COMMUNICATION DEVICE, BASE STATION, AND METHOD

Abstract

This communication device (100) comprises: a communication unit (110) which receives, from a base station (200), a radio resource control (RRC) message containing information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH), and which receives, from the base station (200) by the PDCCH, downlink control information (DCI) containing an information field relating to monitoring of the PDCCH; and a control unit (120) which controls the skipping of the monitoring of the PDCCH across the skipping period on the basis of a value set in the information field. The control unit (120) controls so as not to execute skipping of the monitoring of the PDCCH when a timer relating to retransmission for an intermittent reception (DRX) operation is in operation.

Description

CROSS-REFERENCE TO RELATED ART

[0001] This application is based on and claims the benefit of priority to patent application No. 2021-079343, filed May 7, 2021, the entire contents of which are incorporated herein by reference. [Technical field]

[0002] The present disclosure relates to a communication device, a base station, and a method for use in a mobile communication system. [Background technology]

[0003] In recent years, the 3GPP (registered trademark; the same applies below) (3rd Generation Partnership Project), a standardization project for mobile communication systems, has been considering introducing power saving technology that reduces power consumption of user equipment in a radio resource control (RRC) connected state into the fifth generation (5G) system (see, for example, non-patent document 1).

[0004] For example, in order to reduce the power consumption required for monitoring a physical downlink control channel (PDCCH) in a user device, consideration is being given to lengthening the period of a search space corresponding to candidate timings at which a PDCCH is provided, or switching to a state in which monitoring of the PDCCH in the search space is skipped (hereinafter referred to as a "power saving state").

[0005] In particular, by dynamically switching to a power saving state during an active time in discontinuous reception (DRX) in a radio resource control (RRC) connected state, it is possible to obtain a greater power consumption reduction effect than the power consumption reduction achieved by DRX. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] 3GPP contribution RP-200938 “Revised WID UE Power Saving Enhancements for NR” Summary of the Invention

[0007] A communication device according to a first aspect includes a communication unit that receives a radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH) from a base station, and receives downlink control information (DCI) including an information field related to monitoring of the PDCCH from the base station on the PDCCH, and a control unit that controls skipping of monitoring of the PDCCH over the skipping period based on a value set in the information field. The control unit controls not to execute skipping of monitoring of the PDCCH while a timer related to retransmission for discontinuous reception (DRX) operation is operating.

[0008] A base station according to a second aspect includes a communication unit that transmits a radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH) to a communication device, and transmits downlink control information (DCI) including an information field related to monitoring of the PDCCH to the communication device on the PDCCH, and a control unit that controls skipping of monitoring of the PDCCH over the skipping period based on a value set in the information field. The control unit controls not to execute skipping of monitoring of the PDCCH while a timer related to retransmission for discontinuous reception (DRX) operation is operating.

[0009] A method according to a third aspect is a method executed by a communication device, comprising the steps of receiving a radio resource control (RRC) message from a base station, the RRC message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH), receiving downlink control information (DCI) including an information field related to monitoring of the PDCCH from the base station on the PDCCH, and controlling skipping of monitoring of the PDCCH for the skipping period based on a value set in the information field. In the controlling step, the control is performed so that skipping of monitoring of the PDCCH is not performed while a timer related to retransmission for discontinuous reception (DRX) operation is in operation.

[0010] A method according to a fourth aspect is a method executed by a base station, and includes the steps of: transmitting a radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH) to a communication device, transmitting downlink control information (DCI) including an information field related to monitoring of the PDCCH to the communication device on the PDCCH, and controlling skipping of monitoring of the PDCCH for the skipping period based on a value set in the information field. In the controlling step, the skipping of monitoring of the PDCCH is controlled not to be performed while a timer related to retransmission for discontinuous reception (DRX) operation is operating. [Brief description of the drawings]

[0011] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: [Figure 1] FIG. 1 is a diagram showing a configuration of a mobile communication system according to an embodiment; [Diagram 2] FIG. 2 is a diagram illustrating an example of a protocol stack configuration according to an embodiment; [Diagram 3] FIG. 3 is a diagram illustrating an overview of a wireless communication operation according to the embodiment; [Figure 4] FIG. 4 is a diagram illustrating an overview of PDCCH skipping according to an embodiment; [Diagram 5] FIG. 5 is a diagram illustrating an overview of search space set switching (SSSG switching) according to an embodiment. [Figure 6] FIG. 6 is a diagram showing a DRX and power saving state according to an embodiment; [Figure 7] FIG. 7 is a diagram showing a configuration of a UE according to an embodiment; [Figure 8] FIG. 8 is a diagram showing a configuration of a base station according to an embodiment; [Figure 9] FIG. 9 is a diagram showing a first operation example according to the embodiment; [Figure 10] FIG. 10 is a diagram illustrating a first operation example focusing on a downlink. [Figure 11] FIG. 11 is a diagram illustrating a first operation example focusing on an uplink. [Figure 12] FIG. 12 is a diagram showing a second operation example according to the embodiment; [Figure 13] FIG. 13 is a diagram showing a third operation example according to the embodiment; [Figure 14] FIG. 14 is a diagram showing a first configuration example of information elements included in an RRC message in a third operation example; [Figure 15] FIG. 15 is a diagram showing a first configuration example of information elements included in an RRC message in a third operation example; [Figure 16] FIG. 16 is a diagram showing a second configuration example of information elements included in an RRC message in the third operation example; [Figure 17] FIG. 17 is a diagram showing a second configuration example of information elements included in an RRC message in the third operation example; [Figure 18] FIG. 18 is a diagram showing a fourth operation example according to the embodiment; [Figure 19] FIG. 19 is a diagram showing a specific example 1 of an operation using a switching timer according to the fourth operation example; [Figure 20]FIG. 20 is a diagram showing a specific example 2 of the operation using the switching timer according to the fourth operation example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Assume that a downlink control information (DCI) indicating radio resources allocated from a base station to a user device is used as a switching instruction for instructing switching to a power saving state. Such DCI is called a scheduling DCI. When a user device is instructed to switch to a power saving state by a scheduling DCI, data transmission and reception occurs between the base station and the user device, and data retransmission processing by hybrid automatic repeat reQuest (HARQ) may be required. As a result of detailed study by the inventors, a problem has been found that if the user device immediately starts switching to the power saving state in response to receiving a scheduling DCI instructing switching to the power saving state, the HARQ processing cannot be performed appropriately.

[0013] Therefore, an object of the present disclosure is to enable appropriate data retransmission processing by HARQ even when a scheduling DCI is used as an instruction to switch to a power saving state.

[0014] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0015] (System Configuration) First, the configuration of a mobile communication system 1 according to this embodiment will be described with reference to Fig. 1. The mobile communication system 1 is, for example, a system that complies with the Technical Specification (TS) of 3GPP. In the following, the mobile communication system 1 will be described by taking as an example a 5th Generation System (5GS) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio).

[0016] The mobile communication system 1 includes a network 10 and a user equipment (UE) 100 that communicates with the network 10. The network 10 includes a next generation radio access network (NG-RAN) 20 that is a 5G radio access network, and a 5G core network (5GC) 30 that is a 5G core network.

[0017] The UE 100 is a device used by a user. The UE 100 is a mobile device such as a mobile phone terminal such as a smartphone, a tablet terminal, a notebook PC, a communication module, or a communication card. The UE 100 may be a vehicle (e.g., a car, a train, etc.) or a device provided therein. The UE 100 may be a transport body other than a vehicle (e.g., a ship, an airplane, etc.) or a device provided therein. The UE 100 may be a sensor or a device provided therein. The UE 100 may be called by another name such as a mobile station, a mobile terminal, a mobile device, a mobile unit, a subscriber station, a subscriber terminal, a subscriber device, a subscriber unit, a wireless station, a wireless terminal, a wireless device, a wireless unit, a remote station, a remote terminal, a remote device, or a remote unit.

[0018] The NG-RAN 20 includes a plurality of base stations 200. Each base station 200 manages at least one cell. A cell constitutes the smallest unit of a communication area. One cell belongs to one frequency (carrier frequency) and is composed of one component carrier. The term "cell" may represent a wireless communication resource, and may represent a communication target of the UE 100. Each base station 200 can perform wireless communication with the UE 100 located in the cell. The base station 200 communicates with the UE 100 using a protocol stack of a Radio Access Network (RAN). The base station 200 provides an NR user plane and a control plane protocol termination for the UE 100, and is connected to the 5GC 30 via an NG interface. Such an NR base station 200 may be referred to as a gNodeB (gNB).

[0019] The 5GC 30 includes a core network device 300. The core network device 300 includes, for example, an Access and Mobility Management Function (AMF) and / or a User Plane Function (UPF). The AMF performs mobility management of the UE 100. The UPF provides a function specialized for user plane processing. The AMF and the UPF are connected to the base station 200 via an NG interface.

[0020] Next, an example of the configuration of a protocol stack according to this embodiment will be described with reference to FIG.

[0021] The protocol of the wireless section between the UE 100 and the base station 200 includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and an RRC layer.

[0022] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the base station 200 via a physical channel.

[0023] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the base station 200 via a transport channel. The MAC layer of the base station 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to the UE 100.

[0024] The RLC layer transmits data to the RLC layer on the receiving side by using the functions of the MAC layer and the PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the base station 200 via logical channels.

[0025] The PDCP layer performs header compression / decompression and encryption / decryption.

[0026] A Service Data Adaptation Protocol (SDAP) layer may be provided above the PDCP layer. The Service Data Adaptation Protocol (SDAP) layer maps IP flows, which are units for QoS control by the core network, to radio bearers, which are units for QoS control by the access stratum (AS).

[0027] The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of the UE 100 and the RRC layer of the base station 200. When there is an RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC connected state. When there is no RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC idle state. When the RRC connection between the RRC of the UE 100 and the RRC of the base station 200 is suspended, the UE 100 is in an RRC inactive state.

[0028] The NAS layer located above the RRC layer performs session management and mobility management for the UE 100. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the core network device 300 (AMF). The UE 100 has an application layer and the like in addition to the protocol of the radio interface.

[0029] (Overview of wireless communication operation) Next, an overview of a wireless communication operation according to this embodiment will be described with reference to Fig. 3. In this embodiment, a search space may be referred to as a search space set.

[0030] The base station 200 sets, for the UE 100, a search space corresponding to a candidate timing at which the PDCCH is provided. The UE 100 in the RRC connected state monitors the PDCCH in the set search space and receives downlink control information (DCI) carried by the PDCCH. Then, the UE 100 receives a physical downlink shared channel (PDSCH) and / or transmits a physical uplink shared channel (PUSCH) according to resource allocation (scheduling) indicated by the DCI. For example, the UE 100 may monitor a set of PDCCH candidates according to the corresponding search space. That is, the UE 100 may monitor a set of PDCCH candidates in a control resource set (CORESET) in a downlink BWP (DL BWP: BandWidth Part) in a serving cell in which monitoring of the PDCCH is set according to the corresponding search space. Here, monitoring may indicate decoding each of the PDCCH candidates according to the monitored DCI format.

[0031] As shown in FIG. 3, in step S1, the base station 200 transmits an RRC message including setting information (PDCCH setting information) related to the PDCCH to the UE 100, and performs various settings related to the PDCCH for the UE 100. This RRC message is a UE-specific RRC message, and may be, for example, an RRC Reconfiguration message. Here, the search space setting among the settings related to the PDCCH includes a search space period (also referred to as a PDCCH monitoring period), a search space offset (also referred to as a PDCCH monitoring offset), a search space duration (for example, the number of consecutive slots), a symbol for PDCCH monitoring, an aggregation level, a search space type, and a DCI format. Here, each of the search spaces (each of the search space settings) may be associated with one CORESET. In addition, the search space setting may be set for each of one or more DL BWPs. Here, the search space type may include a UE-specific search space (USS: UE-specific Search Space) and / or a UE common search space (CSS: Common Search Space).

[0032] There are two types of DCI formats: a scheduling DCI format used for scheduling a PDSCH or a PUSCH, and a non-scheduling DCI format not used for such scheduling. DCI transmitted in a scheduling DCI format is called a scheduling DCI, and DCI transmitted in a non-scheduling DCI format is called a non-scheduling DCI.

[0033] The scheduling DCI formats include downlink DCI formats (e.g., DCI format 1_0, DCI format 1_1, DCI format 1_2) used for PDSCH scheduling and uplink DCI formats (e.g., DCI format 0_0, DCI format 0_1, DCI format 0_2) used for PUSCH scheduling. The scheduling DCI may be a UE-specific DCI that is transmitted to each UE individually. For example, the scheduling DCI may be transmitted by applying an RNTI (Radio Network Temporary Identifier) ​​that is assigned to each UE individually.

[0034] On the other hand, the non-scheduled DCI format includes, for example, DCI format 2_0 and DCI format 2_6. The non-scheduled DCI may be DCI that can be simultaneously transmitted to a plurality of UEs 100. For example, the non-scheduled DCI may be transmitted by applying a common RNTI to the plurality of UEs 100.

[0035] In step S2, UE 100 starts monitoring the PDCCH in a search space set by base station 200. For example, DCI format 1_0, DCI format 0_0, DCI format 1_1, DCI format 0_1, DCI format 1_2, and DCI format 0_2 are set in UE 100. Then, UE 100 monitors the PDCCH (DCI) based on the setting. For example, base station 200 may set UE 100 to monitor DCI format 1_0 and DCI format 0_0 in a certain search space. Also, base station 200 may set UE 100 to monitor DCI format 1_1 and DCI format 0_1 ​​in a certain search space. Also, base station 200 may set UE 100 to monitor DCI format 1_2 and DCI format 0_2 in a certain search space. That is, for example, when a CSS is configured for a certain search space, the base station 200 may configure the UE 100 to monitor PDCCH candidates for DCI format 1_0 and DCI format 0_0. When a CSS is configured for a certain search space, the base station 200 may configure the UE 100 to monitor PDCCH candidates for DCI format 2_0. When a USS is configured for a certain search space, the base station 200 may configure the UE 100 to monitor PDCCH candidates for DCI format 1_0 and DCI format 0_0, or DCI format 1_1 and DCI format 0_1. When a USS is configured for a certain search space, the base station 200 may configure the UE 100 to monitor PDCCH candidates for DCI format 1_0 and DCI format 0_0, or DCI format 1_2 and DCI format 0_2.

[0036] In step S3, the UE 100 receives and detects DCI addressed to the UE from the base station 200. For example, the UE 100 receives and detects a DCI (C-RNTI) assigned to the UE 100 by the base station 200. 、 The base station 200 performs blind decoding of the PDCCH using the Modulation and Coding Scheme-C-RNTI (MCS-C-RNTI) or the Configured Scheduling-RNTI (CS-RNTI), and obtains the successfully decoded DCI as the DCI addressed to the base station 200. 、 CRC parity bits scrambled by the MCS-C-RNTI or CS-RNTI are added.

[0037] If the DCI indicates scheduling of the PDSCH, in step S4, the UE 100 receives downlink data from the base station 200 on the scheduled PDSCH.

[0038] If the DCI indicates scheduling of the PUSCH, in step S5, the UE 100 transmits uplink data to the base station 200 on the scheduled PUSCH.

[0039] (Outline of power saving technology) Next, an overview of PDCCH skipping according to this embodiment will be described with reference to Fig. 4. In the following, it is assumed that the UE 100 is in an RRC connected state.

[0040] First, UE 100 monitors a PDCCH provided at a predetermined period in a search space based on a search space setting set by base station 200. Such a PDCCH monitoring state is an example of a first state.

[0041] Secondly, the base station 200 transmits a skip instruction DCI instructing PDCCH skipping to the UE 100. The skip instruction DCI is an example of a switching instruction DCI. The skip instruction DCI is a scheduling DCI or a non-scheduling DCI, but in this embodiment, it is mainly assumed that the scheduling DCI is used as the skip instruction DCI.

[0042] Thirdly, the UE 100 skips monitoring the PDCCH for a predetermined period in response to receiving a skip command DCI from the base station 200. Such a PDCCH skipping state is an example of a second state (power saving state). The predetermined period for skipping monitoring the PDCCH may be set by higher layer signaling (RRC message). The predetermined period may be determined by a timer value (i.e., a setting value of a switching timer), or may be determined by the number of consecutive slots or the number of consecutive search spaces.

[0043] Such PDCCH skipping reduces the power consumption required for the UE 100 to monitor the PDCCH, thereby achieving dynamic power saving.

[0044] Next, with reference to FIG. 5, an overview of search space set switching according to this embodiment will be described.

[0045] First, base station 200 configures a plurality of search space sets, which are sets of settings related to search spaces, in UE 100 by higher layer signaling (RRC message). Such a set of settings related to search spaces is called a search space set (SSS) or a search space set group (SSSG), but will be mainly referred to as SSSG in the following. One SSSG includes one or more search space settings and is identified by an SSSG index. Here, base station 200 configures SSSG#0 (first search space set) in which a search space is provided at a predetermined period and SSSG#1 (second search space set) in which a search space is provided at a period longer than the predetermined period, in UE 100. Here, an example is shown in which base station 200 configures two SSSGs, SSSG#0 and SSSG#1, in UE 100, but three or more SSSGs may be configured in UE 100 for each of one or more BWPs (e.g., DL BWP). In addition, setting a plurality of BWPs (or three or more SSSGs) in UE 100 may mean setting a plurality of SSSGs (or three or more SSSGs) for one BWP. Setting a plurality of BWPs (or three or more SSSGs) in UE 100 may mean setting a plurality of SSSGs (or three or more SSSGs) for a plurality of BWPs.

[0046] Secondly, the UE 100 monitors the PDCCH provided at a predetermined cycle in the search space based on the SSSG #0. Such a state in which the SSSG #0 is applied is an example of the first state.

[0047] Third, the base station 200 transmits, to the UE 100, a switching instruction DCI instructing the SSSG switching. switching The instruction DCI may be a scheduling DCI or a non-scheduling DCI, but in this embodiment, it is mainly assumed that a scheduling DCI is used as a switching instruction DCI. That is, the base station 200 uses the scheduling DCI to instruct the UE 100 to switch from SSSG #0 to SSSG #1.

[0048] Fourth, UE 100 starts switching to SSSG #1 in response to receiving the switching instruction DCI. UE 100 performs switching to SSSG #1 at a symbol after a switching delay time (Switch delay) from the last symbol of the PDCCH in SSSG #0. Such a switching delay time is set in UE 100 by base station 200 through higher layer signaling (RRC message).

[0049] Fifth, the UE 100 monitors the PDCCH provided at a period longer than a predetermined period in the search space based on the SSSG #1. Such a state in which the SSSG #1 is applied is an example of the second state (power saving state).

[0050] By switching the search space set in this manner, the power consumption required for the UE 100 to monitor the PDCCH is reduced, and dynamic power saving can be achieved.

[0051] In addition, the base station 200 may instruct the switching from SSSG#1 to SSSG#0 by DCI, as in the case of switching from SSSG#0 to SSSG#1, or the UE 100 may switch from SSSG#1 to SSSG#0 using a timer. The timer value of such a switching timer is set in the UE 100 by the base station 200 by higher layer signaling (RRC message). In response to detection of the switching instruction DCI to SSSG#1, the UE 100 starts monitoring the PDCCH in SSSG#1, sets the value of the switching timer to the value set by the higher layer, and starts the switching timer. The UE 100 decrements the value of the switching timer, and when the switching timer expires, stops monitoring the PDCCH in SSSG#1, and starts monitoring the PDCCH in SSSG#0 after a switching delay time. Here, "#0" in SSSG#0 and "#1" in SSSG#1 indicate an index (also called a search space group ID) for a set (group) of search spaces. That is, one or more search space sets may be associated with a set (group) of search spaces identified by an index. For example, base station 200 may configure a set (group) of search spaces for UE 100 by configuring an index associated with the one or more search space sets. Here, in this embodiment, the name SSSG is merely an example, and any name may be used as long as the set (group) of search spaces is associated with one or more search space sets.

[0052] In the search space set switching, one SSSG set in the UE 100 is set to have no search space, and switching to the one SSSG is instructed by DCI, thereby realizing an operation similar to the above-mentioned PDCCH skipping. In addition, another SSSG set in the UE 100 can be set to have a long search space period, and switching to the one SSSG can be instructed by DCI. In order to realize such an operation, it is necessary to set a total of three SSSGs in the UE 100, including an SSSG with a normal search space period, an SSSG with no search space, and an SSSG with a long search space period. In addition, when an SSSG with a longer search space period is set in the UE 100, it is necessary to set a total of four SSSGs in the UE 100. By setting such various SSSGs in the UE 100 and instructing switching of the SSSGs by DCI, flexible power saving can be realized.

[0053] Next, the DRX and power saving state according to this embodiment will be described with reference to FIG.

[0054] When DRX is configured in the UE 100, the UE 100 utilizes a DRX operation to discontinuously monitor the PDCCH. Specifically, the DRX operation is controlled by the following DRX parameters:

[0055] DRX cycle: Specifies the period during which the UE 100 wakes up.

[0056] On-duration: This is the period during which the UE 100 waits to receive the PDCCH after waking up. If the UE 100 successfully decodes the PDCCH, the UE 100 remains in the awake state and starts an inactivity timer.

[0057] Inactivity timer: This is the time period during which the UE 100 waits after the last successful PDCCH decoding, and specifies the period during which the UE 100 goes to sleep again if the PDCCH decoding fails.

[0058] · Retransmission timer: Specifies the time interval during which retransmissions are expected.

[0059] In this way, since the UE 100 configured with DRX does not need to monitor the PDCCH in the sleep state (i.e., the reception off period), the power consumption of the UE 100 can be reduced. Meanwhile, the UE 100 waits to receive the PDCCH during the active time and monitors the PDCCH in the search space. The active time is the time during which any of the on duration timer (drx-onDurationTimer), the inactivity timer (drx-InactivityTimer), the downlink retransmission timer (drx-RetransmissionTimerDL), and the uplink retransmission timer (drx-RetransmissionTimerUL) is operating. The downlink retransmission timer (drx-RetransmissionTimerDL) and the uplink retransmission timer (drx-RetransmissionTimerUL) are examples of retransmission-related timers for DRX operation in the RRC connected state.

[0060] By performing the above-mentioned PDCCH skipping or search space set switching within the active time of DRX, it is possible to dynamically switch to a power saving state within the active time, thereby achieving a greater power consumption reduction effect than the power consumption reduction achieved by DRX.

[0061] Here, when a scheduling DCI is used as a switching instruction DCI for instructing switching to a power saving state, data retransmission processing by HARQ may be required in addition to data transmission and reception between the base station 200 and the UE 100. Therefore, if the UE 100 immediately starts switching to the power saving state in response to reception of a scheduling DCI for instructing switching to the power saving state, there is a concern that the HARQ processing may not be performed appropriately.

[0062] Furthermore, UE 100 in the RRC connected state transmits a sounding reference signal (SRS) to base station 200, measures channel state information (CSI), and reports CSI to base station 200. The period during which UE 100 is in the power saving state is considered to be a period during which data transmission and reception are temporarily not performed, and therefore it is desirable to be able to reduce power consumption required for SRS transmission, CSI measurement, and CSI reporting.

[0063] (Configuration of user device) Next, a configuration of the UE 100 according to this embodiment will be described with reference to Fig. 7. The UE 100 includes a communication unit 110 and a control unit 120.

[0064] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving radio signals to and from the base station 200. The communication unit 110 has at least one receiver and at least one transmitter. The receiver and the transmitter may be configured to include an antenna and an RF circuit. The antenna converts a signal into radio waves and radiates the radio waves into space. The antenna also receives radio waves in space and converts the radio waves into a signal. The RF circuit performs analog processing of the signal transmitted and received via the antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, and the like.

[0065] The control unit 120 performs various controls in the UE 100. The control unit 120 controls communication with the base station 200 via the communication unit 110. The above-mentioned and below-mentioned operations of the UE 100 may be operations controlled by the control unit 120. The control unit 120 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute a program to perform the operation of the control unit 120. The control unit 120 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a protocol stack of the RAN. The memory stores a program executed by the processor, parameters related to the program, and data related to the program. The memory may include at least one of a ROM (Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory), a RAM (Random Access Memory), and a flash memory. All or a part of the memory may be included in the processor.

[0066] In the UE 100 according to this embodiment, in a first state in which the PDCCH is monitored in a search space, the communication unit 110 receives a scheduling DCI indicating radio resources (specifically, PDSCH resources, PUSCH resources) allocated to the UE 100 from the base station 200 on the PDCCH. The control unit 120 controls the communication unit 110 to receive or transmit data using the radio resources based on the scheduling DCI. When the communication unit 110 receives a scheduling DCI instructing switching to a second state (for example, a power saving state) in which a setting related to the search space is different from the first state, the control unit 120 suspends the start of switching while a retransmission-related timer associated with the HARQ processing for the data is operating. This makes it possible to appropriately perform the HARQ processing even when the scheduling DCI is used as a switching instruction to the power saving state. Details of such an operation will be described in a first operation example described later.

[0067] In the UE 100 according to this embodiment, the control unit 120 performs predetermined control to control at least one operation among SRS transmission to the base station 200, CSI measurement, and CSI reporting to the base station 200 in a first state in which the PDCCH is monitored in a search space. The communication unit 110 receives a switching instruction DCI on the PDCCH from the base station 200 to instruct switching to a second state (for example, a power saving state) in which the setting related to the search space is different from the first state. In response to receiving the switching instruction DCI, the control unit 120 performs control different from the predetermined control for at least one operation among SRS transmission, CSI measurement, and CSI reporting. This makes it possible to apply control optimized for the power saving state to SRS transmission, CSI measurement, and CSI reporting. Therefore, it is possible to realize further power saving while reducing the power consumption required for monitoring the PDCCH. Details of such operations will be described in a second operation example described later.

[0068] The first state may be a state in which a first SSSG is applied from among a plurality of SSSGs set in the UE 100 by the base station 200. The second state may be a state in which a second SSSG different from the first SSSG is applied from among the plurality of SSSGs. The communication unit 110 may receive a scheduling DCI instructing switching from the first SSSG to the second SSSG as a switching instruction. The first state may be a state in which a PDCCH provided at a predetermined period is monitored in a search space. The second state may be a state in which a PDCCH is monitored in a search space provided at a period longer than the predetermined period, or a state in which monitoring of the PDCCH is skipped. The second state may be realized by the above-mentioned second SSSG.

[0069] In the UE 100 according to this embodiment, the communication unit 110 receives from the base station 200 correspondence information indicating a correspondence between each index of one or more SSSGs set in the UE 100 and a value set in an information field in a switching instruction DCI instructing switching of the SSSG applied by the UE 100. The one or more SSSGs include at least one of an SSSG that periodically monitors the PDCCH and an SSSG that skips monitoring the PDCCH. When the communication unit 110 receives a switching instruction DCI on the PDCCH, the control unit 120 controls monitoring of the PDCCH using an SSSG having an index corresponding to a value set in an information field in the received switching instruction DCI based on the correspondence information. This makes it possible to realize flexible power saving using various search space sets. In addition, one information field provided in the switching instruction DCI can specify one of multiple search space sets with different search space periods, or specify a search space set that does not monitor the PDCCH, so that an increase in the size of the DCI can be suppressed even when various search space sets are used. Such an operation will be described in detail in a third operation example described later.

[0070] In the UE 100 according to this embodiment, the communication unit 110 receives a switching instruction DCI from the base station 200, which instructs switching to one SSSG among three or more SSSGs set in the UE 100. The control unit 120 may start a timer that determines the duration for which the one SSSG is applied based on the reception of the switching instruction DCI. When the timer expires, the UE 100 (control unit 120) switches to a default SSSG set by the base station 200 among the three or more SSSGs. This makes it possible to realize flexible power saving using various search space sets. Specifically, when the UE 100 switches the SSSG on a timer basis, even if three or more SSSGs are set in the UE 100, the base station 200 can grasp the SSSG to which the SSSG is switched. It becomes possible to switch to various SSSGs on a timer basis. Details of such an operation will be described in a fourth operation example described later.

[0071] (Base station configuration) Next, the configuration of the base station 200 according to this embodiment will be described with reference to Fig. 8. The base station 200 has a communication unit 210, a network interface 220, and a control unit 230.

[0072] The communication unit 210, for example, receives a wireless signal from the UE 100 and transmits a wireless signal to the UE 100. The communication unit 210 may include one or more receivers that receive the wireless signal and one or more transmitters that transmit the wireless signal.

[0073] The network interface 220 transmits and receives signals to and from the network. For example, the network interface 220 receives signals from adjacent base stations connected via an Xn interface, which is an interface between base stations, and transmits signals to the adjacent base stations. The network interface 220 also receives signals from the core network device 300 connected via an NG interface, and transmits signals to the core network device 300.

[0074] The control unit 230 performs various controls in the base station 200. For example, the control unit 230 controls communication with the UE 100 via the communication unit 210. The control unit 230 also controls communication with a node (for example, an adjacent base station, the core network device 300) via the network interface 220. The operations of the base station 200 described above and below may be operations under the control of the control unit 230. The control unit 230 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute a program to perform the operation of the control unit 230. The control unit 230 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a protocol stack of the RAN. The memory stores the program executed by the processor, parameters related to the program, and data related to the program. All or a part of the memory may be included in the processor.

[0075] A base station 200 according to this embodiment performs wireless communication with a UE 100 that monitors a PDCCH in a search space. A communication unit 210 transmits, to the UE 100, correspondence relationship information indicating a correspondence relationship between each index of one or more SSSGs set in the UE 100 and a value set in an information field in a switching instruction DCI that instructs switching of an SSSG applied in the UE 100. The one or more SSSGs include at least one of an SSSG that periodically monitors a PDCCH and an SSSG that skips monitoring of the PDCCH.

[0076] In the base station 200 according to this embodiment, the communication unit 210 transmits to the UE 100 a switching instruction DCI instructing the UE 100 to switch to one of the three or more SSSGs set in the UE 100. The control unit 230 may set to the UE 100 a default SSSG to be used as a switching destination when a timer that determines the duration for which the one SSSG is applied expires.

[0077] (First operation example) Next, a first operation example according to this embodiment will be described with reference to FIG.

[0078] As described above, when using a scheduling DCI as a switching instruction DCI, since a HARQ process, which is a data retransmission process by HARQ, may be necessary, there is a concern that if the UE 100 immediately starts switching to the power saving state, the HARQ process may not be performed appropriately. Therefore, the UE 100 (control unit 120) suspends the start of switching instructed by the switching instruction DCI while a retransmission-related timer associated with the HARQ process for data scheduled by the switching instruction DCI (scheduling DCI) is operating.

[0079] 9, in step S11, UE 100 (communication unit 110) receives a scheduling DCI as a switching instruction DCI on a PDCCH from base station 200. Such a scheduling DCI may include an information field indicating a switching destination SSSG in addition to an information field indicating a PDSCH resource or a PUSCH resource allocated to UE 100.

[0080] In step S12, the UE 100 (communication unit 110) receives or transmits data scheduled by the scheduling DCI. For example, the UE 100 (communication unit 110) receives downlink data using the assigned PDSCH resource, or transmits uplink data using the assigned PUSCH resource. When the UE 100 (communication unit 110) receives downlink data, the UE 100 (control unit 120) attempts data decoding of the received downlink data, and feeds back HARQ feedback indicating whether the data decoding has been successful, i.e., ACK or NACK, to the base station 200. When the UE 100 (communication unit 110) transmits uplink data, the UE 100 (control unit 120) receives HARQ feedback indicating whether the base station 200 has successfully decoded the uplink data, i.e., ACK or NACK, from the base station 200. The UE 100 (control unit 120) manages the HARQ process for each piece of data to be received or transmitted using a timer, and continues the HARQ process until data decoding of the data is completed.

[0081] In step S13, the UE 100 (control unit 120) determines whether or not any of the following retransmission related timers used in the HARQ process is in operation.

[0082] Downlink HARQ RTT timer (drx-HARQ-RTT(Round Trip Time)-TimerDL) This timer is used for HARQ processing of downlink data and specifies the minimum period until downlink allocation for HARQ retransmission expected by the MAC entity of UE 100. UE 100 (control unit 120) starts the downlink HARQ RTT timer in response to transmission of HARQ feedback for downlink data. UE 100 (control unit 120) does not need to monitor the PDCCH while the downlink HARQ RTT timer is operating.

[0083] Downlink retransmission timer (drx-RetransmissionTimerDL) This timer is used for HARQ processing of downlink data and specifies the maximum period until receiving downlink retransmission. When the downlink HARQ RTT timer expires, the UE 100 (control unit 120) starts the downlink retransmission timer if the downlink data decoding is not successful. During the operation of the downlink retransmission timer, the UE 100 (control unit 120) monitors the PDCCH and waits for retransmission data.

[0084] Uplink HARQ RTT timer (drx-HARQ-RTT-TimerUL) This timer is used for HARQ processing of uplink data and specifies the minimum period until the MAC entity of the UE 100 receives a HARQ retransmission grant. The UE 100 (control unit 120) starts the downlink retransmission timer in response to transmission of uplink data. The UE 100 (control unit 120) does not need to monitor the PDCCH while the uplink HARQ RTT timer is operating.

[0085] Uplink retransmission timer (drx-RetransmissionTimerUL) This timer is used for the HARQ process of uplink data and specifies the maximum period until an uplink retransmission permission is received. The UE 100 (control unit 120) starts the uplink retransmission timer when the uplink HARQ RTT timer expires. The UE 100 (control unit 120) monitors the PDCCH while the uplink retransmission timer is operating.

[0086] If any of these retransmission-related timers is operating (step S13: YES), in step S14, the UE 100 (control unit 120) suspends the start of switching instructed by the switching instruction DCI received in step S11.

[0087] On the other hand, if none of the retransmission related timers are operating (step S13: NO), in step S15, the UE 100 (control unit 120) starts or executes the switching instructed by the switching instruction DCI received in step S11. For example, the UE 100 (control unit 120) may execute the SSSG switching from the first slot after the retransmission related timers expire.

[0088] In this way, in the first operation example, the period during which the retransmission-related timer is operating constitutes at least a part of the switch delay of the switch instructed by the switch instruction DCI. Note that, when the switch delay is set by higher layer signaling (RRC message), the UE 100 (control unit 120) may suspend the start of the switch instructed by the switch instruction DCI during the period during which the retransmission-related timer is operating, even if the switch delay set by the higher layer signaling has elapsed.

[0089] The switching delay time may also include a period during which a retransmission-related timer is running, such as:

[0090] The duration of the drx-HARQ-RTT-TimerDL started for the corresponding HARQ process at the first symbol after the end of DL HARQ feedback transmission: The duration of the drx-RetransmissionTimerDL, which is started if the corresponding HARQ process of the first symbol after the drx-HARQ-RTT-TimerDL expires is not successfully decoded: The duration of the running drx-HARQ-RTT-TimerUL started for the corresponding HARQ process at the first symbol after the end of the first transmission (in a bundle) of the corresponding PUSCH transmission: ·The duration of the running drx-RetransmissionTimerUL, started for the corresponding HARQ process at the first symbol after the expiration of the drx-HARQ-RTT-TimerUL.

[0091] Furthermore, when UE 100 (control unit 120) is executing a plurality of HARQ processes, if at least one retransmission-related timer of the plurality of HARQ processes is operating, the initiation of switching instructed by the switching instruction DCI may be suspended. For example, UE 100 may execute SSSG switching based on expiration of drx-RetransmissionTimerDL corresponding to all HARQ processes and / or expiration of drx-RetransmissionTimerUL corresponding to all HARQ processes (for example, from the first slot after expiration).

[0092] In addition, UE 100 (control unit 120) may perform the above operation when receiving a configured DL assignment (i.e., a downlink DCI format having a CRC scrambled with the CS-RNTI) and / or a configured UL grant (i.e., an uplink DCI format having a CRC scrambled with the CS-RNTI).

[0093] In addition, in the first operation example, various existing timers for DRX are used, but the present invention is not limited to this, and timers used for HARQ processing and retransmission processing for PDCCH skipping and / or SSSG switching set in a higher layer may be used. Such timers are, for example, DCIbasedPowerSaving-HARQ-RTT-TimerDL, DCIbasedPowerSaving-HARQ-RTT-TimerUL, DCIbasedPowerSaving-RetransmissionTimerDL, DCIbasedPowerSaving-RetransmissionTimerUL, etc. Here, DCIbasedPowerSaving-HARQ-RTT-TimerDL is an example of a downlink HARQ RTT timer. DCIbasedPowerSaving-HARQ-RTT-TimerUL is an example of an uplink HARQ RTT timer. DCIbasedPowerSaving-RetransmissionTimerDL is an example of a downlink retransmission timer. DCIbasedPowerSaving-RetransmissionTimerUL is an example of an uplink retransmission timer.

[0094] Next, a first operation example according to this embodiment will be described with reference to FIG. 10, focusing on the downlink.

[0095] In step S101, the UE 100 (communication unit 110) receives downlink scheduling DCI as a switching instruction DCI on the PDCCH. The downlink scheduling DCI is DCI that allocates radio resources (i.e., PDSCH resources) for downlink data. The UE 100 (communication unit 110) receives downlink data from the base station 200 using the PDSCH resources allocated by the downlink scheduling DCI. The UE 100 (control unit 120) attempts to decode the received downlink data.

[0096] In step S102, the UE 100 (communication unit 110) transmits, to the base station 200, HARQ feedback indicating whether or not the downlink data received in step S102 has been successfully decoded.

[0097] In step S103, the UE 100 (control unit 120) starts a downlink HARQ RTT timer in response to transmission of HARQ feedback corresponding to the downlink data. The UE 100 (control unit 120) suspends the start of switching instructed by the switching instruction DCI during the operation of the downlink HARQ RTT timer.

[0098] If the downlink HARQ RTT timer has expired (step S104: YES), in step S105, the UE 100 (control unit 120) determines whether the decoding of the downlink data has been successful. If the decoding of the downlink data has been successful (step S105: YES), in step S106, the UE 100 (control unit 120) starts the switching instructed by the switching instruction DCI.

[0099] On the other hand, if the downlink data has not been successfully decoded (step S105: NO), in step S107, the UE 100 (control unit 120) starts a downlink retransmission timer in response to expiration of the downlink HARQ RTT timer. During the operation of the downlink retransmission timer, the UE 100 (control unit 120) monitors the PDCCH and suspends the start of switching instructed by the switching instruction DCI.

[0100] If the downlink retransmission timer has expired (step S108: YES), in step S106, the UE 100 (control unit 120) starts the switching instructed by the switching instruction DCI. If retransmission data is received from the base station 200 while the downlink retransmission timer is operating, the UE 100 (control unit 120) may stop the downlink retransmission timer and return the process to step S102.

[0101] Next, a first operation example according to this embodiment will be described with reference to FIG. 11, focusing on the uplink.

[0102] In step S201, the UE 100 (the communication unit 110) receives an uplink scheduling DCI as a switching instruction DCI on a PDCCH. The uplink scheduling DCI is DCI that allocates radio resources (i.e., PUSCH resources) for uplink data.

[0103] In step S202, the UE 100 (communication unit 110) transmits uplink data to the base station 200 by using the PUSCH resource allocated by the uplink scheduling DCI.

[0104] In step S203, the UE 100 (control unit 120) starts an uplink HARQ RTT timer in response to the transmission of uplink data. The UE 100 (control unit 120) suspends the start of switching instructed by the switching instruction DCI while the uplink HARQ RTT timer is operating.

[0105] If the uplink HARQ RTT timer has expired (step S204: YES), in step S205, the UE 100 (control unit 120) starts an uplink retransmission timer. During the operation of the uplink retransmission timer, the UE 100 (control unit 120) monitors the PDCCH and suspends the start of switching instructed by the switching instruction DCI.

[0106] If the uplink retransmission timer has expired (step S206: YES), in step S207, the UE 100 (control unit 120) starts the switching instructed by the switching instruction DCI.

[0107] In this way, according to the first operation example of the present embodiment, the UE 100 that has received the scheduling DCI as a switching instruction suspends the start of switching while a retransmission-related timer associated with the HARQ process for the data scheduled by the scheduling DCI is in operation. This makes it possible to appropriately perform the HARQ process even when the scheduling DCI is used as a switching instruction.

[0108] In the first operation example, CSI reporting to base station 200 may be taken into consideration. For example, when UE 100 that has received a switching instruction DCI is instructed by a scheduling DCI to non-periodically report CSI to base station 200, UE 100 (control unit 120) may transmit a CSI report to base station 200 in a scheduled PUSCH, and may suspend initiation of switching instructed by the switching instruction DCI until this CSI report is performed. Then, UE 100 (control unit 120) may start switching instructed by the switching instruction DCI in response to transmitting the CSI report in the scheduled PUSCH. Details of CSI reporting will be described in a second operation example described later.

[0109] (Second operation example) Next, a second operation example according to this embodiment will be described with reference to FIG.

[0110] As described above, since the period during which UE 100 is in the power saving state is considered to be a period during which data transmission and reception is temporarily not performed, it is desirable to reduce the power consumption required for SRS transmission, CSI measurement, and CSI reporting.

[0111] Here, SRS transmission refers to an operation of transmitting an SRS, which is an uplink physical signal for channel estimation used by the base station 200 to estimate the uplink channel state, to the base station 200, and the UE 100 transmits the SRS according to the setting from the base station 200. The SRS report is an operation for uplink link adaptation. The link adaptation is to adapt the modulation and coding scheme (MCS) applied to data transmission to the channel state. During the period when the UE 100 is in the power saving state, there is little need to perform uplink link adaptation, so the SRS transmission is suppressed.

[0112] CSI measurement refers to an operation of measuring a reference signal used for estimating a downlink channel state, and UE 100 performs CSI measurement according to a setting from base station 200. For example, UE 100 performs CSI measurement based on at least one of a channel state information reference signal (CSI-RS) and a synchronization signal / physical broadcast channel (SS / PBCH) block transmitted by base station 200. CSI reporting refers to an operation of transmitting a CSI report indicating a channel state estimated according to a result of CSI measurement to base station 200, and UE 100 performs CSI reporting according to a setting from base station 200. For example, the channel state includes one or more of a channel quality indicator (CQI), a rank indicator (RI), a precoding matrix indicator (PMI), a SS / PBCH block resource indicator (SSBRI), a CSI-RS resource indicator (CRI), a layer indicator (LI), and a layer 1 reference signal received power (L1-RSRP). The CSI reporting may be performed on a PUCCH or a PUSCH. The CSI measurement and the CSI reporting are operations for downlink link adaptation. During a period in which the UE 100 is in a power saving state, the need to perform downlink link adaptation is low, and therefore, the CSI measurement and the CSI reporting are suppressed.

[0113] As shown in FIG. 12, in step S301, in a first state in which the UE 100 (control unit 120) monitors the PDCCH in a search space, the UE 100 (control unit 120) performs a predetermined control to control at least one operation of SRS transmission to the base station 200, CSI measurement, and CSI reporting to the base station 200. In the first state, the UE 100 (control unit 120) may periodically perform at least one operation of SRS transmission, CSI measurement, and CSI reporting. For example, in the first state, the UE 100 (control unit 120) performs at least one operation of periodic SRS transmission and periodic CSI reporting. The periodic SRS transmission may include semi-persistent SRS transmission. The periodic CSI reporting may include semi-persistent CSI reporting on the PUCCH or PUSCH.

[0114] In step S302, the UE 100 (communication unit 110) receives a switching instruction DCI on the PDCCH, which instructs switching to a second state (for example, a power saving state) in which a setting related to a search space is different from the first state. In the second operation example, the switching instruction DCI is not limited to the above-mentioned scheduling DCI, and may be a non-scheduling DCI. The switching instruction DCI may include an information field indicating a switching destination SSSG.

[0115] In step S303, in response to receiving the switching command DCI, the UE 100 (control unit 120) performs control different from the predetermined control for at least one operation among the SRS transmission, the CSI measurement, and the CSI report.

[0116] For example, the UE 100 (control unit 120) stops at least one of the operations of SRS transmission, CSI measurement, and CSI reporting within a switch delay from the first state to the second state. The UE 100 (control unit 120) may stop periodic SRS transmission and periodic CSI reporting within the switch delay time. Such control is referred to as "P switch During the switching delay time consisting of symbols, the UE Periodic SRS transmission and semi-persistent SRS transmission Semi-persistent CSI configured for PUSCH Periodic CSI reporting, which is L1-RSRP, on PUCCH when ps-TransmitPeriodicL1-RSRP is not configured with the value true. · If ps-TransmitOtherPeriodicCSI is not configured with the value true, it may be expressed as "It is not expected to perform periodic CSI reporting other than L1-RSRP on PUCCH."

[0117] In the second operation example, the first state may be a state in which a PDCCH provided at a predetermined period is monitored in a search space, and the second state may be a state in which monitoring of the PDCCH is skipped (PDCCH skipping state) (see FIG. 4). In the second state, UE 100 (control unit 120) may not need to perform at least one of the operations of SRS transmission, CSI measurement, and CSI reporting.

[0118] In the second operation example, the first state may be a state in which a PDCCH provided at a predetermined period is monitored in a search space, and the second state may be a state in which a PDCCH is monitored in a search space provided at a period longer than the predetermined period (see FIG. 5). Switching from the first state to the second state may be realized by SSSG switching. In the second state, UE 100 (control unit 120) may perform at least one of the operations of SRS transmission, CSI measurement, and CSI reporting only in the time interval of the search space.

[0119] For example, in the second state, the UE 100 (control unit 120) may perform aperiodic SRS transmission only in monitoring slots that are time periods of the search space. Such control may be expressed as "a UE for which SSSG switching is configured by higher layer signaling does not expect SRS resources to be available in slots other than the corresponding monitoring slots to trigger aperiodic SRS transmission when the period of the search space is longer than a predetermined value (e.g., 80 milliseconds)."

[0120] Furthermore, in the second state, UE 100 (control unit 120) may perform CSI measurement only in monitoring slots, which are time intervals of the search space. Such control may be expressed as "a UE configured with SSSG switching by higher layer signaling excludes slots other than the monitoring slot corresponding to the search space from the most recent CSI measurement opportunity for CSI reporting." Also, such control may be expressed as "a UE configured with SSSG switching by higher layer signaling does not expect CSI-RS resources to be available in slots other than the corresponding monitoring slot when the period of the search space is longer than a predetermined value (e.g., 80 milliseconds)."

[0121] In this way, according to the second operation example of the present embodiment, the UE 100 that has received the switching command DCI performs control for at least one of the operations of SRS transmission, CSI measurement, and CSI reporting, in response to reception of the switching command DCI, that is different from the control performed before receiving the switching command DCI. This makes it possible to apply control optimized for a power saving state, for example, control optimized for an extended search space period, to SRS transmission, CSI measurement, and CSI reporting, thereby making it possible to reduce power consumption required for monitoring the PDCCH and to achieve further power saving.

[0122] (Third operation example) Next, a third operation example according to this embodiment will be described with reference to FIG.

[0123] In the third operation example, an operation of performing power saving by SSSG switching is assumed. Specifically, one or more SSSGs can be set to UE 100 from various SSSGs including multiple SSSGs having different search space periods and an SSSG having no search space, and flexible power saving is realized by instructing the switching of the SSSG by DCI.

[0124] As shown in Fig. 13, in step S401, the base station 200 (communication unit 210) transmits one or more RRC messages to the UE 100. The one or more RRC messages may include a dedicated RRC message (e.g., an RRC Reconfiguration message) transmitted individually to the UE. The UE 100 (communication unit 110) receives the RRC message.

[0125] The RRC message includes correspondence relationship information indicating a correspondence relationship between each index of one or more SSSGs set in the UE 100 and a value set in an information field (hereinafter referred to as an "SSSG information field") in a switching instruction DCI that instructs switching of the SSSG applied by the UE 100. The one or more SSSGs include at least one of an SSSG for periodically monitoring the PDCCH and an SSSG for skipping monitoring the PDCCH.

[0126] For example, when four SSSGs are configured in the UE 100, the correspondence information includes information such as "SSSG index #0: value "00", "SSSG index #1: value "01", "SSSG index #2: value "10", and "SSSG index #3: value "11". The base station 200 is not limited to configuring these four SSSGs in the UE 100 all at once, and may configure the four SSSGs in the UE 100 in two separate sessions, for example, two SSSGs each. The value set in the SSSG information field may be configured in a bitmap format. For example, the position of the bit that is "1" (code point) may be associated with the SSSG index, such as "SSSG index #0: value "1000", "SSSG index #1: value "0100", "SSSG index #2: value "0010", and "SSSG index #3: value "0001".

[0127] The RRC message further includes search space configuration information associated with each of the SSSG indices. The search space configuration information includes one or more search space configurations. Each search space configuration includes a search space period, a search space offset, a search space duration (e.g., a number of consecutive slots), a symbol for PDCCH monitoring, an aggregation level, a type of search space, and a DCI format, etc.

[0128] For example, the search space configuration information associated with SSSG index #0 is information for setting a first search space period as the search space period. The search space configuration information associated with SSSG index #1 is information for setting a second search space period as the search space period. The search space configuration information associated with SSSG index #2 is information for setting a third search space period as the search space period. The search space configuration information associated with SSSG index #4 is information indicating that no search space is set. In other words, SSSG index #4 is associated with search space configuration information indicating PDCCH skipping.

[0129] The RRC message may include field setting information indicating the presence or absence of an SSSG information field for each of one or more DCI formats. The switching instruction DCI is a DCI having a DCI format indicated by the field setting information that the SSSG information field is present. The presence or absence (presence / absence) of the SSSG information field may be set commonly or independently for the non-scheduling DCI and / or the scheduling DCI. The presence or absence (presence / absence) of the SSSG information field may be set commonly for DCI format 1_1 and DCI format 0_1, and commonly for DCI format 1_2 and DCI format 0_2.

[0130] The RRC message may include bit number setting information indicating the number of bits of the SSSG information field for one or more DCI formats. The number of bits of the SSSG information field may be directly set for the non-scheduling DCI and / or the scheduling DCI, either in common or independently. The number of bits of the SSSG information field may be set in common for DCI format 1_1 and DCI format 0_1, and / or in common for DCI format 1_2 and DCI format 0_2. For example, an SSSG information field of up to 2 bits may be set for DCI format 1_1 and / or DCI format 0_1, and / or an SSSG information field of 1 bit may be set for DCI format 1_2 and DCI format 0_2.

[0131] The RRC message may include a timer setting value of a switching timer for each of one or more SSSGs. Details of such a switching timer will be described in a fourth operation example below.

[0132] In step S402, the UE 100 (control unit 120) stores the information set by the base station 200.

[0133] In step S403, the base station 200 (communication unit 210) may transmit to the UE 100 a MAC CE (hereinafter referred to as an "SSSG state selection MAC CE") that specifies activation or deactivation of an SSSG for each SSSG index. The UE 100 (communication unit 110) receives the SSSG state selection MAC CE. The SSSG state selection MAC CE instructs activation / deactivation for each SSSG index. The activated SSSG becomes valid as a switching destination SSSG, and the deactivated SSSG becomes invalid as a switching destination SSSG. However, deactivation may be prohibited for the default SSSG. The default SSSG will be described in a fourth operation example below.

[0134] For example, the SSSG state selection MAC CE is identified by a MAC subheader having a LCID defined for the SSSG state selection MAC CE. The SSSG state selection MAC CE may include a "cell ID field" indicating a serving cell to which the SSSG state selection MAC CE applies. The SSSG state selection MAC CE may include a "Ti field" indicating activation / deactivation for each entry "i" of the SSSG index list consisting of SSSG indices. The "Ti field" includes "T0 field" to "T(n-1) field", and is set to a value of "1" for the SSSG to be activated. Here, "n" indicates the maximum number of SSSGs that can be activated, for example, "4". Assuming that SSSG index #0 is activated, SSSG index #1 is deactivated, SSSG index #2 is activated, and SSSG index #3 is deactivated, the "T0 field" is set to "1", the "T1 field" is set to "0", the "T2 field" is set to "1", and the "T3 field" is set to "1", respectively.

[0135] The SSSG information field may be configured in a bitmap format for only the activated SSSGs. For example, the first activated SSSG is mapped to code point 1 in the SSSG information field, and the second activated SSSG is mapped to code point 2 in the SSSG information field. Assuming that SSSG index #0 is activated, SSSG index #1 is deactivated, SSSG index #2 is activated, and SSSG index #3 is deactivated, the number of bits in the SSSG information field is "2", with "10" indicating SSSG index #0 and "01" indicating SSSG index #2.

[0136] In step S404, base station 200 (communication unit 210) transmits a switching instruction DCI having an SSSG information field to UE 100 on a PDCCH. UE 100 (communication unit 110) receives the switching instruction DCI on a PDCCH. UE 100 (control unit 120) may determine whether or not the DCI format of the detected DCI corresponds to the switching instruction DCI, based on field setting information set by base station 200.

[0137] In step S405, the UE 100 (control unit 120) acquires the value set in the SSSG information field of the switching command DCI received in step S404. The UE 100 (control unit 120) sets the number of bits in the SSSG information field based on the number of bits setting information set by the base station 200. decision Alternatively, the UE 100 (control unit 120) may set the number of bits in the SSSG information field based on the number of SSSG indexes set in the UE 100 (i.e., the number of entries in the set SSSG index list). decision For example, if the number of SSSG indexes set in the UE 100 is "I", the UE 100 (control unit 120) calculates the number of bits in the SSSG information field by rounding up the decimal point of log2(I) to an integer value, and identification You may do so.

[0138] In step S406, UE 100 (control unit 120) switches to an SSSG having an SSSG index corresponding to the value set in the SSSG information field in the received switching instruction DCI based on the correspondence relationship information set from base station 200, and monitors the PDCCH according to the switching destination SSSG. For example, in the example of Fig. 13, when the value set in the SSSG information field is "11", UE 100 (control unit 120) determines that an instruction to switch to the SSSG with SSSG index #3 has been issued, and switches to the SSSG with SSSG index #3.

[0139] Next, a first configuration example of information elements included in an RRC message in the third operation example will be described with reference to Figs.

[0140] As shown in Figure 14, the RRC message includes a PDCCH configuration (PDCCH-Config) information element, which is used to configure UE-specific PDCCH parameters, such as a control resource set (CORESET), a search space, and additional parameters for acquiring the PDCCH.

[0141] The PDCCH configuration (PDCCH-Config) information element may include an SSSG addition / modification list (searchSpaceSetToAddModList) and / or an SSSG release list (searchSpaceSetToReleaseList). The SSSG addition / modification list is a list of SSSGs to be configured in UE 100 (SEQUENCE (SIZE (1..maxNrofSearchSpaceSets-r17)) OF SearchSpaceSet-r17). The SSSG release list is a list of SSSGs to be released in UE 100 (SEQUENCE (SIZE (1..maxNrofSearchSpaceSets-r17)) OF SearchSpaceSet-r17). Here, "maxNrofSearchSpaceSets-r17" indicates the maximum number of configurable SSSGs.

[0142] As shown in Figure 15, "SearchSpaceSet-r17", which constitutes each entry of the SSSG addition / modification list and the SSSG release list, includes "SearchSpaceSetId-r17", which is an index of the SSSG, and "searcSpaces-r17", which are each search space setting included in this SSSG. "searcSpaces-r17" is composed of a list of search space IDs of each search space setting included in this SSSG (SEQUENCE (SIZE (0..maxNrofSearchSpaces-r17)) OF SearchSpaceId). "SearchSpaceSetId-r17", which is an index of the SSSG, has the number of bits "0..maxNrofSearchSpaceSets-1-r17".

[0143] Next, a second configuration example of the information element included in the RRC message in the third operation example will be described with reference to Fig. 16 and Fig. 17. The second configuration example indicates, for each search space setting, the SSSG to which the search space setting belongs.

[0144] As shown in Fig. 16, the PDCCH configuration (PDCCH-Config) information element can include a search space addition / modification list (searchSpacesToAddModListExt2-r17). The search space addition / modification list is a list consisting of "SearchSpaceExt2-r17" from 1 to 10.

[0145] As shown in FIG. 17, the search space setting (SearchSpace) information element includes "searchSpaceSetIdList-r17" which is a list of indices of SSSGs to which this search space setting is associated. One search space setting can be associated with multiple SSSGs. For an SSSG to which none of the search space settings configured in the UE 100 is associated, the UE 100 does not monitor the PDCCH while using the SSSG.

[0146] In this way, according to the third operation example, correspondence information indicating a correspondence between each SSSG index of one or more SSSGs set in the UE 100 and a value set in an SSSG information field in a switching instruction DCI instructing switching of an SSSG applied by the UE 100 is received from the base station 200. The one or more SSSGs include at least one of an SSSG that periodically monitors a PDCCH and an SSSG that skips monitoring of a PDCCH. This makes it possible to realize flexible power saving using various SSSGs. In addition, since one SSSG information field provided in the switching instruction DCI can specify one of multiple SSSGs with different search space periods or specify an SSSG that does not monitor a PDCCH, an increase in the size of the DCI can be suppressed even when various SSSGs are used.

[0147] (Fourth operation example) Next, a fourth operation example according to the present embodiment will be described with reference to Fig. 18. In the fourth operation example, it is assumed that the UE 100 switches the SSSG on a timer basis, and three or more SSSGs may be set in the UE 100.

[0148] In a fourth operation example, the base station 200 (control unit 230) may set one of the SSSGs set in the UE 100 as a default SSSG in the UE 100. For example, the base station 200 (control unit 230) may designate one of the SSSG indexes set in the UE 100 as "defaultSSSG-Id". The default SSSG may be an SSSG determined by a predetermined rule shared in advance between the base station 200 and the UE 100, among the SSSGs set in the UE 100. The default SSSG may be an SSSG set in the UE 100 by the base station 200 as the default SSSG.

[0149] As shown in FIG. 18, in step S501, the UE 100 (control unit 120), in which multiple SSSGs have been set by the base station 200, monitors the PDCCH using one of the multiple SSSGs.

[0150] In step S502, the UE 100 (communication unit 110) receives a switch instruction DCI from the base station 200 on the PDCCH, the switch instruction DCI instructing a switch to another SSSG.

[0151] In step S503, the UE 100 (control unit 120) switches to the SSSG specified in the switching instruction DCI, and starts a timer (switching timer) associated with the SSSG.

[0152] In step S504, the UE 100 (control unit 120) determines whether the switching timer has expired.

[0153] If the switching timer has expired (step S504: YES), in step S505, UE 100 (control unit 120) switches to a default SSSG from among the multiple SSSGs that have been set. Here, by switching to the SSSG specified by base station 200 as "defaultSSSG-Id", base station 200 can know the SSSG to which UE 100 has switched. Note that since the switching timer is a value set by base station 200, base station 200 manages the switching timer in the same way as UE 100, and can know that the switching timer has expired in UE 100.

[0154] When a default SSSG has not been set by the base station 200, specifically, when a default SSSG has not been explicitly specified as "defaultSSSG-Id" by the base station 200, the UE 100 (control unit 120) determines a default SSSG according to a predetermined rule. The predetermined rule is, for example, a rule defined in the technical specifications of 3GPP, and is a rule shared in advance between the base station 200 and the UE 100.

[0155] Here, the predetermined rule may be a rule that determines, as the default SSSG, the SSSG corresponding to the smallest SSSG index or the SSSG corresponding to the largest SSSG index among the SSSG indices set in the UE 100. For example, in the example of FIG. 13, if the rule is that the SSSG corresponding to the smallest SSSG index is the default SSSG, the UE 100 (control unit 120) determines the SSSG of SSSG index #0 as the default SSSG. If the rule is that the SSSG corresponding to the largest SSSG index is the default SSSG, the UE 100 (control unit 120) determines the SSSG of SSSG index #4 as the default SSSG.

[0156] As described above, UE 100 (communication unit 110) may receive correspondence information indicating the correspondence between the SSSG index set in UE 100 and the value set in the SSSG information field in the switching instruction DCI from base station 200. The predetermined rule may be a rule for determining, as the default SSSG, an SSSG corresponding to an SSSG index indicated by a specific value (e.g., "0") as the value set in the SSSG information field in the switching instruction DCI. For example, UE 100 (control unit 120) determines, as the default SSSG, an SSSG having an SSSG index indicated by a value set in the SSSG information field in the switching instruction DCI as "0".

[0157] The predetermined rule may be a rule that determines, as the default SSSG, an SSSG corresponding to an SSSG index (eg, index #0) having a predetermined value among the SSSG indices configured in the UE 100.

[0158] The predetermined rule may be a rule that determines, as a default SSSG, an SSSG other than an SSSG for skipping PDCCH monitoring, among the SSSGs set in the UE 100. That is, the UE 100 (control unit 120) may assume that an SSSG index corresponding to PDCCH skipping is not set as the default SSSG.

[0159] When DRX is configured in the UE 100, the UE 100 (control unit 120) may apply a specific SSSG when switching from a DRX reception-off period to a DRX reception-on period (active time). The predetermined rule may be a rule that determines the specific SSSG as a default SSSG. That is, the UE 100 (control unit 120) may determine the first SSSG that monitors the PDCCH after the DRX reception-off period has elapsed as the default SSSG.

[0160] In the fourth operation example, the UE 100 (the communication unit 110) may receive, as the switching instruction DCI, a scheduling DCI indicating radio resources allocated to the UE 100. After receiving the scheduling DCI as the switching instruction DCI, the UE 100 (the control unit 120) may start a switching timer at the timing of switching to one SSSG (specifically, the slot at which the SSSG switching is executed). As described in the first operation example, the UE 100 (the control unit 120) may suspend the SSSG switching while a retransmission-related timer related to the HARQ process is operating. For this reason, when the scheduling DCI is received as the switching instruction DCI, the switching timer is started at the timing of executing the SSSG switching, not at the timing of receiving the switching instruction DCI.

[0161] The UE 100 (control unit 120) may use a common value as a switching timer value to be applied to two or more SSSGs among the three or more SSSGs set in the UE 100. The base station 200 (control unit 230) may set a common value as a switching timer value to be applied to two or more SSSGs among the three or more SSSGs set in the UE 100.

[0162] The UE 100 (control unit 120) may use an individual value for each SSSG as the value of the switching timer to be applied to each SSSG set in the UE 100. The base station 200 (control unit 230) may set in the UE 100 an individual switching timer setting value for each SSSG.

[0163] When the switching destination SSSG is an SSSG that supports PDCCH skipping, UE 100 (control unit 120) may start a switching timer associated with the SSSG at the timing (slot) at which switching to the SSSG is started. When in a PDCCH skipping state, that is, during a predetermined period during which PDCCH monitoring is skipped, resources used for PDCCH monitoring are not occupied, and switching to the SSSG can be started at any timing. By utilizing this advantage, it is possible to minimize the impact of switching delay time without impeding the operation of PDCCH monitoring. Note that, after the switching timer expires, UE 100 (control unit 120) assumes a default SSSG and starts switching to the SSSG. PDCCH may be monitored.

[0164] Next, a specific example 1 of the operation using the switching timer according to the fourth operation example will be described with reference to FIG.

[0165] 19, a total of three SSSGs, namely, a default SSSG, SSSG#x, and SSSG#y, are set in the UE 100. Here, it is assumed that the base station 200 (control unit 230) sets in the UE 100 one common switching timer value for the SSSG#x and SSSG#y that are not the default SSSG.

[0166] In period T11, UE 100 (control unit 120) monitors the PDCCH using the default SSSG. UE 100 (communication unit 110) receives a non-scheduling DCI instructing switching to SSSG#x in the last search space of period T11. UE 100 (control unit 120) starts a switching timer when receiving the non-scheduling DCI, since HARQ processing does not occur in the case of the non-scheduling DCI.

[0167] In a period T12, the UE 100 (control unit 120) monitors the PDCCH using SSSG#x while the switching timer is operating. The SSSG#x is an SSSG with a longer search space period than the default SSSG. When the switching timer expires, the UE 100 (control unit 120) switches to the default SSSG after a switching delay time has elapsed.

[0168] In period T13, UE 100 (control unit 120) monitors the PDCCH using the default SSSG. UE 100 (communication unit 110) receives a scheduling DCI (Scheduling DCI) instructing switching to SSSG#y in the last search space of period T13. Since HARQ processing occurs in the case of a scheduling DCI, UE 100 (control unit 120) does not start a switching timer when receiving the scheduling DCI, but starts a switching timer at the timing (slot) when switching to SSSG#y is executed.

[0169] In period T14, while the switching timer is operating, UE 100 (control unit 120) monitors the PDCCH using SSSG#y. SSSG#y is an SSSG with a shorter search space period than the default SSSG. When the switching timer expires, UE 100 (control unit 120) switches to the default SSSG after a switching delay time (Switch delay) has elapsed. Then, in period T15, UE 100 (control unit 120) monitors the PDCCH using the default SSSG.

[0170] Next, a specific example 2 of the operation using the switching timer according to the fourth operation example will be described with reference to FIG.

[0171] 20, a total of three SSSGs, a default SSSG, an SSSG#x for PDCCH skipping, and an SSSG#y for PDCCH skipping, are set in the UE 100. Here, it is assumed that the base station 200 (control unit 230) sets individual switching timer values ​​in the UE 100 for the SSSG#x and SSSG#y that are not the default SSSG.

[0172] In period T21, UE 100 (control unit 120) monitors the PDCCH using a default SSSG. UE 100 (communication unit 110) receives a non-scheduling DCI instructing switching to SSSG#x in the last search space of period T11. Since the switching destination SSSG#x is an SSSG corresponding to PDCCH skipping, UE 100 (control unit 120) starts a switching timer (Switching timer-1) set independently for SSSG#x at the timing (slot) when switching to SSSG#x is executed.

[0173] In a period T22, the UE 100 (control unit 120) skips monitoring the PDCCH while the switching timer-1 is operating. When the switching timer-1 expires, the UE 100 (control unit 120) switches to the default SSSG after a switch delay has elapsed.

[0174] In period T23, UE 100 (control unit 120) monitors the PDCCH using the default SSSG. UE 100 (communication unit 110) receives a scheduling DCI (Scheduling DCI) instructing switching to SSSG#y in the last search space of period T23. Since the switching destination SSSG#x is an SSSG corresponding to PDCCH skipping, UE 100 (control unit 120) starts a switching timer (Switching timer-2) set independently for SSSG#y at the timing (slot) when switching to SSSG#y is executed. The timer value of Switching timer-2 is greater than the timer value of Switching timer-1.

[0175] In period T24, UE 100 (control unit 120) skips monitoring the PDCCH while switching timer-2 is operating. When switching timer-2 expires, UE 100 (control unit 120) switches to the default SSSG after a switch delay has elapsed. Then, in period T25, UE 100 (control unit 120) monitors the PDCCH using the default SSSG.

[0176] In this way, according to the fourth operation example, even if the UE 100 switches the SSSG on a timer basis and three or more SSSGs can be set in the UE 100, the base station 200 can grasp the SSSG to which the SSSG is to be switched by defining a default SSSG. Therefore, it becomes possible to switch to various SSSGs on a timer basis.

[0177] (Other embodiments) The first to fourth operation examples described above may be implemented separately and independently, or two or more operation examples may be combined and implemented. In addition, the steps in the first to fourth operation examples do not necessarily have to be executed in chronological order according to the order described in the flow diagram or sequence diagram. For example, the steps in the operations may be executed in an order different from the order described in the flow diagram or sequence diagram, or may be executed in parallel. In addition, some of the steps in the operations may be deleted, and further steps may be added to the process. Furthermore, each of the above-mentioned operation flows is not limited to being implemented separately and independently, but can be implemented by combining two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow.

[0178] In the above embodiment, the base station 200 may include a plurality of units. The plurality of units may include a first unit hosting a higher layer included in a protocol stack and a second unit hosting a lower layer included in the protocol stack. The higher layer may include an RRC layer, an SDAP layer, and a PDCP layer, and the lower layer may include an RLC layer, a MAC layer, and a PHY layer. The first unit may be a Central Unit (CU), and the second unit may be a Distributed Unit (DU). The plurality of units may include a third unit performing processing below the PHY layer. The second unit may perform processing above the PHY layer. The third unit may be a Radio Unit (RU). The base station 200 may be one of the plurality of units, and may be connected to other units of the plurality of units. The base station 200 may also be an Integrated Access and Backhaul (IAB) donor or an IAB node.

[0179] In the above-described embodiment, an NR-based mobile communication system has been described as an example of the mobile communication system 1. However, the mobile communication system 1 is not limited to this example. The mobile communication system 1 may be a system that complies with a TS of any of LTE or other generation systems (e.g., 6th generation) of the 3GPP standard. The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination toward the UE 100 in LTE. The mobile communication system 1 may be a system that complies with a TS of a standard other than the 3GPP standard.

[0180] A program may be provided that causes a computer to execute each process performed by the UE 100 or the base station 200. The program may be recorded in a computer-readable medium. Using the computer-readable medium, it is possible to install the program in the computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. In addition, a circuit that executes each process performed by the UE 100 or the base station 200 may be integrated, and at least a part of the UE 100 or the base station 200 may be configured as a semiconductor integrated circuit (chip set, SoC (System-on-a-Chip)).

[0181] In the above-mentioned embodiment, "transmit" may mean performing processing of at least one layer in a protocol stack used for transmission, or may mean physically transmitting a signal wirelessly or wired. Alternatively, "transmit" may mean a combination of performing processing of at least one layer and physically transmitting a signal wirelessly or wired. Similarly, "receive" may mean performing processing of at least one layer in a protocol stack used for reception, or may mean physically receiving a signal wirelessly or wired. Alternatively, "receive" may mean a combination of performing processing of at least one layer and physically receiving a signal wirelessly or wired. Similarly, "obtain / acquire" may mean obtaining information from stored information. Also, "obtain / acquire" may mean obtaining information from information received from another node. Alternatively, "obtain / acquire" may mean obtaining information by generating information. Similarly, "include" and "comprise" do not mean including only the listed items, but may include only the listed items. Also, "include" and "comprise" mean including additional items in addition to the listed items. Similarly, in this disclosure, "or" does not mean an exclusive or, but does mean a logical or.

[0182] Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure.

[0183] The features of the present disclosure are as follows:

[0184] [Appendix 1] A communication unit (110) that receives a radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH) from a base station (200) and receives downlink control information (DCI) including an information field regarding monitoring of the PDCCH from the base station (200) via the PDCCH; A control unit (120) that controls skipping of monitoring the PDCCH over the skipping period based on a value set in the information field, The control unit (120) controls not to execute skipping of monitoring the PDCCH while a timer related to retransmission for discontinuous reception (DRX) operation is in operation. A communication device (100).

[0185] [Appendix 2] The control unit (120) controls to execute skipping of monitoring of the PDCCH when a timer related to retransmission for discontinuous reception (DRX) operation is not operating. 2. The communication device (100) of claim 1.

[0186] [Appendix 3] The timer associated with the retransmission is a timer that specifies a maximum period for receiving a grant for an uplink retransmission. The communication device (100) according to claim 1 or 2.

[0187] [Appendix 4] The control of skipping of the monitoring of the PDCCH is performed on a DCI format used for scheduling a Physical Uplink Shared Channel (PUSCH) having a CRC scrambled with a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI). A communication device (100) according to any one of Supplementary Note 1 to Supplementary Note 3.

[0188] [Appendix 5] A communication unit (210) that transmits a radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH) to a communication device (100) and transmits downlink control information (DCI) including an information field regarding monitoring of the PDCCH to the communication device (100) via the PDCCH; A control unit (230) that controls skipping of monitoring the PDCCH over the skipping period based on a value set in the information field, The control unit (230) controls not to execute skipping of monitoring the PDCCH while a timer related to retransmission for discontinuous reception (DRX) operation is in operation. Base station (200).

[0189] [Appendix 6] The control unit (230) controls to skip monitoring of the PDCCH when a timer related to retransmission for discontinuous reception (DRX) operation is not operating. The base station (200) according to claim 5.

[0190] [Appendix 7] The timer associated with the retransmission is a timer that specifies a maximum period for receiving a grant for an uplink retransmission. The base station (200) according to claim 5 or 6.

[0191] [Appendix 8] The control of skipping of the monitoring of the PDCCH is performed on a DCI format used for scheduling a Physical Uplink Shared Channel (PUSCH) having a CRC scrambled with a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI). A base station (200) according to any one of Supplementary Note 5 to Supplementary Note 7.

[0192] [Appendix 9] A method implemented in a communication device (100), comprising: Receiving a radio resource control (RRC) message from a base station (200), the radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH); receiving downlink control information (DCI) from the base station (200) on the PDCCH, the DCI including an information field related to monitoring the PDCCH; and controlling skipping of monitoring the PDCCH over the skipping period based on a value set in the information field; In the step of controlling, while a timer related to retransmission for discontinuous reception (DRX) operation is operating, control is performed so as not to skip monitoring of the PDCCH. method.

[0193] [Appendix 10] In the step of controlling skipping of the PDCCH monitoring, when a timer related to retransmission for discontinuous reception (DRX) operation is not operating, control is performed to skip the PDCCH monitoring. 10. The method according to claim 9.

[0194] [Appendix 11] The timer associated with the retransmission is a timer that specifies a maximum period for receiving a grant for an uplink retransmission. 11. The method according to claim 9 or 10.

[0195] [Appendix 12] The control of skipping of the monitoring of the PDCCH is performed on a DCI format used for scheduling a Physical Uplink Shared Channel (PUSCH) having a CRC scrambled with a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI). 12. The method according to any one of claims 9 to 11.

[0196] [Appendix 13] A method performed in a base station (200), comprising: A step of transmitting a radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH) to a communication device (100); transmitting downlink control information (DCI) including an information field related to monitoring of the PDCCH to the communication device (100) via the PDCCH; and controlling skipping of monitoring the PDCCH over the skipping period based on a value set in the information field; In the step of controlling, while a timer related to retransmission for discontinuous reception (DRX) operation is operating, control is performed so as not to skip monitoring of the PDCCH. method.

[0197] [Appendix 14] In the step of controlling skipping of the PDCCH monitoring, when a timer related to retransmission for discontinuous reception (DRX) operation is not operating, control is performed to skip the PDCCH monitoring. 14. The method according to claim 13.

[0198] [Appendix 15] The timer associated with the retransmission is a timer that specifies a maximum period for receiving a grant for an uplink retransmission. 15. The method according to claim 13 or 14.

[0199] [Appendix 16] The control of the execution of skipping of the monitoring of the PDCCH is performed for a DCI format used for scheduling a physical uplink shared channel (PUSCH) having a CRC scrambled with a CS-RNTI (Configured Scheduling Radio Network Temporary Identifier). 16. The method according to any one of claims 13 to 15.

Claims

1. A control unit (120) that performs monitoring of a physical downlink control channel (PDCCH) during an active time in a discontinuous reception (DRX) operation; A communication unit (110) that receives a radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of the PDCCH from a base station (200), The communication unit (110) receives downlink control information (DCI) including an information field regarding monitoring of the PDCCH from the base station (200) via the PDCCH; The control unit controls skipping of monitoring the PDCCH for the skipping period during the active time in the discontinuous reception (DRX) operation based on a value set in the information field. A communication device (100).

2. The DCI is used for scheduling a physical uplink shared channel (PUSCH) or a physical downlink shared channel (PDSCH). The communication device (100) of claim 1.

3. The DCI is added with a CRC scrambled by a CS-RNTI (Configured Scheduling Radio Network Temporary Identifier). A communication device (100) according to claim 1 or claim 2.

4. A control unit (120) for controlling monitoring of a physical downlink control channel (PDCCH) during an active time in a discontinuous reception (DRX) operation; A communication unit (210) that transmits a radio resource control (RRC) message including information for setting a skipping period for skipping monitoring of a physical downlink control channel (PDCCH) to a communication device (100), The communication unit (210) transmits downlink control information (DCI) including an information field regarding monitoring of the PDCCH to the communication device (100) via the PDCCH; The control unit controls skipping of monitoring the PDCCH for the skipping period during the active time in the discontinuous reception (DRX) operation based on a value set in the information field. Base station (200).

5. The DCI is used for scheduling a physical uplink shared channel (PUSCH) or a physical downlink shared channel (PDSCH). The base station (200) of claim 4.

6. The DCI is added with a CRC scrambled by a CS-RNTI (Configured Scheduling Radio Network Temporary Identifier). A base station (200) according to claim 4 or claim 5.

7. A method performed in a communication device (100), comprising: performing monitoring of a physical downlink control channel (PDCCH) during an active time in a discontinuous reception (DRX) operation; receiving a radio resource control (RRC) message from a base station (200) including information for setting a skipping period for skipping monitoring of the PDCCH; receiving downlink control information (DCI) from the base station (200) on the PDCCH, the DCI including an information field related to monitoring of the PDCCH; and controlling skipping of monitoring the PDCCH for the skipping period during the active time in the discontinuous reception (DRX) operation based on a value set in the information field. method.

8. The DCI is used for scheduling a physical uplink shared channel (PUSCH) or a physical downlink shared channel (PDSCH). The method according to claim 7.

9. The DCI is added with a CRC scrambled by a CS-RNTI (Configured Scheduling Radio Network Temporary Identifier). The method according to claim 7 or claim 8.

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