COMMUNICATION DEVICE, COMMUNICATION METHOD, AND INTEGRATED CIRCUIT

Abstract

This communication device comprises: a control circuit which determines a transmission time for a transmission signal on the basis of a sensing interval corresponding to a sensing method for checking the availability of a channel; and a transmission circuit which transmits the transmission signal during the transmission time.

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. The international standardization organization 3GPP (3rd Generation Partnership Project) is considering the advancement of communication systems from both the perspective of upgrading the Long Term Evolution (LTE) system and New Radio (NR). For example, with the increasing capacity of communication, 3GPP is considering the use of unlicensed bands in addition to licensed bands.

[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 37.213 V17.1.0, “Physical layer procedures for shared spectrum channel access,”

[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 a control circuit that determines a transmission time of a transmission signal based on a sensing interval corresponding to a sensing method for checking the availability of a channel, and a transmission circuit that transmits the transmission signal during the transmission time.

[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 allocation of PSCCH, PSSCH, and PSFCH in slots. Block diagram showing an example configuration of a part of a base station. Block diagram showing an example configuration of a part of a terminal. Diagram showing an example of sidelink communication in a licensed band. Diagram showing an example of sidelink communication in operation example 1-1 of embodiment 1. Diagram showing an example of sidelink communication in operation example 1-2 of embodiment 1. Block diagram showing a configuration of a terminal according to embodiment 1. Diagram showing a first example of sidelink communication in operation example 2-1 of embodiment 2. Diagram showing an example of resources for sidelink communication in a modified version of operation example 2-1 of embodiment 2. Diagram showing an example of resources for sidelink communication in operation example 2-2 of embodiment 2. Block diagram showing a configuration of a terminal according to embodiment 2. Diagram showing an example of resources for sidelink communication in operation example 3-1 of embodiment 3. Diagram showing a first example of sidelink communication in operation example 4-1 of embodiment 4. Diagram showing a second example of sidelink communication in operation example 4-1 of embodiment 4. Diagram showing a third example of sidelink communication in operation example 4-1 of embodiment 4. Diagram of an exemplary architecture of a 3GPP NR system. Schematic diagram showing functional separation between NG-RAN and 5GC. RRC (Radio Resource Control) A sequence diagram of the procedure for setup / reconfiguration of a 5G (Mobile Broadband Control) connection. A schematic diagram illustrating usage scenarios for enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communications (URLLC). A block diagram illustrating an exemplary 5G system architecture for a non-roaming scenario.

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

[0012] [Vehicle to X (V2X)] An expansion of communication systems known as 5th Generation mobile communication systems (5G) is being considered. 5G is being considered to provide flexible functions for each use case that requires increased communication traffic, an increase in the number of connected devices, high reliability, and low latency.

[0013] 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 been studying support for V2X (vehicle to X) in the LTE system. NR, which can use a wider bandwidth than LTE, is also studying support for V2X (see, for example, Non-Patent Document 1).

[0014] In addition to V2X, further expansion of communication using side links 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) communication.

[0015] In V2V, V2I, and V2P, signals can be transmitted and received directly between terminals using a link called a sidelink (SL) 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.

[0016] In addition, the use of sidelink communication in unlicensed bands is also being considered (see, for example, Non-Patent Document 3).

[0017] [NR Sidelink] NR sidelink supports unicast, groupcast, and broadcast transmissions. Unicast is assumed to be one-to-one transmission from a transmitting terminal (e.g., Tx UE) to a receiving terminal (e.g., Rx UE). Groupcast is assumed to be transmission from a transmitting terminal to one or more receiving terminals included in a group. Broadcast is assumed to be transmission from a transmitting terminal without specifying a receiving terminal.

[0018] In the NR sidelink, a control signal called SCI (sidelink control information) is transmitted and received. The SCI may also be referred to as control information. The SCI is divided into a first-stage SCI and a second-stage SCI. The first-stage SCI is allocated to a physical SL control channel (PSCCH). The second-stage SCI is allocated to at least a portion of a physical SL shared channel (PSSCH) 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 different from terminal A, understanding the resource usage status of the other terminal, and then determining the resources terminal A will use for transmission. This function is also referred to as sensing. Note that, hereinafter, different terminals may be distinguished from one another using notations such as terminal A, terminal B, terminal C, terminal X, and terminal Y.

[0019] 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).

[0020] Note that a signal transmitted and received in a sidelink may be referred to as a sidelink signal. Also, for example, "transmission of information (or a signal) allocated to a PSCCH" may be abbreviated as "transmission of a PSCCH" hereinafter. Also, in the following description, PSCCH may refer to a resource defined as a PSCCH, or may refer to information (or a signal) allocated to a resource defined as a PSCCH. Channels other than a PSCCH may also be abbreviated as PSCCH.

[0021] 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, example (a) and example (b).

[0022] Note that the PSFCH may be arranged as shown in example (a). Alternatively, as shown in example (b), the PSFCH may not be arranged depending on the setting. If the PSFCH is not arranged, the PSSCH area may be increased.

[0023] 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 is changed depending on the arrangement of the DMRS of the PSSCH (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 example (a), a copy of the PSFCH is also arranged before the PSFCH symbol for AGC.

[0024] In example (a), gaps for switching between transmission and reception are placed in the interval between the PSSCH and the PSFCH and in the interval after the last symbol of the PSFCH. In example (b), gaps for switching between transmission and reception are placed in the interval after the last symbol of the PSSCH. The gaps may correspond to intervals in which no signals are transmitted or received.

[0025] NR sidelink communication has two modes, Mode 1 and Mode 2. In Mode 1, the base station determines the resources that a terminal will use on the sidelink. In Mode 2, the terminal determines the resources to use on the sidelink from resources in a predetermined resource pool. Mode 1 is intended for use in an environment where the base station and terminal are connected and 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, allowing communication on the sidelink with terminals under different operators and / or terminals outside the base station's coverage.

[0026] [Background: NR-U] As communication capacity increases, 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).

[0027] 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, the communication device sets a channel occupancy time (COT). Within the COT, the communication device can transmit and receive signals in downlink (DL) resources and UL resources.

[0028] There are two methods for operating LBT. The first method is LBE (Load Based Equipment). In LBE, when a communication device acquires a COT, it performs Type 1 LBT (also known as category 4 LBT). In addition, except at the beginning of the COT, the communication device can perform Type 2 LBT and start transmission after it has performed it.

[0029] 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.

[0030] Table 1 shows an example of the sensing interval of the LBT for acquiring the transmission right in the LBE and the interval to be applied.

[0031] In Type 1 LBT, each parameter related to LBT is set by setting the Channel Access Priority Class. Table 2 shows an example of the setting of each parameter shown in Non-Patent Document 4. Table 2 shows the correspondence between the Channel Access Priority Class and each parameter.

[0032] The terminal (an example of a communication device) is 16+9*m p In addition to the sensing interval, carrier sense is repeated for 9*N sensing intervals, and if it is confirmed that the channel is free, transmission can be started. Note that a state in which the channel is free is sometimes referred to as an idle state, and a state in which the channel is not free (for example, a state in which the channel is in use) is sometimes referred to as a busy state. Confirming that the channel is free may be confirmation that other devices are not transmitting signals. Furthermore, the sensing interval may be replaced with other notations such as sensing time or carrier sense interval.

[0033] The value of N is decremented (counted down) by 1 each time it is confirmed that the channel is free. If the channel is busy, the countdown of N is stopped and it is counted down to 16+9*m p After confirming that the channel is free during this period, it counts down again. The initial value of N is randomly selected from 0 to CW_p. CW_p is selected from the allowed CW_p sizes. The initial value of CW_p is CW_(min,p). If a specified number of communication errors occurred due to collisions in the previous transmission, the value of CW_p is increased by one step. For example, if Channel Access Priority Class p=1 and CW_p=CW_(min,p), then according to Table 2, CW_p=3. In this case, the initial value of N is randomly set from 0 to 3, i.e., from {0,1,2,3}. For example, when the initial values ​​of N are 0, 1, 2, and 3, the sensing periods are 25 μs, 34 μs, 43 μs, and 52 μs, respectively.

[0034] In Type 2A, if the interval between two consecutive resources is 25 μs, the terminal performs LBT within 25 μs. The terminal can start transmission if it does not confirm transmission from other devices in the LBT. In Type 2B, if the interval between two consecutive resources is 16 μs, the terminal performs LBT within 16 μs. The terminal can start transmission if it does not confirm transmission from other devices. 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 DRS (Discovery Reference Signal), since the transmission time of the DRS is short, it is possible to start transmission by performing Type 2A LBT instead of Type 1 LBT.

[0035] Type 1 LBT, Type 2A LBT, Type 2B LBT, and Type 2C LBT are examples of sensing methods for checking the availability of a channel. As described above, the sensing period is defined depending on the sensing method.

[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] In each of the following embodiments, an example of performing sidelink communication in an unlicensed band is shown.

[0038] In sidelink communication, even if all 14 symbols in a slot can be used for sidelink communication, the last symbol is a guard symbol that cannot be used for transmission or reception, assuming the time it takes for the terminal to switch between transmission and reception.

[0039] Table 3 shows the correspondence between SCS (Subcarrier Spacing) and the length of one symbol (Symbol duration). As shown in Table 3, the length of one symbol differs depending on the SCS.

[0040] When transmission is performed using Type 1 LBT in an unlicensed band, for example, if the Channel Access Priority Class is 1 and the initial value of N is selected from {0, 1, 2, 3}, the sensing intervals for the cases where the initial value of N is 0, 1, 2, and 3 are 25 μs, 34 μs, 43 μs, and 52 μs, respectively. Therefore, the terminal performs sensing for 25 μs, 34 μs, 43 μs, or 52 μs before starting transmission. If the sensing result confirms that the channel is free, the terminal can start transmission.

[0041] If the sensing period (e.g., 25 μs, 34 μs, 43 μs, and 52 μs) is longer than the length of one symbol, performing Type 1 LBT with one symbol may not be able to start transmission in time for the start of the slot. For example, performing Type 1 LBT with one symbol means performing Type 1 LBT with the last symbol (e.g., guard symbol) of a sidelink communication slot.

[0042] Furthermore, when Type 2 LBT is implemented, if the time interval between two resources arranged consecutively in the time direction is 25 μs or more, the transmission on those two resources is not recognized as a transmission within the COT. For example, when the SCS is 15 kHz and 30 kHz, the length of one symbol is 25 μs or more, so two resources spanning two slots may not be recognized as belonging to the same COT. For example, if the last symbol in a slot is a guard symbol, the interval between slots becomes 25 μs, so the two resources spanning two slots are not recognized as belonging to the same COT. If they are not recognized as belonging to the same COT, Type 2 LBT cannot be implemented and Type 1 LBT must be implemented, which results in a longer sensing period and ineffective resource utilization.

[0043] In one non-limiting example embodiment of the present disclosure, a method is described that can improve resource utilization efficiency for sidelink communication in unlicensed bands.

[0044] For example, in the following embodiments, the sidelink signal transmission time is controlled based on the sensing period, thereby adjusting the sidelink signal interval and transmitting the signal at an appropriate timing after the LBT, thereby improving resource utilization efficiency of sidelink communication.

[0045] In the embodiments described below, sidelink communication is exemplified, but the present disclosure is not limited to sidelink communication.

[0046] [Overview of Communication System] A communication system according to an embodiment of the present disclosure includes a base station 100 and a terminal 200.

[0047] Fig. 2A 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. 2A, a control unit 102 controls communication between a terminal 200 and the base station 100 via a link called Uu. The radio transceiver unit 101 transmits a signal via the link called Uu under the control of the control unit 102. The control unit 102 may also perform control related to sidelink communication between multiple terminals (e.g., determining resources in Mode 1).

[0048] 2B is a block diagram showing an example of the configuration of a portion of terminal 200. In terminal 200 shown in FIG. 2B, control unit 220 (e.g., corresponding to a control circuit) determines a transmission time of a transmission signal based on a sensing period corresponding to a sensing method for checking the availability of a channel. Furthermore, wireless transceiver unit 221 (e.g., corresponding to a transmission circuit) transmits the transmission signal during the transmission time. Note that the transmission signal may be, for example, a sidelink signal, or may be a signal different from the sidelink signal. Furthermore, determining the transmission time of the transmission signal may correspond to determining at least one of the timing for ending transmission, the timing for starting transmission, and the transmission interval of the transmission signal.

[0049] (Embodiment 1) In this embodiment 1, the length of the sidelink signal (the length of the resources used for sidelink communication) is shortened and guard symbols are added between slots. According to this embodiment 1, when Type 1 LBT is performed and the channel is in an idle state, transmission can start from the beginning of the slot after Type 1 LBT is performed.

[0050] [Operation Example 1-1] In this operation example 1-1, a terminal transmitting a sidelink signal shortens the length of the time domain of the PSSCH. By shortening the length of the time domain of the PSSCH, a sensing period is provided in which a terminal transmitting a sidelink signal in an unlicensed band senses whether or not there is another transmission before transmission.

[0051] 3A is a diagram showing an example of sidelink communication in a licensed band. FIG. 3B is a diagram showing an example of sidelink communication in operation example 1-1 of the first embodiment. The horizontal axis of FIG. 3A and FIG. 3B represents the time axis, and the vertical axis represents the frequency axis. Note that, hereinafter, the resources of the 2nd stage SCI are included in the PSSCH and are not explicitly shown.

[0052] As shown in FIG. 3A, in the licensed band, when the number of symbols included in one slot of sidelink communication is 14, the last symbol is a guard symbol.

[0053] As shown in Fig. 3B , in the first embodiment, a time interval in which no signal is transmitted is added to ensure a sensing interval in the unlicensed band. In the example of Fig. 3B , a time interval called an "additional guard period" is added to the last symbol of each slot, which is a guard symbol. In the example of Fig. 3B , Type 1 LBT is performed in interval T0, which includes the guard symbol and the "additional guard period."

[0054] No signal is transmitted during the additional guard period. In other words, in the example of Fig. 3B, the length of the time domain of the PSSCH transmitted in each slot is shortened by the length of time corresponding to the additional guard period. The length of the additional guard period may correspond to the shortened length in the time domain of the PSSCH.

[0055] The length of the additional guard period does not have to be an integer multiple of the symbol length, but may be an integer multiple of the symbol length. In other words, the length of the time domain of the PSSCH does not have to be shortened in symbol units, but may be shortened in symbol units. When the length of the additional guard period is an integer multiple of the symbol length, the additional guard period may be referred to as an "additional guard symbol."

[0056] For example, when the length of the time domain of the PSSCH is shortened by a symbol, since the last symbol in a slot is set as a guard symbol in the sidelink communication format, an additional guard symbol is added to the guard symbol of one symbol, as shown in FIG. 3B.

[0057] Table 4 shows the relationship between SCSs and additional guard symbols. Table 4 associates SCSs with the symbol lengths corresponding to the SCSs (referred to as "Symbol duration" in Table 4) and the number of additional guard symbols specified for each symbol length. The number of additional guard symbols is specified for sensing intervals of 25 μs, 34 μs, 43 μs, and 52 μs. As shown in Table 4, the number of additional guard symbols may differ for each SCS or for each sensing interval. For example, a terminal adds the number of additional guard symbols shown in Table 4 as guard symbols between slots.

[0058] For example, in Table 4, the symbol length for a 15 kHz SCS is 66.67 μs. Therefore, the length of the guard symbol, which is the last symbol in a slot in the sidelink communication format (i.e., 66.67 μs), is longer than any of the sensing intervals of 25 μs, 34 μs, 43 μs, and 52 μs. Therefore, when the SCS is 15 kHz, the additional guard symbol may be 0 for any sensing interval. Also, for example, the symbol length for a 60 kHz SCS is 16.67 μs. Therefore, a total of two guard symbols are required to ensure a 25 μs sensing interval. Therefore, one additional guard symbol is added to the guard symbol, which is the last symbol in a slot in the sidelink communication format.

[0059] The sensing period required for Type 1 LBT (hereinafter referred to as the "Type 1 LBT sensing period") varies depending on at least one of the Channel Access Priority Class, whether a collision occurred in the previous transmission, and a randomly selected value. For example, as shown in Table 2, the initial value of N, which determines the Type 1 LBT sensing period, is randomly selected from candidates determined by the Channel Access Priority Class. The value of N is then decremented depending on whether a collision occurred, etc.

[0060] For example, during operation, it is assumed that the sensing interval for Type 1 LBT when transmitting in consecutive slots is an interval up to 43 μs in length. However, if the initial value of N is 3 and 52 μs is selected as the sensing interval, transmission in consecutive slots is not possible. In this case, instead of transmitting in consecutive slots, transmission is possible when one slot of the channel is available, or after sensing in a guard period of multiple slots. The assumed sensing interval may be configurable for each resource pool, or may be determined in advance.

[0061] The following methods can be considered for setting the sensing period: - Setting a guard period value in the resource pool configuration, also called (pre-)configured. - Setting a small number of PSSCH symbols in the resource pool configuration, also called (pre-)configured, taking the guard period into account. - Reducing the number of symbols of the sidelink signal (e.g., PSSCH) in sidelink communication in unlicensed bands.

[0062] In the above, an example has been given in which an additional guard period is set in symbol length units, but the additional guard period may be set in units shorter than symbol units or in units longer than symbol units.

[0063] By shortening the PSSCH time domain in this way, a Type 1 LBT sensing period can be secured between consecutive slots, and sidelink communication resources can be secured in consecutive slots for transmitting and receiving sidelink signals, thereby improving resource utilization efficiency for sidelink communication.

[0064] [Operation Example 1-2] In a slot in which a PSFCH is allocated, a guard period of one symbol is allocated before the PSFCH is transmitted, as shown in Figure 1. In unlicensed bands, sensing must also be performed before the PSFCH is transmitted.

[0065] Here, a case will be described in which Type 1 LBT is performed before transmitting the PSFCH and before transmitting the PSSCH in the next slot. In this case, a sensing period similar to that in the example shown in Operation Example 1-1 is required.

[0066] Therefore, in operation example 1-2, a Type 1 LBT sensing period is secured both before transmitting the PSFCH and before transmitting the PSSCH in the next slot after transmitting the PSFCH.

[0067] Fig. 4 is a diagram showing an example of sidelink communication in operation example 1-2 of embodiment 1. The horizontal axis of Fig. 4 represents the time axis, and the vertical axis represents the frequency axis.

[0068] As shown in FIG. 4, an additional guard period is added before the transmission of the PSFCH and after the transmission of the PSFCH.

[0069] For example, in the licensed band, as shown in example (a) of FIG. 1, the PSFCH is placed in the penultimate symbol of the sidelink slot, and a copy of the PSFCH for AGC of the PSFCH is placed in the symbol before that. In operation example 1-2 of this embodiment 1, the position of the symbol in which the PSFCH is placed is moved forward on the time axis by the amount of the guard period added to the last symbol of the slot. In addition, the length of the time domain of the PSSCH is shortened. For example, shortening the length of the time domain of the PSSCH corresponds to reducing the number of symbols of the PSSCH.

[0070] For example, intervals T1 and T2 in Fig. 4 each have a length including one symbol and an additional guard period. In the example of slot #K-1 in Fig. 4 (K may be an integer equal to or greater than 1), the position of the symbol in which the PSFCH is allocated is moved forward on the time axis by the additional guard period of interval T1. Also, in the example of slot #K-1 in Fig. 4, the length of the time domain of the PSSCH is shortened by the additional guard period of interval T2. The length including one symbol and the additional guard period corresponds to, for example, the sensing interval of Type 1 LBT. Note that the sensing interval of Type 1 LBT may be the same as that in Operation Example 1-1.

[0071] Note that the position of the transmission symbol of the PSFCH (for example, the transmission symbol number of the PSFCH) may be set for each resource pool.

[0072] Furthermore, in unlicensed bands, it may be specified that terminals do not transmit or receive the PSFCH. For example, when the SCS is 30 kHz or 60 kHz, as shown in Table 4, the number of symbols required for the guard period (the number of additional guard symbols in Table 4) increases. Therefore, when the SCS is 30 kHz and 60 kHz, the PSFCH may not be supported. In this case, when the SCS is other than 30 kHz and other than 60 kHz, the PSFCH may be supported. Furthermore, when the SCS is 60 kHz, the PSFCH may not be supported. In this case, when the SCS is other than 60 kHz, the PSFCH may be supported. Furthermore, when the SCS is 30 kHz, the PSFCH may not be supported. In this case, when the SCS is other than 30 kHz, the PSFCH may be supported.

[0073] Furthermore, in the unlicensed band, it may be determined that the PSFCH is not transmitted or received in a slot in which the PSFCH is transmitted or received. In this case, the position of the transmission symbol of the PSFCH may be determined to be earlier than that of the licensed band in order to ensure a sensing period for Type 1 LBT after the transmission or reception of the PSFCH.

[0074] [Configuration of Terminal 200] Fig. 5 is a block diagram showing the configuration of terminal 200 according to the first embodiment. Terminal 200 shown in Fig. 5 includes receiving section 201, LBT carrier sensing section 202, signal separation section 203, demodulation section 204, control signal sensing section 205, error correction decoding section 206, guard period setting section 207, signal allocation section 208, error correction coding section 209, modulation section 210, control signal generation section 211, and transmission section 212. Note that LBT carrier sensing section 202, signal separation section 203, demodulation section 204, control signal sensing section 205, error correction decoding section 206, guard period setting section 207, signal allocation section 208, error correction coding section 209, modulation section 210, and control signal generation section 211 may be included in control section 220. Furthermore, the receiving unit 201 and the transmitting unit 212 may correspond to the wireless transmitting / receiving unit 221 shown in FIG. 2B.

[0075] In sidelink communication, the terminal 200 may be a transmitting terminal that transmits a sidelink signal or a receiving terminal that receives a sidelink signal.

[0076] 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 is, for example, a side link signal including a PSSCH and / or a PSCCH. The side link 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 other than the side link signal. The receiving unit 201 outputs the received signal after reception processing to the signal separating unit 203 and the LBT carrier sense unit 202.

[0077] The LBT carrier sense unit 202 performs carrier sensing (also referred to as LBT) based on the received signal output from the receiving unit 201. The LBT carrier sense unit 202 may determine whether the channel state is "busy" or "idle" based on the received signal output 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 output from the receiving unit 201. The LBT carrier sense unit 202 outputs information indicating the determined channel state to the transmitting unit 212.

[0078] The signal separating unit 203 outputs a received data signal from the received signal to the demodulating unit 204. The received data signal is, for example, mapped to a PSSCH. The signal separating unit 203 also separates from the received signal a 1st stage SCI mapped to the PSCCH and a 2nd stage SCI mapped to a part of the PSSCH. The separated information may be referred to as control signal sensing information. The signal separating unit 203 outputs the control signal sensing information to the control signal sensing unit 205.

[0079] The demodulation unit 204 performs demodulation processing on the received signal and outputs the demodulated signal obtained by performing the demodulation processing to the error correction decoding unit 206.

[0080] The error correction decoding unit 206 decodes the demodulated signal output from the demodulation unit 204 and outputs it as received data. The error correction decoding unit 206 also outputs a higher layer control signal related to the guard period, which is included in the received data, to the guard period setting unit 207.

[0081] Based on the 1st stage SCI, the control signal sensing unit 205 grasps resource allocation information indicating which resources are reserved for other terminals. Then, the control signal sensing unit 205 determines resource allocation so as to avoid overlap with other reserved resources, and notifies the signal allocation unit 208 of the determined resource allocation. Furthermore, the control signal sensing unit 205 grasps the transmission ID and reception ID based on the 2nd stage SCI. If there is a resource allocation addressed to its own terminal, the control signal sensing unit 205 notifies the signal separation unit 203. The above-mentioned signal separation unit 203 separates the received signal based on the notified resource allocation.

[0082] The guard period setting unit 207 determines the length of the guard period from information about the guard period that is determined based on a control signal from a higher layer and / or a preset setting called "pre-configured." Since the length of the guard period is set based on the number of transmission symbols of the PSSCH, determining the length of the guard period corresponds to determining the number of transmission symbols of the PSSCH. The guard period setting unit 207 notifies the determined PSSCH transmission symbol number signal allocation unit 208.

[0083] The error correction coding unit 209 acquires the data signal, performs error correction coding on the data signal, and outputs the error correction coded data signal to the modulation unit 210 .

[0084] The modulation unit 210 modulates the data signal received from the error correction coding unit 209 and outputs the modulated signal to the signal allocation unit 208 .

[0085] The control signal generator 211 generates first stage SCI and second stage SCI signals from the control information and inputs the first stage SCI and second stage SCI signals to the signal allocation unit 208.

[0086] The signal allocation unit 208 allocates the modulated signal output from the modulation unit 210 to resources. At that time, the signal allocation unit 208 may allocate the signal to resources taking into consideration information output from the control signal sensing unit 205. The signal allocation unit 208 determines the number of symbols of the PSSCH in accordance with the information output from the guard period setting unit 207, and allocates the determined number of PSSCH symbols to resources. After allocating resources, the signal allocation unit 208 outputs the transmission signal to the transmission unit 212.

[0087] If the sensing result obtained from the LBT carrier sense unit 202 indicates an idle state, the transmitting unit 212 performs transmission processing such as upconversion on the transmission signal, and transmits the transmission signal after the transmission processing via the antenna.

[0088] As described above, in the first embodiment, the sensing interval for Type 1 LBT is secured by adjusting the length of the time domain (e.g., the number of symbols in the PSSCH) of the sidelink signal (e.g., the PSSCH). For example, in the first embodiment described above, when sidelink communication is performed in an unlicensed band, the length of the time domain of the PSSCH is shortened in the slot before transmitting resources acquired by Type 1 LBT. In this way, adjusting the length of the time domain of the PSSCH secures the sensing interval for Type 1 LBT, thereby preventing resources from being wasted by providing a sensing interval and improving resource utilization efficiency of sidelink communication.

[0089] In this second embodiment, an example will be described in which COT (Channel Occupancy Time) is shared between terminals performing sidelink communication, and Type 2 LBT is performed. By sharing COT and performing Type 2 LBT in this manner, transmission and reception can be performed in consecutive slots while maintaining the long PSSCH symbol length.

[0090] [Operation Example 2-1] In this operation example 2-1, when sidelink transmission is performed in an unlicensed band, the COT is shared between terminals. In sidelink communication, each terminal in the same resource pool understands the resources reserved by other terminals and determines the resources to be transmitted by the terminal itself. In slots in which the PSCCH can be received, each terminal understands the resources reserved by other terminals by receiving the PSCCH.

[0091] Therefore, the terminal notifies the COT duration in the PSCCH so that the length of the COT can be known among the terminals in the resource pool.

[0092] Fig. 6 is a diagram showing a first example of sidelink communication in operation example 2-1 of embodiment 2. The horizontal axis of Fig. 6 represents the time axis, and the vertical axis represents the frequency axis.

[0093] For example, as shown in Fig. 6, when a certain terminal (hereinafter referred to as terminal A) acquires a COT by Type 1 LBT in slot #K (K may be an integer equal to or greater than 0), terminal A notifies information indicating that the COT duration is 4 slots in the PSCCH transmitted in slot #K. Information indicating the number of slots in the COT duration may be referred to as COT duration information. The COT duration information is an example of information related to the COT.

[0094] Terminal B, which is another terminal of terminal A, receives the PSCCH transmitted by terminal A in slot #K and confirms that the COT duration is 4 slots. If terminal B confirms that the COT duration is greater than 1, it executes Type 2 LBT from the beginning of the last symbol of slot #K in order to transmit in the next slot, slot #K+1.

[0095] Note that, among Type 2 LBT, whether it is Type 2A, Type 2B, or Type 2C may be determined in advance or may be determined according to conditions.

[0096] As shown in Table 1, the sensing period is 25 μs for Type 2A and 16 μs for Type 2B. For example, in Type 2A, terminal B may start transmission if it confirms that the channel is not in use for 25 μs from the beginning of the last symbol of slot #K. In this case, terminal B may start transmission midway through the last symbol of slot #K (e.g., 25 μs after the beginning of the last symbol of slot #K), as shown in FIG. 6. Similarly, in Type 2B, terminal B may start transmission if it confirms that the channel is not in use for 16 μs from the beginning of the last symbol of slot #K. In this case, terminal B may start transmission midway through the last symbol of slot #K (e.g., 16 μs after the beginning of the last symbol of slot #K).

[0097] As shown in Table 1, sensing is not required for Type C. For Type C, terminal B may start transmission from the beginning of the last symbol of slot #K. In this case, the signal transmitted by terminal B in the last symbol of slot #K may be a signal with an extended CP length from the signal transmitted by terminal B in slot #K+1. Here, the signal with an extended CP length from the signal transmitted in slot #K+1, or the process of extending the CP length, may be referred to as CP (Cyclic prefix) extension.

[0098] Terminal B subtracts one slot from the number of slots, 4, notified in slot #K, and notifies information indicating that the COT duration is three slots in the PSCCH transmitted in slot #K+1.

[0099] In Fig. 6, terminal C, which has received the PSCCH in slot #K+1, performs Type 2 LBT from the beginning of the last symbol of slot #K+1 to transmit in slot #K+2, similar to the operation of terminal B in slot #K+1. If terminal C confirms that the channel is not in use, it starts transmission partway through the last symbol of slot #K+1.

[0100] Terminal C subtracts one slot from the number of slots, 3, notified in slot #K+1, and notifies information indicating that the COT duration is 2 slots in the PSCCH transmitted in slot #K+2.

[0101] In the example of Figure 6, there is no terminal transmitting in slot #K+3. Therefore, COT is not continued in slot #K+3. In this case, the COT duration notified in slot #K is 4 slots, but the actual COT duration is 3 slots.

[0102] Since no PSCCH is transmitted in slot #K+3, terminal D, which is scheduled to transmit in slot #K+4, recognizes that no COT exists at the time of slot #K+3. In this case, terminal D performs Type 1 LBT, and when it confirms that the channel is not in use, it transmits a sidelink signal in slot #K+4.

[0103] If the COT continues in slot #K+3 (for example, if there is a terminal transmitting in slot #K+3), the terminal transmitting in slot #K+3 notifies information indicating that the COT duration is 1 slot in the PSCCH of slot #K+3. A terminal receiving the PSCCH of slot #K+3 recognizes that the COT duration is 1 slot, and that the COT will not continue in the next slot #K+4. In this case, the terminal transmitting in slot #K+4 performs Type 1 LBT to acquire the COT and transmit in order to transmit in slot #K+4.

[0104] As described above, a terminal transmits information indicating the COT duration via the PSCCH, thereby enabling different terminals to share the COT. Sharing the COT allows different terminals to execute Type 2 LBT within the COT, shortening the sensing interval and enabling transmission and reception of signals allocated to resources in consecutive slots. Furthermore, because Type 2 LBT can be executed within the COT, resource utilization efficiency can be improved without shortening the length of the PSSCH.

[0105] When a terminal transmits in a slot with a COT duration of 1 slot (for example, slot #K+3 in FIG. 6 ), the time interval of the PSSCH may be shortened to provide an interval before the next slot in which Type 1 LBT can be performed, as in the example shown in Embodiment 1. Explaining this with reference to FIG. 6 , when a terminal transmits in slot #K+3 with a COT duration of 1 slot, the time interval of the PSSCH transmitted in slot #K+3 may be shortened to provide a sensing interval before slot #K+4 in which Type 1 LBT is performed.

[0106] The COT duration may be determined by the terminal that acquires the COT. The terminal that acquires the COT may determine the number of slots for the COT duration. However, a limit may be set for the COT duration. For example, the COT duration may be limited to a value that does not exceed the range of T_(mcot,p) defined for each Channel Access Priority Class shown in Table 2.

[0107] The COT duration when the terminal acquires the COT may be a predetermined value. For example, the COT duration when the terminal acquires the COT may be set in advance for each resource pool.

[0108] As a modification of the operational example 2-1, when the COT duration is greater than one slot, the end of the transmission interval of the PSSCH may be set to the middle of the final symbol.

[0109] Fig. 7 is a diagram showing an example of resources for sidelink communication in a modification of operation example 2-1 of embodiment 2. The horizontal axis of Fig. 7 represents the time axis, and the vertical axis represents the frequency axis.

[0110] For example, as shown in FIG. 7 , if terminal A acquires a COT using Type 1 LBT in slot #K, terminal A notifies, via the PSCCH, information indicating that the COT duration is four slots. Terminal A also transmits the PSSCH up to the middle of the final symbol of slot #K. The length of the interval transmitted in the final symbol of slot #K may be determined based on the sensing interval of Type 2 LBT. For example, the interval transmitted in the final symbol may be one symbol length minus the sensing interval of Type 2 LBT.

[0111] For example, if the SCS is 30 kHz and the Type 2 LBT is Type 2A, terminal B, which is a different terminal from terminal A, receives the PSCCH transmitted by terminal A in slot #K and confirms that the COT duration is greater than 1. In this case, terminal B performs transmission in the next slot, slot #K+1, and therefore performs Type 2 LBT from the timing at which transmission of the PSSCH in slot #K ends. As described above, in slot #K, the PSSCH is transmitted up to the middle of the final symbol, and therefore the timing at which transmission of the PSSCH ends may be the timing at which the final symbol of the PSSCH ends.

[0112] [Operation Example 2-2] In this operation example 2-2, an example is shown in which the value of the COT duration (for example, the number of slots) is determined based on a rule common to terminals. Illustratively, the following shows an example in which the value of the COT duration is determined in association with the slot number. By determining the value of the COT duration based on a rule common to terminals, when multiple terminals acquire COT in the same slot, the same COT duration value can be determined between the terminals.

[0113] If the maximum value of the COT duration is k, the value k - mod(slot number, k) may be used as the number of slots for the COT duration. Here, mod(slot number, k) indicates the remainder when the slot number is divided by k. The maximum value k of the COT duration is set so that it does not exceed the range of T_(mcot, p) defined for each Channel Access Priority Class.

[0114] For example, when k=4, the COT duration is 4 slots for slot numbers 0, 4, 8, . . . , and the COT duration is 3 slots for slot numbers 1, 5, 9, .

[0115] Fig. 8 is a diagram showing an example of sidelink communication in operation example 2-2 of embodiment 2. The horizontal axis of Fig. 8 represents the time axis, and the vertical axis represents the frequency axis.

[0116] As shown in Fig. 8, when terminal A ("UE-A" in Fig. 8) acquires COT with Type 1 LBT in slot #0, the COT duration associated with slot number 0 is 4 slots, and therefore terminal A notifies information indicating that the COT duration is 4 slots in the PSCCH. Similarly, when terminal E ("UE-E" in Fig. 8), which is different from terminal A, acquires COT with Type 1 LBT in slot #0, it notifies information indicating that the COT duration is 4 slots in the PSCCH.

[0117] In this way, by determining the value of the COT duration based on common rules between terminals, when multiple terminals acquire COT for different resources, the multiple terminals can notify the same value of the COT duration.

[0118] For example, in the example of FIG. 8, terminal B ("UE-B"), which transmits in slot #1, receives the PSCCH transmitted by terminal A or terminal E in slot #0. Terminal B performs Type 2 LBT from the beginning of the last symbol of slot #0, as in operation example 2-1. The sensing interval during which Type 2 LBT is performed is 25 μs for Type 2A and 16 μs for Type 2B. If terminal B confirms that the channel is not in use during the sensing interval, it starts transmission from the middle of the last symbol of slot #0. In the case of Type C, terminal B starts transmission from the beginning of the last symbol of slot #0.

[0119] In Figure 8, there is no terminal transmitting in slot #2. Terminal C ("UE-C") transmitting in slot #3 attempts to receive the PSCCH in slot #2, but cannot detect the PSCCH because no transmission is being performed in slot #2. If terminal C cannot detect the PSCCH in slot #2, it recognizes that there was no transmission in slot #2 and performs Type 1 LBT after slot #2 to acquire the COT in slot #3.

[0120] If terminal C performs Type 1 LBT and acquires the COT, it performs transmission in slot #3. In this case, the COT duration is calculated based on k - mod (slot number, k). When k = 4, the slot number is 3, so the COT duration is 1 slot. In slot #3, where the COT duration is 1 slot, the time domain of the PSSCH may be shortened as in embodiment 1, to create a sensing period in which Type 1 LBT is performed before the next slot #4. In this case, the operation of the terminal in slot #4 may be the same as that in slot #0.

[0121] Note that, in the above example, an example has been shown in which information indicating the COT duration is notified via the PSCCH, but the present disclosure is not limited to this. For example, in operation example 2-2, instead of explicitly notifying the COT duration via the PSSCH, a calculation method for the COT duration may be commonly recognized among terminals, and each terminal may calculate the COT duration. By each terminal calculating the COT duration, information indicating the COT duration is not notified to the terminal, and therefore the number of bits used for notification can be reduced.

[0122] In addition, in the operation example 2-2, as in the modified example of the operation example 2-1, when the COT duration is longer than one slot, the transmission section of the PSSCH may be set to the middle of the last symbol of the slot. In this case, the beginning of the next slot may be set to the beginning of the slot.

[0123] [Operation Example 2-3] In this Operation Example 2-3, the CP extension that starts transmission from a symbol before the slot start symbol in Operation Example 2-1 or Operation Example 2-2 is also applied to the signal transmitted after Type 1 LBT is performed. If the CP extension is applied to the signal transmitted after Type 1 LBT is performed and the CP extension length is longer than that of signals transmitted by other terminals, transmission can start earlier than signals transmitted by other terminals. In other words, transmission can start with priority over signals transmitted by other terminals.

[0124] The possible lengths of the CP extension are as follows:

[0125] (1) When transmitting after performing Type 1 LBT, the terminal shortens the length of the CP extension compared to when transmitting after performing Type 2 LBT. This allows transmission by a terminal that transmits after performing Type 2 LBT to be prioritized over transmission by a terminal that transmits after performing Type 1 LBT. For example, when terminal X, which receives a PSCCH in the previous slot and recognizes that the COT duration is continuing, performs Type 2 LBT, transmission by terminal X can be prioritized over transmission by terminal Y, which does not recognize that the COT duration is continuing.

[0126] (2) When transmission is performed after performing Type 1 LBT and resources for the slot in which transmission is performed are reserved in a slot prior to the slot in which transmission is performed, the length of the CP extension may be increased compared to when resources are not specified in advance. For example, when resources are specified in the time resource assignment or resource reservation period in the SCI format transmitted on the PSCCH, the length of the CP extension may be increased compared to when resources are not specified in advance. This allows transmissions by terminals that have reserved resources in advance to be prioritized over transmissions by terminals that have reserved resources in advance.

[0127] (3) When transmission is performed after Type 1 LBT and transmission is performed using a transmission method called random selection, the length of the CP extension may be shortened compared to transmission methods other than random selection. A transmission method called random selection is a transmission method that is performed when a PSCCH is not received (or detected), or when a portion of the PSCCH is not received, or when sensing is performed but no resources available for transmission are found. In this way, transmissions using transmission methods other than random selection can be prioritized over transmissions using the random selection transmission method.

[0128] In the case of random selection, CP extension does not have to be performed. Also, if PSCCH sensing is not performed, CP extension does not have to be performed. By not performing CP extension, a terminal that has not received PSCCH can confirm by Type 1 LBT sensing that there is no transmission from other terminals and can then transmit, thereby reducing the probability of collision.

[0129] (4) When transmission is performed after Type 1 LBT, the length of the CP extension may be set according to the transmission priority. For example, when determining based on the priority included in the SCI format transmitted on the PSCCH, the smaller the priority value, the higher the priority, and the longer the CP extension length. By making the CP extension length longer for higher priorities, it is possible to prioritize transmissions from terminals with lower priority values ​​(i.e., higher priorities).

[0130] [Configuration of Terminal 200a] Figure 9 is a block diagram showing the configuration of terminal 200a according to the second embodiment. In Figure 9, the same components as those in Figure 5 are denoted by the same reference numerals, and their description may be omitted. The LBT carrier sense unit 202a, signal separation unit 203, demodulation unit 204, control signal sensing unit 205a, error correction decoding unit 206, guard period setting unit 207a, signal allocation unit 208a, error correction coding unit 209, modulation unit 210, and control signal generation unit 211a may be included in control unit 220a. Control unit 220a may be regarded as another example of control unit 220 shown in Figure 5. Furthermore, receiving unit 201 and transmitting unit 212a may correspond to radio transmitting / receiving unit 221 shown in Figure 2B.

[0131] In sidelink communication, the terminal 200a may be a transmitting terminal that transmits a sidelink signal or a receiving terminal that receives a sidelink signal. The terminal 200a may be regarded as another example of the terminal 200 shown in Fig. 5. Differences between the terminal 200 shown in Fig. 5 and the terminal 200a will be described below.

[0132] The LBT carrier sense unit 202a performs carrier sensing (also referred to as LBT) based on the received signal output from the receiving unit 201. The LBT carrier sense unit 202a determines whether to perform Type 1 LBT or Type 2 LBT based on information related to COT (e.g., information on COT duration) output from the control signal sensing unit 205a. The LBT carrier sense unit 202a may also determine the timing to start LBT based on information such as priority (not shown). The LBT carrier sense unit 202a may determine whether the channel state is "busy" or "idle" (in other words, whether the channel is available or not) based on the received signal output from the receiving unit 201. The carrier sense unit 202a outputs information indicating the determined channel state to the transmitting unit.

[0133] Based on the 1st stage SCI, the control signal sensing unit 205a grasps resource allocation information indicating which resources are reserved for other terminals. The control signal sensing unit 205a then determines resource allocation so as to avoid overlap with other reserved resources, and notifies the signal allocation unit 208a of the determined resource allocation. The control signal sensing unit 205a also outputs information related to the COT (e.g., information on the COT duration) to the LBT carrier sense unit 202a, the signal allocation unit 208a, and the control signal generation unit 211a. The control signal sensing unit 205a grasps the transmission ID and reception ID based on the 2nd stage SCI. If there is a resource allocation addressed to its own terminal, the control signal sensing unit 205a notifies the signal separation unit 203. The signal separation unit 203 separates the received signal based on the notified resource allocation.

[0134] The guard period setting unit 207a determines the number of transmission symbols of the PSSCH from information about a defined guard period based on a control signal from an upper layer and / or a pre-configured setting, and notifies the signal allocation unit 208a.

[0135] The control signal generation unit 211a generates 1st stage SCI and 2nd stage SCI signals from the control information. The control signal generation unit 211a outputs the 1st stage SCI and 2nd stage SCI signals to the signal allocation unit 208a. When the terminal 200a acquires a COT, the control signal generation unit 211a determines the COT duration. Furthermore, the control signal generation unit 211a acquires information on the COT duration of the previous slot from the control signal sensing unit 205a. When the COT duration is 2 or more, the control signal generation unit 211a sets the COT duration to a number obtained by subtracting 1.

[0136] The signal allocation unit 208a allocates the modulated signal output from the modulation unit 210 to resources. At that time, the signal allocation unit 208a may allocate the signal to resources taking into consideration information output from the control signal sensing unit 205a. The signal allocation unit 208a acquires information related to the COT (e.g., information on the COT duration) from the control signal sensing unit 205a. If the acquired information indicates that the previous COT duration is 2 or more, the signal allocation unit 208a determines the number of symbols for the PSSCH in the corresponding slot according to information output from the guard period setting unit 207a, and allocates the determined number of PSSCH symbols to resources. After allocating resources, the signal allocation unit 208a outputs the transmission signal to the transmission unit 212a.

[0137] When the sensing result acquired from the LBT carrier sense unit 202a indicates an idle state, the transmitter 212a performs transmission processing such as upconversion on the transmission signal and transmits the processed transmission signal via the antenna. At this time, the transmitter 212a performs CP extension and starts transmission from the timing when the LBT is completed.

[0138] As described above, in the second embodiment, information related to the COT is shared among multiple terminals (e.g., terminals in a resource pool), and an LBT to be performed is determined based on the information related to the COT. For example, if the information related to the COT indicates that the COT duration in the previous slot is two slots or more, the terminal performs Type 2 LBT. In this way, by sharing the information related to the COT, consecutive slots can be treated as transmissions within the same COT to transmit sidelink signals. This makes it possible to lengthen the time interval of the PSSCH and improve resource utilization efficiency of sidelink communication.

[0139] Furthermore, in the second embodiment, by adjusting the length of the time domain of the sidelink signal (for example, the length of the CP), the conditions for implementing Type 2 LBT can be met and the sensing period for Type 2 LBT can be secured.

[0140] Although the information indicating the COT duration is transmitted on the PSCCH, the information indicating the COT duration may be added to the 2nd stage SCI and transmitted on the PSSCH. Also, the information indicating the COT duration may be transmitted on another new channel.

[0141] (Embodiment 3) In this embodiment 3, an example will be described in which a terminal performs an LBT but is unable to acquire a transmission right because the channel is in use (because it is in a busy state), and is therefore unable to transmit the PSCCH and / or PSSCH from the beginning of a slot, and then transmits the PSCCH and / or PSSCH from the middle of the slot. According to this embodiment 3, even if a transmission right cannot be acquired at the beginning of a slot, there is a possibility that transmission can be performed from the middle of the slot.

[0142] The configuration of the terminal according to the third embodiment may be the same as that of terminal 200a shown in Fig. 9 or may be the same as that of terminal 200 shown in Fig. 5. Alternatively, the configuration of the terminal according to the third embodiment may be the same as that of terminal 200a shown in Fig. 9 or that of terminal 200 shown in Fig. 5, with the addition of a function to perform the operation example described below.

[0143] [Operation Example 3-1] Fig. 10 is a diagram showing an example of sidelink communication in Operation Example 3-1 of Embodiment 3. The horizontal axis of Fig. 10 represents the time axis, and the vertical axis represents the frequency axis.

[0144] In slot #0, terminal A transmits to terminal B, and reserves resources for slot #K+1, which is the subsequent slot, in the PSCCH of slot #0.

[0145] However, in the example of Fig. 10, terminal A detects that the channel is in use due to the LBT performed to transmit a signal (e.g., resource) from the beginning of slot #K+1. In this case, even though the resource for slot #K+1 has been reserved, transmission from the beginning of slot #K+1 is not possible.

[0146] In this operation example 3-1, terminal A continues the LBT in slot #K+1 as shown in Fig. 10. Then, when terminal A confirms that the channel is not in use for a certain period of time through the continued LBT, it starts transmission from a symbol in the middle of slot #K+1.

[0147] According to the operation example 3-1, transmission can be started from a position other than the beginning of the slot, thereby enabling effective use of resources.

[0148] Terminal B recognizes that resources for transmission from terminal A to terminal B are reserved in slot #K+1 in slot #0, and attempts to detect the PSCCH allocated in the symbols before slot #K+1 from the symbols before slot #K+1 (for example, the first symbol of slot #K+1). However, as described above, terminal A cannot transmit from the beginning of slot #K+1, so terminal B cannot detect the PSCCH in the symbols before slot #K+1.

[0149] In operation example 3-1, if terminal B is unable to detect the PSCCH in the symbols ahead of slot #K+1, it attempts to detect the PSCCH located in the second candidate position (for example, the second candidate symbol). The second candidate symbol may be predetermined. For example, the second candidate symbol may be predetermined as symbol #4 and symbol #5. If terminal B is able to detect the PSCCH in the second candidate, it receives the PSCCH based on the detected PSCCH.

[0150] If terminal B cannot receive the PSCCH from the second candidate, terminal B recognizes that there was no transmission of the PSCCH and / or PSSCH from terminal A to terminal B in slot #K+1.

[0151] In operation example 3-1, the terminal detects the second candidate in, for example, a resource reserved in advance (slot #K+1 in the example of FIG. 9 ), but does not need to detect the second candidate in unreserved resources. By performing such detection, the terminal can detect PSCCHs that are arranged in different symbols within a slot in resources that are likely to include a signal addressed to the terminal, without increasing the number of times the terminal detects the PSCCH. Note that the resource that is likely to include a signal addressed to the terminal is, for example, a resource reserved for a signal addressed to the terminal. Furthermore, the different symbols within a slot correspond to, for example, the preceding symbol and the second candidate symbol.

[0152] In this operation example 3-1, the PSCCH candidates are limited to the second candidate, but the number of candidates may be increased to a third candidate, a fourth candidate, and so on.

[0153] In addition, the transmission start position of the PSSCH when the PSCCH can be detected in the second candidate may be determined in advance, or information indicating the transmission start position of the PSSCH (e.g., symbol number) may be notified by a bit of the PSCCH.

[0154] In addition, it may be specified that resources after the resource from which the PSCCH is transmitted cannot be reserved for a PSCCH placed in a candidate other than the first candidate. This specification makes it possible to prevent resources after the resource from being reserved for a PSCCH that is not detected by the terminal.

[0155] 10 illustrates an example in which the resource of the signal transmitted in slot #K is a sidelink resource of NR, but the present disclosure is not limited to this. For example, the signal transmitted in slot #K in the example of FIG. 10 may be another signal such as Wi-Fi.

[0156] 10 shows an example in which the LBT is Type 1 LBT, but the present disclosure is not limited to this. For example, an operation similar to the above example operation may be performed using Type 2 LBT.

[0157] As described above, in the third embodiment, if a transmission right cannot be acquired at the beginning of a slot reserved in advance, a sidelink signal is transmitted from a symbol after the beginning of the slot. This allows the pre-reserved resources to be used effectively, thereby improving resource utilization efficiency. Furthermore, in the third embodiment, when the resource is reserved in advance, the PSCCH is transmitted from the second candidate position, so that a terminal that is a target for receiving the reserved resource can efficiently detect the PSCCH. Furthermore, since terminals that are not a target for receiving the reserved resource do not detect the PSCCH, an increase in the number of detections by terminals that are not a target for receiving the reserved resource can be suppressed.

[0158] (Embodiment 4) In this embodiment 4, a terminal performs Type 2 LBT in a slot in which a PSCCH is detected or in which a PSCCH is transmitted, and then transmits a PSFCH, and in a slot in which a PSCCH is not detected or in which a PSCCH is not transmitted, a terminal performs Type 1 LBT and then transmits a PSFCH. According to this embodiment 4, in slots in which a PSCCH and / or a PSSCH is transmitted, the PSCCH and / or a PSSCH and the PSFCH can be transmitted in the same COT, thereby improving resource utilization efficiency.

[0159] The configuration of the terminal according to the fourth embodiment may be the same as that of terminal 200a shown in Fig. 9 or may be the same as that of terminal 200 shown in Fig. 5. Alternatively, the configuration of the terminal according to the fourth embodiment may be the same as that of terminal 200a shown in Fig. 9 or that of terminal 200 shown in Fig. 5, with the addition of a function to perform the operation example described below.

[0160] [Operation Example 4-1] Fig. 11 is a diagram showing a first example of sidelink communication in Operation Example 4-1 of Embodiment 4. The horizontal axis of Fig. 11 represents the time axis, and the vertical axis represents the frequency axis.

[0161] In FIG. 11, terminal A transmits the PSFCH after the slot in which terminal B transmits the PSCCH and / or PSSCH.

[0162] Terminal A detects the PSCCH transmitted by terminal B and recognizes that a PSCCH and / or a PSSCH are present in the slot. When terminal A recognizes that a PSCCH and / or a PSSCH are present in the slot, it performs Type 2 LBT from the beginning of the symbol following the last symbol of the PSSCH. When terminal A recognizes that the channel is not being used by Type 2 LBT, it starts transmitting the PSFCH immediately after the end of Type 2 LBT. When terminal A starts transmitting the PSFCH immediately after the end of Type 2 LBT, it performs CP extension, lengthens the CP length of the symbol that transmits a copy of the PSFCH for AGC (hereinafter referred to as the "AGC symbol"), and starts transmission from the symbol before the AGC symbol.

[0163] By transmitting the PSFCH in this manner, it can be assumed that the PSCCH and / or PSSCH transmitted by terminal B and the PSFCH transmitted by terminal A are transmitted in the same COT.

[0164] In addition, since PSFCH can be multiplexed and transmitted by multiple terminals, there is a possibility that terminals other than terminal A may also transmit simultaneously, but by implementing Type 2 LBT with sensing intervals of the same length among multiple terminals, multiple terminals can start transmitting simultaneously, making multiplexing possible.

[0165] Note that, when terminal A is the terminal receiving the PSCCH and / or PSSCH transmitted by terminal B, terminal A needs to switch from reception to transmission before transmitting the PSFCH. If there is insufficient time to switch from reception to transmission and if transmission of the PSFCH is prioritized over reception of the PSSCH, terminal A may stop reception of the PSSCH midway and switch to transmission of the PSFCH. Note that, if there is insufficient time to switch from reception to transmission and if reception of the PSSCH is prioritized over transmission of the PSFCH, terminal A does not need to transmit the PSFCH.

[0166] Fig. 12 is a diagram showing a second example of sidelink communication in operation example 4-1 of embodiment 4. The horizontal axis of Fig. 12 represents the time axis, and the vertical axis represents the frequency axis.

[0167] In FIG. 12, terminal A, which is the same terminal that transmits the PSCCH and / or PSSCH, transmits the PSFCH after the slot in which terminal A transmits the PSCCH and / or PSSCH.

[0168] In this case, terminal A operates at the same timing as in the example shown in Fig. 11. For example, terminal A performs Type 2 LBT from the beginning of the symbol following the final symbol of the PSSCH. Then, when terminal A recognizes that the channel is not being used by Type 2 LBT, it starts transmitting the PSFCH immediately after Type 2 LBT ends. When terminal A starts transmitting the PSFCH immediately after Type 2 LBT ends, it performs CP extension, lengthens the CP length of the symbol that transmits a copy of the PSFCH for AGC (hereinafter referred to as the "AGC symbol"), and starts transmission from the symbol before the AGC symbol.

[0169] By transmitting the PSFCH as illustrated in FIG. 12 , even if the terminal transmitting the PSCCH and / or PSSCH is the same as the terminal transmitting the PSFCH, by providing a sensing period in which Type 2 LBT is performed, when a PSFCH transmitted by a terminal other than the terminal that transmitted the PSCCH and / or PSSCH is multiplexed, it is possible to ensure a sensing period in which the other terminal performs Type 2 LBT.

[0170] Fig. 13 is a diagram showing a third example of sidelink communication in operation example 4-1 of embodiment 4. The horizontal axis of Fig. 13 represents the time axis, and the vertical axis represents the frequency axis.

[0171] 13 shows a case where terminal A does not detect a PSCCH in a slot. In this case, terminal A that does not detect a PSCCH in a slot performs Type 1 LBT before transmitting a PSFCH, and starts transmitting the PSFCH. Note that in this case, unlike the examples of FIGS. 11 and 12, there is no need to perform a CP extension.

[0172] The start position of AGC in the figure may be the position where transmission of the PSFCH starts.

[0173] As described above, in Embodiment 4, a terminal performs Type 2 LBT in a slot in which a PSCCH is detected or in which a PSCCH is transmitted, and then transmits a PSFCH, and in a slot in which a PSCCH is not detected or in which a PSCCH is not transmitted, a terminal performs Type 1 LBT and then transmits a PSFCH. According to Embodiment 4, in slots in which a PSCCH and / or a PSSCH is transmitted, the PSCCH and / or a PSSCH and the PSFCH can be transmitted in the same COT, thereby improving resource utilization efficiency.

[0174] [Variations] The operation examples of the above-described embodiments may be used in combination.

[0175] 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.

[0176] When the sidelink configuration is preconfigured, the configuration method may be preconfigured in specifications or preconfigured in a Subscriber Identity Module (SIM). Alternatively, the sidelink configuration may be preconfigured in an application layer called "pre-configured," in a system information block (SIB) called "configured" and / or other higher layers such as radio resource control (RRC), or in medium access control (MAC).

[0177] Although the above-described embodiments have been described as 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.

[0178] Note that 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.

[0179] 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.

[0180] 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.

[0181] The guard symbol may also be called a gap symbol.

[0182] Depending on the SCS, the availability of each of the above embodiments or each of the operation examples may be changed.

[0183] Note that Type 1 LBT and Type 2 LBT may be called by different names in sidelink communication.

[0184] The SCI format transmitted on the PSCCH may be SCI format 1-A or a newly added SCI format.

[0185] The above embodiment may be applied to S-PSS / SSS / PSBCH.

[0186] Note that 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 time and frequency widths of the signals illustrated in each figure are not limited to the illustrated examples. Furthermore, the slot size, resource size, channel size, signal size, etc. are not limited to the above-described examples. Furthermore, the SCS value, LBT sensing period, etc. are not limited to the above-described examples.

[0187] In addition, in the above-described embodiments, the length of the sidelink signal is adjusted by increasing the CP length of the sidelink signal using the CP extension, but the present disclosure is not limited to this. Instead of increasing the CP length, the length may be adjusted by adding a known signal.

[0188] 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."

[0189] 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.

[0190] The base station may be referred to as a gNodeB or a gNB, and the terminal may be referred to as a UE.

[0191] 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.

[0192] Furthermore, the notation "... section" in the above-described embodiments may be replaced with other notations such as "... circuitry," "... device," "... unit," or "... module."

[0193] It should be noted that terms such as "interpretation," "identification," "judgment," "determination," "decision," "calculation," "grasp," "recognition," "confirmation," or "understanding" may be used interchangeably.

[0194] (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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] (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.

[0200] 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.

[0201] (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.

[0202] (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.

[0203] 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.

[0204] (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.

[0205] (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).

[0206] (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, a Single Carrier-Frequency Division Multiplexing (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.

[0207] (Frequency Band) An embodiment of the present disclosure may be applied to either a licensed band or an unlicensed band.

[0208] (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.

[0209] 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.

[0210] (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.

[0211] 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).

[0212] For example, the system architecture generally assumes a Next Generation - Radio Access Network (NG-RAN) comprising 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).

[0213] 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 the 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.

[0214] For example, the Medium-Access-Control layer handles logical channel multiplexing and scheduling and scheduling-related functions, including handling various numerologies.

[0215] 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.

[0216] 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.

[0217] 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 valid 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.

[0218] 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).

[0219] <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.

[0220] 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.

[0221] The Access and Mobility Management Function (AMF) hosts the following main functions: - Termination of Non-Access Stratum (NAS) signaling; - Security of NAS signaling; - Security control of Access Stratum (AS); - Signaling 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).

[0222] Furthermore, the User Plane Function (UPF) hosts the following main functions: - anchor point for intra-RAT / 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.

[0223] 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.

[0224] <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).

[0225] 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 Signaling Radio Bearer 2 (SRB2) and 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.

[0226] 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.

[0227] <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).

[0228] The URLLC use case has stringent performance requirements for throughput, latency, and availability. It is envisioned as one of the enabling technologies for future applications such as wireless control of industrial production 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.

[0229] 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.

[0230] 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.

[0231] 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 and extends battery life from the UE's perspective.

[0232] 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.

[0233] For NR URLLC, further use cases with more stringent requirements are envisaged, such as factory automation, transportation, and power distribution, with high reliability (up to 10-6 level reliability), 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)).

[0234] 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).

[0235] <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.

[0236] 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.

[0237] 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.

[0238] 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.

[0239] 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.

[0240] 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.

[0241] 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.

[0242] 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.

[0243] 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.

[0244] 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.

[0245] 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.

[0246] 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.

[0247] 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.

[0248] A communication device according to one embodiment of the present disclosure includes a control circuit that determines a transmission time of a transmission signal based on a sensing interval corresponding to a sensing method for checking the availability of a channel, and a transmission circuit that transmits the transmission signal during the transmission time.

[0249] In one embodiment of the present disclosure, the control circuit shortens the transmission time when the length of the sensing interval is longer than the length of one symbol of the transmission signal, more than when the length of the sensing interval is shorter than the length of one symbol of the transmission signal.

[0250] In one embodiment of the present disclosure, the control circuit determines k such that the length of k+1 symbols (k is an integer greater than or equal to 1) is longer than the length of the sensing interval, and shortens the transmission time by reducing the number of symbols of the transmission signal by k symbols.

[0251] In one embodiment of the present disclosure, when the control circuit confirms that the channel is free, it sets a channel occupancy time, and the transmission circuit transmits information regarding the channel occupancy time to another communication device.

[0252] In one embodiment of the present disclosure, when the control circuit confirms that the channel is free, it sets the channel occupancy time based on the slot number.

[0253] In one embodiment of the present disclosure, when the control circuit acquires information indicating that the channel occupancy time is two slots or more, it checks the availability of the channel using a sensing method used within the range in which the channel occupancy time is set.

[0254] In one embodiment of the present disclosure, when the control circuit confirms that the channel is vacant using a sensing method used within the range in which the channel occupancy time is set, it determines the timing immediately after the end of the sensing period as the timing to start transmitting the transmission signal.

[0255] In one embodiment of the present disclosure, the control circuit adjusts the transmission start timing by changing the length of a cyclic prefix added to the beginning of the transmission signal.

[0256] In one embodiment of the present disclosure, the control circuit determines a transmission start timing of the transmission signal according to a priority of the transmission signal.

[0257] In one embodiment of the present disclosure, the control circuit adjusts the transmission start timing of the transmission signal by changing the length of a cyclic prefix added to the beginning of the transmission signal.

[0258] In one embodiment of the present disclosure, when the control circuit reserves transmission in the Kth slot (K is an integer greater than or equal to 0) and is unable to confirm that the channel in the Kth slot is available in a first sensing period before the beginning of the Kth slot, the control circuit checks the availability of the channel in a second sensing period after the beginning of the Kth slot.

[0259] In one embodiment of the present disclosure, if the control circuit confirms that the channel is available in the second sensing period after the beginning of the Kth slot, it places a control signal after the second sensing period in the Kth slot.

[0260] In one embodiment of the present disclosure, when the control circuit confirms that the channel is free during the sensing period starting from the end timing of the control signal in the slot in which the control signal is detected, the control circuit controls the transmission of a feedback signal from the end timing of the sensing period, and the transmitting circuit transmits the feedback signal based on the control of the control circuit.

[0261] In a communication method according to one embodiment of the present disclosure, a communication device determines a transmission time of a transmission signal based on a sensing interval corresponding to a sensing method for checking the availability of a channel, and transmits the transmission signal at the determined transmission time.

[0262] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2022-069209, filed on April 20, 2022, are incorporated herein by reference in their entirety.

[0263] One aspect of the present disclosure is useful in wireless communication systems.

[0264] 100 Base station 101, 221 Radio transmission / reception unit 102, 220, 220a Control unit 200, 200a Terminal 201 Receiving unit 202, 202a LBT carrier sense unit 203 Signal separation unit 204 Demodulation unit 205, 205a Control signal sensing unit 206 Error correction decoding unit 207, 207a Guard period setting unit 208, 208a Signal allocation unit 209 Error correction coding unit 210 Modulation unit 211, 211a Control signal generation unit 212, 212a Transmission unit

Claims

1. A control circuit for determining the length of a cyclic prefix added to the beginning of a transmitted signal, A transmitting circuit that transmits the aforementioned transmission signal, Equipped with, The length of the cyclic prefix is ​​determined based on one value selected from a plurality of values. Communication device.

2. The one value is randomly selected from the plurality of values, and the plurality of values ​​include a sensing interval of 25 μs for Type A. The communication device according to claim 1.

3. The plurality of values ​​include 34 μs, 43 μs, and 52 μs, The communication device according to claim 2.

4. The length of the cyclic prefix is ​​the period obtained by subtracting the period determined based on the one value from the period based on the symbol length. The communication device according to claim 1.

5. The transmitting circuit, when it confirms that the channel is idle using Type 2A or Type 2B sensing, transmits the transmission signal at the timing immediately after the sensing. The communication device according to claim 1.

6. The control circuit determines the length of the cyclic prefix according to the priority of the transmitted signal. The communication device according to claim 1.

7. The priority is notified by side link control information (SCI), The communication device according to claim 6.

8. If the control circuit cannot confirm that a channel is available for transmitting the transmit signal from a first start symbol in a slot, it checks the availability of the channel for transmitting the transmit signal from a second start symbol that is later than the first start symbol in the slot. The communication device according to claim 1.

9. The second start symbol is set in advance by the upper layer parameter. The communication device according to claim 8.

10. The transmitting circuit shares channel occupancy time corresponding to a control channel or data channel transmitted from another communication device and transmits a feedback signal within a range in which the channel occupancy time is set. The communication device according to claim 1.

11. The control circuit applies the cyclic prefix to the feedback signal. The communication device according to claim 10.

12. A communication device, Determine the length of the cyclic prefix to be added to the beginning of the transmitted signal. The aforementioned transmission signal is transmitted, The length of the cyclic prefix is ​​determined based on one value selected from a plurality of values. Communication method.

13. A control circuit for controlling the determination of the length of a cyclic prefix added to the beginning of a transmitted signal, A transmitting circuit that controls the transmission of the aforementioned transmission signal, Equipped with, The length of the cyclic prefix is ​​determined based on one value selected from a plurality of values. Integrated circuit.