UE. PDCCH monitoring is started at the start of the DRX inactivity period, at which point (at least) a first Inactivity timer is started by the UE. The second Inactivity timer is operated according to the various implementations described in connection with Figures 11 to 16. Correspondingly, the second Inactivity timer is started after the inactivity PDCCH monitoring is started, in particular at the start of the gNB COT, and accumulates the PDCCH monitoring during the remaining gNB COT (and possibly further gNB COT) and upon its expiry triggers the UE to stop monitoring the PDCCH (see Figures 12 and 13). Alternatively, the second inactivity timer is started simultaneously with the first inactivity timer at the start of PDCCH monitoring (see Figures 14-16), and upon its expiry, the UE is triggered to check the COT status to decide whether to continue monitoring until the end of the COT (if the gNB determines that it has currently acquired unlicensed spectrum) or to continue monitoring the PDCCH until expiry of the first timer (e.g., until the end of the inactivity period). Furthermore, when no PDCCH is received for the UE and PDCCH monitoring is stopped based on the first or second inactivity timers, the UE may subsequently enter a short DRX period if configured to do so.

[0154] On the other hand, if a PDCCH for the UE is received during monitoring of the PDCCH (eg, a downlink grant or an uplink grant), the UE restarts the first and second inactivity timers accordingly and continues to monitor the PDCCH.

[0155] Thus, the second inactivity timer allows the UE to stop inactivity PDCCH monitoring early (especially when the unlicensed channel is free and the gNB can acquire the unlicensed channel), thus allowing the UE to save significant power.

[0156] Furthermore, the PDCCH is monitored as part of the random access function to check whether a random access response message is received from the gNB in ​​response to a RACH preamble sent earlier by the UE by the gNB. In implementing the improved PDCCH monitoring procedure in the random access function, the first timer can be a timer for counting the length of a random access response (RAR) window (e.g., see section 5.1 of TS38.321 v15.5.0 for ra-ResponseWindow). In one exemplary implementation, the first timer value can be increased to cover an extended RAR window (having a longer length) for operation in an unlicensed frequency spectrum of an unlicensed radio cell. And the second timer is a new timer for RAR monitoring used when operating in an unlicensed radio cell. The timer value of the second timer can be, for example, a timer value corresponding to a RAR window size configured for the UE when in a licensed scenario.

[0157] The thus configured operation of the random access function is then executed by the UE. PDCCH monitoring is started at the start of the RAR window, at which point (at least) a first Inactivity timer is started by the UE. The second RAR window timer is operated according to the various implementations described in connection with Figures 11 to 16. Correspondingly, the second RAR window timer is started after the RAR window monitoring is started, in particular at the start of the gNB COT, and accumulates the PDCCH monitoring during the remaining gNB COT (and possibly further gNB COT) and upon its expiry triggers the UE to stop monitoring the PDCCH (see Figures 12 and 13). Alternatively, a second RAR window timer may be started simultaneously with the first RAR window at the start of PDCCH monitoring (see Figures 14-16), and upon its expiry, the UE may be triggered to check the COT status to determine whether to continue monitoring until the end of the COT (if the gNB determines that it has currently acquired unlicensed spectrum) or to continue monitoring the PDCCH until expiry of the first timer (e.g., end of the RAR window). Furthermore, if no random access response is received for the UE and PDCCH monitoring is stopped based on the first or second RAR window timer, the UE may then proceed to the next step of the RACH procedure (e.g., retransmission of the RACH preamble).

[0158] On the other hand, if an RAR is received while monitoring the PDCCH, the UE proceeds to random access (eg, via msg 3).

[0159] The second RAR window therefore allows the UE to stop RAR monitoring earlier (especially when the unlicensed channel is free and the gNB can acquire the unlicensed channel). Thus, the UE can significantly save power. Furthermore, the improved PDCCH monitoring allows to reduce the random access delay, since the next step of the random access can start earlier.

[0160] Furthermore, the PDCCH is monitored as part of the PDCP reordering function to check whether missing PDUs have been received so as to provide in-order data packets to the upper layers. In implementing the improved PDCCH monitoring procedure in the PDCP reordering function, the first timer may be a reordering timer that counts the length of the PDCP reordering window (see, for example, sections 5.1.2, 5.2.1, 5.2.2 of TS38.323 v15.5.0 for t-Reordering timers). In one example implementation, the first timer value may be increased to cover an extended PDCP reordering window (having a longer length) due to operation in an unlicensed frequency spectrum of an unlicensed radio cell. And the second timer is a new timer for the PDCP reordering window used when operating in an unlicensed radio cell. The timer value of the second timer may be, for example, a timer value corresponding to a PDCP reordering window configured for the UE when in a licensed scenario.

[0161] The so configured operation of the PDCP reordering function is then executed by the UE. PDCCH monitoring is started at the start of the PDCP reordering window, at which point (at least) the first reordering timer is started by the UE. The second reordering timer is operated according to the various implementations described in relation to Figures 11 to 16. Correspondingly, the second reordering timer is started after the reordering window monitoring is started, in particular at the start of the gNB COT, and accumulates PDCCH monitoring during the remaining gNB COT (and possibly further gNB COT) and triggers the UE to stop PDCCH monitoring upon its expiry (see Figures 12 and 13). Alternatively, a second reordering window timer may be started simultaneously with the first reordering window timer at the start of PDCCH monitoring (see Figures 14-16), and upon its expiration, the UE is triggered to check the COT status to determine whether to continue monitoring until the end of the COT (if the gNB determines that it has currently acquired unlicensed spectrum) or to continue monitoring the PDCCH until the expiration of the first timer (e.g., the end of the reordering window). Furthermore, if missing data packets (which enable in-order delivery to higher layers) are not received and PDCCH monitoring is stopped based on the first or second reordering window timers, the UE may then proceed to the next step of the PDCP data exchange (e.g., sending a PDCP status report to the gNB to request retransmission of the missing PDUs).

[0162] On the other hand, if a missing data packet is received while monitoring the PDCCH, the UE stops monitoring the PDCCH for the reordering function until the next time when reordering is required (e.g., all packets are in order and reordering is now unnecessary). Furthermore, the UE may proceed to deliver in-order data packets to higher layers. Thus, the second reordering window timer allows the UE to stop reordering monitoring earlier (especially when the unlicensed channel is free and the gNB can acquire the unlicensed channel). Thus, the UE can significantly save power. Furthermore, the improved PDCCH monitoring allows to reduce the delay of the PDCP protocol processing (less delay in data reception due to early retransmission), since the next stage of the reordering function can be performed earlier (e.g., PDCP status report).

[0163] The above description of the improved downlink control channel monitoring has focused on the UE side. However, the improved downlink control channel monitoring is also applicable to the gNB side. The different functions described above include monitoring of the PDCCH, but from the gNB's perspective, these various functions include transmitting information on the PDCCH. In particular, the UE monitors the PDCCH as part of a particular function, while the reverse operation by the gNB is to transmit corresponding information on the PDCCH to the UE. Thus, the gNB may perform the same or similar parallel operation of two timers to determine when to transmit information to the UE via the downlink control channel and when to monitor the downlink control channel. For example, the gNB may perform a transmission to the UE on the PDCCH only when it determines that the UE is actually monitoring the PDCCH at that time, otherwise no PDCCH transmission is required since the UE does not monitor the PDCCH and does not receive the PDCCH transmission in any way. Correspondingly, the various implementations and variations described above in relation to Figures 11-16 are correspondingly applicable to gNB operation.

[0164] For example, according to one exemplary implementation, the base station determines when the UE monitors the PDCCH based on the operation of the first and second timers as described with respect to FIG. 11, based on the first implementation described in connection with FIGS. 12 and 13, or based on the second implementation described in connection with FIGS. 14, 15 and 16.

[0165] In addition, the base station is also responsible for configuring various functions in the UE, including the first and second timers and their timer values, in which case the gNB may transmit appropriate configuration information using RRC protocol messages.

[0166] Further Aspects According to a first aspect, a UE is provided having a processing circuit for operating functions related to monitoring a downlink control channel of an unlicensed radio cell for information intended for the UE, the unlicensed radio cell operating in an unlicensed spectrum and controlled by a base station communicating with the user equipment. The processing circuit and the receiver of the UE perform the monitoring of the downlink control channel based on a first timer and a second timer operating in parallel. The first timer is used to limit a maximum time for which the downlink control channel is monitored by starting the first timer at the start of the monitoring of the downlink control channel and stopping the monitoring of the downlink control channel upon expiry of the first timer. The second timer is used to stop the monitoring of the downlink control channel earlier than the first timer depending on the channel occupancy status of the unlicensed spectrum of the radio cell by the base station.

[0167] According to a second aspect provided in addition to the first aspect, the second timer is operated to accumulate a time during which the downlink control channel is monitored during a period during which the unlicensed spectrum is occupied by the base station. In an optional realization thereof, the second timer is executed during a period during which the unlicensed spectrum is occupied by the base station. In a further optional realization, the monitoring of the downlink control channel is executed while either of the two timers is running, and the expiration of either the first timer or the second timer stops the monitoring of the downlink control channel. In a further optional realization, the second timer is started when the base station occupies the unlicensed spectrum at a first time after the start of the first timer, the second timer is stopped when the base station does not occupy the unlicensed spectrum, and the second timer is restarted when the base station reoccupies the unlicensed spectrum.

[0168] According to a third aspect provided in addition to the second aspect, the function is a paging message monitoring function, and a downlink control channel is monitored for receipt of a paging message. Upon receipt of the paging message, the first timer, the second timer, and monitoring of the downlink control channel for the paging message monitoring function are stopped until a next paging interval. In an optional implementation thereof, the first timer counts a length of one or more paging occasions and the second timer counts a length of one or more paging occasions during a period in which the unlicensed spectrum is occupied by the base station.

[0169] Additionally or alternatively, the function is a system information acquisition function, and the downlink control channel is monitored for receipt of a system information message, and upon receipt of the system information message, the first timer, the second timer and the monitoring of the downlink control channel for the system information acquisition function are stopped until the next time the UE needs to acquire system information, in an optional implementation thereof, the first timer counts the length of one or more system information acquisition windows and the second timer counts the length of one or more system information acquisition windows during a period in which the unlicensed spectrum is occupied by the base station.

[0170] Additionally or alternatively, the function is a notification monitoring operation for a discontinuous reception (DRX) function, and the downlink control channel is monitored for any downlink control information related to the downlink control channel directed to the user equipment. Upon receiving the downlink control information, the first timer and the second timer are stopped and monitoring of the downlink control channel continues. In an optional implementation thereof, the first timer counts a length of a DRX on duration and the second timer counts a length of a DRX on duration during which the unlicensed spectrum is occupied by the base station.

[0171] Additionally or alternatively, the function is an inactivity monitoring operation for a discontinuous reception (DRX) function, and the downlink control channel is monitored for any downlink control information on the downlink control channel for the user equipment. Upon receiving the downlink control information, the first timer and the second timer are restarted and monitoring of the downlink control channel continues. In an optional implementation thereof, the first timer counts a length of DRX inactivity duration and the second timer counts a length of DRX inactivity duration during a period in which the unlicensed spectrum is occupied by the base station.

[0172] Additionally or alternatively, the function is a random access response reception for a random access function, the downlink control channel being monitored for a random access response message transmitted by the base station in response to a random access preamble previously transmitted by the user equipment to the base station. Upon reception of the random access response, the first timer and the second timer are stopped and a next step of the random access function is executed. In an optional realization thereof, the first timer counts the length of a random access response window and the second timer counts the length of the random access response window during a period during which the unlicensed spectrum is occupied by the base station.

[0173] Additionally or alternatively, the function is a Packet Data Convergence Protocol (PDCP) layer reordering function, where the downlink control channel is monitored for missing out-of-order data destined for the user equipment, and upon receipt of the missing out-of-order data, the first timer and the second timer are stopped and monitoring of the downlink control channel continues until the next time that out-of-order delivery of data is detected. In an optional implementation thereof, the first timer counts the length of a reordering time window and the second timer counts the length of the reordering time window during which the unlicensed spectrum is occupied by the base station.

[0174] According to a fourth aspect provided in addition to the first aspect, expiry of the second timer causes the processing circuit to determine whether the base station is currently occupying the unlicensed spectrum. When the base station is currently occupying the unlicensed spectrum, monitoring is stopped at the end of the current channel occupancy of the unlicensed spectrum and, optionally, the first timer is stopped. When the base station is not currently occupying the unlicensed spectrum, monitoring is performed until expiry of the first timer. In an optional implementation, the second timer is started at the same time that the first timer is started.

[0175] According to a fifth aspect provided in addition to the fourth aspect, the function is a paging message monitoring function, and a downlink control channel is monitored for receipt of a paging message. Upon receipt of the paging message, the first timer, the second timer, and monitoring of the downlink control channel for the paging message monitoring function are stopped until a next paging interval. In an optional implementation thereof, the first timer and the second timer count the length of one or more paging occasions.

[0176] Additionally or alternatively, the function is a system information acquisition function, and the downlink control channel is monitored for receipt of a system information message. Upon receipt of the system information message, the first timer, the second timer, and the monitoring of the downlink control channel for the system information acquisition function are stopped until the next time the UE needs to acquire system information. In an optional implementation thereof, the first timer and the second timer count the length of one or more system information acquisition windows.

[0177] Additionally or alternatively, the function is a notification monitoring operation for a discontinuous reception (DRX) function, and the downlink control channel is monitored for any downlink control information related to the downlink control channel directed to the user equipment. Upon receiving the downlink control information, the first timer and the second timer are stopped, monitoring of the downlink control channel continues, and optionally a timer for DRX inactive duration is started. In an optional implementation thereof, the first timer and the second timer count the length of the DRX on duration.

[0178] Additionally or alternatively, the function is an inactivity monitoring operation for a discontinuous reception (DRX) function, and the downlink control channel is monitored for any downlink control information related to the downlink control channel for the user equipment. Upon receiving the downlink control information, the first timer and the second timer are restarted and the monitoring of the downlink control channel is continued. In an optional implementation thereof, the first timer and the second timer count a length of the DRX inactivity duration.

[0179] Additionally or alternatively, the function is a random access response reception for a random access function, the downlink control channel being monitored for a random access response message sent by the base station in response to a random access preamble previously sent by the user equipment to the base station. Upon receiving the random access response, the first and second timers are stopped and a next step of the random access function is executed. In an optional implementation thereof, the first and second timers count the length of a random access response window.

[0180] Additionally or alternatively, the function is a Packet Data Convergence Protocol (PDCP) layer reordering function, and the downlink control channel is monitored for missing out-of-order data destined for the user equipment. Upon receiving the missing out-of-order data, the first and second timers are stopped and monitoring of the downlink control channel continues until the next time that out-of-order delivery of data is detected. In an optional implementation thereof, the first and second timers count the length of a reordering time window.

[0181] According to a sixth aspect provided in addition to one of the first to fifth aspects, the processing circuit determines a channel occupancy by the base station based on a channel occupancy signal received by the receiver from the base station. In an optional realization form thereof, the channel occupancy signal is transmitted by the base station when the base station occupies an unlicensed spectrum and is not transmitted by the base station when the base station does not occupy the unlicensed spectrum. In an optional realization form thereof, the channel occupancy signal indicates an occupancy length of the unlicensed spectrum by the base station.

[0182] According to a seventh aspect provided in addition to one of the first to sixth aspects, the receiver receives configuration information from the base station for setting a first timer value of the first timer. The processing circuit determines a second timer value of the second timer based on a portion of the timer value of the first timer. In an optional realization form thereof, the portion is utilized to determine a second timer value of the second timer for one or more of the operated functions described below (e.g., a paging message monitoring function, a system information acquisition function, a notification monitoring operation for a discontinuous reception (DRX) function, a non-activity monitoring operation for a discontinuous reception (DRX) function, a random access response reception for a random access function, and a reordering function of a Packet Data Convergence Protocol (PDCP) layer). Alternatively, the receiver receives configuration information from the base station for setting a first timer value of the first timer and a second timer value of the second timer.

[0183] In two alternative optional implementations, the second timer value of the second timer is less than the first timer value of the first timer. In two further alternative optional implementations, the configuration information is received using a Radio Resource Control (RRC) protocol message.

[0184] According to an eighth aspect provided in addition to one of the first to seventh aspects, the function to be operated is the following function operated by the user device: - Paging message monitoring function - System information acquisition function Notification monitoring operation for discontinuous reception (DRX) function - Non-activity monitoring for DRX function · Receiving random access responses for random access functions - PDCP (Packet Data Convergence Protocol) layer reordering function It is one of the following.

[0185] In the above optional implementation, the UE operates one or more of the above functions, each of which is separately related to monitoring a downlink control channel and to operating a first timer and a second timer as described in one of the first to seventh aspects above.

[0186] According to a ninth aspect provided in addition to one of the first to eighth aspects, a first timer value of the first timer and a second timer value of the second timer are set for operation of the function in the unlicensed radio cell. A different first timer value of the first timer is set for operation of the function in the licensed radio cell. The different first timer value in the licensed radio cell is smaller than the first timer value in the unlicensed radio cell. In an optional implementation form, the second timer value of the second timer is the same as the first timer value of the first timer set for operation in the licensed radio cell.

[0187] According to a tenth aspect, a base station is provided having a processing circuit for operating functions related to transmitting information to a user equipment (UE) via a downlink control channel of an unlicensed radio cell monitored by the UE for information intended for the UE. The unlicensed radio cell is controlled by the base station operating in an unlicensed spectrum and communicating with the user equipment. The processing circuit determines when the UE monitors the downlink control channel based on a first timer and a second timer operated in parallel to determine when to transmit information to the UE via the downlink control channel. The first timer is utilized to limit a maximum time that the downlink control channel is monitored by the UE by starting the first timer at the start of monitoring the downlink control channel and stopping monitoring the downlink control channel upon expiration of the first timer. The second timer is utilized to stop monitoring the downlink control channel earlier than the first timer depending on a channel occupancy status of the unlicensed spectrum of the radio cell by the base station. A transmitter of the base station transmits information to the UE on the downlink control channel based on a previous determination based on the first timer and the second timer.

[0188] According to an eleventh aspect provided in addition to the tenth aspect, a transmitter transmits configuration information to a UE for setting a first timer value of a first timer. A processing circuit determines a second timer value of a second timer based on a portion of the timer value of the first timer. In an optional implementation, the transmitter transmits the configuration information regarding the portion to the UE during operation. Alternatively, the transmitter transmits the configuration information to the UE for setting the first timer value of the first timer and the second timer value of the second timer during operation.

[0189] In an optional realization of the above two alternatives, the second timer value of the second timer is smaller than the first timer value of the first timer. In a further optional realization of the above two alternatives, the configuration information is transmitted using a Radio Resource Control (RRC) protocol message.

[0190] According to a twelfth aspect, there is provided a method, executed by a user equipment (UE), comprising the steps of: - operating a function related to monitoring a downlink control channel of an unlicensed radio cell for information intended for the UE, the unlicensed radio cell being controlled by a base station operating in an unlicensed spectrum and communicating with the user equipment; and performing monitoring of the downlink control channel based on a first timer and a second timer operated in parallel, the first timer being used to limit a maximum time for which the downlink control channel is monitored by starting the first timer at the start of monitoring the downlink control channel and stopping monitoring of the downlink control channel upon expiry of the first timer, and the second timer being used to stop monitoring of the downlink control channel earlier than the first timer depending on a channel occupancy state of the unlicensed spectrum of the radio cell by the base station.

[0191] Hardware and Software Implementations of the Disclosure The present disclosure can be realized by software, hardware, or software interlocked with hardware. Each functional block used in the description of each embodiment above can be partially or entirely realized by an LSI such as an integrated circuit, and each process described in each embodiment can be partially or entirely controlled by the same LSI or a combination of LSIs. The LSI may be formed as an individual chip, or a single chip may be formed to include some or all of the functional blocks. The LSI may include data input / output coupled thereto. Here, the LSI may be called an IC (Integrated Circuit), a system LSI, a super LSI, or an ultra LSI depending on the degree of integration. However, the technology for realizing the integrated circuit is not limited to the LSI, and may be realized using a dedicated circuit, a general-purpose processor, or a processor for a specific application. Furthermore, an FPGA (Field Programmable Gate Array) that can be programmed after the manufacture of an LSI or a reconfigurable processor that can reconfigure the connection and settings of the circuit cells arranged inside the LSI may be used. The present disclosure can be realized as digital processing or analog processing. If future integrated circuit technologies replace LSI as a result of advances in semiconductor technology and other derived technologies, the functional blocks can be integrated using the future integrated circuit technologies. Biotechnology can also be applied.

[0192] The present disclosure may be implemented by any type of apparatus, device or system having communication capabilities, referred to as a communications apparatus.

[0193] Some non-limiting examples of such communications devices include telephones (e.g., mobile (cell) phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, digital book readers, telehealth / telemedicine (remote health and remote medical) devices, and vehicles (e.g., automobiles, airplanes, ships) that provide communications capabilities, and various combinations thereof.

[0194] The communications apparatus is not limited to being portable or mobile, but may include any type of apparatus, device or system that is non-portable or fixed, such as smart home devices (e.g., appliances, lighting, smart meters, control panels), vending machines, and any other "thing" in an "Internet of Things (IoT)" network.

[0195] Communications may include, for example, exchanging data via cellular systems, wireless LAN systems, satellite systems, and the like, as well as various combinations thereof.

[0196] A communications apparatus may include devices such as a controller or a sensor coupled to the communications device to perform the communications functions described in this disclosure. For example, a communications apparatus may include a controller or a sensor that generates control or data signals used by the communications device to perform the communications functions of the communications apparatus.

[0197] The communications equipment may also include infrastructure facilities such as base stations, access points, and any other equipment, devices or systems that communicate with or control equipment such as those in the non-limiting examples above.

[0198] Furthermore, the various embodiments may also be implemented by means of software modules executed directly by a processor or by hardware. Also, a combination of software modules and hardware implementations may be possible. The software modules may be stored on any type of computer-readable storage medium, for example a RAM, an EPROM, an EEPROM, a flash memory, a register, a hard disk, a CD-ROM, a DVD, etc. It should further be noted that individual features of the different embodiments may be the subject of other embodiments individually or in any combination.

[0199] It will be understood by those skilled in the art that numerous variations and / or modifications may be made to the present disclosure as set forth in the specific embodiments, and the present embodiments are therefore to be considered in all respects as illustrative and not restrictive.

Claims

1. An integrated circuit for controlling a process in a user equipment (UE), the process comprising: a processing function relating to monitoring a downlink control channel of an unlicensed radio cell for information intended for a UE, the unlicensed radio cell being controlled by a base station operating in an unlicensed spectrum and communicating with the user equipment; monitoring the downlink control channel based on a first timer and a second timer operating in parallel; the first timer is utilized to limit a maximum time for which the downlink control channel is monitored by starting the first timer at the start of monitoring the downlink control channel and stopping monitoring the downlink control channel upon expiration of the first timer; the second timer is adapted to stop monitoring the downlink control channel earlier than the first timer depending on a channel occupancy status of an unlicensed spectrum of the unlicensed radio cell by the base station.

2. the second timer is operated to accumulate a time for which the downlink control channel is monitored during a time that the unlicensed spectrum is occupied by the base station, the second timer running during a time that the unlicensed spectrum is occupied by the base station; monitoring the downlink control channel is performed while any of the two timers is running, and monitoring of the downlink control channel is stopped upon expiration of either the first timer or the second timer; 2. The integrated circuit of claim 1, wherein the second timer is started when the base station occupies the unlicensed spectrum at a first time after starting the first timer, the second timer is stopped when the base station does not occupy the unlicensed spectrum, and the second timer is restarted when the base station reoccupies the unlicensed spectrum.

3. 3. The integrated circuit of claim 2, wherein the function is a paging message monitoring function, the downlink control channel is monitored for receipt of a paging message, and upon receipt of the paging message, the first timer, the second timer, and monitoring of the downlink control channel for the paging message monitoring function are stopped until a next paging interval, the first timer counting a length of one or more paging occasions, and the second timer counting a length of the one or more paging occasions during a time that the unlicensed spectrum is occupied by the base station.

4. determining, upon expiration of the second timer, whether the base station is currently occupying the unlicensed spectrum; when the base station is currently occupying the unlicensed spectrum, the monitoring is stopped at the end of a current channel occupancy of the unlicensed spectrum and the first timer is stopped; When the base station is not currently occupying the unlicensed spectrum, the monitoring is performed until expiry of the first timer; 2. The integrated circuit of claim 1, wherein the second timer is started at the same time that the first timer is started.

5. 5. The integrated circuit of claim 4, wherein the function is a paging message monitoring function, the downlink control channel is monitored for receipt of a paging message, and upon receipt of the paging message, the first timer, the second timer, and monitoring of the downlink control channel for the paging message monitoring function are stopped until a next paging interval, and the first timer and the second timer count the length of one or more paging occasions.

6. determining channel occupancy by the base station based on a channel occupancy signal received by a receiver from the base station; the channel occupation signal is transmitted by the base station when the base station occupies the unlicensed spectrum, and is not transmitted by the base station when the base station does not occupy the unlicensed spectrum; The integrated circuit of claim 1 , wherein the channel occupancy signal indicates an occupancy length of the unlicensed spectrum by the base station.

7. receiving configuration information from the base station that sets a first timer value of the first timer, the integrated circuit determining a second timer value of the second timer based on a portion of the timer value of the first timer, the portion being determined based on the received configuration information, the same portion being used to determine a second timer value of the second timer for one or more of the functions to be operated; or receiving setting information from the base station for setting a first timer value of the first timer and a second timer value of the second timer; a second timer value of the second timer is less than a first timer value of the first timer; The integrated circuit of claim 1 , wherein the configuration information is received using a Radio Resource Control (RRC) protocol message.

8. The functions to be operated include the following functions operated by the user device: - Paging message monitoring function - System information acquisition function Notification monitoring operation for discontinuous reception (DRX) function Non-activity monitoring operation for DRX function ・Receiving a random access response for the random access function PDCP (Packet Data Convergence Protocol) layer reordering function 2. The integrated circuit of claim 1, wherein the first and second inputs are one of:

9. a first timer value of the first timer and a second timer value of the second timer are set for an operation of the function in an unlicensed radio cell, a different first timer value of the first timer is set for an operation of the function in a licensed radio cell, and the different first timer value in the licensed radio cell is smaller than the first timer value in the unlicensed radio cell; The integrated circuit of claim 1 , wherein a second timer value of the second timer is the same as a first timer value of the first timer that is set for operation in a licensed radio cell.

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