COMMUNICATION DEVICE, BASE STATION, AND METHOD

Abstract

A communication device (100) comprises: a transmission unit (111) that transmits a scheduling request (SR); and a control unit (120) that, on the basis of the transmission of the SR or a trigger of the SR, controls a state related to the monitoring of a physical downlink control channel (PDCCH).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority to Patent Application No. 2021-097597, filed on June 10, 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 communication method used in a mobile communication system. [Background technology]

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

[0004] For example, in order to reduce the power consumption required for monitoring the physical downlink control channel (PDCCH) in a communication device, it is considered to lengthen the PDCCH monitoring period or to switch to a power saving state in which monitoring of the PDCCH is skipped. In particular, in a communication device, by dynamically switching the PDCCH monitoring state during an active time in discontinuous reception (DRX) in an 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]

[0005] [Non-Patent Document 1] 3GPP contribution RP-200938 “Revised WID UE Power Saving Enhancements for NR” [Non-Patent Document 2] 3GPP contribution R1-2104253 “Extension(s) to Rel-16 DCI-based power saving adaptation for an active BWP” [Non-Patent Document 3] 3GPP contribution R1-2105505 “UE power saving enhancements for Active Time” Summary of the Invention

[0006] A communication device according to a first aspect includes a transmitting unit that transmits a scheduling request (SR) and a control unit that controls a state related to monitoring of a physical downlink control channel (PDCCH) based on the transmission of the SR or the triggering of the SR.

[0007] A base station according to a second aspect includes a controller that controls transmission of a scheduling request (SR) from a communication device and controls a state related to monitoring of a physical downlink control channel (PDCCH). The state related to monitoring of the PDCCH is controlled based on the transmission of the SR or the trigger of the SR.

[0008] A communication method of a communication device according to a third aspect includes a step of transmitting a scheduling request (SR) and a step of controlling a state related to monitoring of a physical downlink control channel (PDCCH) based on the transmission of the SR or the triggering of the SR.

[0009] A communication method of a base station according to a fourth aspect includes the steps of controlling transmission of a scheduling request (SR) from a communication device, and controlling a state related to monitoring of a physical downlink control channel (PDCCH). The state related to monitoring of the PDCCH is controlled based on the transmission of the SR or the trigger of the SR. [Brief description of the drawings]

[0010] [Figure 1] 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 the configuration of a protocol stack according to the embodiment. [Diagram 3] FIG. 1 is a diagram showing an overview of a wireless communication operation in a mobile communication system according to an embodiment. [Figure 4] FIG. 1 is a diagram showing an overview of PDCCH skipping according to an embodiment. [Diagram 5] FIG. 1 is a diagram showing an overview of search space set (SSSG) switching according to an embodiment. [Figure 6] FIG. 1 is a diagram showing a DRX and power saving state according to an embodiment. [Figure 7] A figure showing an example of SSSG switching according to an embodiment. [Figure 8] A figure showing an example of timer-based SSSG switching according to an embodiment. [Figure 9] FIG. 11 is a diagram showing a specific example 1 of an operation using a switching timer according to the embodiment. [Figure 10] FIG. 11 is a diagram showing a specific example 2 of an operation using a switching timer according to the embodiment. [Figure 11] FIG. 1 is a diagram showing an overview of SR transmission according to an embodiment. [Figure 12] FIG. 1 is a diagram showing an overview of RACH transmission according to an embodiment. [Figure 13] FIG. 2 is a diagram showing the configuration of a UE according to an embodiment. [Figure 14] FIG. 2 is a diagram illustrating a configuration of a base station according to an embodiment. [Figure 15] FIG. 11 is a diagram illustrating an example 1 of an operation sequence related to an SR-induced switching process according to the embodiment. [Figure 16] FIG. 11 is a diagram illustrating an example 2 of an operation sequence related to the SR-induced switching process according to the embodiment. [Figure 17] FIG. 2 is a diagram illustrating a first example of a configuration of an RRC message according to the embodiment. [Figure 18] FIG. 11 is a diagram illustrating a second example of a configuration of an RRC message according to the embodiment. [Figure 19] FIG. 11 is a diagram illustrating a third example of an RRC message configuration according to the embodiment. [Figure 20] FIG. 11 is a diagram illustrating a specific example 1 of the SR-induced switching process according to the embodiment. [Figure 21] FIG. 11 is a diagram illustrating a specific example 2 of the SR-induced switching process according to the embodiment. [Figure 22] FIG. 11 is a diagram illustrating an example 1 of an operation sequence related to a RACH-induced switching process according to an embodiment. [Diagram 23] FIG. 11 is a diagram illustrating an example 2 of an operation sequence related to a RACH-induced switching process according to an embodiment. [Figure 24] FIG. 11 is a diagram illustrating an example 3 of an operation sequence related to a RACH-induced switching process according to an embodiment. [Diagram 25] FIG. 2 is a diagram illustrating an example of the configuration of an RRC message according to the embodiment. [Figure 26] FIG. 2 is a diagram illustrating an example of the configuration of a MAC CE according to an embodiment. [Figure 27] FIG. 11 is a diagram illustrating a specific example 1 of the RACH-induced switching process according to the embodiment. [Figure 28] FIG. 11 is a diagram showing a specific example 2 of the RACH-induced switching process according to the embodiment. [Figure 29] FIG. 11 is a diagram illustrating an example 1 of an operation sequence related to a simultaneous switching process according to the embodiment. [Diagram 30] FIG. 11 is a diagram illustrating an example 2 of an operation sequence related to a simultaneous switching process according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In a method in which a communication device switches a PDCCH monitoring state in response to an SR transmission, if the communication device autonomously switches the PDCCH monitoring state, a mismatch may occur between the actual PDCCH monitoring state in the communication device and the PDCCH monitoring state recognized by the base station. Therefore, there is a concern that the base station may not be able to properly perform wireless communication with the communication device after the communication device switches the PDCCH monitoring state in response to an SR transmission.

[0012] Therefore, in the embodiments, a communication device, a base station, and a communication method are provided that enable appropriate wireless communication even when the PDCCH monitoring state is switched.

[0013] 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.

[0014] (1) Mobile communication systems A mobile communication system according to this embodiment will be described.

[0015] 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 3GPP Technical Specification (TS). In the following, the mobile communication system 1 will be described by taking as an example a 3GPP standard 5th Generation System (5GS), that is, a mobile communication system based on NR (New Radio).

[0016] The mobile communication system 1 includes a network 10 and a communication device (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 its own cell. The base station 200 communicates with the UE 100 using a protocol stack of the RAN. The base station 200 provides NR user plane and control plane protocol terminations toward 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] Next, an overview of the wireless communication operation in the mobile communication system 1 according to this embodiment will be described with reference to FIG.

[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, receives downlink control information (DCI) carried by the PDCCH, and 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 bandwidth portion (DL BWP) in a serving cell in which PDCCH monitoring 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 a setting related to the PDCCH (PDCCH setting) 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 an individual UE. For example, the scheduling DCI may be transmitted by applying an RNTI that is assigned to an individual UE.

[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, and 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. 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. Here, the downlink data is also referred to as data of a downlink shared channel (DL-SCH). Also, the uplink data is also referred to as data of an uplink shared channel (UL-SCH). Here, the downlink shared channel (DL-SCH) and the uplink shared channel (UL-SCH) are transport channels, and the PDSCH and the PUSCH are physical channels. For example, the downlink data (data of the DL-SCH) is mapped to the PDSCH, and the uplink data (data of the UL-SCH) is mapped to the PUSCH.

[0038] (2) Overview of power-saving technology An overview of the power saving technique according to this embodiment will be described.

[0039] First, 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, based on a search space setting set by base station 200, UE 100 monitors a PDCCH provided at a predetermined period in a search space.

[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 may be a scheduling DCI or a non-scheduling DCI.

[0042] Thirdly, in response to receiving a skip instruction DCI from the base station 200, the UE 100 skips monitoring of the PDCCH for a predetermined period. The predetermined period for skipping monitoring of 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. Such PDCCH skipping reduces power consumption required for the UE 100 to monitor the PDCCH, and dynamic power saving can be realized. Note that PDCCH skipping may mean skipping monitoring of the PDCCH, and PDCCH skipping may be referred to as PDCCH monitoring skipping.

[0043] Next, with reference to FIG. 5, an overview of search space set switching according to this embodiment will be described.

[0044] First, the base station 200 configures a plurality of search space sets, which are sets of settings related to search spaces, in the 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 an SSSG in the following. One SSSG includes one or more search space settings and is identified by an SSSG index. In the example of FIG. 5, the base station 200 configures the UE 100 with an SSSG#0 (first search space set) in which a search space is provided at a predetermined period and an SSSG#1 (second search space set) in which a search space is provided at a period longer than the predetermined period. Here, an example is shown in which the base station 200 configures two SSSGs, SSSG#0 and SSSG#1, in the UE 100, but three or more SSSGs may be configured in the UE 100 for each of one or more BWPs (e.g., DL BWP). In addition, setting a plurality of SSSGs (or three or more SSSGs) in UE 100 may mean setting a plurality of SSSGs (or three or more SSSGs) for one BWP, or may mean setting a plurality of SSSGs (or three or more SSSGs) for a plurality of BWPs. In addition, taking into consideration that the search space includes a UE-specific search space and / or a UE-common search space as described above, a set of settings related to a UE-specific search space may be referred to as a UE-specific search space set, and a set of settings related to a UE-common search space may be referred to as a UE-common search space set.

[0045] Secondly, the UE 100 monitors the PDCCH provided at a predetermined cycle in the search space based on the SSSG#0.

[0046] Third, the base station 200 transmits a switching instruction DCI for instructing the UE 100 to switch the SSSG. The switching instruction DCI may be a scheduling DCI or a non-scheduling DCI. That is, the base station 200 uses the DCI to instruct the UE 100 to switch from the SSSG #0 to the SSSG #1.

[0047] 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 may be set in UE 100 by base station 200 through higher layer signaling (RRC message).

[0048] Fifth, based on SSSG#1, UE 100 monitors the PDCCH set at a period longer than the predetermined period in the search space. By switching the search space set in this manner, the power consumption required for UE 100 to monitor the PDCCH is reduced, and dynamic power saving can be realized.

[0049] In addition, the switching from SSSG#1 to SSSG#0 may be instructed by base station 200 using DCI, as in the case of switching from SSSG#0 to SSSG#1, or UE 100 may switch from SSSG#1 to SSSG#0 using a timer. The timer value of such a switching timer is set in UE 100 by base station 200 using higher layer signaling (RRC message). UE 100 starts monitoring the PDCCH in SSSG#1 in response to detection of a switching instruction DCI to SSSG#1, and sets the value of the switching timer to a value set by the higher layer to start the switching timer. UE 100 decrements the value of the switching timer, and when the switching timer expires, ends monitoring the PDCCH in SSSG#1, and starts monitoring the PDCCH in SSSG#0 after a switching delay time (Switch delay).

[0050] Note that "#0" in SSSG#0 and "#1" in SSSG#1 indicate an index (also referred to as 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 setting an index associated with the one or more search space sets. In this embodiment, the name SSSG is merely an example, and any name is acceptable as long as it is a set (group) of search spaces to which one or more search space sets are associated.

[0051] 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. Also, by setting a search space in one SSSG set in the UE 100 and not setting a monitoring opportunity for the search space (or setting a parameter related to the monitoring opportunity to a predetermined value (for example, "0" or "Null")), an operation similar to the above-mentioned PDCCH skipping may be realized. Hereinafter, for ease of explanation, a description will be given of one SSSG having no search space as a setting for realizing an operation similar to the above-mentioned PDCCH skipping, but it goes without saying that this may be replaced with not setting a monitoring opportunity (or setting a parameter related to the monitoring opportunity to a predetermined value). Also, another SSSG set in the UE 100 may be set to have a long search space period, and switching to the one SSSG may be instructed by DCI. To achieve such an operation, a total of three SSSGs, an SSSG with a normal search space cycle, an SSSG without a search space, and an SSSG with a long search space cycle, are configured in the UE 100. Flexible power saving can be achieved by configuring such various SSSGs in the UE 100 and instructing SSSG switching by DCI.

[0052] Next, in this embodiment, DRX will be described with reference to FIG. 6, and the power saving state will be described.

[0053] 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:

[0054] DRX cycle: Specifies the period during which the UE 100 wakes up.

[0055] 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.

[0056] 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 when the PDCCH decoding fails. In addition to this, the on duration may be started after a predetermined setting value DRX slot offset (DRX-SlotOffset) has elapsed after the inactivity timer expires. Figure 6 corresponds to the operation in which the setting value of DRX-SlotOffset is set to zero.

[0057] · Retransmission timer: Specifies the time interval during which retransmissions are expected.

[0058] In this way, since the UE 100 for which DRX is set 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 one 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.

[0059] 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.

[0060] Next, an example of SSSG switching according to this embodiment will be described with reference to FIG.

[0061] Here, it is assumed that one or more SSSGs can be set to UE 100 from among various SSSGs including multiple SSSGs having different search space periods (different PDCCH periods) and an SSSG that has no search space, and flexible power saving is achieved by instructing SSSG switching by DCI.

[0062] As shown in Fig. 7, in step S11, the base station 200 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 receives the RRC message.

[0063] 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.

[0064] 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".

[0065] The RRC message further includes a search space configuration associated with each of the SSSG indices. The search space configuration 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.

[0066] For example, the search space setting associated with SSSG index #0 is information for setting a first search space period as the search space period. The search space setting associated with SSSG index #1 is information for setting a second search space period as the search space period. The search space setting associated with SSSG index #2 is information for setting a third search space period as the search space period. The search space setting associated with SSSG index #4 is information indicating that no search space is set. In other words, SSSG index #4 is associated with a search space setting indicating PDCCH skipping.

[0067] The RRC message may include a field setting 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 in which the presence of an SSSG information field is indicated by the field setting. 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.

[0068] The RRC message may include a bit number setting 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 commonly or independently. The number of bits of the SSSG information field may be set commonly for DCI format 1_1 and DCI format 0_1, and / or commonly 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.

[0069] The RRC message may include a timer setting value of a switching timer for one or more SSSGs.

[0070] In step S12, the UE 100 stores the information set by the base station 200.

[0071] In step S13, base station 200 may transmit to 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. UE 100 receives the SSSG state selection MAC CE. The SSSG state selection MAC CE instructs activation / deactivation for each SSSG index. An activated SSSG becomes valid as a switching destination SSSG, and a deactivated SSSG becomes invalid as a switching destination SSSG.

[0072] In step S14, the base station 200 transmits a switching instruction DCI having an SSSG information field to the UE 100 on the PDCCH. The UE 100 receives the switching instruction DCI on the PDCCH. The UE 100 may determine whether or not the DCI format of the detected DCI corresponds to the switching instruction DCI, based on the field setting set by the base station 200.

[0073] In step S15, the UE 100 acquires the value set in the SSSG information field of the switching command DCI received in step S14. The UE 100 sets the number of bits in the SSSG information field based on the number of bits setting set by the base station 200. decision Alternatively, the UE 100 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 calculates the number of bits in the SSSG information field by rounding up the decimal point of log2(I) to an integer value, and decision You may do so.

[0074] In step S16, UE 100 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, when the value set in the SSSG information field is "11", UE 100 determines that it has been instructed to switch to the SSSG with SSSG index #3, and switches to the SSSG with SSSG index #3.

[0075] Next, an example of timer-based SSSG switching according to the present embodiment will be described with reference to Fig. 8. Here, 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.

[0076] The base station 200 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 may designate one of the SSSG indexes set in the UE 100 as "defaultSSSG-Id". For example, the base station 200 may set "defaultSSSG-Id" using an RRC message. That is, the base station 200 may set a default SSSG for the UE 100 using information included in the RRC message. 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 as the default SSSG by the base station 200.

[0077] As shown in FIG. 8, in step S31, UE 100 for which multiple SSSGs have been set by base station 200 monitors the PDCCH using one of the multiple SSSGs.

[0078] In step S32, the UE 100 receives a switch instruction DCI from the base station 200 on the PDCCH, the switch instruction DCI instructing the UE 100 to switch to another SSSG.

[0079] In step S33, the UE 100 switches to the SSSG specified in the switching instruction DCI, and starts a timer (switching timer) associated with the SSSG.

[0080] In step S34, the UE 100 determines whether the switching timer has expired.

[0081] If the switching timer has expired (step S34: YES), in step S35, UE 100 switches to a default SSSG from among the multiple SSSGs that have been set. Here, by switching to the SSSG specified as "defaultSSSG-Id" by base station 200, 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.

[0082] When a default SSSG is not set by the base station 200, specifically, when a default SSSG is not explicitly specified as "defaultSSSG-Id" by the base station 200, the UE 100 determines a default SSSG according to a predetermined rule. For example, when information for setting a default SSSG is not included in an RRC message, the UE 100 may determine a default SSSG according to a predetermined rule. The predetermined rule is, for example, a rule specified in a 3GPP technical specification, and is a rule shared in advance between the base station 200 and the UE 100.

[0083] 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 case where the rule is that the SSSG corresponding to the smallest SSSG index is the default SSSG, the UE 100 determines the SSSG of SSSG index #0 as the default SSSG. In the case where the rule is that the SSSG corresponding to the largest SSSG index is the default SSSG, the UE 100 determines the SSSG of SSSG index #4 as the default SSSG.

[0084] As described above, the UE 100 may receive correspondence information indicating a correspondence between an SSSG index set in the UE 100 and a value set in the SSSG information field in the switching instruction DCI from the 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 a value set in the SSSG information field in the switching instruction DCI. For example, the UE 100 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".

[0085] 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.

[0086] 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 may assume that an SSSG index corresponding to PDCCH skipping is not set as the default SSSG.

[0087] When DRX is configured in the UE 100, the UE 100 may apply a specific SSSG when switching from a DRX reception-off period to a reception-on period (active time). The predetermined rule may be a rule for determining the specific SSSG as a default SSSG. That is, the UE 100 may determine the first SSSG for monitoring the PDCCH after the DRX reception-off period has elapsed as the default SSSG. For example, the base station 200 may transmit an RRC message including information for setting the specific SSSG, and the UE 100 may determine the specific SSSG as the default SSSG. Also, the base station 200 may transmit an RRC message including information for setting the default SSSG, and the UE 100 may use the default SSSG as the first SSSG for monitoring the PDCCH after the DRX reception-off period has elapsed.

[0088] The UE 100 may receive, as a 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 may start a switching timer at a timing for switching to one SSSG (specifically, a slot for executing the SSSG switching).

[0089] UE 100 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 UE 100. Base station 200 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 UE 100.

[0090] The UE 100 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 may set in the UE 100 an individual switching timer setting value for each SSSG.

[0091] When the SSSG to be switched to is an SSSG corresponding to PDCCH skipping, the UE 100 may start a switching timer associated with the SSSG at the timing (slot) at which switching to the SSSG is started. In the PDCCH skipping state, that is, during a predetermined period in which PDCCH monitoring is skipped, the resources used for PDCCH monitoring are not dedicated, and switching to the SSSG can be started at any timing. By utilizing this advantage, it is possible to minimize the effect of switching delay time without impeding the operation of PDCCH monitoring. Note that, after the switching timer expires, the UE 100 may monitor the PDDCH assuming a default SSSG.

[0092] Next, a specific example 1 of an operation using the switching timer according to the present embodiment will be described with reference to FIG.

[0093] 9, 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 sets in the UE 100 one common switching timer value for the SSSG#x and SSSG#y that are not the default SSSG.

[0094] In period T11, UE 100 monitors the PDCCH using the default SSSG. UE 100 receives a non-scheduling DCI instructing switching to SSSG#x in the last search space of period T11. Since HARQ processing does not occur in the case of the non-scheduling DCI, UE 100 starts a switching timer when receiving the non-scheduling DCI.

[0095] In a period T12, while the switching timer is running, the UE 100 monitors the PDCCH using SSSG#x. The SSSG#x is an SSSG with a longer search space period than the default SSSG. When the switching timer expires, the UE 100 switches to the default SSSG after a switching delay time has elapsed.

[0096] In period T13, UE 100 monitors the PDCCH using the default SSSG. UE 100 receives a Scheduling DCI instructing switching to SSSG#y in the last search space of period T13. Since HARQ processing occurs in the case of the Scheduling DCI, UE 100 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.

[0097] In period T14, while the switching timer is operating, UE 100 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 switches to the default SSSG after a switching delay time has elapsed. Then, in period T15, UE 100 monitors the PDCCH using the default SSSG.

[0098] Next, a second specific example of the operation using the switching timer according to the present embodiment will be described with reference to FIG.

[0099] 10, a total of three SSSGs, namely, a default SSSG (Default SSSG), an SSSG#x for PDCCH skipping (PDCCH skipping SSSG#x), and an SSSG#y for PDCCH skipping (PDCCH skipping SSSG#y), are set in the UE 100. Here, it is assumed that the base station 200 sets individual switching timer values ​​for the SSSG#x and SSSG#y that are not the default SSSG in the UE 100.

[0100] In period T21, UE 100 monitors the PDCCH using the default SSSG. UE 100 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 starts a switching timer (Switching timer-1) set independently for SSSG#x at the timing (slot) when switching to SSSG#x is executed.

[0101] In a period T22, while the switching timer-1 is operating, the UE 100 skips monitoring the PDCCH. When the switching timer-1 expires, the UE 100 switches to the default SSSG after a switch delay has elapsed.

[0102] In period T23, UE 100 monitors the PDCCH using the default SSSG. UE 100 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 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 larger than the timer value of Switching timer-1.

[0103] In a period T24, while Switching timer-2 is operating, UE 100 skips monitoring the PDCCH. When Switching timer-2 expires, UE 100 switches to the default SSSG after a switch delay has elapsed. Then, in a period T25, UE 100 monitors the PDCCH using the default SSSG.

[0104] (3) Overview of SR and RACH transmission An overview of SR transmission and RACH transmission according to this embodiment will be described.

[0105] First, an overview of SR transmission according to this embodiment will be described with reference to Fig. 11. UE 100 transmits an SR on a PUCCH to request an uplink radio resource for a new transmission, specifically, an uplink shared channel (UL-SCH) resource. For example, the SR may be used to request an uplink shared channel (UL-SCH) resource for an initial transmission. Also, for example, the uplink shared channel (UL-SCH) resource may be used to transmit uplink data (i.e., data of the UL-SCH).

[0106] In step S31, the base station 200 transmits an RRC message including an SR configuration for setting parameters for an SR resource to the UE 100. The SR configuration includes a plurality of SR resource configurations each associated with a logical channel. Each SR resource configuration includes, for a corresponding logical channel, information for setting a PUCCH resource used for transmitting an SR, information for setting a period and / or an offset used for transmitting an SR, and information for setting an SR priority (phy-Priority). Here, the SR priority (phy-Priority) may indicate the priority of the corresponding SR resource in the physical layer. For example, the SR priority (phy-Priority) may indicate whether the corresponding SR resource is high priority (high-priority) or low priority (low-priority) in priority processing in the physical layer. The UE 100 stores the information set by the RRC message.

[0107] In step S32, the UE 100 detects an SR transmission trigger. The SR transmission trigger may be any of the following: uplink data to be transmitted to the base station 200 and / or a buffer status report (BSR) is generated; uplink data to be transmitted to the base station 200 arrives at the MAC layer of the UE 100; and SR transmission is instructed from the MAC layer to the physical (PHY) layer in the UE 100. That is, the SR transmission trigger may be that an SR is triggered.

[0108] In step S33, based on the SR configuration set in step S31, UE 100 transmits an SR on the PUCCH to base station 200 in response to the SR transmission trigger. Specifically, UE 100 transmits an SR using an SR resource configuration corresponding to a logical channel to be subjected to SR transmission, i.e., a logical channel for transmitting uplink data.

[0109] In step S34, in response to receiving the SR from the UE 100, the base station 200 allocates the UL-SCH resource to the UE 100. Specifically, the base station 200 transmits a scheduling DCI including a UL grant for allocating the UL-SCH resource to the UE 100 on the PDCCH. Here, the scheduling DCI including the UL grant for allocating the UL-SCH resource may correspond to a DCI format used for scheduling the PUSCH.

[0110] Next, an overview of RACH transmission according to this embodiment will be described with reference to Fig. 12. For example, in order to perform beam failure recovery (BFR), the UE 100 transmits a RACH transmission, specifically, a RACH preamble (also referred to as a random access preamble) on a physical random access channel (PRACH). The RACH transmission may mean starting a RACH procedure (also referred to as a random access procedure). The UE 100 may perform RACH transmission in response to the absence of a PUCCH resource for SR for a logical channel corresponding to the generated uplink data.

[0111] In step S41, the base station 200 transmits to the UE 100 an RRC message including a BFR configuration for configuring a RACH resource for BFR (specifically, a PRACH resource). The BFR configuration includes information for configuring a RACH resource (e.g., a dedicated RACH preamble) and information on a reference signal resource used for detecting a beam failure. That is, the RACH resource includes a PRACH resource and / or a RACH preamble. Alternatively, the base station 200 may transmit to the UE 100 an RRC message including a RACH configuration for configuring a RACH resource not for BFR. The UE 100 stores the information configured by the RRC message.

[0112] In step S42, the UE 100 detects a transmission trigger of the RACH. The transmission trigger of the RACH may be either that the UE 100 detects a beam failure or that there is no PUCCH resource for SR for a logical channel corresponding to the generated uplink data. That is, the transmission trigger of the RACH may be that the RACH is triggered.

[0113] In step S43, the UE 100 transmits a RACH preamble on the RACH (PRACH) to the base station 200 in response to a RACH transmission trigger based on the BFR configuration or the RACH configuration set in step S41. Specifically, the UE 100 transmits to the base station 200 a dedicated RACH preamble set in the BFR configuration or the RACH configuration.

[0114] In step S44, in response to receiving the RACH from the UE 100, the base station 200 allocates a UL-SCH resource to the UE 100. Specifically, the base station 200 transmits a scheduling DCI including a UL grant for allocating a UL-SCH resource to the UE 100 on the PDCCH.

[0115] In this way, the UE 100 performs SR transmission in response to the SR transmission trigger, and performs RACH transmission in response to the RACH transmission trigger. Such SR transmission and RACH transmission may occur in the above-mentioned power saving state (i.e., a state in which the PDCCH monitoring period is lengthened or PDCCH monitoring is skipped). After the SR transmission or RACH transmission, wireless communication is performed between the UE 100 and the base station 200, so it is preferable to switch the PDCCH monitoring state from the power saving state and exit from the power saving state in response to the SR or RACH transmission or transmission trigger.

[0116] Here, when UE 100 switches the PDCCH monitoring state in response to transmission of SR or RACH (or a transmission trigger), if UE 100 autonomously switches the PDCCH monitoring state, a mismatch may occur between the actual PDCCH monitoring state in UE 100 and the PDCCH monitoring state recognized by base station 200. Therefore, there is a concern that after UE 100 switches the PDCCH monitoring state, base station 200 may not be able to appropriately perform wireless communication with UE 100. Therefore, in this embodiment, it is possible to switch the PDCCH monitoring state based on transmission of SR or RACH (or a transmission trigger) under the control of base station 200.

[0117] Furthermore, the UE 100 to which carrier aggregation or dual connectivity is applied can perform wireless communication using multiple serving cells simultaneously. Therefore, when the UE 100 switches the PDCCH monitoring state in response to the transmission (or transmission trigger) of SR or RACH, it may be inefficient to switch the PDCCH monitoring state only for the serving cell in which SR transmission or RACH transmission is performed. Therefore, in this embodiment, it is possible to simultaneously switch the PDCCH monitoring state based on the transmission (or transmission trigger) of SR or RACH in units of a group (hereinafter referred to as a "cell group") consisting of multiple serving cells.

[0118] Here, the "PDCCH monitoring state" in this embodiment may include skipping PDCCH monitoring and / or performing PDCCH monitoring in a set SSSG. For example, switching the PDCCH monitoring state may include switching the operation from skipping PDCCH monitoring to monitoring the PDCCH in a set SSSG. Also, switching the PDCCH monitoring state may include switching the operation from monitoring the PDCCH in a set SSSG to skipping PDCCH monitoring. Also, switching the PDCCH monitoring state may include switching the operation from monitoring the PDCCH in a set first SSSG (for example, SSSG#x in FIG. 9) to monitoring the PDCCH in a set second SSSG (for example, SSSG#y in FIG. 9).

[0119] Also, switching of the PDCCH monitoring state may include switching of the SSSG used for monitoring the PDCCH. For example, switching of the PDCCH monitoring state may include switching of the SSSG from an SSSG set for PDCCH skipping (e.g., SSSG#x and / or SSSG#y in FIG. 10) to an SSSG set for PDCCH monitoring (e.g., SSSG#x and / or SSSG#y in FIG. 9). Also, switching of the PDCCH monitoring state may include switching of the SSSG from an SSSG set for PDCCH monitoring (e.g., SSSG#x and / or SSSG#y in FIG. 9) to an SSSG set for PDCCH skipping (e.g., SSSG#x and / or SSSG#y in FIG. 10). Furthermore, switching the PDCCH monitoring state may also include switching the SSSG from a first SSSG (e.g., SSSG#x in FIG. 9) configured for monitoring the PDCCH to a second SSSG (e.g., SSSG#y in FIG. 10) configured for monitoring the PDCCH.

[0120] Here, in this embodiment, for ease of explanation, the SSSG used for monitoring the PDCCH is also referred to as a PDCCH monitoring state. As described above, the set SSSG includes a default SSSG.

[0121] (4) Configuration of communication device The configuration of the UE 100 according to this embodiment will be described with reference to Fig. 13. The UE 100 includes a communication unit 110 and a control unit 120.

[0122] 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 transmission unit 111 and at least one reception unit 112. The transmission unit 111 and the reception unit 112 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.

[0123] 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.

[0124] In the UE 100 according to this embodiment, the transmitter 111 performs SR transmission to the base station 200. The controller 120 performs an SR-induced switching process for switching a PDCCH monitoring state related to PDCCH monitoring in response to an SR transmission or an SR transmission trigger. The receiver 112 receives an RRC message including switching control information for controlling the SR-induced switching process from the base station 200. The controller 120 controls the SR-induced switching process based on the switching control information. This makes it possible to switch the PDCCH monitoring state based on an SR transmission or a transmission trigger under the control of the base station 200, and makes it possible to appropriately perform wireless communication even when the PDCCH monitoring state is switched.

[0125] Moreover, in the UE 100 according to this embodiment, the transmitter 111 performs RACH transmission to the base station 200. The controller 120 performs RACH-induced switching processing for switching a PDCCH monitoring state related to PDCCH monitoring in response to RACH transmission or a RACH transmission trigger. The receiver 112 receives an RRC message or a MAC control element (MAC CE) including switching control information for controlling the RACH-induced switching processing from the base station 200. The controller 120 controls the RACH-induced switching processing based on the switching control information. This makes it possible to switch the PDCCH monitoring state based on the RACH transmission or a transmission trigger under the control of the base station 200, and makes it possible to appropriately perform wireless communication even when the PDCCH monitoring state is switched.

[0126] Furthermore, in the UE 100 according to this embodiment, the receiver 112 receives an RRC message for setting a cell group from the base station 200. The transmitter 111 transmits an SR or a RACH to the base station 200. The controller 120 performs a simultaneous switching process for simultaneously switching the PDCCH monitoring state related to the monitoring of the PDCCH for each serving cell in the cell group in response to the transmission (or transmission trigger) of the SR or RACH. This makes it possible to simultaneously switch the PDCCH monitoring state based on the transmission (or transmission trigger) of the SR or RACH in cell group units consisting of a plurality of serving cells, and makes it possible to efficiently switch the PDCCH monitoring state.

[0127] (5) Base station configuration The configuration of the base station 200 according to this embodiment will be described with reference to Fig. 14. The base station 200 has a communication unit 210, a network interface 220, and a control unit 230.

[0128] The communication unit 210 receives a radio signal from the UE 100 and transmits the radio signal to the UE 100, for example. The communication unit 210 has at least one transmission unit 211 and at least one reception unit 212. The transmission unit 211 and the reception unit 212 may be configured to include an antenna and an RF circuit. The antenna converts a signal into a radio wave and radiates the radio wave into space. The antenna also receives a radio wave in space and converts the radio wave into a signal. The RF circuit performs analog processing of a 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.

[0129] 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.

[0130] 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.

[0131] In the base station 200 according to this embodiment, the receiver 212 receives an SR from the UE 100 on the PUCCH. The transmitter 211 transmits to the UE 100 an RRC message including switching control information for controlling the SR-induced switching process. The SR-induced switching process is a process in which the UE 100 switches a PDCCH monitoring state related to PDCCH monitoring in response to an SR transmission or an SR transmission trigger. This makes it possible to switch the PDCCH monitoring state based on the SR transmission or transmission trigger under the control of the base station 200, and makes it possible to appropriately perform wireless communication even when the PDCCH monitoring state is switched.

[0132] In the base station 200 according to this embodiment, the receiver 212 receives a RACH preamble on the RACH (PRACH) from the UE 100. The transmitter 211 transmits to the UE 100 an RRC message or a MAC CE including switching control information for controlling the RACH-induced switching process. The RACH-induced switching process is a process in which the UE 100 switches a PDCCH monitoring state related to monitoring of the PDCCH in response to a RACH transmission or a RACH transmission trigger. This makes it possible to switch the PDCCH monitoring state based on the RACH transmission or a transmission trigger under the control of the base station 200, and makes it possible to appropriately perform wireless communication even when the PDCCH monitoring state is switched.

[0133] Furthermore, in the base station 200 according to this embodiment, the receiving unit 212 receives an SR or RACH preamble from the UE 100. The transmitting unit 211 transmits an RRC message for setting a cell group to the UE 100. The cell group is a group of serving cells for which the UE 100 simultaneously switches a PDCCH monitoring state related to PDCCH monitoring in response to an SR or RACH transmission or trigger. This makes it possible to simultaneously switch the PDCCH monitoring state based on an SR or RACH transmission (or a transmission trigger) in cell group units consisting of a plurality of serving cells, thereby making it possible to efficiently switch the PDCCH monitoring state.

[0134] (6) SR-induced switching process Based on the above-mentioned configuration and operation, the SR-induced switching process according to this embodiment will be described.

[0135] (6.1) Example of operation sequence for SR-induced switching process An operation sequence example 1 regarding the SR caused switching process according to the present embodiment will be described with reference to Fig. 15. In this operation sequence example 1, the UE 100 (control unit 120) performs the SR caused switching process in response to the SR transmission, thereby switching the PDCCH monitoring state after the transmission of the SR.

[0136] In step S101, the base station 200 (transmitter 211) transmits an RRC message to the UE 100. The RRC message may be a dedicated RRC message (for example, an RRC Reconfiguration message) transmitted individually to the UE. The UE 100 (receiver 112) receives the RRC message.

[0137] The RRC message includes an SR configuration for setting parameters for SR resources. The SR configuration includes switching control information for controlling the SR triggered switching process. This allows the switching control information for controlling the SR triggered switching process to be efficiently configured for the UE 100.

[0138] The SR configuration may include multiple SR resource configurations, each of which is associated with a logical channel. Each of the multiple SR resource configurations may include switching control information. This allows the SR-induced switching process to be controlled independently for each logical channel.

[0139] The RRC message may include a PDCCH configuration for configuring UE-specific PDCCH parameters. The PDCCH configuration may include switching control information for controlling the SR triggered switching process. The RRC message may further include information for configuring the above-mentioned PDCCH skipping and / or SSSG switching.

[0140] The switching control information may be information on whether to enable the SR induced switching process. The switching control information may include 1-bit flag information indicating whether to enable or disable the SR induced switching process. This allows the base station 200 to control whether the UE 100 performs the SR induced switching process.

[0141] The switching control information may be information specifying a PDCCH monitoring state after switching by the SR triggered switching process. For example, the switching control information may include an index indicating an SSSG after switching by the SR triggered switching process. This allows the base station 200 to specify a PDCCH monitoring state (e.g., SSSG) of a switching destination when the UE 100 performs the SR triggered switching process.

[0142] When the RRC message does not include switching control information, the UE 100 (control unit 120) may control not to perform the SR caused switching process. For example, when the UE 100 (control unit 120) is not set to enable the SR caused switching process and / or the PDCCH monitoring state (e.g., SSSG) of the switching destination when performing the SR caused switching process is not set, the UE 100 (control unit 120) does not perform the SR caused switching process even if it transmits an SR. This can prevent a mismatch between the actual PDCCH monitoring state in the UE 100 and the PDCCH monitoring state recognized by the base station 200.

[0143] In step S102, the base station 200 (transmitter 211) transmits, on the PDCCH, a switching instruction DCI instructing PDCCH skipping or SSSG switching to the UE 100. The UE 100 (receiver 112) receives the switching instruction DCI.

[0144] In step S103, UE 100 (control unit 120) switches the PDCCH monitoring state in response to receiving a switching instruction DCI. If PDCCH skipping is set, UE 100 (control unit 120) may skip monitoring the PDCCH for a predetermined period in response to receiving a switching instruction DCI (skip instruction DCI). If SSSG switching is set, UE 100 (control unit 120) may switch to the SSSG instructed by the switching instruction DCI in response to receiving the switching instruction DCI. As a result, UE 100 enters a power saving state in which power consumption required for monitoring the PDCCH is reduced.

[0145] In step S104, the UE 100 (control unit 120) detects an SR transmission trigger. The SR transmission trigger may be any of the following: uplink data and / or a BSR to be transmitted to the base station 200 has been generated; uplink data to be transmitted to the base station 200 has arrived at the MAC layer of the UE 100; and the MAC layer of the UE 100 has instructed the physical (PHY) layer to transmit an SR.

[0146] In step S105, the UE 100 (transmitter 111) transmits an SR to the base station 200 on the PUCCH in response to an SR transmission trigger based on the SR configuration set in step S101. For example, the UE 100 transmits an SR using an SR resource configuration corresponding to a logical channel to be subjected to SR transmission, i.e., a logical channel to transmit uplink data. The base station 200 (receiver 212) receives the SR.

[0147] In step S106, the UE 100 (control unit 120) switches the PDCCH monitoring state in response to the transmission of the SR (SR-induced switching process). The SR-induced switching process is a process of switching the PDCCH monitoring state from the first monitoring state to the second monitoring state. The first monitoring state corresponds to the above-mentioned power saving state. The second monitoring state is a state in which the PDCCH is monitored more frequently than the first monitoring state. This makes it easier to handle wireless communication (data communication) that occurs after the transmission of the SR. That is, the UE 100 (control unit 120) may execute the above-mentioned PDCCH skipping and / or SSSG switching based on the SR transmission (or an SR transmission trigger). The SR-induced switching process may correspond to a process related to the PDCCH skipping and / or SSSG switching based on the SR transmission (or an SR transmission trigger).

[0148] For example, the first monitoring state may be a state in which the PDCCH is monitored at a first cycle, and the second monitoring state may be a state in which the PDCCH is monitored at a second cycle shorter than the first cycle. For example, after SSSG switching is configured and switching to an SSSG having a long PDCCH monitoring cycle is instructed by DCI, the UE 100 (control unit 120) switches to an SSSG having a short PDCCH monitoring cycle in response to transmission of an SR.

[0149] Also, the first monitoring state may be a state in which the PDCCH is not monitored (i.e., PDCCH skipping), and the second monitoring state may be a state in which the PDCCH is periodically monitored. For example, the UE 100 (control unit 120) is configured with PDCCH skipping, and after being instructed by DCI to perform PDCCH skipping, the UE 100 (control unit 120) switches to a state in which the PDCCH is monitored in response to the transmission of an SR.

[0150] The UE 100 (control unit 120) may perform the SR induced switching process only when the UE 100 (control unit 120) performs SR transmission when the UE 100 is in a power saving state. That is, the UE 100 (control unit 120) may not perform the SR induced switching process when the UE 100 (control unit 120) performs SR transmission when the UE 100 is not in a power saving state. Alternatively, the UE 100 (control unit 120) may perform the SR induced switching process only when the UE 100 (control unit 120) performs SR transmission in a state in which PDCCH skipping and / or SSSG switching is set. That is, the UE 100 (control unit 120) may not perform the SR induced switching process when PDCCH skipping and / or SSSG switching is not set.

[0151] The UE 100 (control unit 120) may perform the SR caused switching process only when the switching control information indicates that the SR caused switching process is to be enabled. When the UE 100 (control unit 120) performs the SR caused switching process based on the switching control information indicating that the SR caused switching process is to be enabled, the UE 100 (control unit 120) may switch to a predetermined PDCCH monitoring state in the SR caused switching process. The predetermined PDCCH monitoring state may be the above-mentioned default SSSG.

[0152] When the switching control information specifies a PDCCH monitoring state (e.g., SSSG) to be switched to by the SR-induced switching process, the UE 100 (control unit 120) may switch to the PDCCH monitoring state specified by the switching control information. For example, when the switching control information includes an index indicating the SSSG after switching by the SR-induced switching process, the UE 100 (control unit 120) switches to the SSSG indicated by the index.

[0153] When switching control information is set for each logical channel, UE100 (control unit 120) may control the SR-induced switching process based on the switching control information corresponding to one logical channel in response to SR transmission in the one logical channel. For example, when switching control information is set for each of logical channels #0 to #4 of UE100 and an SR is transmitted for logical channel #1, UE100 (control unit 120) controls the SR-induced switching process using the switching control information corresponding to logical channel #1. This makes it possible to appropriately control the SR-induced switching process for each logical channel.

[0154] Here, the UE 100 (transmitter 111) may transmit not only a positive SR but also a negative SR. For example, the positive SR may be an SR whose value is set to "1", and the negative SR may be an SR whose value is set to "0". Also, for example, the positive SR may be used to request an uplink shared channel (UL-SCH) resource, and the negative SR may be used to not request an uplink shared channel (UL-SCH) resource. When transmitting a negative SR to the base station 200, the UE 100 (controller 120) controls not to perform an SR-induced switching process. That is, the UE 100 (controller 120) performs an SR-induced switching process only when transmitting a positive SR to the base station 200.

[0155] In step S107, in response to receiving the SR from the UE 100, the base station 200 (control unit 230) allocates UL-SCH resources to the UE 100. Specifically, the base station 200 (transmission unit 211) transmits, to the UE 100, scheduling DCI including a UL grant for allocating UL-SCH resources, on the PDCCH.

[0156] 16, an operation sequence example 2 regarding the SR caused switching process according to the present embodiment will be described, focusing mainly on differences from the above-mentioned operation sequence example 1. In this operation sequence example 2, the UE 100 (control unit 120) performs the SR caused switching process in response to an SR transmission trigger, thereby switching the PDCCH monitoring state before transmitting an SR.

[0157] In FIG. 16, the operations in steps S111 to S114 are similar to the operations in steps S101 to S104 in FIG.

[0158] In step S115, the UE 100 (control unit 120) switches the PDCCH monitoring state in response to the SR transmission trigger (SR-induced switching process).

[0159] In step S116, the UE 100 (transmitter 111) transmits an SR to the base station 200 on the PUCCH.

[0160] In step S117, the base station 200 (control unit 230) allocates UL-SCH resources to the UE 100 in response to receiving the SR from the UE 100.

[0161] In this way, according to this operation sequence example 2, the SR induced switching process can be started at an earlier stage than the above-mentioned operation sequence example 1. In the case where the UE 100 requires a certain time to switch the PDCCH monitoring state in the SR induced switching process, if the SR induced switching process is started after transmitting an SR, there is a possibility that the UL grant from the base station 200 will not be received in time. Therefore, by starting the SR induced switching process before transmitting an SR, the UL grant from the base station 200 can be received more reliably.

[0162] In addition, whether the SR caused switching process is to be triggered by SR transmission (i.e., after SR transmission) or an SR transmission trigger (i.e., before SR transmission) may be set by the base station 200 to the UE 100. For example, the base station 200 (transmitter 211) may transmit switching control information including information for setting whether the SR caused switching process is to be triggered by SR transmission or an SR transmission trigger to the UE 100 by an RRC message.

[0163] (6.2) Example of RRC message configuration for SR-induced switching processing A first configuration example of an RRC message according to this embodiment will be described with reference to Fig. 17. In this first configuration example, switching control information for controlling an SR-induced switching process is included in an SR configuration (SchedulingRequestConfig).

[0164] The base station 200 (transmitting unit 211) transmits an RRC message including an SR configuration (SchedulingRequestConfig) shown in FIG. 17 to the UE 100. The SchedulingRequestConfig can include a list of SRs (schedulingRequestToAddModList) whose configuration is to be added or changed, and a list of SRs (schedulingRequestToReleaseList) whose configuration is to be released. The schedulingRequestToAddModList includes the configuration of the SR to be added or changed (SchedulingRequestToAddMod), and the SchedulingRequestToAddMod includes an SR identifier (schedulingRequestId) for identifying the SR resource configuration. The schedulingRequestId is associated with a logical channel. Specifically, the logical channel configuration (LogicalChannelConfig) of each logical channel includes the schedulingRequestId, and the UE 100 (control unit 120) applies the SR resource configuration indicated by the schedulingRequestId to the logical channel.

[0165] In this configuration example 1, as shown in A1 of Fig. 17, SchedulingRequestConfig includes a list of SSSGs (schedulingRequestToAddModListExt-r17) that are destinations of switching in the SR-induced switching process. SchedulingRequestToAddModListExt-r17 is associated with schedulingRequestId. As shown in A2 of Fig. 17, schedulingRequestToAddModListExt-r17 includes information (SchedulingRequestToAddMod-v17xy) that sets an SSSG that is destination of switching in the SR-induced switching process, and the SchedulingRequestToAddMod-v17xy includes an identifier or index (searchSpaceSetId-r17) of the SSSG. The information as shown in A1 and A2 of Fig. 17 corresponds to switching control information for controlling the SR-induced switching process.

[0166] In response to an SR transmission or an SR transmission trigger for a certain logical channel, the UE 100 (control unit 120) switches to an SSSG indicated by searchSpaceSetId-r17 in SchedulingRequestToAddMod-v17xy associated with the logical channel. When SchedulingRequestToAddMod-v17xy and / or searchSpaceSetId-r17 associated with the logical channel are not set, the UE 100 (control unit 120) may not switch the SSSG in response to an SR transmission or an SR transmission trigger, or may switch the SSSG to a default SSSG in response to an SR transmission or an SR transmission trigger.

[0167] A second configuration example of an RRC message according to this embodiment will be described with reference to Fig. 18. In this first configuration example, switching control information for controlling an SR-induced switching process is included in an SR resource configuration (SchedulingRequestResourceConfig).

[0168] The base station 200 (transmitter 211) transmits an RRC message including an SR resource configuration (SchedulingRequestResourceConfig) shown in FIG. 18 to the UE 100. SchedulingRequestResourceConfig can include an SR identifier (schedulingRequestId) associated with a logical channel, information (resource) for setting a PUCCH resource used for SR transmission, information (periodicityAndOffset) for setting a periodicity and / or offset used for SR transmission, and information (phy-PriorityIndex-r16) for setting a priority of SR. In this configuration example 2, as shown in B1 of FIG. 18, SchedulingRequestResourceConfig includes an identifier or index (searchSpaceSetId-r17) of an SSSG to be switched to in the SR-induced switching process. The information shown in B1 of FIG. 18 corresponds to switching control information for controlling the SR-induced switching process.

[0169] The UE 100 (control unit 120) switches to an SSSG indicated by searchSpaceSetId-r17 associated with a certain logical channel in response to an SR transmission or an SR transmission trigger for that logical channel. If the searchSpaceSetId-r17 associated with that logical channel is not set, the UE 100 (control unit 120) may not switch the SSSG in response to an SR transmission or an SR transmission trigger, or may switch the SSSG to a default SSSG in response to an SR transmission or an SR transmission trigger.

[0170] A third configuration example of the RRC message according to the present embodiment will be described with reference to FIG.

[0171] The base station 200 (transmitter 211) transmits an RRC message including a PDCCH setting (PDCCH-Config) shown in Fig. 19 to the UE 100. The PDCCH-Config includes, as shown in C1 of Fig. 19, information for setting a default SSSG (defaultSearchSpaceSet-r17) and the initial SSSG. S It can also include information for setting G (firstSearchSpaceSet-r17).

[0172] The defaultSearchSpaceSet-r17 is composed of an index (SearchSpaceSetId-r17) of a default SSSG. The firstSearchSpaceSet-r17 is composed of an index (SearchSpaceSetId-r17) of a first SSSG. The first SSSG refers to the SSSG that the UE 100 should apply first. When the firstSearchSpaceSet-r17 is configured for the primary cell (SpCell), the UE 100 (control unit 120) enables the SSSG configured in the firstSearchSpaceSet-r17 at the time of RRC configuration or RRC reconfiguration. When the firstSearchSpaceSet-r17 is configured for the secondary cell (SCell), the UE 100 (control unit 120) uses the SSSG configured in the firstSearchSpaceSet-r17 when the secondary cell is enabled.

[0173] The UE 100 (control unit 120) may switch to a default SSSG (defaultSearchSpaceSet) in response to an SR transmission or an SR transmission trigger when the SSSG to be switched to by the SR caused switching process is not explicitly specified by the base station 200. Alternatively, the UE 100 (control unit 120) may switch to a first SSSG (firstSearchSpaceSet) in response to an SR transmission or an SR transmission trigger when the SSSG to be switched to by the SR caused switching process is not explicitly specified by the base station 200.

[0174] (6.3) Specific examples of SR-induced switching processing A first specific example of the SR induced switching process according to this embodiment will be described with reference to Fig. 20. As described above, the SR induced switching process is a process of switching the PDCCH monitoring state from a first monitoring state to a second monitoring state. The first monitoring state corresponds to the above-mentioned power saving state. In this first specific example, the first monitoring state is a state in which the PDCCH is monitored in a first period, and the second monitoring state is a state in which the PDCCH is monitored in a second period that is shorter than the first period.

[0175] At time t11, the UE 100 (receiving unit 112) receives a switching instruction DCI instructing an SSSG from the base station 200 in the downlink BWP in a certain serving cell.

[0176] At time t12, in response to receiving the switching instruction DCI, UE 100 (control unit 120) starts application of the instructed SSSG (i.e., starts the first monitoring state). At the start of the first monitoring state, UE 100 (control unit 120) starts a first timer that determines the duration of the first monitoring state. For example, period Z is set as a timer value in the first timer. The timer value (timer setting value) of the first timer may be set in UE 100 from base station 200 by an RRC message.

[0177] At time t13, the UE 100 (transmitter 111) transmits an SR to the base station 200 on the PUCCH in the uplink BWP in the serving cell. The UE 100 (controller 120) performs an SR-induced switching process to switch to a predetermined SSSG in response to the SR transmission or the SR transmission trigger (i.e., starts the second monitoring state). The predetermined SSSG may be an SSSG set by the base station 200 through the SR setting, a default SSSG (defaultSearchSpaceSet), or a first SSSG (firstSearchSpaceSet).

[0178] The UE 100 (control unit 120) stops the first timer when performing the SR-induced switching process. By stopping the first timer, it is possible to prevent switching to the default SSSG due to expiration of the first timer.

[0179] When performing the SR-induced switching process, the UE 100 (control unit 120) starts a second timer that determines the duration of the second monitoring state. For example, a period Y is set as a timer value in the second timer. The timer value (timer setting value) of the second timer may be set to the UE 100 by the base station 200 via an RRC message. When performing the SR-induced switching process, the UE 100 (control unit 120) starts the second timer to which the timer value is set. This allows the base station 200 to control the duration of the second monitoring state.

[0180] In the second monitoring state, the UE 100 (the receiver 112) may receive from the base station 200 a scheduling DCI (for example, a DCI format used for PDSCH scheduling or a DCI format used for PUSCH scheduling) used for radio resource allocation. The UE 100 (the controller 120) may restart the second timer in response to reception of the scheduling DCI. Since data communication occurs due to reception of the scheduling DCI, the duration of the second monitoring state can be extended by restarting the second timer. Furthermore, in the second monitoring state, the UE 100 (the controller 120) may restart the second timer in response to an SR transmission or an SR transmission trigger. Since data communication occurs due to the SR transmission, the duration of the second monitoring state can be extended by restarting the second timer.

[0181] The UE 100 (control unit 120) switches to a predetermined PDCCH monitoring state in response to expiration of the second timer. That is, the UE 100 (control unit 120) ends the second monitoring state when the period Y expires. The predetermined PDCCH monitoring state to which the switching is to be made upon expiration of the second timer may be a default SSSG (defaultSearchSpaceSet) or a first SSSG (firstSearchSpaceSet).

[0182] A specific example 2 of the SR induced switching process according to this embodiment will be described with reference to Fig. 21. In this specific example 2, the first monitoring state is a state in which PDCCH monitoring is not performed (i.e., PDCCH skipping), and the second monitoring state is a state in which PDCCH monitoring is performed periodically.

[0183] At time t21, the UE 100 (reception unit 112) receives, from the base station 200, a switching instruction DCI instructing PDCCH skipping in the downlink BWP in a certain serving cell.

[0184] At time t22, in response to receiving the switching command DCI, the UE 100 (control unit 120) starts PDCCH skipping (i.e., starts the first monitoring state). At the start of the first monitoring state, the UE 100 (control unit 120) starts a first timer that determines the duration of the first monitoring state. For example, a period X is set as a timer value in the first timer. The timer value (timer setting value) of the first timer may be set in the UE 100 from the base station 200 by an RRC message.

[0185] At time t23, the UE 100 (transmitter 111) transmits an SR to the base station 200 on the PUCCH in the uplink BWP in the serving cell. The UE 100 (controller 120) performs an SR-induced switching process to switch to a predetermined SSSG in response to the SR transmission or the SR transmission trigger (i.e., starts the second monitoring state). As a result, the PDCCH skipping ends, and monitoring of the PDCCH starts (resumes). The predetermined SSSG may be an SSSG set by the base station 200 through the SR setting, a default SSSG (defaultSearchSpaceSet), or an initial SSSG (firstSearchSpaceSet).

[0186] The UE 100 (control unit 120) stops the first timer when performing the SR-induced switching process. By stopping the first timer, it is possible to prevent switching to the default SSSG due to expiration of the first timer.

[0187] When performing the SR-induced switching process, the UE 100 (control unit 120) starts a second timer that determines the duration of the second monitoring state. For example, a period Y is set as a timer value in the second timer. The timer value (timer setting value) of the second timer may be set to the UE 100 by the base station 200 via an RRC message. When performing the SR-induced switching process, the UE 100 (control unit 120) starts the second timer to which the timer value is set. This allows the base station 200 to control the duration of the second monitoring state.

[0188] In the second monitoring state, the UE 100 (the receiver 112) may receive from the base station 200 a scheduling DCI (for example, a DCI format used for PDSCH scheduling or a DCI format used for PUSCH scheduling) used for radio resource allocation. The UE 100 (the controller 120) may restart the second timer in response to reception of the scheduling DCI. Since data communication occurs due to reception of the scheduling DCI, the duration of the second monitoring state can be extended by restarting the second timer. Furthermore, in the second monitoring state, the UE 100 (the controller 120) may restart the second timer in response to an SR transmission or an SR transmission trigger. Since data communication occurs due to the SR transmission, the duration of the second monitoring state can be extended by restarting the second timer.

[0189] The UE 100 (control unit 120) switches to a predetermined PDCCH monitoring state in response to expiration of the second timer. That is, the UE 100 (control unit 120) ends the second monitoring state when the period Y expires. The predetermined PDCCH monitoring state to which the switching is to be made upon expiration of the second timer may be a default SSSG (defaultSearchSpaceSet) or a first SSSG (firstSearchSpaceSet).

[0190] (7) RACH-induced switching process Based on the above-mentioned configuration and operations, the RACH-induced switching process according to this embodiment will be described.

[0191] (7.1) Example of operation sequence for RACH-induced switching process An operation sequence example 1 regarding the RACH caused switching process according to the present embodiment will be described with reference to Fig. 22. In this operation sequence example 1, the UE 100 (control unit 120) performs the RACH caused switching process in response to the RACH transmission (specifically, the RACH preamble transmission) to switch the PDCCH monitoring state after the RACH transmission.

[0192] In step S201, the base station 200 (transmitter 211) transmits an RRC message to the UE 100. The RRC message may be a dedicated RRC message (for example, an RRC Reconfiguration message) transmitted individually to the UE. The UE 100 (receiver 112) receives the RRC message.

[0193] The RRC message includes a beam failure recovery (BFR) configuration for setting a RACH resource for BFR and a reference signal resource for detecting a beam failure. The RACH configuration includes switching control information for controlling a RACH-induced switching process. This allows the switching control information for controlling a RACH-induced switching process to be efficiently set for the UE 100. Note that the MAC layer of the UE 100 monitors a reference signal in a reference signal resource set by the BFR configuration for a primary cell, and when a beam failure instance is detected in a physical layer a predetermined number of times within a predetermined time, starts a RACH procedure for the primary cell using the RACH resource set by the BFR configuration.

[0194] The BFR configuration may include multiple BFR resource configurations, each of which is associated with a RACH preamble. Each of the multiple RACH resource configurations may include switching control information, which allows the RACH induced switching process to be controlled independently for each RACH preamble.

[0195] The RRC message may include a PDCCH configuration for configuring UE specific PDCCH parameters. The PDCCH configuration may include switching control information for controlling a RACH induced switching process. The RRC message may further include information for configuring the above-mentioned PDCCH skipping and / or SSSG switching.

[0196] The switching control information may be information on whether to enable the RACH induced switching process. The switching control information may include 1-bit flag information indicating whether to enable or disable the RACH induced switching process. This allows the base station 200 to control whether the UE 100 performs the RACH induced switching process.

[0197] The switching control information may be information that specifies a PDCCH monitoring state after switching by the RACH-induced switching process. For example, the switching control information may include an index that indicates an SSSG after switching by the RACH-induced switching process. This allows the base station 200 to specify a PDCCH monitoring state (e.g., SSSG) to be switched to when the UE 100 performs the RACH-induced switching process.

[0198] When the RRC message does not include the switching control information, the UE 100 (control unit 120) may control not to perform the RACH-induced switching process. For example, when the RACH-induced switching process is not set to be enabled and / or the PDCCH monitoring state (e.g., SSSG) of the switching destination when performing the RACH-induced switching process is not set, the UE 100 (control unit 120) does not perform the RACH-induced switching process even if the RACH is transmitted. This can prevent a mismatch between the actual PDCCH monitoring state in the UE 100 and the PDCCH monitoring state recognized by the base station 200.

[0199] In step S202, the base station 200 (transmitter 211) transmits, on the PDCCH, a switching instruction DCI instructing PDCCH skipping or SSSG switching to the UE 100. The UE 100 (receiver 112) receives the switching instruction DCI.

[0200] In step S203, UE 100 (control unit 120) switches the PDCCH monitoring state in response to receiving a switching instruction DCI. If PDCCH skipping is set, UE 100 (control unit 120) may skip monitoring the PDCCH for a predetermined period in response to receiving a switching instruction DCI (skip instruction DCI). If SSSG switching is set, UE 100 (control unit 120) may switch to the SSSG instructed by the switching instruction DCI in response to receiving the switching instruction DCI. As a result, UE 100 enters a power saving state in which power consumption required for monitoring the PDCCH is reduced.

[0201] In step S204, the UE 100 (control unit 120) detects a transmission trigger of the RACH. The transmission trigger of the RACH may be any of the following: the MAC layer of the UE 100 detects a beam failure for a primary cell; there is no PUCCH resource for SR for a logical channel corresponding to uplink data generated in the UE 100; and the MAC layer in the UE 100 instructs the physical layer to transmit the RACH.

[0202] In step S205, the UE 100 (transmitter 111) transmits a RACH preamble on the PRACH to the base station 200 in response to a transmission trigger of the RACH based on the RACH configuration set in step S201. For example, the UE 100 controls a RACH-induced switching process based on switching control information corresponding to one RACH preamble in response to the transmission or transmission trigger of the one RACH preamble set in the BFR configuration. The base station 200 (receiver 212) receives the RACH.

[0203] In step S206, the UE 100 (control unit 120) switches the PDCCH monitoring state in response to the transmission of the RACH (RACH-induced switching process). The RACH-induced switching process is a process of switching the PDCCH monitoring state from a first monitoring state to a second monitoring state. The first monitoring state corresponds to the above-mentioned power saving state. The second monitoring state is a state in which the PDCCH is monitored more frequently than the first monitoring state. This makes it easier to handle radio communication (data communication) that occurs after the transmission of the RACH. That is, the UE 100 (control unit 120) may execute the above-mentioned PDCCH skipping and / or SSSG switching based on the transmission of the RACH (or a RACH transmission trigger). Furthermore, the RACH-induced switching process may correspond to a process related to PDCCH skipping and / or SSSG switching based on the transmission of the RACH (or a RACH transmission trigger).

[0204] For example, the first monitoring state may be a state in which the PDCCH is monitored at a first cycle, and the second monitoring state may be a state in which the PDCCH is monitored at a second cycle shorter than the first cycle. For example, after SSSG switching is configured and switching to an SSSG having a long PDCCH monitoring cycle is instructed by DCI, the UE 100 (control unit 120) switches to an SSSG having a short PDCCH monitoring cycle in response to transmission of a RACH.

[0205] Also, the first monitoring state may be a state in which the PDCCH is not monitored (i.e., PDCCH skipping), and the second monitoring state may be a state in which the PDCCH is periodically monitored. For example, the UE 100 (control unit 120) is configured with PDCCH skipping, and after being instructed by DCI to perform PDCCH skipping, the UE 100 (control unit 120) switches to a state in which the PDCCH is monitored in response to transmission of the RACH.

[0206] The UE 100 (control unit 120) may perform the RACH induced switching process only when the UE 100 (control unit 120) performs RACH transmission when the UE 100 is in a power saving state. That is, the UE 100 (control unit 120) may not perform the RACH induced switching process when the UE 100 (control unit 120) performs RACH transmission when the UE 100 is not in a power saving state. Alternatively, the UE 100 (control unit 120) may perform the RACH induced switching process only when the UE 100 (control unit 120) performs RACH transmission in a state in which PDCCH skipping and / or SSSG switching is set. That is, the UE 100 (control unit 120) may not perform the RACH induced switching process when PDCCH skipping and / or SSSG switching is not set.

[0207] The UE 100 (control unit 120) may perform the RACH-induced switching process only when the switching control information indicates that the RACH-induced switching process is enabled. When the UE 100 (control unit 120) performs the RACH-induced switching process based on the switching control information indicating that the RACH-induced switching process is enabled, the UE 100 (control unit 120) may switch to a predetermined PDCCH monitoring state in the RACH-induced switching process. The predetermined PDCCH monitoring state may be the above-mentioned default SSSG.

[0208] When a PDCCH monitoring state (e.g., SSSG) of a switching destination by the RACH-induced switching process is specified by the switching control information, the UE 100 (control unit 120) may switch to the PDCCH monitoring state specified by the switching control information. For example, when the switching control information includes an index indicating the SSSG after switching by the RACH-induced switching process, the UE 100 (control unit 120) switches to the SSSG indicated by the index.

[0209] When switching control information is set for each RACH preamble, the UE 100 (control unit 120) may control the RACH-induced switching process based on the switching control information corresponding to one RACH preamble in response to transmission of the one RACH preamble. For example, when switching control information is set for each of the RACH preambles #0 to #4 set in the UE 100 and RACH transmission is performed using the RACH preamble #1, the UE 100 (control unit 120) controls the RACH-induced switching process using the switching control information corresponding to the RACH preamble #1. This allows the RACH-induced switching process to be appropriately controlled for each RACH preamble.

[0210] In step S207, in response to receiving the RACH preamble from UE 100, base station 200 (control unit 230) allocates UL-SCH resources to UE 100. Specifically, base station 200 (transmission unit 211) transmits scheduling DCI including a UL grant for allocating UL-SCH resources to UE 100 on the PDCCH.

[0211] 23, an operation sequence example 2 related to a RACH-induced switching process according to the present embodiment will be described, focusing mainly on differences from the above-mentioned operation sequence example 1. In this operation sequence example 2, the UE 100 (control unit 120) performs a RACH-induced switching process in response to a RACH transmission trigger, thereby switching the PDCCH monitoring state before transmitting a RACH preamble.

[0212] In FIG. 23, the operations in steps S211 to S214 are similar to the operations in steps S201 to S204 in FIG.

[0213] In step S215, the UE 100 (control unit 120) switches the PDCCH monitoring state in response to a transmission trigger of the RACH (RACH-induced switching process).

[0214] In step S216, the UE 100 (transmitter 111) transmits a RACH preamble to the base station 200 on the PRACH.

[0215] In step S217, the base station 200 (control unit 230) allocates UL-SCH resources to the UE 100 in response to the reception of the RACH preamble from the UE 100.

[0216] In this way, according to the present operation sequence example 2, the RACH induced switching process can be started at an earlier stage than the above-mentioned operation sequence example 1. In the case where the UE 100 requires a certain time to switch the PDCCH monitoring state in the RACH induced switching process, if the UE 100 starts the RACH induced switching process after transmitting the RACH preamble, there is a possibility that the UL grant from the base station 200 will not be received in time. Therefore, by starting the RACH induced switching process before transmitting the RACH preamble, the UL grant from the base station 200 can be received more reliably.

[0217] In addition, whether the RACH caused switching process is triggered by RACH transmission (i.e., after RACH preamble transmission) or a RACH transmission trigger (i.e., before RACH preamble transmission) may be set by base station 200 to UE 100. For example, base station 200 (transmitter 211) may transmit switching control information including information for setting whether the RACH caused switching process is triggered by RACH transmission or a RACH transmission trigger to UE 100 by an RRC message.

[0218] With reference to Fig. 24, an operation sequence example 3 related to a RACH-induced switching process according to this embodiment will be described, focusing mainly on differences from the above-mentioned operation sequence examples 1 and 2. In this operation sequence example 3, the UE 100 (control unit 120) switches the PDCCH monitoring state at the end of the RACH procedure by performing a RACH-induced switching process in response to receiving a MAC CE including switching control information from the base station 200 in the RACH procedure. Prior to the operation in Fig. 24, the operations of steps S201 to S203 in Fig. 22 may be performed.

[0219] In step S231, the UE 100 (control unit 120) detects a transmission trigger of the RACH. The transmission trigger of the RACH may be any one of the following: the MAC layer of the UE 100 detects a beam failure for a primary cell, there is no PUCCH resource for SR for a logical channel corresponding to uplink data generated in the UE 100, and the MAC layer in the UE 100 instructs the physical layer to transmit the RACH.

[0220] In step S232, the UE 100 (transmitter 111) transmits a RACH preamble to the base station 200 on the PRACH based on the RACH setting set by the base station 200. The base station 200 (receiver 212) receives the RACH preamble. Here, when the UE 100 transmits a RACH preamble in response to detection of a beam obstruction, a RACH preamble for BFR is applied. In response to receiving the RACH preamble for BFR from the UE 100, the base station 200 (controller 230) can recognize that the UE 100 has started a RACH procedure for BFR. The transmission of the RACH preamble is referred to as Msg1 in the RACH procedure. The UE 100 (controller 120) may perform a RACH-induced switching process in response to a RACH transmission trigger or RACH transmission, similar to the above-mentioned operation sequence examples 1 and 2.

[0221] In step S233, base station 200 (control unit 230) allocates UL-SCH resources to UE 100 in response to receiving the RACH preamble from UE 100. Specifically, base station 200 (transmission unit 211) transmits a scheduling DCI including a UL grant for allocating UL-SCH resources to UE 100 on the PDCCH. UE 100 (reception unit 112) receives the scheduling DCI including the UL grant. The transmission of the UL grant is referred to as Msg2 in the RACH procedure.

[0222] In step S234, the UE 100 (transmitter 111) performs uplink transmission using the UL-SCH resource allocated by the UL grant from the base station 200. The base station 200 (receiver 112) receives the uplink transmission. Such uplink transmission is called Msg3 in the RACH procedure.

[0223] In step S235, the base station 200 (transmitter 211) performs downlink transmission to the UE 100. The UE 100 (receiver 112) receives the downlink transmission. Such downlink transmission is called Msg4 in the RACH procedure. Here, the base station 200 (transmitter 211) transmits to the UE 100 a MAC CE including switching control information that specifies a PDCCH monitoring state (e.g., SSSG) after switching. The UE 100 (receiver 112) receives the MAC CE. That is, after performing the RACH transmission, the UE 100 (receiver 112) receives the MAC CE including the switching control information from the base station 200 in the RACH procedure.

[0224] In step S236, the UE 100 (control unit 120) performs a RACH-induced switching process in response to the reception of the MAC CE. Specifically, the UE 100 (control unit 120) switches to a PDCCH monitoring state (for example, SSSG) designated by switching control information included in the MAC CE.

[0225] Although an example has been described in which base station 200 transmits a MAC CE including the switching control information in Msg4, base station 200 may transmit a MAC CE including the switching control information in Msg2.

[0226] (7.2) Example of message configuration for RACH-induced switching process A configuration example of an RRC message according to this embodiment will be described with reference to Fig. 25. In this configuration example, switching control information for controlling a RACH-induced switching process is included in a BFR configuration (BeamFailureRecoveryConfig).

[0227] The base station 200 (transmitter 211) transmits an RRC message including a BFR configuration (BeamFailureRecoveryConfig) shown in Fig. 25 to the UE 100. BeamFailureRecoveryConfig can include information for configuring a RACH resource for BFR and information for configuring a reference signal (RS) resource used to detect a beam failure. The reference signal resource is an SSB (SS / PBCH Block) resource or a CSI-RS (Channel State Information RS) resource.

[0228] In this configuration example, as shown in D1 of FIG. 25, BeamFailureRecoveryConfig can include information (searchSpaceSetId-r17) for setting a switching destination SSSG in the RACH-induced switching process as an information element common to all RACH preambles. searchSpaceSetId-r17 is an identifier or index of the SSSG. Also, in this configuration example, as shown in D2 and D3 of FIG. 25, BeamFailureRecoveryConfig can include information (searchSpaceSetId-r17) for setting a switching destination SSSG in the RACH-induced switching process as an information element specific to a specific RACH preamble. This makes it possible to set a switching destination SSSG independently for each RACH preamble. The information shown in D1 to D3 of FIG. 25 corresponds to switching control information for controlling the RACH-induced switching process.

[0229] The UE 100 (control unit 120) switches to the SSSG indicated by the searchSpaceSetId-r17 associated with one RACH preamble in response to the RACH transmission or the RACH transmission trigger of the one RACH preamble. When the searchSpaceSetId-r17 associated with the one RACH preamble is not set, the UE 100 (control unit 120) may not switch the SSSG in response to the RACH transmission or the RACH transmission trigger, and may switch the SSSG to the default SSSG in response to the RACH transmission or the RACH transmission trigger.

[0230] With reference to Fig. 26, a configuration example of a MAC CE according to this embodiment will be described. The MAC CE according to this embodiment is a MAC CE for SSSG switching. Such a MAC CE may be referred to as a "Serving Cell Set based Search Space Set Group Indication MAC CE". The SSSG switching MAC CE may be configured to be identifiable by a MAC PDU subheader having an eLCID defined for the SSSG switching MAC CE. The SSSG switching MAC CE is configured with the following fields and has a fixed size.

[0231] Serving Cell ID (Cell Identifier): This field indicates the ID of the serving cell to which the MAC CE applies, and the length of the field is, for example, 5 bits. If the serving cell indicated by the serving cell ID is configured as part of a cell group, this MAC CE applies to all serving cells in the cell group to which the serving cell belongs.

[0232] -BWP ID (BWP Identifier): This field indicates the downlink BWP to which this MAC CE applies. The length of the BWP ID field is, for example, 2 bits.

[0233] -Search Space Set Group ID (SSSG Identifier): This field indicates the Search Space Set Group (SSSG) for which the UE monitors the PDCCH, i.e., the SSSG to which the UE is to switch. The length of the field is, for example, 8 bits.

[0234] -R: Reserved bit, set to "0".

[0235] Upon receiving the SSSG switching MAC CE from the base station 200, the UE 100 (control unit 120) switches to the SSSG indicated by the SSSG switching MAC CE in the downlink BWP of the serving cell indicated by the SSSG switching MAC CE.

[0236] (7.3) Example of RACH-induced switching process A first specific example of the RACH induced switching process according to this embodiment will be described with reference to Fig. 27. As described above, the RACH induced switching process is a process of switching the PDCCH monitoring state from the first monitoring state to the second monitoring state. The first monitoring state corresponds to the above-mentioned power saving state. In this first specific example, the first monitoring state is a state in which the PDCCH is monitored in a first period, and the second monitoring state is a state in which the PDCCH is monitored in a second period that is shorter than the first period.

[0237] At time t31, the UE 100 (the receiver 112) receives a switching instruction DCI instructing an SSSG from the base station 200 in the downlink BWP in a certain serving cell.

[0238] At time t32, in response to receiving the switching command DCI, UE 100 (control unit 120) starts application of the instructed SSSG (i.e., starts the first monitoring state). At the start of the first monitoring state, UE 100 (control unit 120) starts a first timer that determines the duration of the first monitoring state. For example, period Z is set as a timer value in the first timer. The timer value (timer setting value) of the first timer may be set in UE 100 from base station 200 by an RRC message.

[0239] At time t33, the UE 100 (transmitter 111) transmits a RACH preamble to the base station 200 on the PRACH in the uplink BWP in the serving cell. The UE 100 (controller 120) performs a RACH-induced switching process to switch to a predetermined SSSG in response to a RACH transmission or a RACH transmission trigger (i.e., starts a second monitoring state). The predetermined SSSG may be an SSSG set by the base station 200 through RACH configuration, a default SSSG (defaultSearchSpaceSet), or a first SSSG (firstSearchSpaceSet).

[0240] The UE 100 (control unit 120) stops the first timer when performing the RACH-induced switching process. By stopping the first timer, it is possible to prevent switching to the default SSSG due to expiration of the first timer.

[0241] When performing a RACH-induced switching process, the UE 100 (control unit 120) starts a second timer that determines the duration of the second monitoring state. For example, a period Y is set as a timer value in the second timer. The timer value (timer setting value) of the second timer may be set to the UE 100 by the base station 200 via an RRC message. When performing a RACH-induced switching process, the UE 100 (control unit 120) starts the second timer to which the timer value is set. This allows the base station 200 to control the duration of the second monitoring state.

[0242] In the second monitoring state, the UE 100 (the receiver 112) may receive from the base station 200 a scheduling DCI (for example, a DCI format used for PDSCH scheduling or a DCI format used for PUSCH scheduling) used for radio resource allocation. The UE 100 (the controller 120) may restart the second timer in response to reception of the scheduling DCI. Since data communication occurs due to reception of the scheduling DCI, the duration of the second monitoring state can be extended by restarting the second timer. Furthermore, in the second monitoring state, the UE 100 (the controller 120) may restart the second timer in response to a RACH transmission or a RACH transmission trigger. Since data communication occurs due to the RACH transmission, the duration of the second monitoring state can be extended by restarting the second timer.

[0243] The UE 100 (control unit 120) switches to a predetermined PDCCH monitoring state in response to expiration of the second timer. That is, the UE 100 (control unit 120) ends the second monitoring state when the period Y expires. The predetermined PDCCH monitoring state to which the switching is to be made upon expiration of the second timer may be a default SSSG (defaultSearchSpaceSet) or a first SSSG (firstSearchSpaceSet).

[0244] A specific example 2 of the RACH-induced switching process according to the present embodiment will be described with reference to Fig. 28. In this specific example 2, the first monitoring state is a state in which the PDCCH is not monitored (i.e., PDCCH skipping), and the second monitoring state is a state in which the PDCCH is periodically monitored.

[0245] At time t41, the UE 100 (the receiver 112) receives, from the base station 200, a switching instruction DCI instructing PDCCH skipping in the downlink BWP in a certain serving cell.

[0246] At time t42, in response to receiving the switching command DCI, UE 100 (control unit 120) starts PDCCH skipping (i.e., starts the first monitoring state). At the start of the first monitoring state, UE 100 (control unit 120) starts a first timer that determines the duration of the first monitoring state. For example, period X is set as a timer value in the first timer. The timer value (timer setting value) of the first timer may be set in UE 100 from base station 200 by an RRC message.

[0247] At time t43, the UE 100 (transmitter 111) transmits a RACH preamble to the base station 200 on the PRACH in the uplink BWP in the serving cell. The UE 100 (controller 120) performs a RACH-induced switching process to switch to a predetermined SSSG in response to a RACH transmission or a RACH transmission trigger (i.e., starts a second monitoring state). As a result, PDCCH skipping ends, and monitoring of the PDCCH starts (resumes). The predetermined SSSG may be an SSSG set by the base station 200 through RACH configuration, a default SSSG (defaultSearchSpaceSet), or a first SSSG (firstSearchSpaceSet).

[0248] The UE 100 (control unit 120) stops the first timer when performing the RACH-induced switching process. By stopping the first timer, it is possible to prevent switching to the default SSSG due to expiration of the first timer.

[0249] When performing a RACH-induced switching process, the UE 100 (control unit 120) starts a second timer that determines the duration of the second monitoring state. For example, a period Y is set as a timer value in the second timer. The timer value (timer setting value) of the second timer may be set to the UE 100 by the base station 200 via an RRC message. When performing a RACH-induced switching process, the UE 100 (control unit 120) starts the second timer to which the timer value is set. This allows the base station 200 to control the duration of the second monitoring state.

[0250] Here, the timer value of the second timer used in the RACH induced switching process may be set by an RRC message to be common to the timer value of the second timer used in the above-mentioned SR induced switching process. Alternatively, the timer value of the second timer used in the RACH induced switching process may be set by an RRC message to be independent from the timer value of the second timer used in the above-mentioned SR induced switching process.

[0251] In the second monitoring state, the UE 100 (the receiver 112) may receive from the base station 200 a scheduling DCI (for example, a DCI format used for PDSCH scheduling or a DCI format used for PUSCH scheduling) used for radio resource allocation. The UE 100 (the controller 120) may restart the second timer in response to reception of the scheduling DCI. Since data communication occurs due to reception of the scheduling DCI, the duration of the second monitoring state can be extended by restarting the second timer. Furthermore, in the second monitoring state, the UE 100 (the controller 120) may restart the second timer in response to a RACH transmission or a RACH transmission trigger. Since data communication occurs due to the RACH transmission, the duration of the second monitoring state can be extended by restarting the second timer.

[0252] The UE 100 (control unit 120) switches to a predetermined PDCCH monitoring state in response to expiration of the second timer. That is, the UE 100 (control unit 120) ends the second monitoring state when the period Y expires. The predetermined PDCCH monitoring state to which the switching is to be made upon expiration of the second timer may be a default SSSG (defaultSearchSpaceSet) or a first SSSG (firstSearchSpaceSet).

[0253] (8) Simultaneous switching process Based on the above-mentioned configuration and operation, the simultaneous switching process according to this embodiment will be described.

[0254] An operation sequence example 1 regarding the simultaneous switching process according to the present embodiment will be described with reference to Fig. 29. In this operation sequence example 1, the UE 100 (control unit 120) performs the SR triggered switching process or the RACH triggered switching process in units of a cell group including a plurality of serving cells in response to the SR transmission or the RACH transmission.

[0255] In step S301, the base station 200 (the transmitting unit 211) transmits an RRC message to the UE 100. The RRC message may be a dedicated RRC message (e.g., an RRC Reconfiguration message) transmitted individually to the UE. The UE 100 (the receiving unit 112) receives the RRC message. The RRC message includes the above-mentioned switching control information. The RRC message may further include information for setting PDCCH skipping and / or SSSG switching.

[0256] The RRC message includes information for setting at least one cell group in the UE 100. The information for setting the cell group may include an identifier of each cell group and an identifier of each serving cell belonging to the cell group. Here, the cell group set in the UE 100 may be, for example, Cell group #1: Serving cells #1, #2, #3, #4 Cell group #2: Serving cells #5, #6, #7, #8 Cell group #3: Serving cells #9, #10, #11, #12 Cell group #4: Serving cells #13, #14, #15, #16.

[0257] The RRC message may include information for commonly configuring a cell group to which a simultaneous switching process based on SR transmission or a transmission trigger (hereinafter referred to as "SR-induced simultaneous switching process") is applied and a cell group to which a simultaneous switching process based on RACH transmission or a transmission trigger (hereinafter referred to as "RACH-induced simultaneous switching process") is applied. For example, each of the above-mentioned cell groups #1 to #4 is commonly applied to the SR-induced simultaneous switching process and the RACH-induced simultaneous switching process. Information for configuring such a common cell group may be included in the PDCCH configuration in the RRC message. By configuring such a common cell group, the configuration related to the simultaneous switching process can be made more efficient.

[0258] The RRC message may include information for independently configuring a cell group to which the SR-induced simultaneous switching process is applied and a cell group to which the RACH-induced simultaneous switching process is applied. For example, among the above-mentioned cell groups #1 to #4, the cell group #1 and the cell group #2 may be configured in the UE 100 as the cell group to which the SR-induced simultaneous switching process is applied, and the cell group #3 and the cell group #4 may be configured in the UE 100 as the cell group to which the RACH-induced simultaneous switching process is applied. This allows the base station 200 to finely control the simultaneous switching process. In the case of configuring such independent cell groups, information for configuring the cell group to which the SR-induced simultaneous switching process is applied may be included in the SR configuration for configuring parameters for the SR resource. Information for configuring the cell group to which the RACH-induced simultaneous switching process is applied may be included in the BFR configuration for configuring the RACH resource and the RS resource for BFR.

[0259] The RRC message may include information for configuring a primary timing advance group (PTAG) and a secondary timing advance group (STAG) as cell groups. These timing advance groups (cell groups) may be identified by a timing advance group identifier (tag-id). These timing advance groups (cell groups) may be used as cell groups to which the RACH-triggered simultaneous switching procedure is applied.

[0260] In step S302, the base station 200 (transmitter 211) transmits, on the PDCCH, a switching instruction DCI instructing PDCCH skipping or SSSG switching to the UE 100. The UE 100 (receiver 112) receives the switching instruction DCI.

[0261] In step S303, UE 100 (control unit 120) switches the PDCCH monitoring state in response to reception of the switching instruction DCI. When PDCCH skipping is set, UE 100 (control unit 120) may skip monitoring of the PDCCH for a predetermined period in response to reception of the switching instruction DCI (skip instruction DCI). When SSSG switching is set, UE 100 (control unit 120) may switch to the SSSG instructed by the switching instruction DCI in response to reception of the switching instruction DCI. As a result, UE 100 enters a power saving state in which power consumption required for monitoring the PDCCH is reduced. UE 100 (control unit 120) may switch the PDCCH monitoring state in units of cell groups to which the serving cell in which the switching instruction DCI is detected belongs. In the above example, when a switching instruction DCI is detected in serving cell #1, UE 100 (control unit 120) may switch the PDCCH monitoring state for serving cells #1, #2, #3, and #4 included in cell group #1 to which serving cell #1 belongs.

[0262] In step S304, the UE 100 (control unit 120) detects a transmission trigger of an SR or RACH.

[0263] In step S305, the UE 100 (transmitter 111) transmits an SR to the base station 200 on the PUCCH in response to the SR transmission trigger. Alternatively, the UE 100 (transmitter 111) transmits a RACH preamble to the base station 200 on the PRACH in response to the RACH transmission trigger. The base station 200 (receiver 212) receives the SR or the RACH.

[0264] In step S306, the UE 100 (control unit 120) simultaneously switches the PDCCH monitoring state for each serving cell in the cell group in response to the transmission of the SR or RACH (SR-induced simultaneous switching process or RACH-induced simultaneous switching process). The switching process in each serving cell is controlled by switching control information, similar to the above-mentioned SR-induced switching process or RACH-induced switching process.

[0265] The SR-induced simultaneous switching process or the RACH-induced simultaneous switching process is a process of simultaneously switching the PDCCH monitoring state of each serving cell in a cell group from a first monitoring state to a second monitoring state. The first monitoring state corresponds to the above-mentioned power saving state. The second monitoring state is a state in which the PDCCH is monitored more frequently than the first monitoring state.

[0266] Here, in response to the transmission of an SR, UE 100 (control unit 120) may perform an SR-induced simultaneous switching process for a cell group to which a downlink component carrier (DL CC) corresponding to an uplink component carrier (UL CC) through which the SR is transmitted belongs.

[0267] Similarly, in response to transmission of a RACH (RACH preamble), the UE 100 (control unit 120) may perform a RACH-triggered simultaneous switching process for a cell group to which a DL CC corresponding to a UL CC through which the RACH is transmitted belongs.

[0268] The UE 100 (control unit 120) may perform a RACH-triggered simultaneous switching process for the PTAG in response to the transmission of a RACH in the PTAG. The UE 100 (control unit 120) may perform a RACH-triggered simultaneous switching process for the STAG in response to the transmission of a RACH in the STAG.

[0269] The first monitoring state may be a state in which the PDCCH is monitored at a first cycle, and the second monitoring state may be a state in which the PDCCH is monitored at a second cycle shorter than the first cycle. For example, after SSSG switching is configured and switching to an SSSG having a long PDCCH monitoring cycle is instructed by DCI, the UE 100 (control unit 120) switches to an SSSG having a short PDCCH monitoring cycle in response to transmission of an SR or RACH.

[0270] The first monitoring state may be a state in which the PDCCH is not monitored (i.e., PDCCH skipping), and the second monitoring state may be a state in which the PDCCH is periodically monitored. For example, the UE 100 (control unit 120) is configured with PDCCH skipping, and after being instructed by DCI to perform PDCCH skipping, the UE 100 (control unit 120) switches to a state in which the PDCCH is monitored in response to transmission of an SR or RACH.

[0271] In step S307, in response to receiving the SR or RACH preamble from UE 100, base station 200 (control unit 230) allocates UL-SCH resources to UE 100. Specifically, base station 200 (transmission unit 211) transmits scheduling DCI including a UL grant for allocating UL-SCH resources to UE 100 on the PDCCH.

[0272] 30, an operation sequence example 2 related to the simultaneous switching process according to the present embodiment will be described, focusing mainly on differences from the above-mentioned operation sequence example 1. In this operation sequence example 2, the UE 100 (control unit 120) performs an SR-induced switching process or a RACH-induced switching process in units of a cell group consisting of a plurality of serving cells in response to an SR transmission trigger or a RACH transmission trigger.

[0273] In FIG. 30, the operations in steps S311 to S314 are similar to the operations in steps S301 to S304 in FIG.

[0274] In step S315, the UE 100 (control unit 120) switches the PDCCH monitoring state in response to a transmission trigger of the SR or RACH (SR-induced simultaneous switching process or RACH-induced simultaneous switching process).

[0275] Here, in response to a transmission trigger of an SR, the UE 100 (control unit 120) may perform an SR-induced simultaneous switching process for a cell group to which a DL CC corresponding to a UL CC for which the SR is transmitted belongs.

[0276] Similarly, in response to a transmission trigger of a RACH (RACH preamble), the UE 100 (control unit 120) may perform a RACH-triggered simultaneous switching process for a cell group to which a DL CC corresponding to a UL CC through which the RACH is transmitted belongs.

[0277] The UE 100 (control unit 120) may perform a RACH-triggered simultaneous switching process for the PTAG in response to a transmission trigger of the RACH in the PTAG. The UE 100 (control unit 120) may perform a RACH-triggered simultaneous switching process for the STAG in response to a transmission trigger of the RACH in the STAG.

[0278] In step S316, the UE 100 (transmitter 111) transmits an SR or RACH preamble to the base station 200.

[0279] In step S317, the base station 200 (control unit 230) allocates UL-SCH resources to the UE 100 in response to reception of the SR or RACH preamble from the UE 100.

[0280] In the example of the operation sequence related to the simultaneous switching process according to the present embodiment, the cell group to which the simultaneous switching process is applied is set in advance by an RRC message from the base station 200 to the UE 100. However, similarly to the operation of Fig. 24, the base station 200 may instruct the UE 100 of the cell group to which the simultaneous switching process is applied by a MAC CE.

[0281] (9) Other embodiments The operation sequences (and operation flows) in the above-mentioned embodiments 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 that described in the flow diagram or sequence diagram, or may be executed in parallel. Some of the steps in the operations may be deleted, and additional steps may be added to the process. The operation sequences (and operation flows) in the above-mentioned embodiments may be executed separately and independently, or two or more operation sequences (and operation flows) may be executed in combination. 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.

[0282] 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.

[0283] 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.

[0284] 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).

[0285] 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, obtaining information from information received from another node, or obtaining the information by generating the information. Similarly, "include" and "comprise" do not mean including only the items listed, but may mean including only the items listed, or may include additional items in addition to the items listed. Similarly, in this disclosure, "or" does not mean an exclusive or, but rather a logical or.

[0286] 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.

[0287] (10) Additional Notes The following additional features relate to the above-described embodiment.

[0288] (Appendix 1) A communication device (100) that performs wireless communication with a base station (200), A transmission unit (111) that transmits a scheduling request (SR) to the base station (200); A control unit (120) performing an SR-induced switching process for switching a PDCCH monitoring state regarding monitoring of a physical downlink control channel (PDCCH) in response to the SR transmission or an SR transmission trigger; A receiving unit (112) that receives a radio resource control (RRC) message including switching control information for controlling the SR-induced switching process from the base station (200), The control unit (120) controls the SR-induced switching process based on the switching control information. A communication device (100).

[0289] (Appendix 2) The RRC message includes an SR configuration that configures parameters for an SR resource; The SR setting includes the switching control information. 2. The communication device (100) of claim 1.

[0290] (Appendix 3) The SR configuration includes a plurality of SR resource configurations each associated with a logical channel; Each of the plurality of SR resource configurations includes the switching control information; The control unit (120) controls the SR-induced switching process based on the switching control information corresponding to one logical channel in response to the SR transmission or the SR transmission trigger in the one logical channel. 3. The communication device (100) according to claim 2.

[0291] (Appendix 4) The switching control information is information regarding whether to enable the SR-induced switching process, The control unit (120) performs the SR-induced switching process based on the switching control information indicating that the SR-induced switching process is to be enabled. A communication device (100) according to any one of claims 1 to 3.

[0292] (Appendix 5) The control unit (120) switches to a predetermined PDCCH monitoring state in the SR-induced switching process. 5. The communication device (100) according to claim 4.

[0293] (Appendix 6) The switching control information is information for specifying a PDCCH monitoring state after switching by the SR caused switching process, The control unit (120) switches to the PDCCH monitoring state designated by the switching control information in the SR caused switching process. A communication device (100) according to any one of claims 1 to 4.

[0294] (Appendix 7) The control unit (120) performs control so as not to perform the SR induced switching process when the RRC message does not include the switching control information. A communication device (100) according to any one of appendix 1 to 6.

[0295] (Appendix 8) The transmitting unit (111) transmits a negative SR set to a value of "0" to the base station (200), The control unit (120) performs control so as not to perform the SR-induced switching process when the negative SR is transmitted. A communication device (100) according to any one of appendix 1 to 7.

[0296] (Appendix 9) The SR transmission trigger includes instructing the SR transmission from a medium access control (MAC) layer to a physical layer in the communication device (100). A communication device (100) according to any one of appendix 1 to 8.

[0297] (Appendix 10) The SR induced switching process is a process of switching the PDCCH monitoring state from a first monitoring state to a second monitoring state, The second monitoring state is a state in which the PDCCH is monitored more frequently than the first monitoring state. A communication device (100) according to any one of appendix 1 to 9.

[0298] (Appendix 11) The first monitoring state is a state in which the PDCCH is monitored at a first period; The second monitoring state is a state in which the PDCCH is monitored at a second period that is shorter than the first period. 11. The communication device (100) according to claim 10.

[0299] (Appendix 12) The first monitoring state is a state in which the PDCCH is not monitored, The second monitoring state is a state in which the PDCCH is periodically monitored. 11. The communication device (100) according to claim 10.

[0300] (Appendix 13) The control unit (120) starts a first timer at the start of the first monitoring state, the first timer determining a duration of the first monitoring state, The control unit (120) stops the first timer when performing the SR triggered switching process. 13. A communication device (100) according to any one of appendixes 10 to 12.

[0301] (Appendix 14) When performing the SR-induced switching process, the control unit (120) starts a second timer that determines a duration of the second monitoring state. A communication device (100) according to any one of appendixes 10 to 13.

[0302] (Appendix 15) The RRC message includes information for setting a timer value indicating a duration of the second monitoring state, The control unit (120) starts the second timer in which the timer value is set when performing the SR-induced switching process. 15. The communication device (100) according to claim 14.

[0303] (Appendix 16) The receiving unit (112) receives, in the second monitoring state, scheduling downlink control information (DCI) used for radio resource allocation from the base station (200); The control unit (120) restarts the second timer in response to receiving the scheduling DCI. 16. The communication device (100) according to claim 14 or 15.

[0304] (Appendix 17) The control unit (120) restarts the second timer in response to the SR transmission or the SR transmission trigger in the second monitoring state. 17. The communication device (100) according to any one of appendixes 14 to 16.

[0305] (Appendix 18) The control unit (120) switches to a predetermined PDCCH monitoring state in response to expiration of the second timer. 18. A communication device (100) according to any one of appendixes 14 to 17.

[0306] (Appendix 19) A base station (200) that performs wireless communication with a communication device (100), a receiving unit (212) for receiving a scheduling request (SR) from the communication device (100); A transmission unit (211) that transmits a radio resource control (RRC) message including switching control information for controlling an SR-induced switching process to the communication device (100), The SR-induced switching process is a process in which the communication device (100) switches a PDCCH monitoring state regarding monitoring of a physical downlink control channel (PDCCH) in response to an SR transmission or an SR transmission trigger. Base station (200).

[0307] (Appendix 20) A communication method used in a communication device (100) that performs wireless communication with a base station (200), comprising: receiving a radio resource control (RRC) message from the base station (200) including switching control information; A step of transmitting an SR to the base station (200); and performing the SR-induced switching process in response to the SR transmission or an SR transmission trigger based on the switching control information, The SR-induced switching process is a process in which the communication device (100) switches a PDCCH monitoring state regarding monitoring of a physical downlink control channel (PDCCH) in response to an SR transmission or an SR transmission trigger. Communication methods.

Claims

1. A communication device (100), receiving a radio resource control (RRC) message from a base station (200), the radio resource control (RRC) message including first information for setting a plurality of cell groups and second information for setting a period for skipping monitoring of a physical downlink control channel (PDCCH), the period being determined by a number of slots; A receiving unit (112) that receives a downlink control information (DCI) format including an information field related to monitoring of the PDCCH from the base station (200); A control unit (120) that starts skipping the monitoring of the PDCCH during the period in a downlink BWP of a serving cell when the period is set and a predetermined value indicating skipping of the monitoring of the PDCCH during the period is set in the information field; A transmission unit (111) for transmitting a scheduling request (SR), The control unit (120) When a positive SR is transmitted on a physical uplink control channel (PUCCH) after the period is set and the DCI format including the information field set to the predetermined value is received, resume monitoring the PDCCH in all serving cells included in a cell group corresponding to the transmission of the positive SR determined according to the first information. A communication device (100).

2. The DCI format is used for scheduling a physical uplink shared channel (PUSCH) or a physical downlink shared channel (PDSCH), The DCI format is a CRC parity bit that is added to any one of the Cell-Radio Network Temporary Identifier (C-RNTI), Modulation and Coding Scheme-C-RNTI (MCS-C-RNTI), and Configured Scheduling-RNTI (CS-RNTI). The communication device (100) of claim 1.

3. A base station (200), Transmitting a radio resource control (RRC) message to a communication device (100), the message including first information for setting a plurality of cell groups and second information for setting a period for skipping monitoring of a physical downlink control channel (PDCCH), the period being determined by a number of slots; A transmission unit (211) that transmits a downlink control information (DCI) format including an information field related to monitoring of the PDCCH to the communication device (100); A control unit (230) that sets the period and, when a predetermined value indicating skipping of monitoring of the PDCCH during the period is set in the information field, controls the communication device (100) to skip monitoring of the PDCCH during the period in a downlink BWP of a serving cell; A receiving unit (212) for receiving a scheduling request (SR) from the communication device (100), The control unit (230) When a positive scheduling request (SR) is received on a physical uplink control channel (PUCCH) after setting the period and transmitting the DCI format including the information field set to the predetermined value, the communication device (100) is controlled to resume monitoring the PDCCH in all serving cells included in a cell group corresponding to reception of the positive SR determined according to the first information. Base station (200).

4. The DCI format is used for scheduling a physical uplink shared channel (PUSCH) or a physical downlink shared channel (PDSCH), The DCI format is a CRC parity bit that is added to any one of the Cell-Radio Network Temporary Identifier (C-RNTI), Modulation and Coding Scheme-C-RNTI (MCS-C-RNTI), and Configured Scheduling-RNTI (CS-RNTI). The base station (200) of claim 3.

5. A method for a communication device, comprising: receiving a radio resource control (RRC) message from a base station (200), the radio resource control (RRC) message including first information for setting a plurality of cell groups and second information for setting a period for skipping monitoring of a physical downlink control channel (PDCCH), the period being determined by a number of slots; receiving a downlink control information (DCI) format including an information field regarding skipping of monitoring of the PDCCH; When the period is set and a predetermined value indicating skipping of monitoring of the PDCCH during the period is set in the information field, starting skipping of monitoring of the PDCCH during the period in a downlink BWP of a serving cell; and when a positive SR is transmitted on a physical uplink control channel (PUCCH) after receiving the DCI format including the information field in which the period is set and the information field is set to the predetermined value, resuming monitoring of the PDCCH in all serving cells included in a cell group corresponding to the transmission of the positive SR determined according to the first information. method.

6. The DCI format is used for scheduling a physical uplink shared channel (PUSCH) or a physical downlink shared channel (PDSCH), The DCI format is a CRC parity bit that is added to any one of the Cell-Radio Network Temporary Identifier (C-RNTI), Modulation and Coding Scheme-C-RNTI (MCS-C-RNTI), and Configured Scheduling-RNTI (CS-RNTI). The method according to claim 5.

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