Communication device, communication method, and integrated circuit

Abstract

This communication device comprises: a control circuit that allocates a signal to a guard section that is set to an Nth time resource, among the Nth time resource and an N+1th time resource that are included in a plurality of time resources, when a plurality of contiguous time resources are allocated in terminal-to-terminal communication in an unlicensed band; and a transmission circuit that transmits the signal in the plurality of time resources.

Description

Communication device and communication method

[0001] The present disclosure relates to a communication device and a communication method.

[0002] The expansion of communication systems known as 5th Generation mobile communication systems (5G) is currently being considered. 5G is being considered to provide flexible functions for each use case that requires increased communication traffic, an increased number of connected devices, high reliability, and low latency.

[0003] 3GPP, TR 38.885 V16.0.0, “Study on NR Vehicle-to-Everything (V2X)”RP-201385, “WID revision: NR sidelink enhancement,” LG Electronics, June 29 - July 3, 2020RP-213678, “New WID on NR sidelink evolution,” OPPO, LG Electronics, Dec. 6 - 17, 20213GPP, TS 38.212 V17.2.0, “NR; Multiplexing and channel coding”

[0004] However, there is room for further consideration regarding the effective use of communication resources in unlicensed bands.

[0005] Non-limiting embodiments of the present disclosure contribute to providing a communication device and a communication method that can improve the utilization efficiency of communication resources in unlicensed bands.

[0006] A communication device according to one embodiment of the present disclosure includes, when multiple consecutive time resources are allocated in terminal-to-terminal communication in an unlicensed band, a control circuit that allocates a signal to a guard interval set in the nth time resource among the nth time resource and the n+1th time resource included in the multiple time resources, and a transmission circuit that transmits the signal in the multiple time resources.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to one embodiment of the present disclosure, it is possible to improve the utilization efficiency of communication resources in unlicensed bands.

[0009] Further advantages and benefits of certain aspects of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features.

[0010] 1 is a diagram showing an example of channel allocation within a slot; 2 is a diagram showing an example of channel allocation within a slot when a channel is busy; 3 is a block diagram showing an example of the configuration of a portion of a base station; 4 is a block diagram showing an example of the configuration of a portion of a terminal; 5 is a diagram showing an example of sidelink communication in Mode 1; 6 is a diagram showing an example of sidelink communication in Mode 1; 7 is a diagram showing an example of channel allocation within a slot; 8 is a diagram showing an example of sidelink communication in Mode 2; 9 is a block diagram showing an example of the configuration of a terminal; 10 is a diagram showing an example of channel allocation within a slot; 11 is a diagram showing an example of channel allocation within a slot;

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] The 3GPP (3rd Generation Partnership Project), an international standardization organization, is studying the advancement of communication systems from both the perspective of the Long Term Evolution (LTE) system and New Radio (NR). 3GPP has first considered supporting V2X (vehicle to X) in the LTE system. NR, which can use a wider bandwidth than LTE, has also considered supporting V2X (see, for example, Non-Patent Document 1).

[0013] In addition to V2X, further expansion of communication using sidelink (SL) is being considered (see, for example, Non-Patent Document 2). V2X is expected to cover vehicle-to-vehicle (V2V: Vehicle to Vehicle), vehicle-to-infrastructure (V2I: Vehicle to Infrastructure), vehicle-to-pedestrian (V2P: Vehicle to Pedestrian), and vehicle-to-network (V2N: Vehicle to Network) communications.

[0014] In V2V, V2I, and V2P, signals can be transmitted and received directly between terminals using a link called a sidelink or PC5, without going through a network with a base station (for example, a network via a base station). In V2N, communication is assumed to occur via a link called Uu between a base station and a terminal. Note that a base station may be referred to as a gNB in ​​NR or an eNB in ​​LTE. Furthermore, a terminal may be referred to as a UE (User Equipment).

[0015] In addition, the use of sidelink communication in unlicensed bands is also being considered (see, for example, Non-Patent Document 3).

[0016] [NR Sidelink] NR sidelink supports unicast, groupcast, and broadcast transmission / reception. Unicast assumes one-to-one transmission from a transmitting terminal (also called Tx UE, source UE, or source terminal) to a receiving terminal (Rx UE, destination UE, or destination terminal). Groupcast assumes transmission from a transmitting terminal to one or more receiving terminals included in a certain group. Broadcast assumes transmission from a transmitting terminal without specifying a receiving terminal.

[0017] In the NR sidelink, a control signal called SCI (sidelink control information) is transmitted and received. The SCI is divided into a first-stage SCI and a second-stage SCI. The first-stage SCI is allocated to a PSCCH (physical SL control channel). The second-stage SCI is allocated to at least a portion of a PSSCH (physical SL shared channel) that transmits and receives data. Dividing the SCI into two parts can reduce the number of bits and size of the first-stage SCI. In the sidelink, a certain terminal (e.g., terminal A) has a function of receiving a PSCCH transmitted from another terminal other than terminal A, understanding the resource usage status of the other terminal, and then determining the resources that terminal A will use for transmission. This function is also called "sensing."

[0018] In the sidelink, signals are transmitted and received on the following channels: -PSCCH (physical SL control channel): 1st-stage SCI (Sidelink control information) is allocated in the PSCCH. -PSSCH (physical SL shared channel): Data signals and 2nd-stage SCI are allocated in the PSSCH. -PSFCH (physical SL feedback channel): Feedback signals for the PSSCH are allocated in the PSFCH. The feedback signals indicate, for example, an acknowledgement (ACK) indicating successful reception of the PSSCH or a negative acknowledgement (NACK) indicating unsuccessful reception of the PSSCH. The feedback signals can be applied when the PSSCH is unicast or groupcast. In addition, in Release 17 (Rel. 17) and later, the PSFCH may be transmitted as inter-UE coordination when a collision is detected. -PSBCH (physical SL broadcast channel): Broadcast signals are allocated in the PSBCH. The SBCH is transmitted together with a synchronization signal. The synchronization signal may be, for example, a sidelink primary synchronization signal (S-PSS) and / or a sidelink secondarily synchronization signal (S-SSS). The SBCH transmitted together with the synchronization signal is also referred to as a sidelink synchronization signal block (S-SSB).

[0019] Note that a signal transmitted and received in the sidelink may be referred to as a "sidelink signal." Also, for example, "transmission of information (or a signal) allocated to the PSCCH" may be abbreviated as "transmission of the PSCCH" hereinafter. Also, in the following description, the PSCCH may refer to a resource defined as the PSCCH, or may refer to information (or a signal) allocated to the resource defined as the PSCCH. Channels other than the PSCCH may also be abbreviated as the PSCCH.

[0020] Figure 1 shows an example of the arrangement of PSCCH, PSSCH, and PSFCH in a slot. The horizontal axis of Figure 1 represents the time axis, and the vertical axis represents the frequency axis in units of PRB (physical resource block). Figure 1 shows two examples, Figure 1(a) and Figure 1(b).

[0021] Note that the PSFCH may be arranged as shown in Figure 1(a). Alternatively, as shown in Figure 1(b), the PSFCH may not be arranged depending on the setting. If the PSFCH is not arranged, the PSSCH area may be increased.

[0022] The number of symbols of the sidelink signal in a slot may be variable depending on the setting. Furthermore, the arrangement of the 2nd-stage SCI may be changed depending on the arrangement of the PSSCH DMRS (demodulation reference signal), not shown. The 1st-stage SCI is arranged starting from the lowest frequency resource among the frequency resources to which the PSSCH is allocated. A copy of the first symbol of the PSCCH and PSSCH is arranged in the symbol before the first symbol of the PSCCH and PSSCH for AGC (Auto Gain Control). Furthermore, as shown in FIG. 1(a), a copy of the PSFCH is also arranged before the PSFCH symbol for AGC.

[0023] In addition, in FIG. 1(a), guard intervals (for example, guard periods or gaps) for switching between transmission and reception are arranged in the interval between the PSSCH and the PSFCH and in the interval after the last symbol of the PSFCH. In FIG. 1(b), a guard period for switching between transmission and reception is arranged in the interval after the last symbol of the PSSCH. The guard period may correspond to an interval in which no signals are transmitted or received.

[0024] NR sidelink communication has two modes, Mode 1 and Mode 2. In Mode 1, the base station determines (schedules) the resources to be used by the terminal on the sidelink and notifies the terminal of the scheduling result. In Mode 2, the terminal determines (or selects) the resources to be used on the sidelink from resources in a predetermined resource pool. Mode 1 is a state in which the base station and the terminal are connected, and is intended to be used in an environment in which the terminal communicating on the sidelink can receive instructions from the base station. In Mode 2, the terminal can transmit on the sidelink without instructions from the base station, so sidelink communication is possible with terminals under the control of different operators and / or terminals outside the base station's coverage.

[0025] The resources used for the sidelink are set, for example, by the SL BWP (Bandwidth part) and a resource pool.

[0026] The SL BWP specifies a frequency band that can be used for the sidelink and is set separately from the downlink BWP (DL BWP) and uplink BWP (UL BWP) set between the base station and the terminal (Uu). For example, the frequency band of the SL BWP may overlap with the UL BWP.

[0027] A resource pool is a resource within an SL BWP, and resources in the frequency direction and time direction are specified by the resource pool. For example, multiple resource pools may be configured for one terminal. The frequency resources within the resource pool are divided into units called "subchannels," and resource allocation can be configured for each subchannel. A subchannel includes multiple PRBs, and PSSCH allocation can be performed for each subchannel that groups together PRBs.

[0028] [NR-U (NR-Unlicensed)] With the increasing capacity of communications, 3GPP is also considering the use of unlicensed bands in addition to licensed bands. NR that utilizes unlicensed bands is also called NR-U (unlicensed). NR-U adds and enhances operations to maintain fairness when coexisting with other devices, such as Wi-Fi (registered trademark) and / or LTE-based Licensed Assisted Access (LAA).

[0029] In unlicensed bands, a communication device (e.g., an NR-U base station or terminal) performs LBT (Listen Before Talk) to maintain fairness with other devices, and starts transmission only after confirming that no other devices are transmitting signals nearby. LBT may be replaced with other terms such as carrier sense or sensing. After performing LBT and confirming that no other devices are transmitting signals nearby, a channel occupancy time (COT) is set for the communication device. Within the COT, the communication device can transmit and receive signals in downlink (DL) resources and uplink (UL) resources.

[0030] There are two operation methods for LBT. The first operation method is LBE (Load Based Equipment). In LBE, when a communication device acquires a COT, it performs Type 1 channel access (e.g., category 4 LBT or Type 1 LBT). In addition, except at the beginning of the COT, the communication device can perform Type 2 channel access (e.g., Type 2 LBT) and start transmission after performing this.

[0031] In the following description, when a communication device (e.g., a base station or a terminal) "starts transmission after performing LBT," this corresponds to the communication device starting transmission after performing LBT and confirming that no other devices are transmitting signals nearby.

[0032] Table 1 shows an example of the sensing interval of LBT for acquiring the transmission right in DL in LBE and the interval to be applied.

[0033] In Type 2A, if the interval between two consecutive resources is 25 μs, the terminal performs LBT within 25 μs. If the terminal does not confirm transmissions from other devices in the LBT, it can start transmission.

[0034] In Type 2B, if the interval between two consecutive resources is 16 μs, the terminal performs LBT within 16 μs. If the terminal does not confirm transmissions from other devices, it can start transmission.

[0035] In Type 2C, if the interval between two consecutive resources is less than 16 μs, the terminal can start transmission without LBT. As an exception, when transmitting a discovery reference signal (DRS), the terminal can start transmission by implementing Type 2A LBT instead of Type 1 LBT because the transmission time of the DRS is short.

[0036] The second operating method is FBE (Frame Based Equipment). FBE assumes that other devices such as Wi-Fi are not installed in the same space, and operates by fixing the frame period and performing LBT at the beginning of the frame to obtain the COT. In FBE, the COT can only be obtained from the beginning of the frame interval (Fixed Frame Period). FBE also stipulates that an idle period of 5% or more must be set for each frame interval.

[0037] The above is an explanation of NR-U.

[0038] In the following embodiments, an example of performing sidelink communication in an unlicensed band will be described. Sidelink communication utilizing an unlicensed band is also called SL-U (Sidelink unlicensed).

[0039] In unlicensed bands, a terminal performs LBT and starts transmission if it does not confirm transmissions from other devices. On the other hand, in unlicensed bands, a terminal performs LBT, detects signals from other devices, and does not start transmission if it confirms transmissions from other devices. The detection of signals from other devices is also called "busy (or channel busy)," "unavailable," or "LBT failure."

[0040] In the case of an LBT failure, even in the sidelink, the terminal cannot acquire the transmission right for the allocated resource or the selected resource and cannot start transmission.

[0041] FIG. 2 is a diagram showing an example of channel allocation within each slot in the case of an LBT failure.

[0042] For example, Figure 2(a) shows an example in which another device starts transmission in a slot before the slot in which the terminal is scheduled to transmit (a slot for which resources are reserved). Also, Figure 2(b) shows an example in which another device starts transmission in a symbol immediately before the slot in which the terminal is scheduled to transmit. As shown in Figures 2(a) and 2(b), the terminal performs LBT before the slot in which the terminal is scheduled to transmit, resulting in an LBT failure and thus unable to start transmitting a sidelink signal. For example, as shown in Figure 2(b), even if the terminal uses consecutive slots and attempts to transmit by performing LBT Type 2 in a COT, another device may still be able to acquire the transmission right.

[0043] In a non-limiting example, the present disclosure describes a method for allocating or selecting a next resource when a terminal fails to acquire a transmission right in sidelink communication in an unlicensed band. Also, in a non-limiting example, the present disclosure describes a method for reducing the number of LBTs or the occurrence of LBT failures when a terminal uses consecutive slots in sidelink communication in an unlicensed band.

[0044] In the embodiments described below, sidelink communication is exemplified, but the present disclosure is not limited to sidelink communication.

[0045] [Overview of Communication System] A communication system according to an embodiment of the present disclosure includes a base station 100 and a terminal 200.

[0046] Fig. 3 is a block diagram showing an example of the configuration of a portion of the base station 100. In the base station 100 shown in Fig. 3, a control unit controls communication between the terminal 200 and the base station 100 via a link called Uu. The communication unit transmits a signal via the link called Uu under the control of the control unit. The control unit may also perform control related to sidelink communication between multiple terminals (e.g., determining resources in Mode 1).

[0047] Fig. 4 is a block diagram showing a partial configuration example of terminal 200 (e.g., corresponding to a communication device). In terminal 200 shown in Fig. 4, when consecutive time resources are allocated in terminal-to-terminal communication in an unlicensed band, a control unit (e.g., corresponding to a control circuit) allocates a signal to a guard interval (e.g., a guard period) set for the nth time resource among the nth time resource and the (n+1)th time resource included in the consecutive time resources (e.g., slots). A communication unit (e.g., corresponding to a communication circuit) transmits a signal in the consecutive time resources. Note that the transmission signal may be, for example, a sidelink signal or a signal different from the sidelink signal.

[0048] (Embodiment 1) In this embodiment, when terminal 200 experiences an LBT failure and is unable to acquire the transmission right, base station 100 notifies terminal 200 of the next resource or sets resources selectable by terminal 200. In this way, terminal 200 can prepare resources for a signal that cannot be transmitted due to an LBT failure.

[0049] An example of operation according to this embodiment will be described below.

[0050] [Operation Example 1] In Operation Example 1, an operation example in which the base station 100 designates resources in Mode 1 of the side link will be described.

[0051] Fig. 5 is a diagram illustrating an example of operation in Sidelink Mode 1. The example of operation illustrated in Fig. 5 illustrates an example of operation when it is confirmed by LBT that no other devices are transmitting (when LBT is OK).

[0052] In Mode 1, the base station 100 (gNB) instructs the source terminal 200 (source UE) to allocate resources for sidelink communication. The resource allocation for sidelink communication may be indicated by, for example, DCI format 3_0. Note that the base station 100 may specify multiple resources for the sidelink to the terminal 200.

[0053] The source terminal 200 transmits a sidelink signal such as a PSCCH and / or a PSSCH (hereinafter also referred to as "PSCCH / PSSCH") to the destination terminal 200 (destination UE) in accordance with resource allocation (e.g., resource pool, time resource (e.g., slot), frequency resource (e.g., PRB)) instructed by the base station 100. The source terminal 200 may instruct the destination terminal 200, for example, by a PSCCH (SCI format 1A), of at least one resource instructed by DCI format 3_0. Note that the source terminal 200 may start transmitting a sidelink signal if the result of the LBT is LBT OK.

[0054] Destination terminal 200 receives the PSCCH / PSSCH from source terminal 200, and, for example, if HARQ feedback is configured, transmits HARQ-ACK information including an ACK or NACK to source terminal 200 using the PSFCH resource.

[0055] Source terminal 200 notifies base station 100 of information of the HARQ-ACK received from destination terminal 200 via a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH), for example.

[0056] In addition, in sidelink Mode 1 in SL-U, it is also assumed that the base station 100 does not perform LBT (or sensing) in unlicensed bands. For example, in FIG. 5 , the source terminal 200 performs LBT in resources designated by the base station 100. If the LBT result is LBT failure, the base station 100 halts transmission of the PSCCH / PSSCH on the sidelink. Therefore, if the terminal 200 is unable to transmit as a result of the LBT (e.g., in the case of LBT failure), the base station 100 cannot identify that the terminal 200 is unable to transmit a sidelink signal (e.g., LBT failure). Therefore, in sidelink Mode 1, the base station 100 cannot allocate the next sidelink resource (or new resource) to the terminal 200.

[0057] Therefore, in the first operation example, the source terminal 200 notifies the base station 100 of an LBT failure.

[0058] FIG. 6 is a diagram illustrating an operation example in side link Mode 1 according to Operation Example 1.

[0059] In Figure 6, similar to Figure 5, the base station 100 (gNB) instructs the source terminal 200 (source UE) to allocate resources for sidelink communication.

[0060] Source terminal 200 performs LBT using sidelink resources allocated by base station 100. If the result of the LBT is LBT failure, source terminal 200 suspends transmission of the PSCCH / PSSCH on the sidelink. Therefore, the destination terminal cannot sense (or detect) the PSCCH and therefore does not receive the PSSCH.

[0061] Source terminal 200 transmits an LBT failure notification (LBT failure indication) to base station 100. The LBT failure notification may be transmitted, for example, via an uplink (e.g., a PUCCH or a PUSCH) between source terminal 200 and base station 100.

[0062] For example, upon receiving a notification of LBT failure, the base station 100 may allocate (or reallocate) additional resources, if necessary, to the source terminal 200. The base station 100 instructs the source terminal 200 to allocate resources for sidelink communication (resource (re)allocation). Note that the base station 100 may not allocate additional resources to the source terminal 200, for example, based on the degree of congestion of other communications or the reliability of a transmission signal.

[0063] When source terminal 200 is allocated additional resources by base station 100, it performs LBT on the additionally allocated resources. If the result of the LBT is OK, source terminal 200 transmits PSCCH / PSSCH to destination terminal 200 using the additional resources. Then, destination terminal 200 receives the PSCCH / PSSCH from source terminal 200, as in FIG. 5 , and, for example, if HARQ feedback is configured, transmits HARQ-ACK information including an ACK or NACK to source terminal 200 using PSFCH resources. Also, as in FIG. 5 , source terminal 200 notifies base station 100 of the HARQ-ACK information received from destination terminal 200, for example, via PUCCH or PUSCH.

[0064] In this way, according to operation example 1, even if an LBT failure occurs in the source terminal 200 (if the transmission right cannot be acquired), the source terminal 200 notifies the base station 100 of the LBT failure, thereby enabling allocation of additional resources for the transmission of the sidelink signal.

[0065] In addition, a new DCI format may be set for notification for Sidelink Mode 1 of SL-U.

[0066] Next, an example of a method in which source terminal 200 notifies base station 100 of an LBT failure will be described.

[0067] In the following, as an example, a case will be described in which the resources used for notifying LBT failure are resources used to transmit HARQ-ACK (ACK or NACK information) received by source terminal 200 from destination terminal 200 to base station 100. Note that the resources used for notifying LBT failure are not limited to resources for HARQ-ACK, and other resources may be used.

[0068] <Notification Method 1> In notification method 1, source terminal 200 notifies base station 100 of an LBT failure by not transmitting to base station 100 the HARQ-ACK (ACK or NACK information) received from destination terminal 200.

[0069] When base station 100 does not receive a HARQ-ACK that is scheduled to be transmitted from source terminal 200 in a pre-specified resource, base station 100 recognizes that an LBT failure may have occurred in source terminal 200 .

[0070] For example, when PUCCH format 0 is used to transmit HARQ-ACK from source terminal 200 to base station 100, source terminal 200 notifies base station 100 of an LBT failure by not transmitting a PUCCH, as shown in Table 2.

[0071] <Notification Method 2> In notification method 2, source terminal 200 notifies base station 100 of an LBT failure by transmitting the same signal as a NACK in the resource used to transmit the HARQ-ACK received from destination terminal 200 to base station 100.

[0072] For example, when PUCCH format 0 is used to transmit HARQ-ACK from source terminal 200 to base station 100, source terminal 200 notifies base station 100 of an LBT failure by transmitting PUCCH format 0 using the same value as that of NACK (for example, the value of the sequence cyclic shift), as shown in Table 3.

[0073] Base station 100 receives a notification of LBT failure, for example, in a pre-specified resource, as a HARQ-ACK that source terminal 200 receives from destination terminal 200. Note that base station 100 does not distinguish between a NACK and an LBT failure in the received PUCCH format 0, but can recognize that reception has not been successful in sidelink communication.

[0074] The PUCCH format used to notify of LBT failure is not limited to PUCCH format 0. Even when a format other than PUCCH format 0 is used, or when a channel or signal other than PUCCH is used, LBT failure can be notified using the same signal as NACK.

[0075] <Notification Method 3> In notification method 3, source terminal 200 notifies base station 100 of the LBT failure by allocating a signal different from ACK and NACK to the LBT failure in the resources used to transmit the HARQ-ACK received from destination terminal 200 to base station 100.

[0076] For example, when PUCCH format 0 is used to transmit HARQ-ACK from source terminal 200 to base station 100, sequence cyclic shift m_cs=3 may be assigned to LBT failure, as shown in Table 4. Note that m_cs=3 is just an example, and it is sufficient that LBT failure is assigned to a sequence different from the sequence (m_cs) to which ACK and NACK are assigned, and for example, m_cs=9 or another value may also be used.

[0077] Base station 100 receives a notification of an LBT failure, for example, as a HARQ-ACK received by source terminal 200 from destination terminal 200 in a pre-specified resource. Base station 100 can distinguish between an ACK, a NACK, and an LBT failure in the received PUCCH format 0. For example, base station 100 may separately determine (e.g., make different) the amount of resources to be allocated to retransmission in response to a NACK and the amount of resources to be allocated to transmission in response to an LBT failure.

[0078] It should be noted that the PUCCH format used for reporting an LBT failure is not limited to PUCCH format 0. For example, a format different from PUCCH format 0, or a channel or signal different from PUCCH may be used.

[0079] For example, two bits may be allocated in advance to the PUCCH or PUSCH, which is a resource used by source terminal 200 to transmit the HARQ-ACK received from the destination terminal to base station 100, and one of the states (e.g., four states) represented by the two bits may be set to LBT failure, thereby notifying source terminal 200 of LBT failure to base station 100. Table 5 shows an example in which one of the states (e.g., four states) represented by two bits (01) is set to LBT failure. Note that Table 5 shows a case in which the state of two bits 01 is set to LBT failure, but LBT failure may also be set to another state.

[0080] [Operation Example 2] In Operation Example 2, an operation example in which the base station 100 designates resources in Mode 1 of the side link will be described.

[0081] In operation example 2, when the source terminal 200 in Mode 1 experiences an LBT failure and is unable to transmit a sidelink signal in the resources specified by the base station 100, it selects resources as in Mode 2 and performs sidelink communication. In Mode 1, the operation of selecting resources as in Mode 2 is sometimes referred to as "Mode 2 like behavior."

[0082] This allows the source terminal 200 to perform side link communication using resources other than the resources that result in an LBT failure, without waiting for a resource allocation instruction from the base station 100, thereby reducing delays.

[0083] The resources selected by source terminal 200 in the event of an LBT failure may be, for example, resources for a Configured grant (pre-)configured by a base station. For example, when an LBT failure occurs in a certain slot, source terminal 200 may perform an LBT for a slot following the slot if there is a transmittable resource configured by base station 100, and if the LBT is successful, may perform transmission to destination terminal 200 using the resource in that slot.

[0084] When there are multiple slots including transmittable resources, source terminal 200 may select, from among the multiple resources, a resource with lower received power (e.g., RSRP (Reference Signal Received Power)), for example, as in resource selection in Mode 2. Note that resource selection is not limited to this, and a resource with higher received power may also be selected from among the multiple resources. Furthermore, source terminal 200 may determine resources based on communication quality information such as CQI (Channel Quality Indicator) feedback.

[0085] As another resource selection method, for example, even if source terminal 200 has not been notified of resources for Configured grant by base station 100, source terminal 200 may select resources in the same manner as resource selection in Mode 2 at its own discretion, and use the selected resources to perform transmission to destination terminal 200. Also, instead of resource selection in Mode 2, a method called random selection, in which resources are selected randomly from multiple resources, may be applied.

[0086] According to operation example 2, even if the source terminal 200 experiences an LBT failure (is unable to acquire the transmission right) and is unable to transmit the side link using the resources instructed by the base station 100, the source terminal 200 can select the resources to be used for the side link transmission, and can transmit to the destination terminal 200 using the selected resources without waiting for instructions from the base station 100.

[0087] <Variations of Operation Example 2> When operation example 2 is applied, a CP length called a cyclic prefix (CP) extension may be different between Mode 1 transmission (e.g., Mode 1 behavior) in which transmission is performed using resources notified by base station 100 and Mode 2-like transmission (e.g., Mode 2 like behavior) in which transmission is performed using resources selected by source terminal 200.

[0088] For example, the longer the CP length and the earlier the scheduled start time of transmission, the easier it is to acquire the transmission right, and the easier it is for terminal 200 to start transmission while other terminals are performing LBT channel sensing. Therefore, the longer the CP length, the easier it is for terminal 200 to transmit preferentially using the resources.

[0089] FIG. 7 is a diagram showing an example of channel arrangement within a slot in a variation of the second operational example.

[0090] For example, when resources notified by base station 100 are prioritized, the CP length in Mode 1 transmission may be set longer than the CP length in transmission such as Mode 2, as shown in Fig. 7(a). For example, as shown in Fig. 7(a), in Mode 1 transmission, a channel may be placed before the beginning of a slot, and transmission may start before the beginning of the slot. As a result, in Fig. 7(a), Mode 1 transmission is more likely to result in LBT OK than transmission such as Mode 2, and is therefore more likely to be prioritized.

[0091] Alternatively, when resources notified by base station 100 are prioritized, as shown in FIG. 7B, Mode 1 transmission may start from the beginning of the slot, while Mode 2 transmission may start from a position after the beginning of the slot. As a result, in FIG. 7B, Mode 1 transmission is more likely to result in LBT OK than Mode 2 transmission, making it more likely to be prioritized. For example, Mode 2 transmission may start one symbol after the beginning of the slot or from the middle of the first symbol. For example, if Mode 2 transmission starts from the middle of the first symbol, the CP length of the second symbol signal may be extended to the first symbol before transmission. In this way, the first symbol of the slot is used for AGC, and all or part of that symbol is not used for transmission, but Mode 1 transmission can be prioritized and sensing time for Mode 1 transmission can be secured.

[0092] Note that operation example 2 may be combined with operation example 1. In this case, in notification method 2 or notification method 3 of operation example 1, upon receiving a notification of LBT failure, the base station 100 may recognize that the source terminal 200 has selected a resource and performed communication on the side link.

[0093] [Operation Example 3] In operation example 3, an operation example in which source terminal 200 selects resources in Mode 2 of the side link will be described.

[0094] In Mode 2 in which the source terminal 200 selects resources, the source terminal 200 notifies the destination terminal 200 that an LBT failure has occurred and that it is not possible to transmit a sidelink signal using the scheduled resources. Note that operation example 3 can also be applied to Mode 1 transmission.

[0095] FIG. 8 is a diagram showing an example of the operation of the source terminal 200 and the destination terminal 200 in the operation example 3. In FIG.

[0096] In Fig. 8, a source terminal 200 (source UE) transmits a sidelink signal (e.g., PSCCH / PSSCH) to a destination terminal 200 (destination UE). The 1st stage SCI included in the PSCCH can allocate multiple resources, and can also reserve resources in subsequent slots, for example. Note that the source terminal 200 may start transmitting a sidelink signal if the LBT result is LBT OK.

[0097] When destination terminal 200 receives the PSCCH / PSSCH, it recognizes that resources have also been allocated (reserved) in other slots after the slot in which the PSCCH / PSSCH was received. For example, when HARQ feedback is configured, destination terminal 200 transmits a HARQ-ACK including an ACK or NACK to source terminal 200 using the PSFCH resource. Source terminal 200 may perform retransmission control, for example, based on the HARQ-ACK from destination terminal 200 (not shown).

[0098] 8, source terminal 200 performs transmission processing for destination terminal 200, for example, using the rear resources reserved by the 1st stage SCI. Here, for example, if the LBT result is LBT failure in the resources (e.g., unlicensed bands) reserved for transmission to destination terminal 200, source terminal 200 does not transmit a sidelink signal.

[0099] In operation example 3, when an LBT failure occurs in a reserved resource, the source terminal 200 transmits information indicating that a sidelink signal cannot be transmitted in the scheduled resource (for example, a notification of an LBT failure) to the destination terminal 200. Furthermore, the source terminal 200 may notify the destination terminal 200 of information regarding the allocation (or reservation) of an additional resource, in addition to the notification of the LBT failure.

[0100] For example, the PSFCH resource may be used to notify of the LBT failure instead of the scheduled resource. The PSFCH resource is originally (for example, in the case of LBT OK) a resource used to transmit HARQ-ACK from destination terminal 200 to source terminal 200, but in the case of an LBT failure, the PSFCH resource becomes a resource used to notify destination terminal 200 of the LBT failure.

[0101] Table 6 shows an example of a notification of an LBT failure transmitted from source terminal 200 to destination terminal 200. For example, as shown in Table 6, it is possible to notify that an LBT failure has occurred and that additional resources will not be reserved by Sequence cyclic shift=0 of the PSFCH, and to notify that an LBT failure has occurred and that additional resources will be reserved by Sequence cyclic shift=6 of the PSFCH.

[0102] Furthermore, when an occurrence of an LBT failure and the reservation of additional resources are notified, the reservation of new resources may be set, for example, X slots after the resources reserved in the pre-configured state (e.g., the resources where the LBT failure occurred). For example, the value of X may be 4 slots, 5 slots, 10 slots, or any other value.

[0103] Furthermore, the frequency resources among the additional resources may be the same as the frequency resources in the pre-configured reserved resources. This eliminates the need for notification of the frequency positions of the additional resources, and therefore source terminal 200 can specify the positions of the additional resources (resource positions in the time direction and frequency direction) even if the number of bits used for notifying LBT failure is one bit.

[0104] If destination terminal 200 does not receive a PSCCH / PSSCH in the reserved resources, it attempts to receive a signal in a PSFCH resource corresponding to the reserved resources. Then, when destination terminal 200 receives a PSFCH from source terminal 200 and receives a notification of the occurrence of an LBT failure and an instruction to allocate additional resources, it attempts to receive a PSCCH / PSSCH in the additional resources. For example, when destination terminal 200 receives a PSCCH / PSSCH in the additional resources, it transmits a HARQ-ACK including an ACK or NACK to source terminal 200 using the PSFCH resource.

[0105] In the operation example 3, for example, when an LBT failure occurs, the terminal 200 can reserve additional resources that have not been reserved in advance, thereby securing side link transmission resources and reducing delays.

[0106] In addition, in operation example 3, if additional resources are not required, for example, if transmission using the next reserved resource is sufficient, or if reselection of resources is sufficient, additional resources do not need to be secured.

[0107] Furthermore, when destination terminal 200 receives a notification of LBT failure, it becomes easy to switch to reception mode in preparation for receiving additional reserved resources. Furthermore, even if destination terminal 200 does not receive a notification of LBT failure, it may still be able to receive PSCCH / PSSCH from source terminal 200 as an allocation of additional resources.

[0108] [Configuration of terminal 200] Fig. 9 is a block diagram showing an example configuration of terminal 200 according to this embodiment. Terminal 200 shown in Fig. 9 includes receiving section 201, LBT carrier sensing section 202, signal separating section 203, demodulating section 204, error correction decoding section 205, control signal receiving section 206, LBT failure notification receiving section 207, error correction coding section 208, modulating section 209, control signal generating section 210, LBT failure notification generating section 211, signal allocating section 212, and transmitting section 213.

[0109] At least one of the LBT carrier sense unit 202, signal separation unit 203, demodulation unit 204, error correction decoding unit 205, control signal receiving unit 206, LBT failure notification receiving unit 207, error correction coding unit 208, modulation unit 209, control signal generating unit 210, LBT failure notification generating unit 211, and signal allocating unit 212 may be included in the control unit shown in Fig. 4. At least one of the receiving unit 201 and the transmitting unit 213 may be included in the communication unit shown in Fig. 4.

[0110] In sidelink communication, the terminal 200 may be a transmitting terminal (or a source terminal) that transmits a sidelink signal, or a receiving terminal (or a destination terminal) that receives a sidelink signal.

[0111] The receiving unit 201 receives a received signal via an antenna and performs reception processing such as down-conversion on the received signal. The received signal may be, for example, a sidelink signal including a PSSCH / PSCCH. The sidelink signal may also include a PSFCH. The received signal received by the receiving unit 201 may also include a non-transmission interval or a signal different from the sidelink signal (for example, a downlink signal from the base station 100). The receiving unit 201 outputs the received signal after reception processing to the LBT carrier sense unit 202 and the signal separation unit 203.

[0112] The LBT carrier sense unit 202 performs carrier sensing (also referred to as LBT) based on the received signal input from the receiving unit 201. The LBT carrier sense unit 202 may determine whether the channel state is "busy" (or LBT failure) or "idle" (or LBT OK) based on the received signal. In other words, the LBT carrier sense unit 202 may determine whether the channel is available for use based on the received signal input from the receiving unit 201. The LBT carrier sense unit 202 outputs information indicating the determined channel state to the LBT failure notification generation unit 211 and the transmission unit 213.

[0113] Signal separating section 203 outputs a received data signal from the received signal input from receiving section 201 to demodulating section 204. The received data signal is, for example, mapped to a PSSCH. Furthermore, signal separating section 203 separates a 1st stage SCI mapped to a PSCCH and a 2nd stage SCI mapped to part of the PSSCH from the received signal input from receiving section 201, and outputs the separated information to control signal receiving section 206. Furthermore, signal separating section 203 separates an LBT failure notification mapped to a PSFCH from the received signal input from receiving section 201, and outputs the separated LBT failure notification to LBT failure notification receiving section 207.

[0114] Demodulation section 204 performs demodulation processing on the received data signal input from signal separation section 203. Demodulation section 204 outputs the demodulated signal obtained by performing the demodulation processing to error correction decoding section 205.

[0115] The error correction decoder 205 decodes the demodulated signal input from the demodulator 204 and outputs it as received data.

[0116] The control signal receiving unit 206 identifies (or grasps) resource allocation information including reserved resources based on the 1st stage SCI included in the signal input from the signal separating unit 203. The control signal receiving unit 206 outputs the resource allocation information to the signal allocating unit 212, for example, so as to avoid overlap with other resources. Furthermore, for example, the control signal receiving unit 206 identifies (or grasps) a transmitting ID and a receiving ID based on the 2nd stage SCI included in the signal input from the signal separating unit 203. For example, the control signal receiving unit 206 determines whether or not there is a resource allocation addressed to the terminal 200 based on the identified transmitting ID or receiving ID, and if there is a resource allocation addressed to the terminal 200, instructs the signal separating unit 203 to separate the received signal.

[0117] The LBT failure notification receiving unit 207 receives a notification of LBT failure from the source terminal, which is included in the signal input from the signal separating unit 203. Furthermore, when the LBT failure notification receiving unit 207 determines, for example, based on the LBT failure notification that additional resources have been allocated, it instructs the signal separating unit 203 to separate the received signal. Note that the LBT failure notification receiving unit 207 may operate, for example, when the above-described operation example 3 is applied.

[0118] The error correction coding section 208 receives the data signal, performs error correction coding on the data signal, and outputs the error correction coded data signal to the modulation section 209 .

[0119] The modulation section 209 modulates the signal input from the error correction coding section 208 and outputs the modulated signal to the signal allocation section 212 .

[0120] The control signal generator 210 generates first stage SCI and second stage SCI signals based on control information (not shown) and outputs the first stage SCI and second stage SCI signals to the signal allocation unit 212.

[0121] If an LBT failure occurs in a slot where transmission was scheduled, the LBT failure notification generation unit 211 generates information related to the LBT failure notification based on information input from the LBT carrier sense unit 202. For example, in the case of the above-described operation example 1, the LBT failure notification generation unit 211 may generate information related to the LBT failure notification to be transmitted to the base station 100. Furthermore, in the case of the above-described operation example 3, for example, the LBT failure notification generation unit 211 may determine whether or not to allocate additional resources, and generate a signal indicating whether or not additional resources have been allocated. The LBT failure notification generation unit 211 outputs the generated signal to the signal allocation unit 212.

[0122] The signal allocating unit 212 allocates the modulated signal input from the modulating unit 209 to resources. At that time, the signal allocating unit 212 may allocate the signal to resources taking into consideration the signal input from the control signal generating unit 210. Furthermore, the signal allocating unit 212 allocates the signal input from the LBT failure notification generating unit 211 to resources. For example, in the case of the above-mentioned operation example 1, the signal allocating unit 212 may allocate the signal input from the LBT failure notification generating unit 211 to the PUCCH or PUSCH. Furthermore, in the case of the above-mentioned operation example 3, the signal allocating unit 212 may allocate the signal input from the LBT failure notification generating unit 211 to the PSFCH. After allocating resources, the signal allocating unit 212 outputs the transmission signal to the transmitting unit 213.

[0123] When the sensing result obtained from the LBT carrier sense unit 202 indicates an idle state, the transmission unit 213 performs transmission processing such as upconversion on the transmission signal input from the signal allocation unit 212, and transmits the transmission signal after transmission processing via the antenna.

[0124] An example of operation according to this embodiment has been described above.

[0125] As described above, in the present embodiment, when an LBT failure occurs, the terminal 200 allocates the next resource by notifying the base station 100 of the LBT failure, by selecting a resource by the terminal 200, or by notifying the destination terminal of the LBT failure (including reserving additional resources). This allows the terminal 200 to transmit a sidelink signal using the next resource even when it is unable to acquire a transmission right. Therefore, according to the present embodiment, it is possible to improve the resource utilization efficiency of sidelink communication in unlicensed bands.

[0126] Second Embodiment In the second embodiment, the terminal 200a transmits and receives a sidelink signal using a plurality of consecutive slots in sidelink communication.

[0127] Below, an allocation method for allocating a plurality of consecutive slots and a transmission method using a plurality of consecutive slots (hereinafter also referred to as "consecutive slots") will be described.

[0128] For example, source terminal 200a may notify allocation of consecutive slots by means of an SCI transmitted on the PSCCH / PSSCH. Two methods will be described as examples of methods for notifying allocation of consecutive slots.

[0129] [Notification Method 1] In notification method 1, allocation of consecutive slots may be notified by SCI format 1-A (see, for example, Non-Patent Document 4).

[0130] For example, the allocation of consecutive slots may be signaled using "Time resource assignment" included in SCI format 1-A. SCI format 1-A is defined in the standard as follows (see, for example, Non-Patent Document 4): Time resource assignment - 5 bits when the value of the higher layer parameter sl-MaxNumPerReserve is configured to 2; otherwise, 9 bits when the value of the higher layer parameter sl-MaxNumPerReserve is configured to 3, as defined in clause 8.1.5 of [6, TS 38.214].

[0131] For example, "Time resource assignment" allows reservation of the PSSCH in the same slot as the slot in which the PSCCH (SCI format 1-A) is transmitted, as well as the PSSCH in the two following slots. In this case, "Time resource assignment" allows specification of the two nearest slots.

[0132] Notification method 1 allows allocation of consecutive slots using existing parameters or formats.

[0133] [Notification Method 2] In notification method 2, a notification field that instructs allocation of consecutive slots may be newly added to SCI format 1-A, or may be defined in a new SCI format.

[0134] For example, as a method of notifying consecutive slots, a notification that K consecutive slots including the slot in which the SCI format is transmitted will be transmitted may be added to the SCI format.

[0135] For example, if three consecutive slots, slot N, slot N+1, and slot N+2, are allocated for transmission, the number of allocated slots may be counted down for each slot, and the number of remaining consecutive slots at the time of transmitting the SCI may be notified, as shown in Table 7. For example, in Table 7, K=3 may be notified in slot N, K=2 may be notified in slot N+1, and K=1 may be notified in slot N+2.

[0136] Alternatively, for example, one bit may indicate whether or not the slot one slot after the slot in which the SCI is transmitted is also allocated consecutively. For example, when three slots, slot N, slot N+1, and slot N+2, are allocated for consecutive transmission, as shown in Table 8, slots N and N+1, to which the next slot is also allocated consecutively, may be notified with 1 indicating that there is a subsequent slot, and slot N+2, to which the next slot is not allocated for consecutive transmission, may be notified with 0 indicating that there is no subsequent slot.

[0137] An example of a method for notifying allocation of consecutive slots has been described above.

[0138] Next, an example of the operation of sidelink communication when notifying allocation of consecutive slots using these notification methods will be described.

[0139] [Operation Example 1] In operation example 1, when source terminal 200a transmits in consecutive slots, in subsequent consecutive slots in which consecutive transmission is also performed, it also transmits the PSSCH in symbols in an interval corresponding to the last guard period of the slot. For example, when terminal 200a transmits in consecutive slots, the last guard period of the slot does not need to be set in subsequent slots in which consecutive transmission is also performed.

[0140] For example, as shown in Fig. 10, when three consecutive slots, slot N, slot N+1, and slot N+2, are assigned to terminal 200a, source terminal 200a transmits PSSCH even in the symbol of the last guard period in slot N and slot N+1. Also, source terminal 200a sets the guard period in the last symbol in slot N+2.

[0141] As described above, in the first operational example, when multiple consecutive slots are allocated to the terminal 200a in sidelink communication in an unlicensed band, the terminal 200a allocates the PSSCH to an interval of the guard period set in the nth slot (e.g., a slot in which the subsequent slots are also used for transmission; in FIG. 10, n=N or n=N+1) among the nth and n+1th slots included in the multiple slots. For example, the terminal 200a may allocate the PSSCH to an interval of the guard period set in a slot different from the last slot (slot N+2 in FIG. 10) among the consecutive slots, and may set a guard period in the last slot.

[0142] As a result, in the interval corresponding to the guard period between consecutive slot transmissions, source terminal 200a transmits a PSSCH, thereby reducing the probability that another system or another device will acquire the right to transmit. Therefore, source terminal 200 can reduce the probability of an LBT failure, and increase the probability that source terminal 200 can transmit in consecutive slots.

[0143] When transmitting consecutive slots, terminal 200a does not need to perform LBT between consecutive slots and may perform LBT Type 2C, thereby reducing the number of times source terminal 200 performs LBT.

[0144] Here, there may be a case where a terminal other than the terminal 200a that performs consecutive slot transmission performs simultaneous transmission (e.g., FDM (frequency division multiplexing) transmission) using a different PRB in the same RB set as the RB set used by the terminal 200a to transmit a sidelink signal. In this case, when the terminal 200a transmits a PSSCH with a symbol corresponding to the guard period, the other terminal may detect the signal (PSSCH) of the terminal 200a by Type 2 LBT during the guard period, resulting in an LTB failure and preventing the other terminal from starting transmission.

[0145] Therefore, in the first operational example, the conditions for transmitting the PSSCH may be set to symbols in the guard period as follows.

[0146] <Condition 1> Under condition 1, operation example 1 may be applied when all PRBs in an RB set are allocated in the allocation of the PSSCH.

[0147] When sidelink signals are allocated to all PRBs in the RB set used for transmitting sidelink signals, the terminal 200a may allocate the sidelink signals (for example, PSSCH) to the guard period.

[0148] As a result, when it is assumed that other terminals are not transmitting simultaneously within the RB set, the terminal 200a can apply Operation Example 1. For example, when other terminals are transmitting simultaneously within the RB set, the terminal 200a can prevent interference with the LBT (e.g., Type 2 LBT) of other terminals by not allocating sidelink signals to the guard period.

[0149] An RB set is a frequency unit set in units of, for example, 20 MHz, and is the minimum unit for performing LBT, and is also called an LBT set.

[0150] <Condition 2> Under condition 2, operation example 1 may be applied when X% or more of the PRBs in the RB set are allocated in the PSSCH allocation.

[0151] When a sidelink signal is allocated to PRBs (e.g., X% or more) of the RB set used for transmitting the sidelink signal that are equal to or greater than a threshold, the terminal 200a may allocate the sidelink signal (e.g., PSSCH) to the guard period.

[0152] As a result, terminal 200a may determine that it is acceptable for one terminal to transmit within the RB set (even if LBT failure occurs in other terminals) as long as PRBs with a resource amount equal to or greater than a threshold are occupied, even if not all PRBs within the RB set. For example, when the PRB allocation within the RB set is X% or greater, terminal 200a may transmit a PSSCH in symbols corresponding to the guard period (without setting a guard period) as shown in FIG. 10 . When the PRB allocation within the RB set is less than X%, terminal 200a may set a guard period (with setting a guard period) as shown in FIG. 11 . For example, by not allocating a sidelink signal to the guard period and setting a guard period, it is possible to prevent interference with the LBT (e.g., Type 2 LBT) of other terminals. For example, setting a guard period prevents transmission by terminal 200a from affecting the LBT of other terminals, and allows subsequent slots (e.g., slot N+2 in FIG. 11 ) to be used by other terminals.

[0153] <Condition 3> Under Condition 3, Operation Example 1 may be applied when the PSSCH is allocated to the same PRB between consecutive slots. For example, Operation Example 1 does not need to be applied when the PSSCH is allocated to different PRBs between consecutive slots.

[0154] When a sidelink signal is allocated to the same PRB in each of consecutive slots, the terminal 200a may allocate the sidelink signal (e.g., PSSCH) to the guard period.

[0155] For example, when terminal 200a, to which consecutive slots are assigned, transmits using different PRBs within the same RB set in each of the consecutive slots, a guard period is set at the end of the slot, so that the transmission of terminal 200a does not affect the LBT of other terminals, and consecutive transmission (or multiplexed transmission) is possible for multiple terminals within the RB set.

[0156] The conditions for carrying out the first operational example have been described above.

[0157] The signal transmitted in the symbol of the last guard period of a slot may be transmitted over a portion of the time corresponding to that symbol. In this case, the signal transmitted in the symbol of the guard period may be a repetition of the signal transmitted in the second-to-last symbol.

[0158] Consecutive slots are not slots that are consecutive within the sidelink resource pool, but slots that are consecutive on the time axis.

[0159] [Operation Example 2] In Operation Example 2, when terminal 200a receives an SCI for slot N transmitted by another terminal and detects that the “remaining COT duration” notified in slot N is K, terminal 200a may determine that transmission is possible from the next slot N+1 up to K−1 consecutive slots.

[0160] For example, consecutive slots may be set within the COT period. Furthermore, the terminal 200a may set a guard period in at least the last slot of the consecutive slots within the COT period.

[0161] For example, as shown in Fig. 12, when the remaining COT duration included in the SCN of another terminal received in slot N is K = 3, terminal 200a may perform consecutive slot transmission from slot N+1 to slot N+2, which is two consecutive slots (K-1 slots). In this case, as shown in Fig. 12, terminal 200a may transmit PSSCH in the guard period in slot N+1 and slot N+2, and set a guard period in slot N+2 (it is not necessary to transmit PSSCH).

[0162] As a result, for example, the terminal 200a can fit the transmission of consecutive slots within the COT period, and can avoid consecutive transmissions that exceed the COT. Furthermore, the terminal 200a can set a guard period at the end of the COT. By avoiding consecutive transmissions that exceed the COT in this way, fairness with other devices can be maintained.

[0163] If the remaining COT duration is insufficient for the resources assumed by the source terminal 200a for continuous transmission, the following method may be applied.

[0164] <Method 1> The source terminal 200a performs Type 1 LBT and acquires a new COT without using the COT duration acquired by another terminal. This allows the terminal 200a to set (or acquire) a COT duration of the length to be used for continuous transmission.

[0165] <Method 2> Source terminal 200a transmits a signal for K-1 consecutive slots, which is the remaining COT duration. This allows terminal 200a to transmit a signal in the remaining slots within the COT.

[0166] <Method 3> After transmitting a signal for K-1 consecutive slots, which is the remaining COT duration, source terminal 200a performs Type 1 LBT to acquire a new COT and transmits the remaining signal. This allows terminal 200a to transmit signals with reduced delay in continuous transmission compared to other methods.

[0167] Methods 1 to 3 have been described above.

[0168] Alternatively, when transmitting consecutive slots, the source terminal 200a may acquire and transmit a COT, thereby specifying the COT duration to be used for the consecutive transmission.

[0169] [Configuration example of terminal 200a] Fig. 13 is a block diagram showing a configuration example of terminal 200a according to this embodiment. Terminal 200a shown in Fig. 13 has receiving section 201, LBT carrier sensing section 202, signal separating section 203, demodulating section 204, error correction decoding section 205, control signal receiving section 206, error correction coding section 208, modulating section 209, control signal generating section 210, guard period setting section 220, signal allocating section 212, and transmitting section 213.

[0170] The terminal 200a shown in FIG. 13 differs from the terminal 200 shown in FIG. 9 in that it does not include the LBT failure notification receiving unit 207 and the LBT failure notification generating unit 211, but instead newly includes a guard period setting unit 220.

[0171] At least one of the LBT carrier sense unit 202, signal separation unit 203, demodulation unit 204, error correction decoding unit 205, control signal receiving unit 206, error correction coding unit 208, modulation unit 209, control signal generating unit 210, guard period setting unit 220, and signal allocation unit 212 may be included in the control unit shown in Fig. 4. At least one of the receiving unit 201 and the transmitting unit 213 may be included in the communication unit shown in Fig. 4.

[0172] In sidelink communication, the terminal 200a may be a transmitting terminal (or a source terminal) that transmits a sidelink signal, or a receiving terminal (or a destination terminal) that receives a sidelink signal.

[0173] The receiving unit 201 receives a received signal via an antenna and performs reception processing such as down-conversion on the received signal. The received signal may be, for example, a sidelink signal including a PSSCH / PSCCH. The sidelink signal may also include a PSFCH. The received signal received by the receiving unit 201 may also include a non-transmission interval or a signal different from the sidelink signal (for example, a downlink signal from the base station 100). The receiving unit 201 outputs the received signal after reception processing to the LBT carrier sense unit 202 and the signal separation unit 203.

[0174] The LBT carrier sense unit 202 performs carrier sensing (also referred to as LBT) based on the received signal input from the receiving unit 201. The LBT carrier sense unit 202 may determine whether the channel state is "busy" (or LBT failure) or "idle" (or LBT OK) based on the received signal input from the receiving unit 201. In other words, the LBT carrier sense unit 202 may determine whether the channel is available for use based on the received signal input from the receiving unit 201. The LBT carrier sense unit 202 outputs information indicating the determined channel state to the transmitting unit 213.

[0175] Signal separating section 203 outputs a received data signal, of the received signal input from receiving section 201, to demodulating section 204. The received data signal is mapped to, for example, a PSSCH. Furthermore, signal separating section 203 separates, from the received signal input from receiving section 201, a 1st stage SCI mapped to the PSCCH and a 2nd stage SCI mapped to part of the PSSCH, and outputs the separated information to control signal receiving section 206.

[0176] Demodulation section 204 performs demodulation processing on the received data signal input from signal separation section 203. Demodulation section 204 outputs the demodulated signal obtained by performing the demodulation processing to error correction decoding section 205.

[0177] The error correction decoder 205 decodes the demodulated signal input from the demodulator 204 and outputs it as received data.

[0178] The control signal receiving unit 206 identifies (or grasps) resource allocation information including reserved resources based on the 1st stage SCI included in the signal input from the signal separating unit 203. The control signal receiving unit 206 outputs the resource allocation information to the guard period setting unit 220 and the signal allocating unit 212, for example, so as to avoid overlap with other resources. Furthermore, for example, the control signal receiving unit 206 identifies (or grasps) a transmitting ID and a receiving ID based on the 2nd stage SCI included in the signal input from the signal separating unit 203. For example, the control signal receiving unit 206 determines whether or not there is a resource allocation addressed to the terminal 200 based on the identified transmitting ID or receiving ID, and if there is a resource allocation addressed to the terminal 200, instructs the signal separating unit 203 to separate the received signal.

[0179] The error correction coding section 208 receives the data signal, performs error correction coding on the data signal, and outputs the error correction coded data signal to the modulation section 209 .

[0180] The modulation section 209 modulates the signal input from the error correction coding section 208 and outputs the modulated signal to the signal allocation section 212 .

[0181] The control signal generator 210 generates first stage SCI and second stage SCI signals based on control information (not shown) and outputs the first stage SCI and second stage SCI signals to the signal allocation unit 212.

[0182] The guard period setting unit 220 determines whether or not consecutive resources (e.g., consecutive slots) have been allocated based on information about the transmission signal (not shown) and information input from the control signal receiving unit 206, and if consecutive resources have been allocated, instructs the signal allocation unit 212 to set a guard period (e.g., whether or not to set one).

[0183] The signal allocation unit 212 allocates the modulated signal input from the modulation unit 209 to resources. At that time, the signal allocation unit 212 may also take into account the signal input from the control signal generation unit 210 when allocating the signal to resources. The signal allocation unit 212 also determines the number of PSSCH symbols (or whether or not to set a guard period) in accordance with information input from the guard period setting unit 220, and allocates resources. After allocating resources, the signal allocation unit 212 outputs the transmission signal to the transmission unit 213.

[0184] When the sensing result obtained from the LBT carrier sense unit 202 indicates an idle state, the transmission unit 213 performs transmission processing such as upconversion on the transmission signal input from the signal allocation unit 212, and transmits the transmission signal after transmission processing via the antenna.

[0185] An example of operation according to this embodiment has been described above.

[0186] As described above, in the second embodiment, when consecutive slots are allocated to the terminal 200a in sidelink communication in an unlicensed band, the terminal 200a allocates a PSSCH to the guard period set for the nth slot among the nth slot and the (n+1)th slot included in the consecutive slots. As a result, for example, when the terminal 200a uses consecutive slots, it is possible to transmit a sidelink signal while reducing the possibility that another device will acquire the transmission right in the consecutive slot section. Therefore, according to the present embodiment, it is possible to improve the resource utilization efficiency of sidelink communication in an unlicensed band.

[0187] Note that the signal transmitted in the symbols of the guard period is not limited to PSSCH, and may be another signal.

[0188] Furthermore, if Type 2A or Type 2B channel sensing is required when transmitting consecutive slots, the time interval used for Type 2A or Type 2B within the guard period may be set as the guard period.

[0189] The above describes each embodiment.

[0190] [Variations] The operation examples of the above-described embodiments may be used in combination.

[0191] In addition, terminals that transmit and receive on the sidelink include terminals that transmit but do not receive on the sidelink, terminals that receive but do not transmit, and terminals that transmit and receive.

[0192] Furthermore, when the sidelink configuration is configured in advance, the configuration method may be to configure it in advance in a specification (standard) or in advance in a SIM (Subscriber Identity Module). Alternatively, the sidelink configuration may be configured in an application layer called "pre-configured," in a system information block (SIB) called "configured" and / or other higher layers such as RRC (radio resource control), or in MAC (Medium Access Control).

[0193] Furthermore, although the above-described embodiments have shown examples of sidelink communication, the present disclosure is not limited thereto. For example, in the above-described embodiments, the present disclosure may be applied to communication between a base station and a terminal by replacing the PSCCH with a PDCCH, the PSSCH with a PDSCH or a PUSCH, the PSFCH with a PUCCH, and the PSBCH with a PBCH.

[0194] Furthermore, each of the above-described embodiments may be applied to Mode 2 but not to Mode 1, may be applied to both Mode 1 and Mode 2, or may be applied to Mode 1 but not to Mode 2. Furthermore, among the operation examples of each of the above-described embodiments, the operation example applied to Mode 1 and the operation example applied to Mode 2 may be the same or different. For example, there may be an operation example that is applied to Mode 2 but not to Mode 1.

[0195] Furthermore, when the above-described embodiments are applied to Mode 1, the base station may instruct in the licensed band which of Types 2A, 2B, and 2C to select in Type 2 LBT.

[0196] In addition, although the above-described embodiments have shown examples of operation in unlicensed bands, the frequency bands of unlicensed bands may differ from country to country or from region to region. Examples of unlicensed band frequency bands include the 5 GHz band (5150 MHz - 5925 MHz), the 6 GHz band (5925 MHz - 7125 MHz), and 52.6 GHz to 71 GHz.

[0197] Furthermore, whether or not each of the above embodiments or each of the operation examples can be used may be changed depending on the SCS.

[0198] In addition, Type 1 LBT and Type 2 LBT may be called by different names in sidelink communication.

[0199] The SCI format transmitted on the PSCCH may be SCI format 1-A or a newly added SCI format.

[0200] Furthermore, the above embodiment may be applied to S-PSS / SSS / PSBCH.

[0201] In addition, in each of the above embodiments, the destination terminal may refer to multiple terminals in the case of groupcast and broadcast.

[0202] The guard band may also be called an intra-cell guard band.

[0203] Furthermore, the resource allocations for sidelink communication illustrated in the above-described embodiments are merely examples, and the present disclosure is not limited thereto. For example, the resources for sidelink communication may include signals, channels, non-transmission periods, etc. that are not illustrated. Furthermore, the widths of the time and frequency directions of the signals illustrated in each figure are not limited to the illustrated examples. Furthermore, the slot sizes, resource sizes, channel sizes, signal sizes, etc. are not limited to the above-described examples.

[0204] In addition, in each of the above-described embodiments, the length of the sidelink signal is adjusted by lengthening the CP length of the sidelink signal using the CP extension, but the present disclosure is not limited to this. Instead of lengthening the CP length, the length may be adjusted by adding a known signal.

[0205] In addition, in each of the above-described embodiments, checking the availability of a channel may be replaced with an expression such as sensing (or monitoring) the availability of a channel. In this case, the term "channel" may be replaced with other terms such as "carrier" or "resource."

[0206] Furthermore, the method of notifying the control information from the base station 100 to the terminal 200 is not limited to the above-mentioned example, and may be notified (or reported, indicated, or set) by at least one of system information such as MIB and SIB, RRC control information, MAC control information, and downlink control information (DCI), or may be set in advance in the terminal 200, or may be specified in advance in a standard.

[0207] The base station may be referred to as a gNodeB or a gNB, and the terminal may be referred to as a UE.

[0208] A time resource unit such as a slot may be replaced with another unit such as a system frame, time slot, minislot, frame, subframe, or block.

[0209] Furthermore, the notation "... section" in the above-described embodiments may be replaced with other notations such as "... circuitry," "... device," "... unit," or "... module."

[0210] It should be noted that terms such as "interpretation," "identification," "judgment," "determination," "decision," "calculation," "grasp," "recognition," "confirmation," or "understanding" may be used interchangeably.

[0211] (Supplementary Note) Information indicating whether the terminal 200 supports the functions, operations, or processes described in the above-described embodiments may be transmitted (or notified) from the terminal 200 to the base station 100, for example, as capability information or capability parameters of the terminal 200.

[0212] The capability information may include an information element (IE) that individually indicates whether or not the terminal 200 supports at least one of the functions, operations, or processes described in the above-described embodiments. Alternatively, the capability information may include an information element that indicates whether or not the terminal 200 supports a combination of any two or more of the functions, operations, or processes described in the above-described embodiments.

[0213] For example, the base station 100 may determine (or decide or assume) functions, operations, or processes that the terminal 200 that transmitted the capability information supports (or does not support) based on the capability information received from the terminal 200. The base station 100 may perform operations, processes, or control according to the determination result based on the capability information. For example, the base station 100 may control sidelink communication between the terminals 200 based on the capability information received from the terminal 200.

[0214] Note that the fact that terminal 200 does not support some of the functions, operations, or processes described in the above-described embodiments may be interpreted as meaning that such some of the functions, operations, or processes are restricted in terminal 200. For example, information or a request regarding such restrictions may be notified to base station 100.

[0215] Information regarding the capabilities or limitations of terminal 200 may, for example, be defined in a standard, or may be implicitly notified to base station 100 in association with information known at base station 100 or information transmitted to base station 100.

[0216] (Control Signal) In the present disclosure, a downlink control signal (or downlink control information) related to an embodiment of the present disclosure may be, for example, a signal (or information) transmitted in a Physical Downlink Control Channel (PDCCH) of a physical layer, or a signal (or information) transmitted in a Medium Access Control Control Element (MAC CE) or Radio Resource Control (RRC) of a higher layer. Furthermore, the signal (or information) is not limited to being notified by a downlink control signal, but may be predefined in a specification (or standard) or preconfigured in a base station and a terminal.

[0217] In the present disclosure, an uplink control signal (or uplink control information) related to an embodiment of the present disclosure may be, for example, a signal (or information) transmitted in a PUCCH of a physical layer, or a signal (or information) transmitted in a MAC CE or RRC of a higher layer. Furthermore, the signal (or information) is not limited to being notified by an uplink control signal, but may be predefined in a specification (or standard) or preconfigured in a base station and a terminal. Furthermore, the uplink control signal may be replaced with, for example, uplink control information (UCI), 1st stage sidelink control information (SCI), or 2nd stage SCI.

[0218] (Base Station) In an embodiment of the present disclosure, the base station may be a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a parent device, a gateway, or the like. In sidelink communication, a terminal may play the role of a base station. Instead of a base station, a relay device that relays communication between an upper node and a terminal may be used. Alternatively, a roadside unit may be used.

[0219] (Uplink / Downlink / Sidelink) An embodiment of the present disclosure may be applied to, for example, any of the uplink, downlink, and sidelink. For example, an embodiment of the present disclosure may be applied to a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), or a Physical Random Access Channel (PRACH) in the uplink, a Physical Downlink Shared Channel (PDSCH), a PDCCH, or a Physical Broadcast Channel (PBCH) in the downlink, or a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Control Channel (PSCCH), or a Physical Sidelink Broadcast Channel (PSBCH) in the sidelink.

[0220] The PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. The PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel. The PBCH and PSBCH are examples of a broadcast channel, and the PRACH is an example of a random access channel.

[0221] (Data Channel / Control Channel) An embodiment of the present disclosure may be applied to, for example, either a data channel or a control channel. For example, the channel in an embodiment of the present disclosure may be replaced with any of the data channels PDSCH, PUSCH, and PSSCH, or the control channels PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0222] (Reference Signal) In one embodiment of the present disclosure, a reference signal is, for example, a signal known by both a base station and a mobile station, and may also be called a Reference Signal (RS) or a pilot signal. The reference signal may be any of a Demodulation Reference Signal (DMRS), a Channel State Information - Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), or a Sounding Reference Signal (SRS).

[0223] (Time Interval) In one embodiment of the present disclosure, the unit of time resource is not limited to one or a combination of slots and symbols, but may be, for example, a time resource unit such as a frame, a superframe, a subframe, a slot, a time slot subslot, a minislot, or a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, or a Single Carrier-Frequency Division Multiplexing Access (SC-FDMA) symbol, or another time resource unit. Furthermore, the number of symbols included in one slot is not limited to the number of symbols exemplified in the above-mentioned embodiment, and may be another number of symbols.

[0224] (Frequency Band) An embodiment of the present disclosure may be applied to either a licensed band or an unlicensed band.

[0225] (Communication) An embodiment of the present disclosure may be applied to communication between a base station and a terminal (Uu link communication), communication between terminals (Sidelink communication), or Vehicle to Everything (V2X) communication. For example, the channel in an embodiment of the present disclosure may be replaced with any of PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, or PBCH.

[0226] An embodiment of the present disclosure may be applied to a terrestrial network, a non-terrestrial network (NTN) using a satellite or a high altitude pseudo satellite (HAPS), or a terrestrial network in which transmission delay is large compared to the symbol length or slot length, such as a network with a large cell size or an ultra-wideband transmission network.

[0227] (Antenna Port) In one embodiment of the present disclosure, an antenna port refers to a logical antenna (antenna group) consisting of one or more physical antennas. For example, an antenna port does not necessarily refer to a single physical antenna, but may refer to an array antenna consisting of multiple antennas. For example, the number of physical antennas that an antenna port is composed of is not specified, and the antenna port may be specified as the smallest unit by which a terminal station can transmit a reference signal. Furthermore, an antenna port may also be specified as the smallest unit by which a weighting of a precoding vector is multiplied.

[0228] 5G NR System Architecture and Protocol Stack 3GPP continues work on the next release of fifth-generation cellular technology (also referred to simply as "5G"), which includes the development of new radio access technology (NR) operating in the frequency range up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, allowing for the prototyping and commercial deployment of 5G NR-compliant devices (e.g., smartphones).

[0229] For example, the system architecture generally assumes a Next Generation - Radio Access Network (NG-RAN) including gNBs. The gNBs provide UE-side termination of NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols. The gNBs are connected to each other via an Xn interface. The gNBs are also connected to a Next Generation Core (NGC) via a Next Generation (NG) interface, more specifically to an Access and Mobility Management Function (AMF) (e.g., a specific core entity performing AMF) via an NG-C interface, and to a User Plane Function (UPF) (e.g., a specific core entity performing UPF) via an NG-U interface. The NG-RAN architecture is shown in Figure 14 (see, for example, 3GPP TS 38.300 v15.6.0, section 4).

[0230] The NR user plane protocol stack (see, for example, 3GPP TS 38.300, section 4.4.1) includes a PDCP (Packet Data Convergence Protocol (see, for example, TS 38.300, section 6.4)) sublayer, a RLC (Radio Link Control (see, for example, TS 38.300, section 6.3)) sublayer, and a MAC (Medium Access Control (see, for example, TS 38.300, section 6.2)) sublayer, which are terminated on the network side in the gNB. A new access stratum (AS) sublayer (SDAP: Service Data Adaptation Protocol) has also been introduced above PDCP (see, for example, 3GPP TS 38.300, section 6.5). A control plane protocol stack has also been defined for NR (see, for example, TS 38.300, section 4.4.2). An overview of Layer 2 functions is described in Section 6 of TS 38.300. The functions of the PDCP sublayer, RLC sublayer, and MAC sublayer are listed in clauses 6.4, 6.3, and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in clause 7 of TS 38.300.

[0231] For example, the Medium-Access-Control layer handles logical channel multiplexing and scheduling and scheduling-related functions, including handling various numerologies.

[0232] For example, the physical layer (PHY) is responsible for coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. The physical layer also handles mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmitting a specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels include the Physical Random Access Channel (PRACH), the Physical Uplink Shared Channel (PUSCH), and the Physical Uplink Control Channel (PUCCH) as uplink physical channels, and the Physical Downlink Shared Channel (PDSCH), the Physical Downlink Control Channel (PDCCH), and the Physical Broadcast Channel (PBCH) as downlink physical channels.

[0233] NR use cases / deployment scenarios may include enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communication (mMTC), which have diverse requirements in terms of data rate, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps in the downlink and 10 Gbps in the uplink) and effective (user-experienced) data rates approximately three times higher than those offered by IMT-Advanced. On the other hand, URLLC imposes stricter requirements on ultra-low latency (0.5 ms for user plane latency in both UL and DL) and high reliability (1-10-5 within 1 ms). Finally, mMTC preferably requires high connection density (1,000,000 devices / km in urban environments).２ ), wide coverage in adverse environments, and extremely long battery life (15 years) for a low-cost device may be desired.

[0234] Therefore, OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not be effective for another use case. For example, low-latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also referred to as TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with short delay spreads. The subcarrier spacing may be optimized accordingly to maintain similar CP overhead. NR may support one or more subcarrier spacing values. Correspondingly, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, etc. are currently considered. The symbol length Tu and subcarrier spacing Δf are directly related by the formula Δf = 1 / Tu. Similar to LTE systems, the term "resource element" can be used to mean the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0235] In the new radio system 5G-NR, for each numerology and each carrier, a resource grid of subcarriers and OFDM symbols is defined for each uplink and downlink. Each element of the resource grid is called a resource element and is specified based on a frequency index in the frequency domain and a symbol position in the time domain (see 3GPP TS 38.211 v15.6.0).

[0236] <Functional separation between NG-RAN and 5GC in 5G NR> Figure 15 shows the functional separation between NG-RAN and 5GC. The logical node of NG-RAN is gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0237] For example, gNB and ng-eNB host the following main functions: - Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, dynamic allocation (scheduling) of resources to UEs in both uplink and downlink; - IP header compression, ciphering and integrity protection of data; - AMF selection at UE attach time if routing to the AMF cannot be determined from the information provided by the UE; - Routing of user plane data towards the UPF; - Routing of control plane information towards the AMF; - Connection setup and release; - Scheduling and transmission of paging messages; - Scheduling and transmission of system broadcast information (sourced from the AMF or Operation, Admission, Maintenance (OAM)); - Configuration of measurements and measurement reports for mobility and scheduling; - Transport level packet marking in the uplink; - Session management; Support for network slicing; - QoS flow management and mapping to data radio bearers; - Support for UEs in RRC_INACTIVE state; - NAS message delivery function; - Radio access network sharing; - Dual connectivity; - Close coordination between NR and E-UTRA.

[0238] The Access and Mobility Management Function (AMF) hosts the following main functions: - Termination of Non-Access Stratum (NAS) signalling; - Security of NAS signalling; - Security control of Access Stratum (AS); - Signalling between Core Network (CN) nodes for mobility between 3GPP access networks; - Reachability to idle mode UEs (including control and execution of paging retransmissions); - Registration area management; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization including checking of roaming rights; - Mobility management control (subscription and policy); - Support for network slicing; - Selection of Session Management Function (SMF).

[0239] Furthermore, the User Plane Function (UPF) hosts the following main functions: - anchor point for intra-RAT mobility / inter-RAT mobility (if applicable); - external PDU (Protocol Data Unit) session point for interconnection with data networks; - packet routing and forwarding; - packet inspection and policy rule enforcement for the user plane part; - traffic usage reporting; - uplink classifier to support routing of traffic flows to the data network; - branching point to support multi-homed PDU sessions; - QoS processing for the user plane (e.g. packet filtering, gating, UL / DL rate enforcement); - uplink traffic validation (mapping of SDF to QoS flows); - downlink packet buffering and triggering of downlink data notifications.

[0240] Finally, the Session Management Function (SMF) hosts the following main functions: session management; allocation and management of IP addresses for UEs; selection and control of UPF; configuration of traffic steering in the User Plane Function (UPF) to route traffic to the appropriate destination; policy enforcement and QoS of the control part; downlink data notification.

[0241] <RRC connection setup and reconfiguration procedure> Figure 16 shows some of the interactions between the UE, gNB, and AMF (5GC entities) when the UE transitions from RRC_IDLE to RRC_CONNECTED in the NAS part (see TS 38.300 v15.6.0).

[0242] RRC is a higher layer signaling (protocol) used to configure the UE and gNB. With this transition, the AMF prepares UE context data (including, for example, PDU session context, security keys, UE radio capabilities, UE security capabilities, etc.) and sends it to the gNB along with an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security together with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE, and the UE responding with a SecurityModeComplete message to the gNB. The gNB then sends an RRCReconfiguration message to the UE, and upon receiving an RRCReconfigurationComplete from the UE, the gNB performs reconfiguration to set up a Signaling Radio Bearer 2 (SRB2) and a Data Radio Bearer (DRB). For signaling-only connections, the steps related to RRCReconfiguration are omitted because SRB2 and DRB are not set up. Finally, the gNB notifies the AMF that the setup procedure is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0243] Accordingly, the present disclosure provides a 5th Generation Core (5GC) entity (e.g., AMF, SMF, etc.) that includes: a control circuit that, upon operation, establishes a Next Generation (NG) connection with a gNodeB; and a transmitter that, upon operation, transmits an initial context setup message to the gNodeB via the NG connection so that a signaling radio bearer between the gNodeB and a user equipment (UE) is set up. Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling, including a resource allocation configuration information element (IE), to the UE via the signaling radio bearer. The UE then transmits in uplink or receives in downlink based on the resource allocation configuration.

[0244] <IMT Usage Scenarios Beyond 2020> Figure 17 shows some use cases for 5G NR. The 3rd Generation Partnership Project New Radio (3GPP NR) is considering three use cases envisioned by IMT-2020 to support a wide variety of services and applications. The first phase of specifications for enhanced mobile broadband (eMBB) has been completed. Current and future work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to expanding support for eMBB. Figure 17 shows some examples of envisioned usage scenarios for IMT beyond 2020 (see, for example, ITU-R M.2083 Figure 2).

[0245] The URLLC use case has stringent performance requirements, such as throughput, latency, and availability. It is envisioned as one of the enabling technologies for future applications, such as wireless control of industrial or manufacturing processes, remote medical surgery, automated power transmission and distribution in smart grids, and road safety. URLLC's ultra-high reliability is supported by identifying technologies that meet the requirements set by TR 38.913. Key requirements for NR URLLC in Release 15 include a target user plane latency of 0.5 ms on the uplink (UL) and 0.5 ms on the downlink (DL). The overall URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a 32-byte packet size with a user plane latency of 1 ms.

[0246] From a physical layer perspective, reliability can be improved in many possible ways. Current room for reliability improvement includes defining a separate CQI table for URLLC, more compact DCI formats, PDCCH repetition, etc. However, this room can be expanded to achieve ultra-high reliability as NR (with respect to the key requirements of NR URLLC) becomes more stable and developed. Specific use cases for NR URLLC in Release 15 include Augmented Reality / Virtual Reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0247] Additionally, the technology enhancements targeted by NR URLLC aim to improve latency and reliability. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level repetition in the data channel, and preemption in the downlink. Preemption means that a transmission with already allocated resources is stopped and the already allocated resources are used for another transmission with a later requested lower latency / higher priority. Therefore, a previously allowed transmission is preempted by a later transmission. Preemption is applicable regardless of the specific service type. For example, a transmission of service type A (URLLC) may be preempted by a transmission of service type B (eMBB, etc.). Technology enhancements for reliability improvement include a dedicated CQI / MCS table for a target BLER of 1E-5.

[0248] The use case of mMTC (massive machine type communication) is characterized by a very large number of connected devices that typically transmit relatively small amounts of data that are not sensitive to delays. These devices are required to be low-cost and have very long battery life. From the NR perspective, utilizing very narrow bandwidth portions is one solution that saves power from the UE's perspective and enables long battery life.

[0249] As mentioned above, the scope of reliability improvement in NR is expected to be broader. One of the key requirements for all cases, for example, URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can improve reliability from a radio perspective and a network perspective. Generally, there are two to three key areas that can help improve reliability. These areas include compact control channel information, repetition of data channels / control channels, and diversity in the frequency, time, and / or spatial domains. These areas are generally applicable to reliability improvement regardless of the specific communication scenario.

[0250] For NR URLLC, further use cases with more stringent requirements are envisaged, such as factory automation, transportation, and power distribution, such as high reliability (up to 10-6 level), high availability, packet size up to 256 bytes, time synchronization down to a few μs (depending on the use case, the value can be 1 μs or a few μs depending on the frequency range and low latency in the order of 0.5 ms to 1 ms (e.g., 0.5 ms latency on the targeted user plane)).

[0251] Furthermore, for NR URLLC, there may be several technical enhancements from the physical layer perspective. These technical enhancements include PDCCH (Physical Downlink Control Channel) enhancements for compact DCI, PDCCH repetition, and increased PDCCH monitoring. Also, UCI (Uplink Control Information) enhancements relate to enhanced Hybrid Automatic Repeat Request (HARQ) and CSI feedback enhancements. There may also be PUSCH enhancements related to minislot-level hopping and retransmission / repetition enhancements. The term "minislot" refers to a Transmission Time Interval (TTI) that contains fewer symbols than a slot (a slot comprises 14 symbols).

[0252] <QoS Control> The 5G Quality of Service (QoS) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (Guaranteed Bit Rate QoS flows (GBR)) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Thus, at the NAS level, a QoS flow is the finest granularity of QoS classification in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI) carried in an encapsulation header over the NG-U interface.

[0253] For each UE, 5GC establishes one or more PDU sessions. For each UE, the NG-RAN establishes at least one Data Radio Bearer (DRB) for each PDU session, e.g., as shown above with reference to Figure 16. Additional DRBs for the QoS flows of that PDU session can be configured later (when this is up to the NG-RAN). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and 5GC associate UL and DL packets with QoS flows, while AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0254] Figure 18 shows the non-roaming reference architecture for 5G NR (see TS 23.501 v16.1.0, section 4.23). An Application Function (AF) (e.g., an external application server hosting 5G services, as illustrated in Figure 17) interacts with the 3GPP core network to provide services. For example, it accesses the Network Exposure Function (NEF) to support applications that affect traffic routing, or interacts with a policy framework for policy control (e.g., QoS control) (see Policy Control Function (PCF)). Based on operator deployment, Application Functions considered trusted by the operator can interact directly with the associated Network Functions. Application Functions not permitted by the operator to directly access Network Functions interact with the associated Network Functions using an external exposure framework via the NEF.

[0255] Figure 18 further illustrates further functional units of the 5G architecture, namely, Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN, e.g., operator-provided services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and run in a cloud computing environment.

[0256] Therefore, the present disclosure provides an application server (e.g., an AF in a 5G architecture) comprising: a transmitter that, in operation, sends a request including QoS requirements for at least one of a URLLC service, an eMMB service, and an mMTC service to at least one of 5GC functions (e.g., an NEF, an AMF, an SMF, a PCF, an UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE according to the QoS requirements; and a control circuit that, in operation, performs a service using the established PDU session.

[0257] The present disclosure can be realized by software, hardware, or software in conjunction with hardware. Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may also be called an IC, system LSI, super LSI, or ultra LSI.

[0258] The integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0259] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology may be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

[0260] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a radio transceiver and processing / control circuitry. The radio transceiver may include a receiver and a transmitter, or both functions. The radio transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0261] The communication devices are not limited to portable or mobile devices, but also include any kind of non-portable or fixed equipment, devices, and systems, such as smart home devices (such as home appliances, lighting equipment, smart meters or measuring devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0262] Communications include data communications via cellular systems, wireless LAN systems, communication satellite systems, and the like, as well as data communications via combinations of these.

[0263] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0264] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0265] A communication device according to one embodiment of the present disclosure includes, when multiple consecutive time resources are allocated in terminal-to-terminal communication in an unlicensed band, a control circuit that allocates a signal to a guard interval set in the nth time resource among the nth time resource and the n+1th time resource included in the multiple time resources, and a transmission circuit that transmits the signal in the multiple time resources.

[0266] In one embodiment of the present disclosure, the control circuit allocates the signal to the guard interval when the signal is allocated to all resource blocks in a resource block set used for transmitting the signal.

[0267] In an embodiment of the present disclosure, the control circuit allocates the signal to the guard interval when the signal is allocated to a number of resource blocks equal to or greater than a threshold among a set of resource blocks used for transmitting the signal.

[0268] In one embodiment of the present disclosure, the control circuit allocates the signal to the guard interval when the signal is allocated to the same frequency resource in each of the plurality of time resources.

[0269] In one embodiment of the present disclosure, the plurality of time resources are set within a channel occupancy time, and the control circuit sets the guard interval in at least the last time resource of the channel occupancy time among the plurality of time resources.

[0270] In one embodiment of the present disclosure, when multiple consecutive time resources are allocated in terminal-to-terminal communication in an unlicensed band, a signal is allocated to a guard interval set in the nth time resource among the nth time resource and the n+1th time resource included in the multiple time resources, and the signal is transmitted in the multiple time resources.

[0271] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2022-127362, filed on August 9, 2022, are incorporated herein by reference in their entirety.

[0272] One aspect of the present disclosure is useful in wireless communication systems.

[0273] 100 Base station 200, 200a Terminal 201 Receiving unit 202 LBT carrier sense unit 203 Signal separation unit 204 Demodulation unit 205 Error correction decoding unit 206 Control signal receiving unit 207 LBT failure notification receiving unit 208 Error correction coding unit 209 Modulation unit 210 Control signal generating unit 211 LBT failure notification generating unit 212 Signal allocation unit 213 Transmission unit 220 Guard period setting unit

Claims

1. In inter-terminal communication in an unlicensed band, when a plurality of consecutive time resources are allocated, a control circuit that allocates a signal to a guard interval included in the plurality of time resources; In the plurality of time resources, a transmission circuit that transmits the signal; A communication device comprising the above.

2. When the control circuit does not transmit the signal, it notifies the base station of a NACK signal. The communication device according to claim 1.

3. The control circuit does not transmit a PSSCH (physical SL shared channel) due to LBT failure. The communication device according to claim 2.

4. The control circuit notifies the NACK signal in a resource for transmitting HARQ-ACK. The communication device according to claim 2.

5. The control circuit notifies the base station of the NACK signal using the amount of sequence cyclic shift for the NACK signal in PUCCH format 0. The communication device according to claim 2.

6. The amount of sequence cyclic shift used in PUCCH format 0 when the signal is not transmitted and when the data related to the signal is not accurately received is the same. The communication device according to claim 1.

7. When the control circuit performs Type 2B channel access processing, it performs LBT within a sensing period of 16 μs. The communication device according to claim 1.

8. The control circuit determines the plurality of time resources based on upper layer parameters notified by the base station. The communication device according to claim 1.

9. The control circuit sets the guard interval at the end of any one of the plurality of time resources. The communication device according to claim 1.

10. The control circuit makes the length of the signal different between a first situation and a second situation. The communication device according to claim 1.

11. In the second situation, the section where the signal is not transmitted is longer than in the first situation, and in the second situation, the CP (cyclic prefix extension) length is longer than in the first situation. The communication device according to claim 10.

12. The length of the CP (cyclic prefix extension) transmitted in the guard interval is notified by control information. The communication device according to claim 11.

13. The transmission circuit transmits a sidelink signal to the same terminal using the plurality of time resources. The communication device according to claim 1.

14. The resource for transmitting the PSSCH (physical SL shared channel) is notified by the base station. The communication device according to claim 1.

15. The communication device In inter-terminal communication in an unlicensed band, when a plurality of consecutive time resources are allocated, a signal is allocated to a guard interval included in the plurality of time resources. In the plurality of time resources, the signal is transmitted. Communication method.

16. In inter-terminal communication in an unlicensed band, when a plurality of consecutive time resources are allocated, a control circuit that allocates a signal to a guard interval included in the plurality of time resources; A transmission circuit that transmits the signal in the plurality of time resources; An integrated circuit comprising: