Base station, communication terminal, communication method, control method and program

Abstract

The purpose of the present disclosure is to provide a base station capable of performing communication by using a random access channel considering an SBFD operation. A base station according to the present disclosure is provided with a communication unit that delivers, into a cell, system information including resource information indicating whether or not SBFD (subband full non-overlapping duplex) compatible resources can be used. When the resource information indicates that the SBFD compatible resources can be used, an uplink resource to be used for uplink transmission, which is among the SBFD compatible resources, is used for RACH (Random Access Channel) transmission in a communication terminal capable of transmitting data by using the SBFD compatible resources.

Description

Base station, communication terminal, communication method, control method and program

[0001] The present disclosure relates to a base station, a communication terminal, a communication method, a control method, and a program.

[0002] The 3GPP (3rd Generation Partnership Project) (registered trademark), which develops communication standards, is studying subband non-overlapping full duplex (SBFD) operation. SBFD enables simultaneous uplink (UL) and downlink (DL) communications using different subbands with non-overlapping frequency bands in each slot used in TDD (Time Division Duplex) communications. Specifically, a base station performs full-duplex communications that enable simultaneous uplink and downlink communications, and a communication terminal performs uplink or downlink communications by performing half-duplex communications using allocated resources.

[0003] Non-Patent Document 1 indicates that SBFD operation will be clarified in the future for UEs (User Equipment) in RRC (Radio Resource Control)_IDLE / INACTIVE mode to support random access using SBFD symbols. UE is used as a general term for communication terminals in 3GPP.

[0004] Revised WID: Evolution of NR duplex operation: Sub-band full duplex (SBFD), 3GPP TSG RAN Meeting #104 RP-241614

[0005] Currently, it is not clear how a UE in RRC_IDLE / INACTIVE mode communicates with the network using a random access channel using SBFD symbols or SBFD resources.

[0006] One object of the present disclosure is to provide a base station, a communication terminal, a communication method, a control method, and a program that can perform communication using a random access channel that takes SBFD operation into consideration.

[0007] A base station according to the present disclosure includes a communication unit that distributes system information within a cell, the system information including resource information indicating whether or not subband non-overlapping full duplex (SBFD) compatible resources can be used. When the resource information indicates that the SBFD compatible resources can be used, uplink resources used for uplink transmission among the SBFD compatible resources are used for RACH (Random Access Channel) transmission in a communication terminal that can transmit data using the SBFD compatible resources.

[0008] A communication terminal according to the present disclosure includes a receiving unit that receives system information including resource information indicating whether or not SBFD-compatible resources can be used, and a transmitting unit that, when the resource information indicates that the SBFD-compatible resources can be used, performs RACH transmission using uplink resources that are used for uplink transmission among the SBFD-compatible resources.

[0009] The communication method of the present disclosure distributes system information within a cell, including resource information indicating whether SBFD-compatible resources can be used, and if the resource information indicates that the SBFD-compatible resources can be used, uplink resources among the SBFD-compatible resources used for uplink transmission are used for RACH transmission in a communication terminal that can transmit data using the SBFD-compatible resources.

[0010] In the control method of the present disclosure, when a first RACH transmission using SBFD-incompatible resources associated with a first slot and a second RACH transmission using SBFD-compatible resources associated with a second slot that is temporally consecutive to the first slot and is later than the first slot, the control method calculates a first RA-RNTI to be used for the first RACH transmission using identification information of the first slot, and calculates a second RA-RNTI to be included in the second RACH transmission using identification information of the second slot.

[0011] The program of the present disclosure causes a computer to distribute system information within a cell, including resource information indicating whether SBFD-compatible resources can be used, and if the resource information indicates that the SBFD-compatible resources can be used, uplink resources among the SBFD-compatible resources used for uplink transmission are used for RACH transmission in a communication terminal that can transmit data using the SBFD-compatible resources.

[0012] The present disclosure makes it possible to provide a base station, a communication terminal, a communication method, a control method, and a program that are capable of performing communication using a random access channel that takes SBFD operation into consideration.

[0013] FIG. 1 shows an example configuration of a base station. FIG. 2 shows an example configuration of a communication terminal according to the present disclosure. FIG. 3 shows the flow of communication processing between a gNB and a UE. FIG. 4 shows a configuration of radio resources including SBFD-compatible resources. FIG. 5 shows a BWP-UplinkCommonIE included in system information. FIG. 6 shows an SI-SchedulingInfoIE. FIG. 7 shows a rach-ConfigCommonIE. FIG. 8 shows an SI-SchedulingInfoIE. FIG. 9 shows a configuration of radio resources including SBFD-compatible resources. FIG. 10 shows that part of Band #1 overlaps with Band #2. FIG. 11 shows the configuration of a radio frame. FIG. 12 shows a FeatureCombinationIE in which numbers that can be used by SBFD-awarenessUEs are defined. FIG. 13 shows a Codepoint associated with SBFD-awarenessUEs. FIG. 14 is a block diagram showing example configurations of a base station and a gNB. FIG. 15 is a block diagram showing example configurations of a communication terminal and a UE.

[0014] (First Embodiment) FIG. 1 illustrates a configuration example of a base station 10. The base station 10 may be a computer device operated by a processor executing a program stored in a memory. The base station 10 may be a base station system including a device for performing wireless communication and a device for performing baseband processing. In other words, the components constituting the base station 10 may be distributed across multiple devices. The multiple devices may be connected via a network. The base station 10 may be a gNB (g Node B) supporting a wireless communication standard known as 5G (5th Generation) in 3GPP, or an eNB (evolved Node B) supporting a wireless communication standard known as 4G (4th Generation). Alternatively, the base station 10 may be a base station supporting a wireless communication standard known as 6G (6th Generation).

[0015] The base station 10 includes a communication unit 11. The communication unit 11 may be software or a module that performs processing by a processor executing a program stored in a memory. Alternatively, the communication unit 11 may be hardware such as a circuit or a chip. The communication unit 11 may be used as a means for performing communication.

[0016] The communication unit 11 distributes, within the cell, system information including resource information indicating whether or not it is possible to use SBFD-compatible resources. The resource information may indicate whether or not the communication terminal 20 is able to use SBFD-compatible resources in communication with the base station 10. The resource information may be information that explicitly or implicitly indicates that SBFD-compatible resources are configured in communication with the base station 10.

[0017] The SBFD-compatible resource is a resource that allows uplink and downlink communications to be performed simultaneously in a predetermined time domain using different subbands whose frequency domains do not overlap. The resource may be represented, for example, using the time domain and the frequency domain. The time domain may be represented, for example, using slots or symbols. The frequency domain may be represented, for example, using subcarriers, subbands, or PRBs (physical resource blocks). The uplink is a link used when transmitting data from the communication terminal 20 to the base station 10. The downlink is a link used when transmitting data from the base station 10 to the communication terminal 20.

[0018] Specifically, the SBFD-compatible resource may be a resource including, in the same slot, a first subband used for uplink communication and a second subband used for downlink communication. The base station 10 simultaneously performs uplink communication and downlink communication with multiple communication terminals using the SBFD-compatible resource. Furthermore, the communication terminal 20 performs uplink communication or downlink communication with the base station using allocated resources within the SBFD-compatible resource. In other words, the base station 10 performs full-duplex communication using the SBFD-compatible resource, and the communication terminal 20 performs half-duplex communication using the SBFD-compatible resource.

[0019] On the other hand, non-SBFD-compatible resources are resources that are not SBFD-compatible resources. Specifically, non-SBFD-compatible resources may be resources associated with a predetermined time domain and used for performing either uplink or downlink communications.

[0020] The system information is information distributed within a cell formed by the base station 10. The system information may include frequency information used in the cell, information related to communication timing, etc. The cell may be an area in which communication with the base station 10 is possible. The resource information indicating whether SBFD-compatible resources can be used may be information instructing whether to communicate with the base station 10 using SBFD-compatible resources or whether to communicate with the base station 10 using SBFD-compatible resources or whether to communicate with the base station 10 using SBFD-non-compatible resources. Alternatively, the resource information indicating whether SBFD-compatible resources can be used may be information instructing whether to perform uplink communication using SBFD-compatible resources or whether to perform uplink communication using SBFD-non-compatible resources.

[0021] When a communication terminal capable of transmitting and receiving data using SBFD-compatible resources receives resource information indicating that the SBFD-compatible resources can be used, the communication terminal uses the SBFD-compatible resources for RACH (Random Access Channel) transmission. Specifically, a communication terminal capable of transmitting and receiving data using SBFD-compatible resources uses uplink resources used for uplink transmission among the SBFD-compatible resources for RACH transmission. RACH transmission may be, for example, transmitting a preamble using a PRACH (Physical RACH). For example, when the communication terminal 20 is powered on from an OFF state, the communication terminal 20 performs an initial connection to the base station 10. The initial connection performed by the communication terminal 20 may be referred to as random access. The channel used in random access is referred to as RACH.

[0022] FIG. 2 illustrates a configuration example of a communication terminal 20 according to the present disclosure. The communication terminal 20 may be a computer device operated by a processor executing a program stored in a memory. The communication terminal 20 may be a smartphone terminal, an IoT (Internet of Things) terminal, or the like. The communication terminal 20 may be a UE (User Equipment), a generic term used for communication terminals in 3GPP. The communication terminal 20 is assumed to be a communication terminal capable of transmitting and receiving data using SBFD-compatible resources. It is also assumed that the RRC_IDLE / INACTIVE mode is set for the communication terminal 20. In other words, it is assumed that the communication terminal 20 operates in the RRC_IDLE / INACTIVE mode. The RRC_IDLE / INACTIVE mode may be, for example, a state in which the communication terminal 20 does not identify the base station 10. It is also assumed that in the RRC_IDLE mode, the base station 10 does not hold the context of the communication terminal 20, and the core network holds the context of the communication terminal 20. It is also assumed that in the RRC_INACTIVE mode, the base station 10 and the core network hold the context of the communication terminal 20.

[0023] The communication terminal 20 has a receiving unit 21 and a transmitting unit 22. The receiving unit 21 and the transmitting unit 22 may be software or modules that perform processing by a processor executing a program stored in a memory. Alternatively, the receiving unit 21 and the transmitting unit 22 may be hardware such as a circuit or a chip. The receiving unit may be used as a means for receiving data. The transmitting unit may be used as a means for transmitting data.

[0024] The receiver 21 receives system information including resource information indicating whether SBFD-compatible resources can be used. If the resource information indicates that SBFD-compatible resources can be used, the transmitter 22 performs RACH transmission using uplink resources used for uplink transmission among the SBFD-compatible resources. If the communication terminal 20 is a communication terminal that cannot transmit and receive data using SBFD-compatible resources, the transmitter 22 performs RACH transmission using SBFD-incompatible resources.

[0025] As described above, the base station 10 transmits system information including resource information indicating whether or not it is possible to use SBFD-compatible resources to the communication terminal 20. As a result, the communication terminal 20 that can transmit and receive data using the SBFD-compatible resources can use the SBFD-compatible resources for RACH transmission.

[0026] (Embodiment 2) Figure 3 shows the flow of communication processing between gNB 30 and UE 40. gNB 30 corresponds to base station 10 in Figure 1. UE 40 corresponds to communication terminal 20 in Figure 2. Furthermore, UE 40 is a UE capable of transmitting and receiving data using SBFD-compatible resources. A UE capable of transmitting and receiving data using SBFD-compatible resources may be referred to as an SBFD-aware UE, for example. First, gNB 30 transmits system information to UE 40 (S21). The system information includes, for example, information related to RACH configuration. Furthermore, the system information may be a System Information Block (SIB) broadcast to UEs in a cell formed by gNB 30. Specifically, the SIB may be SIB1. SIB1 may include information indicating the timing at which other system information, such as SIB2, is transmitted. Here, in explaining information related to RACH configuration, the configuration of a radio frame used in wireless communication between the gNB 30 and the UE 40 will be explained using Fig. 4. Fig. 4 shows the configuration of radio resources including SBFD-compatible resources.

[0027] The radio frame in FIG. 4 is shown using the time domain and the frequency domain. The radio frame includes slots 1 to 5. Slot 1 is used for downlink transmission. Slot 5 is used for uplink transmission. Slots 2 to 4 are used for downlink and uplink transmission. Specifically, in slots 2 to 4, the frequency domain used for downlink transmission and the frequency domain used for uplink transmission are separated. Slots 2 to 4 are SBFD-compatible resources, and slots 1 and 5 are SBFD-incompatible resources. Each of slots 1 to 5 includes a predetermined number of symbols.

[0028] R1 to R5 indicate identification information of resources used by UE 40 for RACH transmission. R1 is a resource included in slot 5. R2 is a resource included in slot 4. Also, R2 is a resource with the same frequency bandwidth and frequency position as R1. R2 includes a portion of the resources used for downlink transmission. Therefore, UE 40 performs RACH transmission using resources used for uplink transmission among the resources indicated by R2. R3 is a resource included in slot 3. R4 is a resource that spans slots 2 and 3, which are SBFD-compatible resources. R5 is a resource that spans slot 4, which is an SBFD-compatible resource, and slot 5, which is an SBFD-incompatible resource. R1 to R3 are resources assigned to temporally consecutive symbols within a slot. R4 and R5 are resources assigned to temporally consecutive symbols between slots.

[0029] The information on RACH configuration included in the system information may be information specifying, for example, R1 to R5 as RACH occasions (ROs). Alternatively, the information on RACH configuration may be information indicating the start symbol position of the RACH opportunity and the number of symbols consecutively allocated for the RACH opportunity. Furthermore, the information on RACH configuration may include information on frequency bandwidth, information indicating subcarrier spacing, etc. The start symbol position may be indicated by, for example, a slot number and a symbol position. Alternatively, the start symbol position may be indicated only by the symbol position.

[0030] Here, the information regarding the RACH configuration may be one piece of configuration information commonly used for SBFD-compatible resources and non-SBFD-compatible resources. Alternatively, the information regarding the RACH configuration may be two pieces of configuration information, one piece of configuration information used for SBFD-compatible resources and one piece of configuration information used for non-SBFD-compatible resources. For example, the start symbol position in the one piece of configuration information commonly used for SBFD-compatible resources and non-SBFD-compatible resources may be indicated only by the symbol position. Furthermore, when two pieces of configuration information are used, the start symbol position in the configuration information used for SBFD-compatible resources may be indicated by at least one SBFD-compatible slot number and the symbol position.

[0031] The system information further includes information indicating whether SBFD-compatible resources are used for RACH transmission. SBFD-compatible resources may be, for example, symbols included in slots 2 to 4, which correspond to SBFD-compatible resources. Symbols included in slots 2 to 4, which correspond to SBFD-compatible resources, may be referred to as SBFD symbols. Furthermore, symbols included in slots 1 and 5, which correspond to SBFD-incompatible resources, may be referred to as non-SBFD symbols. The information indicating whether SBFD-compatible resources are used may be, for example, information indicating that (A) only SBFD symbols are used, (B) only non-SBFD symbols are used, or (C) all symbols are used for RACH transmission. The system information may include any of (A) to (C).

[0032] Furthermore, the system information may include information indicating whether each slot is an SBFD-compatible resource or a non-SBFD-compatible resource. Furthermore, the system information may include uplink or downlink band information included in the SBFD-compatible resource and band information of the non-SBFD-compatible resource. The band information may be information indicating a frequency bandwidth and a frequency location.

[0033] Here, details of the system information will be explained. Figure 5 shows the BWP (Band Width Part)-Uplink Common IE (Information Element) included in the system information. The BWP-Uplink Common IE is used to set common parameters related to the uplink BWP. The BWP-Uplink Common IE is information specific to the cell formed by the gNB 30. The BWP is, for example, the frequency bandwidth, frequency position, etc. that a UE located in the cell formed by the gNB 30 should use for communication.

[0034] The BWP-UplinkCommon IE includes a rach-ConfigCommon IE. Information about the RACH configuration corresponds to the rach-ConfigCommon IE. Furthermore, the BWP-UplinkCommon IE includes a validROsymbol-SBFD-r19 IE. Information indicating whether SBFD-compatible resources are used for RACH transmission corresponds to the validROsymbol-SBFD-r19 IE.

[0035] Specifically, the validROsymbol-SBFD-r19 IE is set to "non-SBFD symbol only," "SBFD symbol only," or "all." "Non-SBFD symbol only" indicates that the UE 40 uses only ROs of non-SBFD symbols when transmitting the RACH, i.e., R1 in FIG. 4 is a valid RO. "SBFD symbol only" indicates that the UE 40 uses only ROs including SBFD symbols when transmitting the RACH, i.e., R2 to R5 in FIG. 4 are valid ROs. "All" indicates that the UE 40 uses ROs including SBFD symbols or non-SBFD symbols, or uses SBFD symbols and non-SBFD symbols when transmitting the RACH, i.e., all of R1 to R5 in FIG. 4 are valid ROs.

[0036] Returning to FIG. 3 , after receiving the system information, the UE 40 selects resources to be used for RACH transmission (S22). If the validROsymbol-SBFD-r19 IE is set to "non-SBFDsymbol only," the UE 40 selects a random access occasion (occasion) with RACH opportunities in SBFD-incompatible resources as valid ROs. That is, the UE 40 performs RACH transmission with resource R1 in slot 5 as a valid RO (RACH opportunity). If the validROsymbol-SBFD-r19 IE is set to "SBFDsymbol only," the UE 40 selects a random access occasion with RACH opportunities in SBFD-compatible resources as valid ROs. That is, the UE 40 performs RACH transmission with resources R2 to R5 in slots 2 to 4 as valid ROs (RACH transmission opportunities).

[0037] Here, a case will be described in which the information regarding the RACH configuration includes one piece of configuration information commonly used for SBFD-compatible resources and SBFD-non-compatible resources. In this case, the UE 40 may select resource R2, for example, as the same symbol position, frequency band, and frequency bandwidth as resource R1 in slot 1, which is a SBFD-non-compatible resource. Alternatively, based on one piece of configuration information commonly used for SBFD-compatible resources and SBFD-non-compatible resources, the arrangement and interpretation method of frequency designation for SBFD-compatible resources and frequency designation for SBFD-non-compatible resources may be defined. By defining the arrangement and interpretation method of frequency designation, the UE 40 may select resources of different frequency bands and the same frequency bandwidth.

[0038] Furthermore, a case will be described in which two pieces of configuration information, that is, configuration information used for SBFD-compatible resources and configuration information used for SBFD-non-compatible resources, are used as information regarding RACH configuration. In this case, the configuration information used for the SBFD-compatible resources can specify a frequency bandwidth, etc., different from that of the resources for the SBFD-non-compatible resources. Therefore, when selecting an SBFD-compatible resource, UE 40 may select, for example, at least one of resources R3 to R5, which has a different symbol position, a different frequency band, or a different frequency bandwidth from slot 5, which is an SBFD-non-compatible resource.

[0039] When "all" is set in the validROsymbol-SBFD-r19 IE, the UE 40 may select a random access occasion with all of the resources R1 to R5 as valid ROs (RACH opportunities).

[0040] Next, the UE 40 performs RACH transmission using the selected resource (S23). The RACH transmission may be, for example, transmitting a preamble using a PRACH (Physical RACH) as a message 1 used in the RACH procedure.

[0041] As described above, UE40 can perform RACH transmission using SBFD-compatible resources based on information regarding RACH configuration received from gNB30.

[0042] Furthermore, by setting the validROsymbol-SBFD-r19 IE to "SBFDsymbol only" or "all," the gNB 30 can direct the resources used by an SBFD-aware UE when transmitting a RACH to SBFD-compatible resources. Directing an SBFD-aware UE to SBFD-compatible resources may mean offloading the SBFD-aware UE to SBFD-compatible resources. This can reduce the number of UEs that perform RACH transmission using SBFD-incompatible resources. As a result, collisions that occur during RACH transmission can be reduced.

[0043] Furthermore, when the validROsymbol-SBFD-r19 IE is set to "all," the SBFD-aware UE considers both RACH opportunities for SBFD-enabled resources and RACH opportunities for SBFD-incompatible resources to be valid ROs. The SBFD-aware UE may select a random access occasion from the earliest valid RO (RACH opportunity) (a RACH opportunity for SBFD-enabled resources or a RACH opportunity for SBFD-incompatible resources). This allows the SBFD-aware UE to perform RACH transmission earlier.

[0044] Furthermore, the SI-SchedulingInfo IE included in the system information transmitted from the gNB 30 to the UE 40 in step S21 may include information indicating whether or not to use ROs including SBFD-compatible resources. The SI-SchedulingInfo IE indicates relevant information when the UE 40 requests system information from the gNB 30. The request of the UE 40 for system information from the gNB 30 may be referred to as an on-demand system information (on-demand SI) request. The UE 40 transmits the on-demand system information request in the RACH procedure. Specifically, the UE 40 transmits the on-demand system information request to the gNB 30 using message 1 or message 3 in the RACH procedure.

[0045] Fig. 6 shows the SI-SchedulingInfo IE. SI-RequestConfigSBFD-validROsymbol-r19, which indicates information on whether ROs including SBFD-compatible resources are used, is set in the SI-SchedulingInfo IE. SI-RequestConfigSBFD-validROsymbol-r19 may be set to "non-SBFDsymbol only," "SBFD symbol only," or "all," similar to the validROsymbol-SBFD-r19 IE.

[0046] Furthermore, the system information transmitted from the gNB 30 to the UE 40 in step S21 may include an sdt-validROsymbol-SBFD-r19 IE, which is information indicating whether or not to use ROs including SBFD-compatible resources. The sdt-validROsymbol-SBFD-r19 IE indicates information indicating whether or not the UE 40 uses SBFD-compatible resources in a random access procedure in RA-SDT (Random Access Small Data Transmission).

[0047] Also, in FIG. 3, an example has been described in which system information is broadcast within a cell formed by gNB 30, but this is not limiting. For example, system information (e.g., SIB1) may be transmitted to UE 40 during the handover procedure. Specifically, during the handover procedure, a handover source base station (e.g., a source gNB or a source BS (Base Station)) transmits a Handover Request message to a handover destination base station (e.g., a target gNB or a target BS). Next, the handover destination base station transmits a Handover Request Acknowledge message to the handover source base station. After receiving the Handover Request Acknowledge message, the handover source base station transmits an RRC Reconfiguration message to the UE to be handed over. The system information may be included in an RRC Reconfiguration message transmitted from the handover source base station to the UE. Resource information indicating whether SBFD-compatible resources can be used may be included in the RRC Reconfiguration message. Alternatively, the base station (gNB or BS) may send an RRC message including system information to a UE in RRC_CONNECTED mode, not limited to the handover procedure.

[0048] (Embodiment 3) Next, a description will be given of a flow of a resource selection process that differs from the resource selection process described in embodiment 2. Note that transmission and reception of messages between the gNB 30 and the UE 40 will be described with reference to FIG.

[0049] The gNB 30 transmits a BWP-UplinkCommon IE including a rach-ConfigCommon IE and a validROsymbol-SBFD-r19 IE to the UE 40, similar to step S21 of Figure 3. Here, the rach-ConfigCommon IE includes at least one reference information.

[0050] FIG. 7 shows that the rach-ConfigCommon IE includes two pieces of reference information, rsrp-ThresholdSSB-SBFD-1-r19 and rsrp-ThresholdSSB-SBFD-2-r19.

[0051] The reference information indicated as rsrp-ThresholdSSB-SBFD-1-r19 may be, for example, information intended to be used to improve coverage. The improvement in coverage may be, for example, an improvement in uplink coverage in the UE 40. To improve the uplink coverage, the UE 40 performs RACH transmission using, for example, long preamble formats. In other words, to improve the uplink coverage, the UE 40 configures the gNB 30 with RACH opportunities compatible with long preamble formats.

[0052] rsrp-ThresholdSSB-SBFD-1-r19 may be, for example, information to be compared with the reception quality of information consisting of a synchronization signal (SS) and a broadcast channel transmitted from the gNB 30 to the UE 40. The broadcast channel may be, for example, a PBCH (Physical Broadcast Channel). The information consisting of the SS and the PBCH may be referred to as an SSB (SS / PBCH Block). The reception quality may be, for example, RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality). The larger the value of the reception quality, the better the reception quality.

[0053] Here, when the downlink reception quality at UE 40 is below rsrp-ThresholdSSB-SBFD-1-r19, the location of UE 40 is considered to be closer to the cell boundary (cell edge) than when the downlink reception quality is above rsrp-ThresholdSSB-SBFD-1-r19. In such a case, it is desirable to have UE 40 utilize RACH opportunities that support long preamble formats in order to improve uplink coverage. Therefore, UE 40 may select resource R4 or R5, which spans two slots and supports long preamble formats, as valid ROs when the validROsymbol-SBFD-r19 IE is set to "SBFD symbol only" or "all" and the downlink reception quality is below rsrp-ThresholdSSB-SBFD-1-r19. Resources R4 and R5 have a larger number of symbols than resources R2 and R3, and therefore can support long preamble formats. Therefore, resources R4 and R5 can extend uplink coverage compared to resources R2 and R3. UE 40 may select resources R2 or R3 as valid ROs when the validROsymbol-SBFD-r19 IE is set to "SBFDsymbol only" and the downlink reception quality exceeds rsrp-ThresholdSSB-SBFD-1-r19. Alternatively, UE 40 may select ROs of non-SBFD-compatible resources as valid ROs when the validROsymbol-SBFD-r19 IE is set to "all" and the downlink reception quality exceeds rsrp-ThresholdSSB-SBFD-1-r19.

[0054] Next, the reference information indicated as rsrp-ThresholdSSB-SBFD-2-r19 may be, for example, information intended to reduce CLI (Cross Link Interference) as interference between UEs. CLI may be, for example, the effect that UE 40 has on the reception quality of downlink reception from gNB 30 in other UEs when UE 40 performs uplink transmission to gNB 30. The effect that uplink transmission of UE 40 has on the reception quality of downlink reception in other UEs may be interference.

[0055] Here, when the downlink reception quality exceeds rsrp-ThresholdSSB-SBFD-2-r19, the location of UE 40 is considered to be closer to the cell center compared to when the downlink reception quality is below rsrp-ThresholdSSB-SBFD-2-r19. The closer the location of UE 40 is to the cell center, the lower the transmission power during uplink transmission, and therefore the impact of UE 40's uplink transmission on the reception quality of downlink reception of other UEs can be said to be small. In such a case, it is desirable to select an "SBFD symbol only" RACH opportunity as the valid ROs for UE 40.

[0056] UE 40 may select resources R2 or R3 in FIG. 4 as valid ROs when the validROsymbol-SBFD-r19 IE is set to "SBFD symbol only" or "all" and the downlink reception quality exceeds rsrp-ThresholdSSB-SBFD-2-r19. In such a case, since UE 40 is located at or near the cell center, coverage improvement is not required. Therefore, UE 40 may select resources R2 or R3 instead of R4 or R5. UE 40 may select resources R4 or R5 in FIG. 4 as valid ROs when the validROsymbol-SBFD-r19 IE is set to "SBFD symbol only" and the downlink reception quality is below rsrp-ThresholdSSB-SBFD-2-r19. Alternatively, when the validROsymbol-SBFD-r19 IE is set to "all" and the downlink reception quality is lower than rsrp-ThresholdSSB-SBFD-2-r19, the UE 40 may select SBFD-incompatible resources as valid ROs.

[0057] rsrp-ThresholdSSB-SBFD-1-r19 is reference information used to determine whether UE 40 is near a cell boundary, and rsrp-ThresholdSSB-SBFD-2-r19 is reference information used to determine whether UE 40 is near a cell center. Therefore, rsrp-ThresholdSSB-SBFD-1-r19 may be a smaller value than rsrp-ThresholdSSB-SBFD-2-r19.

[0058] As described above, UE 40 selects a RACH opportunity from a plurality of resources included in the SBFD-compatible resources based on at least one reference information received from gNB 30. Furthermore, UE 40 can improve uplink coverage, reduce the impact of CLI, and the like by selecting a RACH opportunity based on the reference information.

[0059] In addition, gNB30 may include rsrp-ThresholdSSB-SBFD-1-r19 and rsrp-ThresholdSSB-SBFD-2-r19 in the SI-SchedulingInfo IE, as shown in FIG. 8.

[0060] In addition, gNB30 may include rsrp-ThresholdSSB-SBFD-1-r19 and rsrp-ThresholdSSB-SBFD-2-r19 in the system information as information regarding RA-SDT.

[0061] (Fourth embodiment) Fig. 9 shows a configuration of radio resources including SBFD-compatible resources. Band #1 in Fig. 9 indicates the frequency bandwidth of an SBFD UL subband used for uplink transmission among the SBFD-compatible resources. Band #2 indicates the frequency bandwidth of an initial BWP. The initial BWP may be, for example, the frequency bandwidth of resources used by UE 40 in a random access procedure. The initial BWP may include an initial UL BWP used for uplink transmission and an initial DL BWP used by a downlink device.

[0062] FIG. 9 shows that Band #1 is a subset of Band #2. In other words, FIG. 9 shows that Band #1 is included in Band #2. In contrast, FIG. 10 shows that a portion of Band #1 overlaps with Band #2. When Band #1 is a subset of Band #2 as in FIG. 9, UE 40 sets the frequency bandwidth (e.g., UL initial BWP) used for communication with gNB 30 to Band #2. The setting of the frequency bandwidth used for communication with gNB 30 by UE 40 may be referred to as, for example, RF-operating or RF-tuning. On the other hand, in the case of FIG. 10, when UE 40 matches the frequency bandwidth used for communication with gNB 30 to Band #2, communication using the SBFD UL subband cannot be performed. Therefore, assuming a configuration such as Band #1 and Band #2, gNB30 sets an SBFD-specific initial UL BWP in the system information as a frequency bandwidth including Band #1 and Band #2.

[0063] The SBFD-specific initial UL BWP may be, for example, a frequency bandwidth from the lower limit frequency of Band #1 to the upper limit frequency of Band #2, or may be a frequency bandwidth from the upper limit frequency of Band #1 to the lower limit frequency of Band #2.

[0064] UE40 can perform communication using SBFD UL subbands and non-SBFD UL subbands by setting the frequency bandwidth indicated in the SBFD-specific initial UL BWP and communicating with gNB30.

[0065] If the system information does not include an SBFD-specific initial UL BWP, the UE 40 may use the initial UL BWP as the frequency bandwidth used for communication with the gNB 30. In this case, the initial UL BWP may be set to Band #2.

[0066] Furthermore, if an SBFD-specific initial UL BWP is not defined, Band #1 may always be configured to be a subset of Band #2, as shown in Fig. 9. In this way, if Band #1 is always a subset of Band #2, UE 40 sets the frequency bandwidth of the initial UL BWP used for communication with gNB 30 to Band #2. This allows UE 40 to perform communication using SBFD UL subbands and non-SBFD UL subbands.

[0067] As described above, when the gNB 30 uses the SBFD-specific initial UL BWP, the UE 40 can perform communication using the SBFD UL subband and the non-SBFD UL subband. For example, a case will be described in which the SBFD-specific initial UL BWP is not defined and there is no assumption that Band #1 is always a subset of Band #2. In this case, the UE 40 needs to switch the frequency bandwidth used for communication with the gNB 30 between Band #1 and Band #2 in order to perform communication using the SBFD UL subband and the non-SBFD UL subband. On the other hand, when the SBFD-specific initial UL BWP is defined, the UE 40 can perform communication using the SBFD UL subband and the non-SBFD UL subband without switching the frequency bandwidth used for communication with the gNB 30.

[0068] (Fifth embodiment) Next, a method for preventing overlapping of RA (Random Access)-RNTI (Radio Network Temporary Identifier) ​​used in the random access procedure will be described. The RA-RNTI is determined based on the preamble of the PRACH transmitted from the UE 40 to the gNB 30. The gNB 30 scrambles control information for the UE 40 to receive an RAR (Random Access Response) using the RA-RNTI associated with the preamble of the PRACH transmitted from the UE 40 to the gNB 30. The UE 40 receives the RAR targeted for the UE 40 by receiving the RAR using the RA-RNTI.

[0069] The RA-RNTI is calculated by the following formula:

[0070] RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id...(Formula 1)

[0071] s_id (s_id is a value between 0 and 14) is the index of the first OFDM symbol of the PRACH Occasion corresponding to the RACH opportunity. t_id (t_id is a value between 0 and 80) is the index of the first slot of the PRACH Occasion in the system frame. f_id (f_id is a value between 0 and 8) is the index of the PRACH Occasion in the frequency domain. ul_carrier_id is the identifier of the uplink carrier used for random access preamble transmission.

[0072] Here, the calculation of the RA-RNTI in the radio frame configuration shown in Fig. 11 will be described. In the radio frame shown in Fig. 11, slot 4 is an SBFD-incompatible resource, and slot 5 is an SBFD-compatible resource. Resources R6 and R8 are set in slot 4. Resource R7 is set as a resource spanning slot 4 and slot 5.

[0073] When a random access procedure is performed using resources R6 and R7, consecutive symbols are assigned to resources R6 and R7, respectively, from the same symbol in slot 4, which is an SBFD-incompatible resource. Therefore, the RA-RNTIs overlap in the random access procedure using resource R6 and the random access procedure using resource R7. Furthermore, when a random access procedure is performed using resources R6 and R8, consecutive symbols are assigned to resources R6 and R8, respectively, from the same symbol in slot 4, which is an SBFD-incompatible resource. Therefore, the RA-RNTIs overlap in the random access procedure using resource R6 and the random access procedure using resource R8.

[0074] To avoid such overlapping of the RA-RNTIs of resources R6 and R7, when SBFD-enabled resources are used, the RA-RNTI may use the index of the slot of the first used SBFD-enabled resource as the t_id. Furthermore, the index of the first OFDM symbol in the SBFD-enabled resource may be used as the s_id. Furthermore, to avoid overlapping of the RA-RNTIs of resources R6 and R8, a restriction may be imposed that the s_id value of R8 is not equal to the s_id value of R6 (i.e., if the s_id value of R8 configured using an additional RACH configuration is equal to the s_id value of R6, an SBFD-aware UE may determine that there is a configuration error in R8 and ignore R8). Alternatively, in order to avoid overlapping of the RA-RNTIs of resources R6 and R8, when SBFD-compatible resources are used (that is, in the case of non-SBFD symbol ROs valid only for SBFD-aware UEs configured using an additional RACH configuration), a value other than 0 or more and less than 8 may be used as f_id for the RA-RNTI. A value other than 0 or more and less than 8 is, for example, a value of 8 or more. A value other than 0 or more and less than 8 may be, for example, a value of 8 or more and less than 16, but the lower and upper limits are not limited thereto and may be "a value of N or more and less than N+M" (N is an integer other than 0 to 7, and M is an integer). For example, resource R6 may be broadcast using a non-additional RACH configuration, specifically, a legacy RACH configuration, and resource R8 may be broadcast using an additional RACH configuration. In such a case, for example, if a first SBFD-awareness UE uses resource R6, a value between 0 and 8 (0 to 7) is used as f_id, and if a second SBFD-awareness UE uses resource R8, a value between 8 and 16 (8 to 15) is used as f_id. As a result, the values ​​of the RA-RNTI for the first SBFD-awareness UE and the second SBFD-awareness UE are different.

[0075] In this way, by using an index related to the SBFD-compatible resource in calculating the RA-RNTI, duplication of RA-RNTI can be avoided in the random access procedure using resources R6 and R7, and R6 and R8 in Figure 11.

[0076] (Embodiment 6) Next, we will explain a method for early indication to gNB30 that UE40 is an SBFD-aware UE during a random access procedure.

[0077] For example, an SBFD-aware UE may be configured to use only SBFD-compatible resources when transmitting Message 1 in the random access procedure. In this case, the gNB 30 can recognize a UE that transmits Message 1 using SBFD-compatible resources as an SBFD-aware UE.

[0078] Alternatively, SBFD may be defined in the Feature Combination IE. Figure 12 shows a Feature Combination IE in which a number that can be used by an SBFD-awareness UE is defined. In this case, the gNB 30 can recognize a UE that has transmitted a message 1 in which a predetermined number that can be used by an SBFD-awareness UE is set as an SBFD-awareness UE.

[0079] Alternatively, a new codepoint that can be used by SBFD-aware UEs may be defined in the Logical Channel ID (LCID) included in the Media Access Control (MAC) subheader. Figure 13 shows codepoints associated with SBFD-aware UEs. In this case, gNB 30 can recognize a UE that transmits message 3 including a MAC subheader that includes a new codepoint (Codepoint 8 or 9) in the LCID as an SBFD-aware UE.

[0080] FIG. 14 is a block diagram showing an example configuration of a base station 10 and a gNB 30 (hereinafter referred to as the base station 10, etc.). Referring to FIG. 14, the base station 10, etc. includes an RF transceiver 1001, a network interface 1003, a processor 1004, and a memory 1005. The RF transceiver 1001 performs analog RF signal processing to communicate with UEs. The RF transceiver 1001 may include multiple transceivers. The RF transceiver 1001 is coupled to an antenna 1002 and a processor 1004. The RF transceiver 1001 receives modulation symbol data (or OFDM symbol data) from the processor 1004, generates a transmit RF signal, and provides the transmit RF signal to the antenna 1002. The RF transceiver 1001 also generates a baseband receive signal based on the receive RF signal received by the antenna 1002 and provides the baseband receive signal to the processor 1004.

[0081] The network interface 1003 is used to communicate with network nodes (e.g., other core network nodes) and may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0082] The processor 1004 performs data plane processing and control plane processing, including digital baseband signal processing for wireless communication.

[0083] The processor 1004 may include multiple processors. For example, the processor 1004 may include a modem processor (e.g., DSP) that performs digital baseband signal processing and a protocol stack processor (e.g., CPU or MPU) that performs control plane processing.

[0084] The memory 1005 is configured by a combination of volatile memory and non-volatile memory. The memory 1005 may include multiple physically independent memory devices. The volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The non-volatile memory may be mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, a hard disk drive, or any combination thereof. The memory 1005 may include storage located remotely from the processor 1004. In this case, the processor 1004 may access the memory 1005 via the network interface 1003 or an I / O interface (not shown).

[0085] The memory 1005 may store software modules (computer programs) including instructions and data for performing processing by the base station 10, etc., described in the above-described embodiments. In some implementations, the processor 1004 may be configured to read and execute the software modules from the memory 1005, thereby performing processing by the base station 10, etc., described in the above-described embodiments.

[0086] FIG. 15 is a block diagram showing an example configuration of a communication terminal 20 and a UE 40 (hereinafter referred to as communication terminal 20, etc.). A radio frequency (RF) transceiver 1101 performs analog RF signal processing to communicate with a gNB 40. The analog RF signal processing performed by the RF transceiver 1101 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1101 is coupled to an antenna 1102 and a baseband processor 1103. That is, the RF transceiver 1101 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1103, generates a transmit RF signal, and supplies the transmit RF signal to the antenna 1102. The RF transceiver 1101 also generates a baseband receive signal based on the receive RF signal received by the antenna 1102 and supplies the baseband processor 1103.

[0087] The baseband processor 1103 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management for Layer 1, Layer 2, and Layer 3.

[0088] The baseband processor 1103 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1104, which will be described later.

[0089] The application processor 1104 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1104 may include multiple processors (multiple processor cores). The application processor 1104 executes a system software program (operating system (OS)) and various application programs (e.g., a call application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1106 or a memory not shown, thereby realizing various functions of the communication terminal 20, etc.

[0090] In some implementations, the baseband processor 1103 and the application processor 1104 may be integrated on a single chip, as indicated by the dashed line (1105) in Figure 15. In other words, the baseband processor 1103 and the application processor 1104 may be implemented as a single System on Chip (SoC) device 1105. An SoC device may also be called a system Large Scale Integration (LSI) or chipset.

[0091] The memory 1106 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1106 may include multiple physically independent memory devices. Volatile memory is, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. Nonvolatile memory is, for example, mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. For example, the memory 1106 may include an external memory device accessible from the baseband processor 1103, the application processor 1104, and the SoC 1105. The memory 1106 may also include an internal memory device integrated within the baseband processor 1103, the application processor 1104, or the SoC 1105. Furthermore, the memory 1106 may include memory within a Universal Integrated Circuit Card (UICC).

[0092] The memory 1106 may store a software module (computer program) including instructions and data for performing processing by the communication terminal 20, etc., described in the above-described embodiments. In some implementations, the baseband processor 1103 or the application processor 1104 may be configured to read and execute the software module from the memory 1106, thereby performing processing by the communication terminal 20, etc., described in the above-described embodiments.

[0093] In the above examples, the program includes instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The program may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable medium or tangible storage medium includes random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disc (DVD), Blu-ray disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The program may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0094] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0095] Each drawing is merely an example for describing one or more embodiments. Each drawing may not relate to only one particular embodiment, but may also relate to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0096] Some or all of the above embodiments may be described as, but are not limited to, the following supplementary notes: (Supplementary Note 1) A base station comprising: a communication unit that distributes system information within a cell, the system information including resource information indicating whether subband non-overlapping full duplex (SBFD)-compatible resources can be used; and when the resource information indicates that the SBFD-compatible resources can be used, uplink resources of the SBFD-compatible resources that are used for uplink transmission are used for Random Access Channel (RACH) transmission in a communication terminal that can transmit data using the SBFD-compatible resources. (Supplementary Note 2) The base station according to Supplementary Note 1, wherein the resource information is any one of first information indicating that the SBFD-compatible resources can be used, second information indicating that SBFD-non-compatible resources can be used, and third information indicating that the SBFD-compatible resources and the SBFD-non-compatible resources can be used. (Supplementary Note 3) The base station according to Supplementary Note 2, wherein the system information includes first reference information and the first information or the third information as the resource information, and when reception quality determined based on a downlink signal transmitted from the base station to the communication terminal exceeds the first reference information and is good, the SBFD-compatible resources are used for RACH transmission in the communication terminal, and when the reception quality is below the first reference information and is poor, the SBFD-compatible resources are not used for RACH transmission in the communication terminal. (Supplementary Note 4) The base station according to Supplementary Note 3, wherein when the reception quality exceeds the first reference information, the communication terminal is located closer to the base station than when the reception quality is below the first reference information.(Supplementary Note 5) The base station according to Supplementary Note 2, wherein the system information includes second reference information and the first information or the third information as the resource information, and when reception quality determined based on a downlink signal transmitted from the base station to the communication terminal is below the second reference information and is poor, the SBFD-compatible resource, another SBFD-compatible resource that is temporally consecutive to the SBFD-compatible resource, or the SBFD-incompatible resource that is temporally consecutive to the SBFD-compatible resource are used for RACH transmission in the communication terminal, and when the reception quality exceeds the second reference information and is good, the SBFD-compatible resource is not used for RACH transmission in the communication terminal. (Supplementary Note 6) The base station according to Supplementary Note 5, wherein when the reception quality is below the second reference information, the communication terminal is located closer to a boundary of the cell than when the reception quality exceeds the second reference information. (Supplementary Note 7) The base station according to Supplementary Note 2, wherein the system information includes first reference information, second reference information, and the third information as the resource information, and when reception quality determined based on a downlink signal transmitted from the base station to the communication terminal exceeds the first reference information and is good, the SBFD-compatible resource is used for RACH transmission in the communication terminal, and when reception quality determined based on a downlink signal transmitted from the base station to the communication terminal falls below second reference information and is poor, the SBFD-compatible resource, another SBFD-compatible resource that is temporally consecutive to the SBFD-compatible resource, or the SBFD-incompatible resource that is temporally consecutive to the SBFD-compatible resource, is used for RACH transmission in the communication terminal, and when the reception quality is below the first reference information and above the second reference information, the SBFD-compatible resource is not used for RACH transmission in the communication terminal. (Supplementary Note 8) The base station according to Supplementary Note 7, wherein the higher the reception quality, the closer the communication terminal is to the base station, and the lower the reception quality, the closer the communication terminal is to a boundary of the cell.(Supplementary Note 9) A base station comprising: a communication unit that distributes, within a cell, system information including frequency information indicating that a band includes a first initial BWP (Band Width Part) and a subband of an SBFD-compatible resource used for uplink transmission. (Supplementary Note 10) A communication terminal comprising: a receiver that receives system information including resource information indicating whether or not an SBFD-compatible resource can be used; and a transmitter that performs RACH transmission using an uplink resource among the SBFD-compatible resources that is used for uplink transmission when the resource information indicates that the SBFD-compatible resource can be used. (Supplementary Note 11) A communication terminal comprising: a communication unit that receives system information including frequency information indicating that a band includes a first initial BWP (Band Width Part) and a subband of the SBFD-compatible resource used for uplink transmission; and when data can be transmitted using the SBFD-compatible resource, the communication unit performs RACH transmission in the first initial BWP or the SBFD-compatible resource used for the uplink transmission based on the frequency information. (Supplementary Note 12) A communication terminal comprising: a control unit that, when performing a first RACH transmission using SBFD-incompatible resources associated with a first slot and a second RACH transmission using SBFD-compatible resources associated with a second slot that is temporally consecutive to the first slot and has a timing later than the first slot, calculates a first RA-RNTI to be used for the first RACH transmission using identification information of the first slot, and calculates a second RA-RNTI to be included in the second RACH transmission using identification information of the second slot. (Supplementary Note 13) A base station that determines that the communication terminal is a communication terminal that can transmit data using the SBFD-compatible resources when it receives a first message for RACH transmission using SBFD-compatible resources, or when it receives the first message or the third message that includes identification information indicating that the communication terminal is a communication terminal that can transmit data using the SBFD-compatible resources.(Supplementary Note 14) A communication method comprising: distributing, within a cell, system information including resource information indicating whether SBFD-compatible resources can be used; and, if the resource information indicates that the SBFD-compatible resources can be used, uplink resources among the SBFD-compatible resources used for uplink transmission are used for RACH transmission in a communication terminal capable of transmitting data using the SBFD-compatible resources. (Supplementary Note 15) A communication method comprising distributing, within a cell, system information including information indicating that a band including a first initial BWP and a subband of the SBFD-compatible resources used for uplink transmission is an initial BWP in a communication terminal capable of transmitting data using the SBFD-compatible resources. (Supplementary Note 16) A communication method comprising: receiving system information including resource information indicating whether SBFD-compatible resources can be used; and, if the resource information indicates that the SBFD-compatible resources can be used, performing RACH transmission using uplink resources among the SBFD-compatible resources used for uplink transmission. (Supplementary Note 17) A communication method comprising: receiving system information including frequency information indicating that a band includes a first initial BWP (Band Width Part) and a subband of an SBFD-compatible resource used for uplink transmission; and, when data can be transmitted using the SBFD-compatible resource, performing RACH transmission in the first initial BWP or the SBFD-compatible resource used for the uplink transmission based on the frequency information. (Supplementary Note 18) A control method comprising: when performing a first RACH transmission using an SBFD-incompatible resource associated with a first slot and a second RACH transmission using an SBFD-compatible resource associated with a second slot that is temporally consecutive to the first slot and later than the first slot, calculating a first RA-RNTI to be used for the first RACH transmission using identification information of the first slot, and calculating a second RA-RNTI to be included in the second RACH transmission using identification information of the second slot.(Supplementary Note 19) A program causing a computer to execute the following: distribute, within a cell, system information including resource information indicating whether SBFD-compatible resources can be used, and, when the resource information indicates that the SBFD-compatible resources can be used, uplink resources among the SBFD-compatible resources to be used for uplink transmission are used for RACH transmission in a communication terminal that can transmit data using the SBFD-compatible resources. (Supplementary Note 20) A program causing a computer to execute the following: receive system information including resource information indicating whether SBFD-compatible resources can be used, and, when the resource information indicates that the SBFD-compatible resources can be used, perform RACH transmission using uplink resources among the SBFD-compatible resources to be used for uplink transmission.

[0097] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 8 that are dependent on Supplementary Note 1 may also be dependent on Supplementary Notes 14 and 19 in the same dependency relationship as Supplementary Notes XX to YY. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods.

[0098] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the invention.

[0099] This application claims priority based on Japanese Patent Application No. 2024-130904, filed August 7, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0100] 10 Base station 11 Communication unit 20 Communication terminal 21 Receiving unit 22 Transmitting unit 30 gNB 40 UE

Claims

1. A base station comprising: a communication means for distributing system information within a cell, the system information including resource information indicating whether or not subband non-overlapping full duplex (SBFD) compatible resources can be used; and when the resource information indicates that the SBFD compatible resources can be used, uplink resources used for uplink transmission among the SBFD compatible resources are used for RACH (Random Access Channel) transmission in a communication terminal capable of transmitting data using the SBFD compatible resources.

2. The base station according to claim 1, wherein the resource information is any one of first information indicating that the SBFD-compatible resources can be used, second information indicating that the SBFD-incompatible resources can be used, and third information indicating that the SBFD-compatible resources and the SBFD-incompatible resources can be used.

3. The base station according to claim 2, wherein the system information includes first reference information and the first information or the third information as the resource information, and when reception quality determined based on a downlink signal transmitted from the base station to the communication terminal exceeds the first reference information and is good, the SBFD-compatible resource is used for RACH transmission in the communication terminal, and when the reception quality is below the first reference information and is poor, the SBFD-compatible resource is not used for RACH transmission in the communication terminal.

4. The base station according to claim 3, wherein when the reception quality exceeds the first reference information, the communication terminal is located closer to the base station than when the reception quality is below the first reference information.

5. The base station according to claim 2, wherein the system information includes second reference information and the first information or the third information as the resource information, and when reception quality determined based on a downlink signal transmitted from the base station to the communication terminal is below the second reference information and is poor, the SBFD-compatible resource, another SBFD-compatible resource that is temporally consecutive to the SBFD-compatible resource, or the SBFD-incompatible resource that is temporally consecutive to the SBFD-compatible resource are used for RACH transmission in the communication terminal, and when the reception quality is above the second reference information and is good, the SBFD-compatible resource is not used for RACH transmission in the communication terminal.

6. The base station according to claim 5, wherein when the reception quality is below the second reference information, the communication terminal is located closer to the boundary of the cell than when the reception quality is above the second reference information.

7. The base station according to claim 2, wherein the system information includes first reference information, second reference information, and the third information as the resource information; when reception quality determined based on a downlink signal transmitted from the base station to the communication terminal exceeds the first reference information and is good, the SBFD-compatible resource is used for RACH transmission in the communication terminal; when reception quality determined based on a downlink signal transmitted from the base station to the communication terminal falls below the second reference information and is poor, the SBFD-compatible resource, another SBFD-compatible resource that is temporally consecutive to the SBFD-compatible resource, or the SBFD-incompatible resource that is temporally consecutive to the SBFD-compatible resource, is used for RACH transmission in the communication terminal; and when the reception quality is below the first reference information and above the second reference information, the SBFD-compatible resource is not used for RACH transmission in the communication terminal.

8. The base station according to claim 7, wherein the greater the reception quality, the closer the communication terminal is to the base station, and the smaller the reception quality, the closer the communication terminal is to the cell boundary.

9. A base station having a communication means for distributing system information within a cell, the system information including frequency information indicating that the band includes a first initial BWP (Band Width Part) and a subband of an SBFD-compatible resource used for uplink transmission.

10. A communication terminal comprising: a receiving means for receiving system information including resource information indicating whether or not SBFD-compatible resources can be used; and a transmitting means for performing RACH transmission using uplink resources used for uplink transmission among the SBFD-compatible resources when the resource information indicates that the SBFD-compatible resources can be used.

11. A communication terminal comprising: a communication means for receiving system information including frequency information indicating that the band includes a first initial BWP (Band Width Part) and a subband of an SBFD-compatible resource used for uplink transmission; and when data can be transmitted using the SBFD-compatible resource, the communication means performs RACH transmission in the first initial BWP or the SBFD-compatible resource used for the uplink transmission based on the frequency information.

12. A communications terminal comprising: control means for calculating a first RA-RNTI to be used in the first RACH transmission using identification information of the first slot, and a second RACH transmission using SBFD-incompatible resources associated with a first slot, the first RACH transmission being temporally consecutive to the first slot and later than the first slot, and for calculating a second RA-RNTI to be included in the second RACH transmission using identification information of the second slot, when performing a first RACH transmission using SBFD-incompatible resources associated with a first slot, and a second RACH transmission using identification information of the second slot.

13. A base station that determines that a communication terminal is a communication terminal capable of transmitting data using the SBFD-compatible resources when it receives a first message for RACH transmission in an SBFD-compatible resource, or when it receives the first message or the third message including identification information indicating that the communication terminal is capable of transmitting data using the SBFD-compatible resource.

14. A communication method comprising: distributing system information within a cell, the system information including resource information indicating whether SBFD-compatible resources can be used; and, if the resource information indicates that the SBFD-compatible resources can be used, an uplink resource among the SBFD-compatible resources used for uplink transmission is used for RACH transmission in a communication terminal capable of transmitting data using the SBFD-compatible resources.

15. A communication method for distributing system information within a cell, the system information including information indicating that a band including a first initial BWP and a subband of an SBFD-compatible resource used for uplink transmission is an initial BWP for a communication terminal capable of transmitting data using an SBFD-compatible resource.

16. A communication method comprising receiving system information including resource information indicating whether SBFD-compatible resources can be used, and if the resource information indicates that the SBFD-compatible resources can be used, performing RACH transmission using uplink resources used for uplink transmission among the SBFD-compatible resources.

17. A communications method comprising receiving system information including frequency information indicating that the band includes a first initial BWP (Band Width Part) and a subband of an SBFD-compatible resource used for uplink transmission, and, if data can be transmitted using the SBFD-compatible resource, performing RACH transmission in the first initial BWP or the SBFD-compatible resource used for the uplink transmission based on the frequency information.

18. A control method for calculating a first RACH transmission using SBFD-incompatible resources associated with a first slot and a second RACH transmission using SBFD-compatible resources associated with a second slot that is temporally consecutive to the first slot and occurs later than the first slot, the method comprising: calculating a first RA-RNTI to be used in the first RACH transmission using identification information of the first slot; and calculating a second RA-RNTI to be included in the second RACH transmission using identification information of the second slot.

19. A program that causes a computer to distribute system information within a cell, the system information including resource information indicating whether SBFD-compatible resources can be used; and if the resource information indicates that the SBFD-compatible resources can be used, an uplink resource among the SBFD-compatible resources that is used for uplink transmission is used for RACH transmission in a communication terminal that can transmit data using the SBFD-compatible resources.

20. A program that causes a computer to receive system information including resource information indicating whether SBFD-compatible resources can be used, and if the resource information indicates that the SBFD-compatible resources can be used, perform RACH transmission using uplink resources that are used for uplink transmission among the SBFD-compatible resources.

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