WO2024071078A1

WO2024071078A1 - Communication device, base station, and communication method

Info

Publication number: WO2024071078A1
Application number: PCT/JP2023/034831
Authority: WO
Inventors: 樹長野
Original assignee: 株式会社デンソー
Priority date: 2022-09-28
Filing date: 2023-09-26
Publication date: 2024-04-04

Abstract

A communication device (100) is provided with a reception unit (112) that receives, from a network (10), bitmap information indicating, for each Hybrid Automatic Repeat Request (HARQ) process, whether to enable a discontinuous reception (DRX) retransmission-related timer for controlling retransmission during DRX operation in the HARQ process.

Description

Communication device, base station, and communication method

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority to patent application serial number 2022-155588, filed September 28, 2022, the entire contents of which are incorporated herein by reference.

This disclosure relates to a communication device, a base station, and a communication method used in a mobile communication system.

3GPP (registered trademark; the same applies below) (3rd Generation Partnership Project), a standardization project for mobile communications systems, has launched a work item to consider power saving technologies suited to the characteristics of XR (Extended Reality) services.

Due to the characteristics of XR services, for example, a communication device may be required to transmit small packets (e.g., pose/control information) that have very strict delay requirements. Even if the communication device retransmits such packets using a hybrid automatic repeat request (HARQ) process, the delay requirements may not be met, so it is expected that a conservative modulation and coding scheme (MCS) will be used to transmit reliable packets.

Therefore, it has been proposed to stop the DRX retransmission related timers for controlling retransmission during discontinuous reception (DRX) operation in the HARQ process, specifically the drx-HARQ-RTT-Timer and/or the drx-RetransmissionTimer (see Non-Patent Document 1). By stopping the drx-HARQ-RTT-Timer and/or the drx-RetransmissionTimer, a communication device in DRX operation does not need to remain in an active state to monitor the physical downlink control channel (PDCCH) for retransmission by the HARQ process, and therefore power saving of the communication device can be achieved.

The communication device according to the first aspect includes a receiving unit that receives bitmap information from a network that indicates whether or not to enable a discontinuous reception (DRX) retransmission-related timer for controlling retransmission during a discontinuous reception (DRX) operation in a hybrid automatic repeat request (HARQ) process.

The base station according to the second aspect includes a transmission unit that transmits bitmap information indicating whether or not to enable a discontinuous reception (DRX) retransmission-related timer for controlling retransmission during a discontinuous reception (DRX) operation in a hybrid automatic repeat request (HARQ) process to a communication device for each HARQ process.

A communication method according to a third aspect is executed by a communication device, and includes a step of receiving, from a network, bitmap information indicating whether or not to enable a discontinuous reception (DRX) retransmission-related timer for controlling retransmission during a discontinuous reception (DRX) operation in a hybrid automatic repeat request (HARQ) process.

The objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.
FIG. 1 is a diagram showing a configuration of a mobile communication system according to an embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack according to the embodiment. FIG. 3 is a diagram for explaining a timer related to DRX. FIG. 4 is a diagram showing a configuration of a UE according to the embodiment. FIG. 5 is a diagram showing a configuration of a base station according to the embodiment. FIG. 6 is a sequence diagram for explaining a first operation example according to the embodiment. FIG. 7 is a flowchart for explaining an example of the operation of UE 100 in a first operation example according to the embodiment. FIG. 8 is a sequence diagram for explaining a second operation example according to the embodiment. FIG. 9 is a flowchart for explaining an example of the operation of UE 100 in the third operation example according to the embodiment.

The mobile communication system according to the embodiment will be described with reference to the drawings. In the drawings, the same or similar parts are denoted by the same or similar reference numerals.

However, the existing 3GPP technical specifications do not have a specific mechanism for stopping the DRX retransmission-related timer for each HARQ process. Therefore, if, for example, the DRX retransmission-related timer is uniformly disabled in all HARQ processes in order to save power in the communication device, there is a problem that a communication device in DRX operation cannot monitor the PDCCH for retransmission by the HARQ process even when retransmission by the HARQ process is enabled.

Therefore, one of the objectives of this disclosure is to provide a communication device, base station, and communication method that enable flexible control of DRX retransmission-related timers for each HARQ process.

(System configuration)
First, the configuration of a mobile communication system 1 according to the present embodiment will be described with reference to Fig. 1. The mobile communication system 1 is, for example, a system conforming to the 3GPP Technical Specification (TS). In the following, the mobile communication system 1 will be described using a 3GPP standard 5th Generation System (5G system), i.e., a mobile communication system based on NR (New Radio) as an example.

The mobile communication system 1 has a network 10 and a user equipment (UE) 100 that communicates with the network 10. The network 10 includes a 5G radio access network, NG-RAN (Next Generation Radio Access Network) 20, and a 5G core network, 5GC (5G Core Network) 30.

UE100 is a communication device that communicates via base station 200. UE100 may be a device used by a user. UE100 may be a user device defined in the technical specifications of 3GPP. UE100 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. UE100 may be a vehicle (e.g., a car, a train, etc.) or a device provided therein. UE100 may be a transport vehicle other than a vehicle (e.g., a ship, an airplane, etc.) or a device provided therein. UE100 may be a sensor or a device provided therein. Note that UE100 may be called by other names such as a terminal, a terminal device, 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. Additionally, UE 100 is an example of a terminal, and terminals may include factory equipment, etc.

NG-RAN20 includes multiple 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). The term "cell" may refer to a wireless communication resource, and may also refer to a communication target of UE100. Each base station 200 can perform wireless communication with UE100 located in its own cell. The base station 200 communicates with UE100 using a protocol stack of the RAN. Details of the protocol stack will be described later. In addition, the base station 200 is connected to other base stations 200 (which may be referred to as adjacent base stations) via an Xn interface. The base station 200 communicates with adjacent base stations via an Xn interface. In addition, the base station 200 provides NR user plane and control plane protocol terminations toward the UE100, and is connected to the 5GC30 via an NG interface. Such an NR base station 200 may be referred to as a gNodeB (gNB).

5GC30 includes a core network device 300. The core network device 300 includes, for example, an AMF (Access and Mobility Management Function) and/or a UPF (User Plane Function). The AMF manages the mobility of the UE 100. The UPF provides functions specialized for U-plane processing. The AMF and the UPF are connected to the base station 200 via an NG interface.

(Example of protocol stack configuration)
Next, an example of the configuration of a protocol stack according to this embodiment will be described with reference to FIG.

The protocol for the wireless section between UE100 and 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.

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.

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 UE100 and the MAC layer of base station 200 via a transport channel. The MAC layer of 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 UE100.

The RLC layer uses the functions of the MAC layer and PHY layer to transmit data to the RLC layer on the receiving side. 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.

The PDCP layer performs header compression/decompression, and encryption/decryption.

The SDAP (Service Data Adaptation Protocol) layer may be provided as a layer above the PDCP layer. The SDAP (Service Data Adaptation Protocol) layer maps IP flows, which are the units by which the core network performs QoS (Quality of Service) control, to radio bearers, which are the units by which the AS (Access Stratum) performs QoS control.

The RRC layer controls logical channels, transport channels, and physical channels in response to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of base station 200. When there is an RRC connection between the RRC of UE100 and the RRC of base station 200, UE100 is in an RRC connected state. When there is no RRC connection between the RRC of UE100 and the RRC of base station 200, UE100 is in an RRC idle state. When the RRC connection between the RRC of UE100 and the RRC of base station 200 is suspended, UE100 is in an RRC inactive state.

The NAS layer, which is located above the RRC layer in UE100, performs session management and mobility management for UE100. NAS signaling is transmitted between the NAS layer of UE100 and the NAS layer of the core network device 300.

In addition, UE100 has an application layer, etc. in addition to the radio interface protocol.

(Radio Frame Structure)
In the 5G system, downlink transmission and uplink transmission are configured within a radio frame of 10 ms duration. For example, a radio frame is configured with 10 subframes. For example, one subframe may be 1 ms. Also, one subframe may be configured with one or more slots. For example, the number of symbols constituting one slot is 14 in a normal CP (Cyclic Prefix) and 12 in an extended CP. Also, the number of slots constituting one subframe changes according to the set subcarrier interval. For example, for a normal CP, when the subcarrier interval is set to 15 kHz, the number of slots per subframe is 1 (i.e., 14 symbols), when the subcarrier interval is set to 30 kHz, the number of slots per subframe is 2 (i.e., 28 symbols), when the subcarrier interval is set to 60 kHz, the number of slots per subframe is 4 (i.e., 56 symbols), and when the subcarrier interval is set to 120 kHz, the number of slots per subframe is 8 (i.e., 112 symbols). Furthermore, when the subcarrier interval is set to 60 kHz for the extended CP, the number of slots per subframe is 4 (i.e., 48 symbols). That is, the number of slots constituting one subframe is determined based on the subcarrier interval set by the base station 200. Also, the number of symbols constituting one subframe is determined based on the subcarrier interval set by the base station 200. That is, the number of symbols constituting a 1 ms subframe is determined based on the subcarrier interval set by the base station 200, and the length of each symbol (length in the time direction) changes.

(DRX)
With reference to Fig. 3, the discontinuous reception (DRX) in the mobile communication system 1 according to the embodiment will be described. Fig. 3A is a diagram for explaining a timer related to DRX in uplink transmission. Fig. 3B is a diagram for explaining a timer related to DRX in downlink transmission.

In order to reduce the power consumption of UE100, UE100 does not constantly monitor the physical downlink control channel (PDCCH) of UE100 as an operation during DRX (hereinafter referred to as DRX operation), but monitors the PDCCH only at regular cycles (i.e., DRX cycles). In particular, DRX performed by UE100 in an RRC connected state is sometimes called C-DRX.

The UE 100 is set with a DRX cycle consisting of an on period and an off period. During the on period, the state of the UE 100 is an awake state in which the UE 100 monitors the PDCCH. The UE 100 in the awake state is active to monitor the PDCCH. The awake state may be referred to as, for example, an active state or a DRX activated state. The on period may also be referred to as, for example, a DRX on period, on time, or active time as a period in which the PDCCH is monitored. During the off period, the state of the UE 100 is a sleep state in which the UE 100 does not need to monitor the PDCCH. The UE 100 in the sleep state is inactive. The sleep state may be referred to as, for example, a DRX sleep state, a sleep mode, a DRX mode, or a power saving mode. The off period may also be referred to as, for example, a DRX off period, off time, or inactive time as a period in which the PDCCH is not monitored.

As DRX cycles, a long DRX cycle and a short DRX cycle are specified. The long DRX cycle consists of an on period and an off period. The short DRX cycle is an additional DRX cycle that is set together with the long DRX cycle. The short DRX cycle is a DRX cycle that is shorter than the long DRX cycle.

DRX setting parameters, such as drx-onDurationTimer, drx-InactivityTimer, drx-HARQ-RTT-TimerDL, drx-HARQ-RTT-TimerUL, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, drx-LongCycleStartOffset, and drx-SlotOffset, are set individually for each cell group set in UE 100.

Hereinafter, in this embodiment, for ease of explanation, it will be described that DRX (DRX operation) is set for one cell group. That is, the operation in this embodiment may be an operation when DRX (DRX operation) is set for one cell group. That is, the operation in this embodiment may be an operation when DRX (DRX operation) is set for one serving cell (for example, a downlink serving cell, also referred to as a downlink component carrier). Also, the operation in this embodiment may be an operation when DRX (DRX operation) is set for each DL BWP (Downlink Bandwidth Part) set in each of one or more serving cells. That is, the operation in this embodiment may be an operation when DRX (DRX operation) is set for each DL BWP in each of one or more serving cells. That is, in this embodiment, the parameters for DRX setting (i.e., DRX (DRX operation)) may be set for each of one or more cell groups. Also, in this embodiment, the parameters for DRX setting (i.e., DRX (DRX operation)) may be set for each of one or more serving cells. Also, in this embodiment, the parameters for DRX setting (i.e., DRX (DRX operation)) may be set for each of one or more DL BWPs.

drx-onDurationTimer may indicate the duration at the beginning of a DRX cycle. For example, drx-onDurationTimer is a parameter that specifies the amount of time of the DRX on period of each DRX cycle. Thus, drx-onDurationTimer is set to the timer value of the DRX on duration timer (drx-onDurationTimer) used to time the DRX on period. As shown in FIG. 3, UE 100 is in an active state (e.g., considered to be in an active time) while the DRX on duration timer (hereinafter sometimes referred to as ODT) is running (operating). If UE 100 does not receive a PDCCH by the expiration of ODT, it transitions to a sleep state until the start of the next on period.

The drx-InactivityTimer may indicate the duration after the PDCCH occasion in which a PDCCH indicates a new UL or DL transmission. Here, the PDCCH indicating the uplink transmission may include a DCI format used for uplink scheduling (e.g., PUSCH scheduling). Also, the PDCCH indicating the downlink transmission may include a DCI format used for downlink scheduling (e.g., PDSCH scheduling). For example, the drx-InactivityTimer is a parameter that specifies the period during which the UE 100 should be active after successfully decoding a PDCCH indicating a new transmission. Therefore, the drx-InactivityTimer is set to the timer value of the DRX inactivity timer (drx-InactivityTimer) used to time the active time, for example. As shown in FIG. 3, the DRX inactivity timer (hereinafter sometimes referred to as IAT) is started or restarted when the UE 100 receives a PDCCH for a new transmission (e.g., UL, DL, or SL (sidelink)) during the on period. Therefore, the UE 100 remains in an awake state while the IAT is running. The IAT may be a timer indicating the period during which the UE 100 should be in an awake state after successfully decoding a PDCCH indicating a new transmission. The UE 100 monitors the PDCCH until the IAT expires. When the IAT expires, the UE 100 transitions to a sleep state (DRX mode).

The drx-HARQ-RTT-TimerUL may indicate the minimum duration before a UL HARQ retransmission grant is expected. Here, the grant may include a PDCCH indicating an uplink transmission. For example, the drx-HARQ-RTT-TimerUL is a parameter used in the retransmission process of uplink data. The drx-HARQ-RTT-TimerUL is a parameter that specifies the period during which the UE 100 can expect an uplink retransmission. The drx-HARQ-RTT-TimerUL is set to the timer value of a timer (drx-HARQ-RTT-TimerUL (timer)) used to time the period. The UE 100 maintains a sleep state while the timer is running. The timer may be hereinafter referred to as a HARQ RTT timer or a HARQ RTT UL timer. As shown in FIG. 3A, the UE 100 starts the HARQ RTT timer (specifically, the drx-HARQ-RTT-TimerUL timer) with the first symbol immediately after transmitting the PUSCH. The UE 100 transitions to an active state in response to expiration of the timer. In addition, drx-HARQ-RTT-TimerUL may be specified (set, controlled) for each uplink HARQ process (per UL HARQ process).

The drx-HARQ-RTT-TimerDL may indicate the minimum duration before a DL assignment for HARQ retransmission. Here, the downlink assignment may include a PDCCH indicating downlink transmission. For example, the drx-HARQ-RTT-TimerDL is a parameter used in the retransmission process of downlink data. The drx-HARQ-RTT-TimerDL is a parameter that specifies the period during which the UE 100 can expect a retransmission. The drx-HARQ-RTT-TimerDL is set to the timer value of a timer (drx-HARQ-RTT-TimerDL (timer)) used to time the period. The UE 100 maintains a sleep state while the timer is running. The timer may be hereinafter referred to as a HARQ RTT timer or a HARQ RTT DL timer. As shown in FIG. 3B, when the UE 100 receives a new downlink transmission, the UE 100 starts the HARQ RTT timer (specifically, the drx-HARQ-RTT-TimerDL timer) with the first symbol after transmitting a negative acknowledgement (NACK) in the uplink. The UE 100 transitions to an active state in response to expiration of the timer. In addition, drx-HARQ-RTT-TimerDL may be specified (set, controlled) for each downlink HARQ process (per UL HARQ process).

drx-RetransmissionTimerUL may indicate the maximum duration until a grant for UL retransmission is received. Here, the grant for uplink retransmission may include a PDCCH indicating uplink retransmission. For example, drx-RetransmissionTimerUL is a parameter used in the retransmission process of uplink data. drx-RetransmissionTimerUL is set to the maximum number of slots that the UE should monitor the PDCCH when the UE can expect a grant for uplink retransmission. The drx-RetransmissionTimerUL is set to the timer value of a timer (drx-RetransmissionTimerUL timer) used to time the duration of a specified slot. This timer may be referred to as a DRX retransmission timer or a DRX retransmission UL timer. This timer may be associated with each HARQ process. As shown in FIG. 3A, the UE 100 starts the DRX retransmission UL timer at the next symbol when the drx-HARQ-RTT-TimerUL timer expires. The UE 100 is in an awake state while this timer is running. The UE 100 stops the DRX retransmission UL timer as soon as it detects an uplink transmission for the corresponding HARQ process. In addition, drx-RetransmissionTimerUL may be specified (set, controlled) for each uplink HARQ process (per UL HARQ process).

drx-RetransmissionTimerDL may indicate the maximum duration until a DL retransmission is received. Here, downlink retransmission may include retransmission of downlink data (i.e., retransmission in PDSCH). Downlink data is also referred to as DL-SCH data. For example, drx-RetransmissionTimerDL is a parameter used in the retransmission process of downlink data. drx-RetransmissionTimerDL is set to the maximum number of slots that the UE should monitor the PDCCH when the UE can expect a retransmission from base station 200. The drx-RetransmissionDL is set to the timer value of a timer (drx-RetransmissionTimerDL timer) used to time the duration of the specified slot. This timer may be referred to as a DRX retransmission timer or a DRX retransmission DL timer. This timer may be associated with each HARQ process. As shown in FIG. 3B, when the drx-HARQ-RTT-TimerDL timer expires, the UE 100 starts the DRX retransmission DL timer at the next symbol. The UE 100 is in an awake state while this timer is running. The UE 100 stops the DRX retransmission DL timer as soon as it detects a downlink transmission for the corresponding HARQ process. In addition, drx-RetransmissionTimerDL may be specified (set, controlled) for each downlink HARQ process (per UL HARQ process).

For example, UE100 may consider the time when drx-onDurationTimer or drx-InactivityTimer set for one cell group is operating as the active time for the serving cell in that one cell group. Also, UE100 may consider the time when drx-RetransmissionTimerUL or drx-RetransmissionTimerDL is operating in any of the serving cells in that one cell group as the active time for the serving cell in that one cell group. For example, UE100 may monitor the PDCCH when the one cell group is in the active time. That is, UE100 may monitor the PDCCH in the serving cell in that one cell group when the one cell group is in the active time. Here, the cell group in which the parameters for DRX setting (i.e., DRX (DRX operation)) are set is also referred to as the DRX group. For example, the base station 200 may transmit an RRC message including information indicating a DRX group including one or more serving cells. The UE 100 may identify the DRX group based on the information indicating the DRX group. For example, the DRX group may be a group of one or more serving cells that have (are set to have) the same active time. When DRX (DRX operation) is set, the active time for the serving cells in one DRX group may include the time during which any of the drx-onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimerUL, and drx-RetransmissionTimerDL set for the one DRX group is operating.

drx-LongCycleStartOffset is a parameter for controlling the start position of the long DRX cycle. drx-LongCycleStartOffset is used to determine the length of the long DRX cycle and the starting subframe number within the long DRX cycle. drx-SlotOffset is a parameter that specifies the start of the on-period with respect to the start of the subframe.

Furthermore, when UE 100 receives a DRX command MAC CE or a long DRX command MAC CE from the network (base station 200), it ends the current on-period (active time). Specifically, UE 100 stops ODT and IAT.

When UE100 receives the DRX command MAC CE, it transitions to a normal DRX cycle. Specifically, when a short DRX cycle is set in UE100, it transitions to a short DRX cycle mode. When a short DRX cycle is not set in UE100, it transitions to a long DRX cycle mode. On the other hand, when UE100 receives a long DRX command MAC CE, it transitions to a long DRX cycle.

(Assumed scenario)
An assumed scenario in the mobile communication system 1 according to the embodiment will be described. In the 3GPP, which is a standardization project for mobile communication systems, a work item has been launched to study power saving technology suited to the characteristics of XR services. The characteristics of XR traffic (XR service) include, for example, a non-integer period such as 60, 120 fps (16.67, 8.33 ms), jitter (variation in the arrival timing of traffic due to encoding and NW transmission delay), and multiple data streams with different traffic characteristics and QoS requirements (multiple flows, for example, I frames and P frames, video and voice/data, etc.).

Due to the characteristics of the XR service for providing XR traffic, for example, the UE 100 may be required to transmit small packets (e.g., pose/control information) with very strict delay requirements. Even if the UE 100 retransmits such packets using a hybrid automatic repeat request (HARQ) process, the delay requirements may not be met, so it is expected that a conservative modulation and coding scheme (MCS) will be used to transmit reliable packets.

Therefore, it has been proposed to stop the DRX retransmission related timers for controlling retransmission during discontinuous reception (DRX) operation in the HARQ process, specifically the HARQ RTT timer and/or the DRX retransmission timer. By stopping the HARQ RTT timer and/or the DRX retransmission timer, the UE 100 during DRX operation does not need to remain in an active state to monitor the physical downlink control channel (PDCCH) for retransmission by the HARQ process, which can reduce the power consumption of the UE 100.

However, in the existing 3GPP technical specifications, there is no specific mechanism for stopping the DRX retransmission related timer for each HARQ process. Therefore, if, for example, the DRX retransmission related timer is uniformly disabled in all HARQ processes in order to save power in the UE 100, there is a problem that the UE 100 in DRX operation cannot monitor the PDCCH for retransmission by the HARQ process even when retransmission by the HARQ process is enabled. Therefore, this disclosure describes an operation for enabling flexible control of the DRX retransmission related timer for each HARQ process.

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

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 multiple antennas and RF circuits. 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, etc.

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 operations of the UE 100 described above and below may be operations under the control of the control unit 120. The control unit 120 may include at least one processor capable of executing programs and a memory for storing the programs. The processor may execute the programs to perform the operations 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 the RAN protocol stack. The memory stores the programs executed by the processor, parameters related to the programs, and data related to the programs. The memory may include at least one of ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), RAM (Random Access Memory), and flash memory. All or a portion of the memory may be contained within the processor.

In the UE 100 configured in this manner, the receiver 112 receives bitmap information indicating whether or not to enable the DRX retransmission related timer for each HARQ process from the network 10 (base station 200). This allows the control unit 120 of the UE 100 to determine whether or not to enable the DRX retransmission related timer for each HARQ process based on the bitmap information. As a result, it becomes possible to flexibly control the DRX retransmission related timer for each HARQ process.

(Base station configuration)
The configuration of the base station 200 according to the embodiment will be described with reference to Fig. 5. The base station 200 includes a communication unit 210, a network communication unit 220, and a control unit 230.

The communication unit 210, for example, receives a radio signal from the UE 100 and transmits a radio signal to the UE 100. 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 RF circuit. 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, etc.

The network communication unit 220 transmits and receives signals to the network. For example, the network communication unit 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 communication unit 220 also receives signals from a core network device 300 connected via an NG interface, and transmits signals to the core network device 300.

The control unit 230 performs various controls in the base station 200. The control unit 230 controls, for example, communication with the UE 100 via the communication unit 210. The control unit 230 also controls, for example, communication with a node (e.g., an adjacent base station, a core network device 300) via the network communication unit 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 operations 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 the RAN protocol stack. 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.

In the base station 200 configured in this manner, the transmission unit 211 transmits to the UE 100 bitmap information indicating whether or not to enable the DRX retransmission related timer for each HARQ process. This allows the control unit 120 of the UE 100 to determine whether or not to enable the DRX retransmission related timer for each HARQ process based on the bitmap information. As a result, it becomes possible to flexibly control the DRX retransmission related timer for each HARQ process. For example, the network 10 controls the UE 100 to stop the DRX retransmission related timer of the HARQ process for small packets with very strict delay requirements, thereby eliminating the need for the UE 100 to maintain an active state and enabling power saving of the UE 100.

(First operation example)
A first operation example of the mobile communication system 1 will be described with reference to Fig. 6 and Fig. 7. In the first operation example, a case where the UE 100 executes a retransmission process (HARQ process) in uplink transmission will be described. In the following, as an example of communication (transmission and/or reception) between the UE 100 and the network 10, communication between the UE 100 and the base station 200 will be described as an example. In this embodiment, the HARQ process includes a HARQ process in a downlink (DL HARQ process) and/or a HARQ process in an uplink (UL HARQ process). Here, the HARQ process in a downlink includes a HARQ process used for downlink transmission (e.g., retransmission process). In addition, the HARQ process in an uplink includes a HARQ process used for uplink transmission (e.g., retransmission process).

Step S101:
6 , the transmitting unit 211 of the base station 200 transmits the bitmap information to the UE 100. The receiving unit 112 of the UE 100 receives the bitmap information from the base station 200.

The bitmap information may be included in, for example, a radio resource control (RRC) message. The bitmap information may be included in at least one of the following: a DRX configuration (DRX-config) used to set parameters related to DRX; a serving cell configuration (ServingCellConfig) used to set (add or change) a serving cell in a UE; a PDSCH serving cell configuration (PDSCH-ServingCellConfig) used to set UE-specific PDSCH parameters common to the entire bandwidth portion (BWP) of a UE of one serving cell; and a PUSCH serving cell configuration (PUSCH-ServingCellConfig) used to set UE-specific PUSCH parameters common to the entire bandwidth portion (BWP) of a UE of one serving cell. That is, the bitmap information may be included in the DRX settings, the serving cell settings, the DL BWP settings (PDSCH parameters included in the DL BWP settings), and/or the UL BWP settings (PUSCH parameters included in the UL BWP settings).

The bitmap information indicates whether or not to enable the DRX retransmission related timer for each HARQ process. The bitmap information may be composed of multiple bits (bit strings). The arrangement of multiple bits constituting the bitmap information may be associated with an identifier of the HARQ process (i.e., HARQ process ID). The identifier of the HARQ process may be an identifier for identifying the HARQ process number. In this embodiment, whether or not to enable a timer (e.g., a DRX retransmission related timer, IAT) may be used to mean the same as whether or not to start or restart the timer. That is, whether or not to enable a timer may be replaced with whether or not to start or restart the timer. That is, enabling a timer may be replaced with starting or restarting a timer. Also, not enabling (disabling) a timer may be replaced with not starting or restarting a timer. That is, the bitmap information may include information used to determine whether or not to start or restart a timer. Also, the bitmap information may include information used to determine whether or not to stop a timer.

For example, the first (or leftmost) bit of the multiple bits indicated by the bitmap information may correspond to HARQ process ID 0, the next bit may correspond to HARQ process ID 1, and the nth bit may correspond to HARQ process ID n-1 (n is a natural number). Each bit may indicate whether or not the DRX retransmission related timer of the corresponding HARQ process (i.e., HARQ process ID) is enabled. For example, each bit may be set to indicate "0" or "1". The DRX retransmission related timer corresponding to a bit set to "0" may be enabled, and the DRX retransmission related timer corresponding to a bit set to "1" may be disabled. Or, the opposite may be true.

The DRX retransmission related timer is a timer for controlling retransmission during DRX operation in the HARQ process. The DRX retransmission related timer is at least one of the drx-HARQ-RTT-TimerUL timer, the drx-HARQ-RTT-TimerDL timer, the drx-RetransmissionTimerUL timer, and the drx-RetransmissionTimerDL timer.

The bitmap information may also indicate whether or not to enable the IAT for each HARQ process, in addition to the DRX retransmission related timer. Note that the base station 200 (network 10) may transmit information indicating whether or not to enable the IAT for each HARQ process (referred to as IAT bitmap information) to the UE 100, separate from the bitmap information. The UE 100 may receive the IAT bitmap information from the base station 200 (network 10).

The bitmap information may further indicate the HARQ mode associated with the DRX retransmission related timer for each HARQ process. The HARQ mode may be, for example, either mode A or mode B. As described above, each bit constituting the bitmap information may indicate the HARQ mode of the corresponding HARQ process. For example, the HARQ mode corresponding to a bit set to "0" may be mode A, and the HARQ mode corresponding to a bit set to "1" may be mode B. Alternatively, the opposite may be true. In mode A, the UE 100 may enable the associated DRX retransmission related timer. For example, mode A may include a mode in which the associated DRX retransmission related timer is started or restarted. In mode B, the UE 100 may not enable (may disable) the associated DRX retransmission related timer. For example, mode B may include a mode in which the associated DRX retransmission related timer is not started or restarted. For example, if the first bit (e.g., corresponding to HARQ process ID 0) in the bitmap information is set to "1" and the next bit (e.g., corresponding to HARQ process ID 1) is set to "0", HARQ process ID 0 may be set as mode A and HARQ process ID 1 may be set as mode B. Here, the DRX retransmission related timer associated with HARQ process ID 0 set as mode A may be enabled. Also, the UE 100 may control to start or restart the DRX retransmission related timer associated with HARQ process ID 0 set as mode A. Also, the DRX retransmission related timer associated with HARQ process ID 1 set as mode B may not be enabled (may be disabled). Also, the UE 100 may control not to start or restart the DRX retransmission related timer associated with HARQ process ID 1 set as mode B.

The bitmap information may be applied only to uplink transmission (i.e., uplink HARQ process). Thus, the bitmap information may be configured individually in UE 100 only for uplink transmission. Alternatively, the bitmap information may be applied only to downlink transmission (i.e., downlink HARQ process). Thus, the bitmap information may be configured individually in UE 100 only for downlink transmission. Alternatively, the bitmap information may be applied to both uplink transmission and downlink transmission. Thus, one bitmap information may indicate for each HARQ process (for each uplink HARQ process and/or for each downlink HARQ process) whether to enable a DRX retransmission related timer for each of uplink transmission and/or downlink transmission. Alternatively, the bitmap information may include bitmap information indicating for each HARQ process whether or not to enable a DRX retransmission related timer for uplink transmission (also referred to as uplink bitmap information, first bitmap information), and bitmap information indicating for each HARQ process whether or not to enable a DRX retransmission related timer for downlink transmission (also referred to as downlink bitmap information, second bitmap information).

The control unit 230 of the base station 200 may generate bitmap information according to the number of HARQ processes supported by the UE 100. The UE 100 may transmit information on the number of HARQ processes supported by the UE 100 to the network 10. The number of HARQ processes supported by the UE 100 may be set independently for downlink transmission and uplink transmission. For example, the UE 100 may transmit the number of HARQ processes supported by the UE 100 (the number of HARQ processes in the downlink and/or the number of HARQ processes in the uplink) included in the capability information. Here, the number of HARQ processes supported by the UE 100 (the number of HARQ processes in the downlink and/or the number of HARQ processes in the uplink) may be specified in advance by a specification or the like. For example, the number of HARQ processes in the downlink supported by the UE 100 may be 16 (or 32). Also, the number of HARQ processes in the uplink supported by the UE 100 may be 16 (or 32). The control unit 230 of the base station 200 may generate bitmap information to be applied (set) to the uplink transmission based on the number of HARQ processes (e.g., the number of HARQ processes in the uplink). For example, when the number of HARQ processes in the uplink transmission is 16 (or 32), the bitmap information may be configured with a bit string of 16 bits (or 32 bits). Alternatively, the control unit 230 of the base station 200 may generate bitmap information according to the maximum number of HARQ processes, regardless of the number of HARQ processes supported by the UE 100. For example, when the maximum number of HARQ processes in the uplink is 32, the bitmap information may be configured with a bit string of 32 bits.

Here, UE 100 may process only bits in the bitmap information that correspond to the HARQ process IDs that are set (or indicated) for downlink and/or uplink transmission. For example, when HARQ process ID 0 and HARQ process ID 2 are set, UE 100 may process only the first bit (the first bit, corresponding to HARQ process ID 0) and the third bit (HARQ process ID 2) in the bitmap information. That is, UE 100 may ignore (or discard) bits in the bitmap information that do not correspond to the set HARQ process IDs. For example, when HARQ process ID 0 and HARQ process ID 2 are set, UE 100 may ignore (or discard) the second bit in the bitmap information (corresponding to HARQ process ID 1, which is not set).

Note that when the base station 200 configures multiple DRX settings for the UE 100, i.e., when the base station 200 transmits multiple DRX settings to the UE 100, the base station 200 may generate bitmap information corresponding to each DRX setting. That is, bitmap information may be configured for each of one or multiple DRX settings.

The control unit 120 of the UE 100 may control the DRX operation based on the DRX setting included in the RRC message in step S101, for example. Alternatively, the control unit 120 of the UE 100 may control the DRX operation based on the DRX setting received before step S101.

Step S102:
The transmission unit 211 of the base station 200 transmits a PDCCH for scheduling a PUSCH to the UE 100. The reception unit 112 of the UE 100 receives the PDCCH from the base station 200. Specifically, the transmission unit 211 of the base station 200 transmits downlink control information (DCI, also referred to as a DCI format) for scheduling a PUSCH on the PDCCH. The reception unit 112 of the UE 100 receives the DCI. For example, the PUSCH may be used to transmit uplink data (also referred to as data of an UL-SCH).

The transmitter 211 of the base station 200 may transmit one DCI (which may be one DCI format) for scheduling multiple PUSCHs to the UE 100. The receiver 112 of the UE 100 may receive the one DCI (which may be one DCI format) from the base station 200. That is, the one DCI (which may be one DCI format) may include scheduling information (e.g., information used to allocate time and/or frequency resources) used for scheduling one or multiple PUSCHs.

Step S103:
The transmitting unit 111 of the UE 100 may transmit the PUSCH scheduled in the DCI to the base station 200. The receiving unit 212 of the base station 200 may receive the PUSCH from the UE 100. Specifically, the transmitting unit 111 of the UE 100 may transmit uplink data on the PUSCH to the base station 200. The receiving unit 212 of the base station 200 may receive the uplink data from the UE 100 on the PUSCH.

For example, when a trigger condition for starting (or re-starting) a DRX retransmission related timer is satisfied, the control unit 120 of the UE 100 may execute the process of step S104 for the HARQ process associated with the triggered DRX retransmission related timer. Also, when bitmap information is set from the network 10 (for example, in step S101), the control unit 120 of the UE 100 may execute the following process.

Step S104:
The control unit 120 of the UE 100 determines whether or not to enable a DRX retransmission related timer for each HARQ process based on the bitmap information. The control unit 120 of the UE 100 may execute the operation shown in FIG. 7 for each HARQ process. The control unit 120 may determine whether or not to enable a DRX retransmission related timer for each HARQ process number used for communication with the base station 200.

When one or more PUSCHs are scheduled using one DCI, the control unit 120 may determine, based on the bitmap information, whether to enable the DRX retransmission-related timers corresponding to the HARQ processes used for each of the one or more PUSCH transmissions.

Step S121:
As shown in FIG. 7, the control unit 120 determines whether to enable the DRX retransmission related timer based on the bitmap information. Therefore, the control unit 120 determines whether the bit corresponding to the target HARQ process ID indicates that the DRX retransmission related timer is enabled based on the bitmap information. The control unit 120 may determine whether to enable the DRX retransmission related timer based on each of the multiple bits constituting the bitmap information. If the bit indicates that the DRX retransmission related timer is enabled, the control unit 120 determines that the DRX retransmission related timer is enabled, and executes the process of step S122. On the other hand, if the bit indicates that the DRX retransmission related timer is disabled (or not enabled), the control unit 120 determines that the DRX retransmission related timer is disabled, and executes the process of step S123.

In addition, when multiple PUSCHs are scheduled using one DCI, the control unit 120 of the UE 100 may determine whether to enable the DRX retransmission related timer for the first PUSCH transmission in the multiple PUSCH transmissions and for subsequent PUSCH transmissions based on the bit corresponding to the corresponding HARQ process ID.

Step S122:
The control unit 120 enables a DRX retransmission related timer. As an operation of enabling a DRX retransmission related timer, the control unit 120 may, for example, set a value designated by a parameter received from the base station 200 to the DRX retransmission related timer and start (or restart) the DRX retransmission related timer. The control unit 120 may execute an operation related to a DRX retransmission related timer defined in an existing specification.

Step S123:
The control unit 120 disables the DRX retransmission related timer. As an operation of disabling the DRX retransmission related timer, the control unit 120 may not start (or restart) the DRX retransmission related timer. For example, the control unit 120 may set the DRX retransmission related timer to infinity or 0.

Then, if the DRX retransmission-related timer is enabled, the control unit 120 starts (or restarts) the DRX retransmission-related timer when the trigger condition for starting the DRX retransmission-related timer is satisfied. On the other hand, if the DRX retransmission-related timer is disabled, the control unit 120 does not start or restart the DRX retransmission-related timer even if the trigger condition for starting the DRX retransmission-related timer is not satisfied or is satisfied.

For example, if the valid DRX retransmission related timers include a HARQ RTT timer (e.g., a HARQ RTT UL timer), the control unit 120 starts (or restarts) the HARQ RTT timer with the first symbol immediately after transmitting the PUSCH. The control unit 120 goes into a sleep state until the timer expires. For example, if the valid DRX retransmission related timers include a DRX retransmission timer (e.g., a DRX retransmission UL timer), the control unit 120 starts (or restarts) the DRX retransmission UL timer with the next symbol when the HARQ RTT UL timer expires. The UE 100 goes into an awake state while the timer is running.

Note that, when the bitmap information indicates whether or not to enable the IAT for each HARQ process, the control unit 120 of the UE 100 may determine whether or not to enable the IAT for each HARQ process based on the bitmap information. Alternatively, when the control unit 120 has received IAT bitmap information (IAT bitmap information is set), it may determine whether or not to enable the IAT for each HARQ process based on the IAT bitmap information.

Furthermore, when the bitmap information indicates the HARQ mode related to the DRX retransmission related timer for each HARQ process in addition to the validity of the DRX retransmission related timer, the control unit 120 of the UE 100 may determine whether to enable the IAT for each HARQ process based on the bitmap information.

As described above, the transmitting unit 211 of the base station 200 transmits to the UE 100 bitmap information indicating whether or not to enable the DRX retransmission related timer for each HARQ process. The receiving unit 112 of the UE 100 receives from the network 10 (base station 200) bitmap information indicating whether or not to enable the DRX retransmission related timer for each HARQ process. This allows the control unit 120 of the UE 100 to determine whether or not to enable the DRX retransmission related timer for each HARQ process based on the bitmap information. As a result, it becomes possible to flexibly control the DRX retransmission related timer for each HARQ process. For example, the network 10 controls the UE 100 to stop the DRX retransmission related timer of the HARQ process for small packets with very strict delay requirements, thereby eliminating the need for the UE 100 to maintain an activated state and enabling power saving of the UE 100.

In addition, the order of the multiple bits constituting the bitmap information may be associated with an identifier of the HARQ process. The control unit 120 may determine whether or not to enable the DRX retransmission related timer of the corresponding HARQ process based on each of the multiple bits. This allows the control unit 120 to regularly determine whether or not to enable the DRX retransmission related timer of the corresponding HARQ process based on the order of the multiple bits.

Furthermore, the receiving unit 112 may receive one DCI that schedules multiple PUSCHs. The control unit 120 may determine whether or not to enable the DRX retransmission related timers corresponding to the HARQ processes of each of the multiple PUSCH transmissions based on the bitmap information. Even when multiple PUSCHs are scheduled by one DCI, the control unit 120 can flexibly control the DRX retransmission related timers for each HARQ process.

The bitmap information may also include uplink bitmap information indicating for each HARQ process whether or not to enable the DRX retransmission related timer for uplink transmission, and downlink bitmap information indicating for each HARQ process whether or not to enable the DRX retransmission related timer for downlink transmission. This allows the control unit 120 to determine for each HARQ process whether or not to enable the DRX retransmission related timer for uplink transmission and downlink transmission independently. As a result, it becomes possible to flexibly control the DRX retransmission related timer.

In addition, the bitmap information may be applied to both uplink transmission and downlink transmission. This reduces the amount of information sent from the network 10 to the UE 100, and saves communication resources, compared to when the bitmap information is applied to only one of the uplink transmission and the downlink transmission.

The bitmap information may further indicate the HARQ mode associated with the DRX retransmission related timer for each HARQ process. This allows the network 10 to omit the transmission of a bitmap indicating the HARQ mode for each HARQ process, thereby reducing the amount of information sent from the network 10 to the UE 100 and saving communication resources.

In addition to the DRX retransmission-related timers, the bitmap information may also indicate for each HARQ process whether the DRX inactivity timer is enabled. This allows for flexible control of not only the DRX retransmission-related timers but also the DRX inactivity timer.

The receiving unit 112 may receive other bitmap information from the network, in addition to the bitmap information, that indicates whether or not to enable the DRX inactivity timer for each HARQ process. The other bitmap information indicates the validity of the DRX inactivity timer independently of the DRX retransmission related timer, allowing for more flexible control of the DRX inactivity timer.

(Second operation example)
A second operation example of the mobile communication system 1 will be described with reference to Fig. 8. In the second operation example, a case will be described in which the UE 100 executes a retransmission process (HARQ process) in downlink transmission. Note that the description of the same operation as that described above will be omitted as appropriate.

Step S201:
This is the same as step S101. Note that the bitmap information indicates, for each HARQ process, whether or not to enable a DRX retransmission related timer for at least downlink transmission.

Step S202:
The transmission unit 211 of the base station 200 transmits a PDCCH for scheduling a PDSCH to the UE 100. The reception unit 112 of the UE 100 receives the PDCCH from the base station 200. Specifically, the transmission unit 211 of the base station 200 transmits a DCI for scheduling a PDSCH for downlink data transmission on the PDCCH. The reception unit 112 of the UE 100 receives the DCI. Note that the transmission unit 211 of the base station 200 may transmit one DCI for scheduling a plurality of PDSCHs to the UE 100. The reception unit 112 of the UE 100 may receive the DCI from the base station 200.

Step S203:
The transmission unit 211 of the base station 200 transmits the PDSCH scheduled by the DCI to the UE 100. The reception unit 112 of the UE 100 receives the PDSCH from the base station 200. Specifically, the transmission unit 211 of the base station 200 may transmit downlink data on the PDSCH to the UE 100. The reception unit 112 of the UE 100 may receive the downlink data from the base station 200 on the PDSCH.

If the downlink data is not successfully received, the control unit 120 of the UE 100 performs control to execute the process of step S204.

Step S204:
The transmission unit 111 of the UE 100 transmits a negative acknowledgement (NACK) to the base station 200 in a HARQ process in which the reception of the downlink data has not been successful. The base station 200 receives the NACK from the UE 100.

The control unit 120 of the UE 100 may execute the process of step S205, for example, when a trigger condition for starting (or re-starting) a DRX retransmission related timer associated with (corresponding to) the HARQ process is satisfied. In addition, the control unit 120 of the UE 100 may execute the following process when bitmap information is set from the network 10 (for example, in step S201).

When multiple PDSCHs are scheduled by one DCI, the control unit 120 may determine, based on the bitmap information, whether to enable the DRX retransmission related timers corresponding to each HARQ process of the multiple PDSCH transmissions scheduled by one DCI.

Step S205:
The control unit 120 of the UE 100 executes the same operation as in step S104. The control unit 120 determines whether to enable the DRX retransmission related timer based on the bitmap information. In this step, the uplink (transmission) in step S104 is replaced with the downlink (transmission).

In addition, when multiple PDSCHs are scheduled with one DCI, the control unit 120 of the UE 100 may determine whether to enable the DRX retransmission related timer not only for the first PDSCH transmission of the multiple PDSCH transmissions but also for subsequent PDSCH transmissions based on the bit corresponding to the corresponding HARQ process ID.

(Third operation example)
A third operation example of the mobile communication system 1 will be described with reference to FIG. 9. In the third operation example, an example of a case in which the UE 100 determines the validity of the DRX retransmission related timer corresponding to the HARQ process for some transmissions without using bitmap information will be described. This operation example is a modified example of the operation of the UE 100 in step S104 or step S205. The control unit 120 may perform the following operation for each HARQ process number used for communication with the base station 200. Although the uplink transmission (specifically, PUSCH) will be described as an example, the same operation may also be performed for the downlink transmission (specifically, PDSCH). Note that the description of the same operation as above will be omitted as appropriate.

Step S301:
The control unit 120 may determine whether the target HARQ process is a HARQ process for a first PUSCH transmission scheduled by one DCI (hereinafter, referred to as a specific HARQ process). If the target HARQ process is a specific HARQ process, the control unit 120 executes the process of step S302. On the other hand, if the target HARQ process is not a specific HARQ process, the control unit 120 executes the process of step S305.

Steps S302 to S304:
This corresponds to steps S121 to S123.

Step S305:
The control unit 120 may determine whether the target HARQ process is a HARQ process for a subsequent PUSCH transmission scheduled by one DCI (hereinafter referred to as a specific HARQ process). If the target HARQ process is a specific HARQ process, the control unit 120 executes the process of step S306. On the other hand, if the target HARQ process is not a specific HARQ process, the control unit 120 executes the process of step S302.

Step S306:
The control unit 120 may apply the same determination to the DRX retransmission related timer corresponding to the HARQ process of the first PUSCH transmission (hereinafter, sometimes referred to as the first DRX retransmission related timer) for the DRX retransmission related timer corresponding to the HARQ process of the first PUSCH transmission, regardless of the bitmap information. Therefore, when the control unit 120 determines that the first DRX retransmission related timer is valid, the control unit 120 determines that the subsequent DRX retransmission related timer is valid, regardless of the bitmap information (i.e., even if the bitmap information indicates that the bitmap information is invalid). On the other hand, when the control unit 120 determines that the first DRX retransmission related timer is invalid, the control unit 120 determines that the subsequent DRX retransmission related timer is invalid, regardless of the bitmap information (i.e., even if the bitmap information indicates that the bitmap information is valid).

Note that when determining the validity of a DRX retransmission-related timer corresponding to a HARQ process for (multiple) PDSCH transmissions scheduled by another DCI received after the above-mentioned DCI, the control unit 120 does not apply the same judgment as for the first DRX retransmission-related timer based on the above-mentioned DCI.

As described above, the control unit 120 may determine whether to enable the DRX retransmission related timer corresponding to the HARQ process of the first PUSCH transmission or the first PDSCH transmission scheduled by one DCI based on the bitmap information. The control unit 120 may apply the same determination to the DRX retransmission related timer corresponding to the HARQ process for the subsequent PUSCH transmission or the subsequent PDSCH transmission scheduled by one DCI as to the DRX retransmission related timer corresponding to the HARQ process of the first PUSCH transmission, regardless of the bitmap information. When the network 10 schedules multiple PUSCH transmissions or multiple PUSCH transmissions by one DCI for traffic with a large amount of data (e.g., video data), for example, it may not be necessary to change the validity of the DRX retransmission related timer for each HARQ process. In such a case, by applying the same determination to the subsequent DRX retransmission related timer as to the first DRX retransmission related timer, the processing load of the UE 100 can be reduced, and power saving of the UE 100 can be further achieved.

Other Embodiments
In at least one of the above-described operation examples, the following operation may be performed. The base station 200 may transmit an RRC message including a parameter (a parameter value) for DRX setting. The UE 100 may specify a parameter (a parameter value) used for DRX operation based on the parameter for DRX setting. Here, the parameter (a parameter value) for DRX setting may include any of drx-onDurationTimer, drx-InactivityTimer, drx-HARQ-RTT-TimerDL, drx-HARQ-RTT-TimerUL, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, and drx-LongCycleStartOffset. Also, one or more HARQ processes (HARQ process IDs) used for downlink and/or uplink transmission may be set for the UE 100. For example, the base station 200 may transmit an RRC message including information indicating one or more HARQ processes (HARQ process IDs) used for downlink and/or uplink transmission. Here, the number of HARQ processes (the number of HARQ process IDs) used for downlink and/or uplink transmission may be predefined by a specification or the like and may be known information between the base station 200 and the UE 100. Also, the base station 200 may set bitmap information. For example, when DRX (DRX operation) is set, the UE 100 may control the processing of a timer (e.g., a retransmission-related timer and/or an IAT) based on the set bitmap information.

For example, when drx-HARQ-RTT-TimerDL expires and data (e.g., downlink data) of the corresponding HARQ process has not been successfully decoded, UE100 may determine whether to enable drx-RetransmissionTimerDL corresponding to the HARQ process based on the value of the bit of bitmap information corresponding to the HARQ process. For example, when the bit of bitmap information corresponding to the HARQ process is set to "1", UE100 may enable drx-RetransmissionTimerDL corresponding to the HARQ process (e.g., may start drx-RetransmissionTimerDL). Here, UE100 may enable drx-RetransmissionTimerDL in the first symbol after drx-HARQ-RTT-TimerDL expires (e.g., may start drx-RetransmissionTimerDL). Also, when the bit of the bitmap information corresponding to the HARQ process is set to "0", UE100 may not enable drx-RetransmissionTimerDL corresponding to the HARQ process (e.g., may not start drx-RetransmissionTimerDL).

Here, in the case where bitmap information is not set (e.g., bitmap information is not included (does not exist) in the RRC message), if drx-HARQ-RTT-TimerDL expires and data (e.g., downlink data) of the corresponding HARQ process is not successfully decoded, UE100 may enable drx-RetransmissionTimerDL corresponding to the HARQ process (e.g., may start drx-RetransmissionTimerDL). For example, UE100 may enable drx-RetransmissionTimerDL (e.g., may start drx-RetransmissionTimerDL) in the first symbol after drx-HARQ-RTT-TimerDL expires.

Furthermore, when the drx-HARQ-RTT-TimerUL expires, the UE100 may determine whether or not to enable the drx-RetransmissionTimerUL corresponding to the HARQ process based on the value of the bit of the bitmap information corresponding to the HARQ process. For example, when the bit of the bitmap information corresponding to the HARQ process is set to "1", the UE100 may enable the drx-RetransmissionTimerUL corresponding to the HARQ process (for example, may start the drx-RetransmissionTimerUL). Here, UE100 may enable drx-RetransmissionTimerUL (e.g., may start drx-RetransmissionTimerUL) in the first symbol after drx-HARQ-RTT-TimerUL expires. Also, when the bit of the bitmap information corresponding to the HARQ process is set to "0", UE100 may not enable drx-RetransmissionTimerUL corresponding to the HARQ process (e.g., may not start drx-RetransmissionTimerUL).

Here, in the case where bitmap information is not set and drx-HARQ-RTT-TimerUL expires, UE100 may enable drx-RetransmissionTimerUL corresponding to the HARQ process (e.g., may start drx-RetransmissionTimerDL). For example, UE100 may enable drx-RetransmissionTimerUL (e.g., may start drx-RetransmissionTimerUL) in the first symbol after drx-HARQ-RTT-TimerUL expires.

Also, as described above, UE100 may monitor the PDCCH in the serving cell in the DRX group when the DRX group is in active time. Here, when the PDCCH indicates downlink transmission, UE100 may determine whether or not to enable the drx-HARQ-RTT-TimerDL corresponding to the HARQ process related to the reported HARQ feedback based on the value of the bit of the bitmap information corresponding to the HARQ process. Here, the case where the PDCCH indicates downlink transmission may include the reception (detection) of a DCI format used for scheduling the downlink transmission (e.g., PDSCH). Also, the reported HARQ feedback may be HARQ feedback (also referred to as downlink HARQ feedback) reported for the downlink transmission (e.g., PDSCH transmission). For example, when the bit of the bitmap information corresponding to the HARQ process is set to "1", the UE 100 may enable the drx-HARQ-RTT-Timer DL corresponding to the HARQ process (for example, may start the drx-HARQ-RTT-Timer DL). For example, the UE 100 may enable the drx-HARQ-RTT-Timer DL (for example, may start the drx-HARQ-RTT-Timer DL) in the first symbol after the transmission of the HARQ feedback. Also, when the bit of the bitmap information corresponding to the HARQ process is set to "0", the UE 100 may not enable the drx-HARQ-RTT-Timer DL corresponding to the HARQ process (for example, may not start the drx-HARQ-RTT-Timer DL).

Here, in the case where bitmap information is not set and the PDCCH indicates downlink transmission, UE100 may enable the drx-HARQ-RTT-TimerDL corresponding to the HARQ process (e.g., may start the drx-HARQ-RTT-TimerDL). For example, UE100 may enable the drx-HARQ-RTT-TimerDL in the first symbol after the transmission of the HARQ feedback (e.g., may start the drx-HARQ-RTT-TimerDL).

In addition, when the PDCCH indicates downlink transmission, UE 100 may stop the drx-RetransmissionTimerDL corresponding to the HARQ process related to the reported HARQ feedback.

In addition, when the PDCCH indicates uplink transmission, the UE 100 may determine whether to enable the drx-HARQ-RTT-TimerUL corresponding to the HARQ process related to the PUSCH transmission based on the value of the bit of the bitmap information corresponding to the HARQ process. Here, the case where the PDCCH indicates uplink transmission may include the reception (detection) of a DCI format used for scheduling the uplink transmission (e.g., PUSCH). For example, when the bit of the bitmap information corresponding to the HARQ process is set to "1", the UE 100 may enable the drx-HARQ-RTT-TimerUL corresponding to the HARQ process (e.g., may start the drx-HARQ-RTT-TimerUL). For example, UE100 may enable drx-HARQ-RTT-TimerUL (e.g., may start drx-HARQ-RTT-TimerUL) in the first symbol after the corresponding PUSCH transmission. Also, when the bit of the bitmap information corresponding to the HARQ process is set to "0", UE100 may not enable drx-HARQ-RTT-TimerUL corresponding to the HARQ process (e.g., may not start drx-HARQ-RTT-TimerUL).

Here, in the case where bitmap information is not set and the PDCCH indicates uplink transmission, UE100 may enable the drx-HARQ-RTT-TimerUL corresponding to the HARQ process (e.g., may start the drx-HARQ-RTT-TimerUL). For example, UE100 may enable the drx-HARQ-RTT-TimerUL (e.g., may start the drx-HARQ-RTT-TimerUL) in the first symbol after the corresponding PUSCH transmission.

In addition, when the PDCCH indicates uplink transmission, the UE 100 may stop the drx-RetransmissionTimerUL corresponding to the HARQ process related to the PUSCH transmission.

In the above embodiment, uplink transmission and downlink transmission are described as examples, but this is not limiting. For example, operations similar to those described above may be performed in sidelink communication, which is communication between terminals.

In the above embodiment, a mobile communication system based on NR 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 the TS of either LTE (Long Term Evolution) or another generation system of the 3GPP standard (e.g., the sixth generation). 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 the TS of a standard other than the 3GPP standard. The base station 200 may be an IAB (Integrated Access and Backhaul) donor or an IAB node.

In the above embodiment, a mobile communication system based on NR 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 the TS of either LTE or another generation system of the 3GPP standard (e.g., the 6th generation). 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 the TS of a standard other than the 3GPP standard.

The steps in the operations of the above-described embodiments do not necessarily have to be executed in chronological order according to the order depicted in the flow diagram or sequence diagram. For example, the steps in the operations may be executed in an order different from that depicted 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. Furthermore, each of the above-described operation flows is not limited to being executed separately and independently, but can be executed by combining two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow.

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 (Compact Disk Read Only Memory) or a DVD-ROM (Digital Versatile Disk Read Only Memory). In addition, circuits that execute each process performed by the UE 100 or the base station 200 may be integrated, and at least a part of the UE 100 or the base station 200 may be configured as a semiconductor integrated circuit (chip set, SoC (System On Chip)).

In the above 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 other nodes, or obtaining the information by generating the information. Similarly, the terms "based on" and "depending on/in response to" do not mean "based only on" or "only in response to," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "in response to" means both "only in response to" and "at least in part on." Similarly, "include" and "comprise" do not mean including only the recited items, but may include only the recited items or may include additional items in addition to the recited items. Similarly, in this disclosure, "or" does not mean an exclusive or, but does mean a logical or. Furthermore, any reference to elements using designations such as "first," "second," etc., used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein, or that the first element must precede the second element in some manner. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles are intended to include the plural unless the context clearly indicates otherwise.

Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

(Additional Note)
The following additional features relate to the above-described embodiment.

(Appendix 1)
A communication device (100),
A communication device comprising: a receiving unit (112) that receives, from a network (10), bitmap information indicating whether or not a discontinuous reception (DRX) retransmission related timer for controlling retransmission during a hybrid automatic repeat request (HARQ) process DRX operation is enabled for each HARQ process.

(Appendix 2)
an order of the plurality of bits constituting the bitmap information is associated with an identifier of the HARQ process;
A control unit (120) that determines whether to enable the DRX retransmission related timer for a corresponding HARQ process based on each of the plurality of bits.

(Appendix 3)
The receiving unit receives one downlink control information (DCI) for scheduling a plurality of physical uplink shared channels (PUSCHs) or a plurality of physical downlink shared channels (PDSCHs);
The communication device according to claim 1 or 2, further comprising: a control unit that determines whether to enable a DRX retransmission related timer corresponding to each HARQ process of a plurality of PUSCH transmissions or a plurality of PDSCH transmissions scheduled by the one DCI, based on the bitmap information.

(Appendix 4)
The receiving unit receives one downlink control information (DCI) for scheduling a plurality of physical uplink shared channels (PUSCHs) or a plurality of physical downlink shared channels (PDSCHs);
a control unit that determines whether to enable the DRX retransmission related timer for each of the HARQ processes based on the bitmap information;
The control unit is
Determine whether to enable a DRX retransmission related timer corresponding to a HARQ process of a first PUSCH transmission or a first PDSCH transmission scheduled by the one DCI based on the bitmap information;
The communication device according to claim 1 or 2, wherein, regardless of the bitmap information, the same determination is applied to a DRX retransmission related timer corresponding to a HARQ process for a subsequent PUSH transmission or a subsequent PDSCH transmission scheduled by the one DCI as to the DRX retransmission related timer corresponding to the HARQ process of the initial PUSH transmission.

(Appendix 5)
The communication device according to any one of Supplementary Notes 1 to 4, wherein the bitmap information includes uplink bitmap information indicating, for each HARQ process, whether or not to enable the DRX retransmission related timer for uplink transmission, and downlink bitmap information indicating, for each HARQ process, whether or not to enable the DRX retransmission related timer for downlink transmission.

(Appendix 6)
6. The communication device according to claim 1, wherein the bitmap information is applied to both uplink transmission and downlink transmission.

(Appendix 7)
The communication device according to any one of Supplementary Notes 1 to 6, wherein the bitmap information further indicates, for each HARQ process, a HARQ mode associated with the DRX retransmission related timer.

(Appendix 8)
The communication device according to any one of Supplementary Notes 1 to 7, wherein the bitmap information indicates, in addition to the DRX retransmission related timer, whether to enable a DRX inactivity timer that specifies a period during which the communication device should be in an awake state after successfully decoding a physical downlink control channel (PDCCH) indicating a new transmission, for each HARQ process.

(Appendix 9)
The communication device according to any one of Supplementary Notes 1 to 8, wherein the receiving unit receives from the network, separately from the bitmap information, other bitmap information indicating whether to enable a DRX inactivity timer for timing a period during which the communication device should be in an awake state after successful decoding of a physical downlink control channel (PDCCH) indicating a new transmission, for each HARQ process.

(Appendix 10)
A base station (200),
A base station comprising: a transmitter (211) that transmits, to a communication device, bitmap information indicating whether or not a discontinuous reception (DRX) retransmission related timer for controlling retransmission during a discontinuous reception (DRX) operation in a hybrid automatic repeat request (HARQ) process is enabled for each HARQ process.

(Appendix 11)
1. A communication method performed in a communication device, comprising:
A communication method comprising: receiving, from a network, bitmap information indicating whether or not a discontinuous reception (DRX) retransmission related timer for controlling retransmission during a discontinuous reception (DRX) operation in a hybrid automatic repeat request (HARQ) process is enabled for each HARQ process.

Claims

A communication device (100),
A communication device comprising: a receiving unit (112) that receives, from a network (10), bitmap information indicating whether or not a discontinuous reception (DRX) retransmission related timer for controlling retransmission during a hybrid automatic repeat request (HARQ) process DRX operation is enabled for each HARQ process.
an order of the plurality of bits constituting the bitmap information is associated with an identifier of the HARQ process;
The communication device according to claim 1 , further comprising: a control unit (120) that determines whether to enable the DRX retransmission related timer for a corresponding HARQ process based on each of the plurality of bits.
The receiving unit receives one downlink control information (DCI) for scheduling a plurality of physical uplink shared channels (PUSCHs) or a plurality of physical downlink shared channels (PDSCHs);
The communication device according to claim 1 or 2, further comprising: a control unit that determines whether to enable a DRX retransmission related timer corresponding to each HARQ process of each of a plurality of PUSCH transmissions or each of a plurality of PDSCH transmissions scheduled by the one DCI based on the bitmap information.
The receiving unit receives one downlink control information (DCI) for scheduling a plurality of physical uplink shared channels (PUSCHs) or a plurality of physical downlink shared channels (PDSCHs);
a control unit that determines whether to enable the DRX retransmission related timer for each of the HARQ processes based on the bitmap information;
The control unit is
Determine whether to enable a DRX retransmission related timer corresponding to a HARQ process of a first PUSCH transmission or a first PDSCH transmission scheduled by the one DCI based on the bitmap information;
The communication device according to claim 1 or 2, wherein, regardless of the bitmap information, the same determination is applied to a DRX retransmission related timer corresponding to a HARQ process for a subsequent PUSH transmission or a subsequent PDSCH transmission scheduled by the one DCI as to the DRX retransmission related timer corresponding to the HARQ process of the initial PUSH transmission.
The communication device according to claim 1 or 2, wherein the bitmap information includes uplink bitmap information indicating, for each HARQ process, whether or not to enable the DRX retransmission related timer for uplink transmission, and downlink bitmap information indicating, for each HARQ process, whether or not to enable the DRX retransmission related timer for downlink transmission.
The communication device according to claim 1 or 2, wherein the bitmap information is applied to both uplink and downlink transmissions.
The communication device according to claim 1 or 2, wherein the bitmap information further indicates, for each of the HARQ processes, a HARQ mode associated with the DRX retransmission related timer.
The communication device according to claim 1 or 2, wherein the bitmap information indicates, in addition to the DRX retransmission related timer, whether to enable a DRX inactivity timer that specifies a period during which the communication device should be in an awake state after successfully decoding a physical downlink control channel (PDCCH) indicating a new transmission, for each HARQ process.
The communication device according to claim 1 or 2, wherein the receiving unit receives from the network, separately from the bitmap information, other bitmap information indicating whether to enable a DRX inactivity timer for timing a period during which the communication device should be in an awake state after successful decoding of a physical downlink control channel (PDCCH) indicating a new transmission, for each HARQ process.
A base station (200),
A base station comprising: a transmitter (211) that transmits, to a communication device, bitmap information indicating whether or not a discontinuous reception (DRX) retransmission related timer for controlling retransmission during a discontinuous reception (DRX) operation in a hybrid automatic repeat request (HARQ) process is enabled for each HARQ process.
1. A communication method performed in a communication device, comprising:
A communication method comprising: receiving, from a network, bitmap information indicating whether or not a discontinuous reception (DRX) retransmission related timer for controlling retransmission during a discontinuous reception (DRX) operation in a hybrid automatic repeat request (HARQ) process is enabled for each HARQ process.