Terminal, wireless communication method, base station and system

Abstract

To appropriately control transport block (TB)-based and / or code block group (CBG)-based transmission (including retransmission) and / or reception.SOLUTION: A terminal according to one aspect of the present invention includes: a receiving unit that receives downlink control information (DCI) including information about transmission of a code block group (CBG); and a control unit that controls reception of the CBG based on the information about transmission of the CBG. A first DCI format used for scheduling the CBG transmitted at a first time and a second DCI format used for scheduling the CBG re-transmitted are a common DCI format. The first DCI format and the second DCI format include a hybrid automatic repeat request (HARQ) process number field, a new data indicator field, and a redundancy version field that are common to a plurality of CBGs.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a terminal, a wireless communication method, a base station and a system in a next-generation mobile communication system. [Background technology]

[0002] In a Universal Mobile Telecommunications System (UMTS) network, Long Term Evolution (LTE) has been specified for the purpose of achieving higher data rates, lower latency, and the like (Non-Patent Document 1). Also, for the purpose of achieving wider bandwidth and higher speeds than LTE (also referred to as LTE Rel. 8 or 9), LTE-A (LTE Advanced, also referred to as LTE Rel. 10-13, etc.) has been specified, and a successor system to LTE (for example, FRA (Future Radio Access), 5G (5th generation mobile communication system), NR (New RAT: Radio Access Technology), also referred to as LTE Rel. 14-, etc.) is also being considered.

[0003] In existing LTE systems (for example, before Rel. 13), adaptive modulation and coding (AMC) is performed as link adaptation, which adaptively changes at least one of the modulation scheme, transport block size (TBS), and coding rate. Here, TBS is the size of a transport block (TB), which is a unit of an information bit sequence. One or multiple TBs are assigned to one subframe.

[0004] In addition, in the existing LTE system, when the TBS exceeds a predetermined threshold (for example, 6144 bits), the TB is divided into one or more segments (code blocks (CB)), and coding is performed on a segment-by-segment basis (code block segmentation). The coded code blocks are concatenated and transmitted.

[0005] In addition, in existing LTE systems, retransmission control (HARQ: Hybrid Automatic Repeat reQuest) of DL signals and / or UL signals is performed in units of TB. Specifically, in existing LTE systems, even if a TB is divided into multiple CBs, retransmission control information (ACK (Acknowledge) or NACK (Negative ACK) (hereinafter abbreviated as A / N), also referred to as HARQ-ACK, etc.) is transmitted in units of TB. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] 3GPP TS 36.300 V8.12.0 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 8)”, April 2010 Summary of the Invention [Problem to be solved by the invention]

[0007] In future wireless communication systems (e.g., 5G, NR, etc.), it is expected that a TBS larger than that of the existing LTE system will be used to support high-speed, large-capacity communication (eMBB: enhanced Mobile Broadband). It is expected that the TB of such a large TBS will be divided into many CBs (e.g., tens of CBs per 1 TB) compared to the existing LTE system.

[0008] In such future wireless communication systems, in addition to the TB base, it is being considered to support transmission (or retransmission) control on a group (Code Block Group (CBG)) base including one or more CBs. Therefore, signaling is required to appropriately control TB-based and / or CBG-based transmission (including retransmission) and / or reception.

[0009] The present invention has been made in consideration of these points, and one of its objectives is to provide a terminal, a wireless communication method, a base station, and a system that can appropriately control TB-based and / or CBG-based transmission (including retransmission) and / or reception. [Means for solving the problem]

[0010] A terminal according to one embodiment of the present invention comprises a receiving unit that receives downlink control information (DCI) including information related to the transmission of a code block group (CBG), and a control unit that controls the reception of the CBG based on information related to the transmission of the CBG, and is characterized in that a first DCI format used for scheduling a CBG that is transmitted for the first time and a second DCI format used for scheduling a CBG that is retransmitted are common DCI formats, and the first DCI format and the second DCI format include a Hybrid Automatic Repeat reQuest (HARQ) process number field, a new data indicator field, and a redundancy version field that are common to multiple CBGs. Effect of the Invention

[0011] According to the present invention, TB-based and / or CBG-based transmission (including retransmission) and / or reception can be appropriately controlled. [Brief description of the drawings]

[0012] [Figure 1] FIG. 11 is a diagram illustrating an example of a transmission process when code block division is applied. [Diagram 2] FIG. 11 is a diagram illustrating an example of a receiving process when code block division is applied. [Diagram 3] FIG. 1 is a diagram illustrating an example of DL retransmission control in an existing LTE system. [Figure 4] FIG. 2 is a diagram illustrating an example of an initial transmission and a retransmission according to the first embodiment. [Diagram 5] 13A to 13C are diagrams illustrating other examples of initial transmission and retransmission according to the first embodiment. [Figure 6] FIG. 11 is a diagram illustrating an example of an initial transmission and a retransmission according to the second embodiment. [Figure 7] FIG. 11 is a diagram showing another example of initial transmission and retransmission according to the second embodiment. [Figure 8] A figure showing an example of a specified field indicating the cause of retransmission of a CBG in the third aspect. [Figure 9] 9A and 9B are diagrams showing other examples of a predetermined field indicating a retransmission cause of a CBG according to the third aspect. [Figure 10] 10A and 10B are diagrams illustrating an example of scheduling of a retransmission CBG according to the third aspect. [Figure 11] 11A and 11B are diagrams illustrating another example of scheduling of a retransmission CBG according to the third aspect. [Figure 12] 1 is a diagram illustrating an example of a schematic configuration of a wireless communication system according to an embodiment of the present invention. [Figure 13] FIG. 2 is a diagram illustrating an example of the overall configuration of a radio base station according to the present embodiment. [Figure 14] FIG. 2 is a diagram illustrating an example of a functional configuration of a radio base station according to the present embodiment. [Figure 15]FIG. 2 is a diagram illustrating an example of the overall configuration of a user terminal according to the present embodiment. [Figure 16] FIG. 2 is a diagram illustrating an example of a functional configuration of a user terminal according to the present embodiment. [Figure 17] A diagram showing an example of the hardware configuration of a radio base station and a user terminal according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Fig. 1 is a diagram showing an example of a transmission process when code block segmentation is applied. Code block segmentation refers to dividing a transport block (hereinafter abbreviated as TB) to which CRC (Cyclic Redundancy Check) bits are added (information bit sequence including CRC bits) into multiple segments when the TB exceeds a predetermined threshold (e.g., 6144 bits or 8192 bits). Code block segmentation is performed, for example, to match a TBS to a size supported by an encoder, and the above-mentioned predetermined threshold may be equal to the maximum size supported by the encoder.

[0014] As shown in Fig. 1, when the TB size (TBS) exceeds a predetermined threshold (for example, 6144 bits or 8192 bits), the information bit sequence including the CRC bits is divided into multiple segments on the transmitting side. Filler bits may be added to the beginning of segment #1.

[0015] As shown in Fig. 1, CRC bits (e.g., 24 bits) are added to each segment, and channel coding (e.g., turbo coding, low-density parity-check code (LDPC) coding, etc.) is performed at a predetermined coding rate (e.g., 1 / 3, 1 / 4, 1 / 8, etc.). By channel coding, systematic bits and parity bits (e.g., first and second parity bits (#1 and #2)) are generated as code bits of each code block (hereinafter abbreviated as CB).

[0016] Each CB is interleaved in a predetermined manner, and a bit sequence corresponding to the scheduled resource amount is selected and transmitted. For example, the systematic bit sequence, the first parity bit sequence, and the second parity bit sequence are each interleaved individually (sub-block interleaving). Then, the systematic bit sequence, the first parity bit sequence, and the second parity bit sequence are each input to a buffer (circular buffer), and code bits for each CB are selected from the buffer based on the number of REs available in the assigned resource block and the redundancy version (RV) (rate matching). Interleaving may be performed between multiple CBs.

[0017] Each CB consisting of selected code bits is concatenated as a code word (CW), which is then subjected to scrambling, data modulation, and the like before being transmitted.

[0018] 2 is a diagram showing an example of a receiving process when code block division is applied. On the receiving side, a TBS is determined based on a TBS index and the number of allocated resource blocks (e.g., PRBs: Physical Resource Blocks), and the number of CBs is determined based on the TBS.

[0019] As shown in Figure 2, at the receiving side, each CB is decoded, and error detection for each CB is performed using the CRC bits added to each CB. The code block division is also undone to restore the TB. Furthermore, error detection for the entire TB is performed using the CRC added to the TB.

[0020] In the receiving side of the existing LTE system, retransmission control information (ACK or NACK, hereinafter abbreviated as A / N, also called HARQ-ACK, etc.) for the entire TB is transmitted to the transmitting side in response to the result of error detection for the entire TB. In response to the NACK from the receiving side, the transmitting side retransmits the entire TB.

[0021] FIG. 3 is a diagram showing an example of retransmission control of DL signals in an existing LTE system. In an existing LTE system, retransmission control is performed in units of TB, regardless of whether a TB is divided into multiple CBs. Specifically, a HARQ process is assigned to each TB. Here, an HARQ process is a processing unit for retransmission control, and each HARQ process is identified by an HARQ process number (HPN). One or more HARQ processes are set in a user terminal (UE: User Equipment), and the same data is retransmitted in the HARQ process of the same HPN until an ACK is received.

[0022] For example, in Fig. 3, HPN = 0 is assigned to TB #1 for new (initial) transmission. When the radio base station (eNB: eNodeB) receives a NACK, it retransmits the same TB #1 with HPN = 0, and when it receives an ACK, it transmits the next TB #2 with HPN = 0 for the initial time.

[0023] In addition, the radio base station can include the above-mentioned HPN, a new data indicator (NDI), and a redundancy version (RV) in downlink control information (DCI) (DL assignment) that assigns a DL signal (e.g., a PDSCH) for transmitting the TB.

[0024] Here, NDI is an identifier that indicates either an initial transmission or a retransmission. For example, when NDI is not toggled (same value as the previous time) in the same HPN, it indicates a retransmission, and when NDI is toggled (different value from the previous time), it indicates an initial transmission.

[0025] RV indicates the difference in redundancy of the transmission data. RV values ​​are, for example, 0, 1, 2, and 3, and 0 is used for the initial transmission because it has the lowest degree of redundancy. By applying different RV values ​​to each transmission of the same HPN, it is possible to effectively obtain the gain of HARQ.

[0026] For example, in FIG. 3, the DCI for the initial transmission of TB#1 includes HPN "0", a toggled NDI, and an RV value "0". Therefore, the user terminal can recognize that HPN "0" is the initial transmission, and decodes TB#1 based on the RV value "0". On the other hand, the DCI for the retransmission of TB#1 includes HPN "0", a non-toggled NDI, and an RV value "2". Therefore, the user terminal can recognize that HPN "0" is a retransmission, and decodes TB#1 based on the RV value "2". The initial transmission of TB#2 is the same as the initial transmission of TB#1.

[0027] As described above, in the existing LTE system, retransmission control is performed on a TB basis, regardless of whether code block division is applied or not. Therefore, when code block division is applied, even if errors are concentrated in some of the C (C>1) CBs formed by dividing the TB, the entire TB is retransmitted.

[0028] Therefore, not only CBs in which an error is detected (decoding has failed) but also CBs in which no error is detected (decoding has succeeded) will be retransmitted, which may result in a decrease in performance (throughput). In future wireless communication systems (e.g., 5G, NR, etc.), it is expected that there will be an increase in cases in which a TB is divided into many CBs (e.g., several tens of CBs), so there is a risk that performance degradation will become significant when retransmitting in units of TB.

[0029] In such future wireless communication systems, in addition to the TB-based, it is considered to support transmission (or retransmission) control on a code block group (CBG) basis including one or more CBs. Therefore, signaling is required to appropriately control TB-based and / or CBG-based transmission (including retransmission) and / or reception.

[0030] Therefore, the inventors have studied a method for appropriately controlling TB-based and / or CBG-based transmission (including retransmission) and / or reception, and have arrived at the present invention. Specifically, the inventors have come up with the idea of ​​controlling a DCI format between an initial transmission and a retransmission (first aspect), controlling a DCI format between a TB and a CBG (second aspect), controlling decoding of a retransmitted CBG based on a cause of retransmission of the CBG (third aspect), and controlling a fallback from the CBG base to the TB base (fourth aspect).

[0031] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the present embodiment, the initial transmission is performed on a TB basis, but may be performed on a CBG basis. Retransmission may be performed on a CBG basis or on a TB basis.

[0032] (First aspect) In the first aspect, control of DCI format (DCI) at the time of initial transmission and retransmission will be described. In the first aspect, different DCI formats may be used between the time of initial transmission and the time of retransmission, or the same (single) DCI format may be used.

[0033] In the first aspect, the user terminal applies the CBG-based retransmission a predetermined period x (e.g., x=1, 2, 3, 4... (slots)) after slot n in which the CBG-based retransmission is set by higher layer signaling. x may be a fixed value or a value that can be freely set by the terminal within a predetermined range.

[0034] <Different DCI formats> Fig. 4 is a diagram showing an example of initial transmission and retransmission according to the first aspect. In Fig. 4, it is assumed that CBG-based retransmission is configured in a user terminal by higher layer signaling. For example, in Fig. 4, it is assumed that a TB includes 3CBG#0 to #2.

[0035] In Fig. 4, the radio base station (gNB) transmits DCI in DCI format X for initial transmission, and performs initial transmission of a TB composed of CBGs #0-#2 via a PDSCH. For example, in Fig. 4, the user terminal fails to decode CBG #2 in the initially transmitted TB, and therefore transmits HARQ-ACK bits (e.g., 3 bits) indicating ACKs for CBGs #0 and #1 and NACKs for CBG #2.

[0036] In response to the NACK of CBG#2 from the user terminal, the radio base station transmits DCI in DCI format Y for retransmission and retransmits CBG#2 via the PDSCH. For example, in FIG. 4, the user terminal successfully decodes the retransmitted CBG#2, and therefore transmits a HARQ-ACK bit (for example, 1 bit) indicating an ACK of the retransmitted CBG#2.

[0037] As shown in Fig. 4, DCI format X for initial transmission may include a value of an HPN field (HPN field value) indicating a HARQ process number (HPN) assigned to the TB, and / or a value of an RV field (RV field value) indicating an RV of the TB. In addition, since the initial transmission is performed in units of TB, DCI format X for initial transmission may not include information on each CBG constituting the TB (e.g., CBG index).

[0038] On the other hand, since retransmission is assumed to be performed in CBG units, the DCI format Y for retransmission includes information (CBG information) indicating the CBG to be retransmitted. The CBG information may be a bitmap with a number of bits equal to the number of CBGs in the TB, or may be a binary number indicating the index value of the retransmitted CBG. For example, as shown in FIG. 4, when CBG#2 is retransmitted, the CBG information may be a bitmap "001" or a binary number "010" indicating the CBG index #2.

[0039] Furthermore, the DCI format Y for retransmission may include an HPN field value indicating the HPN of the retransmission CBG and / or an RV field indicating the RV of the retransmission CBG. Since the HPN is assigned on a TB basis (and is common to CB#0 to #2 constituting the TB), the HPN field of the DCI format Y may indicate the same HPN as that at the time of the initial transmission (for example, HPN=0 in FIG. 4). Furthermore, the RV applied may be different from or the same as that at the time of the initial transmission.

[0040] As shown in Fig. 4, when different DCI formats X and Y are used between the initial transmission and the retransmission, the DCI formats X and Y do not need to include an indicator (NDI) indicating either the initial transmission or the retransmission. On the other hand, the user terminal needs to monitor (blind decode) both DCI formats X and Y.

[0041] As described above, when different DCI formats X and Y are used between the initial transmission and the retransmission, the amount of monitoring (blind decoding) processing in the user terminal increases, but the NDI field is no longer necessary, so the DCI overhead can be reduced.

[0042] In addition, when different DCI formats are used between the initial transmission and the retransmission, the multiple DCIs of the different DCI formats (also simply referred to as different DCI formats) may be transmitted using at least (1) different resources, (2) different transmission schemes, (3) different reference signal (RS) configurations, and (4) different mapping schemes.

[0043] (1) Using different resources The different resources on which DCI format X at the time of initial transmission and DCI format Y at the time of retransmission are transmitted may be different search spaces or different control resource sets (CORESETs). CORESETs may also be called control subbands, control resources, or control regions. For example, when DCI formats X and Y are transmitted in different search spaces, the user terminal may assume a single DCI format (DCI payload) for blind decoding of each search space.

[0044] (2) When using different transmission methods For example, DCI format X at the time of initial transmission may be transmitted by user terminal-specific beamforming and / or precoding, and DCI format Y for retransmission may be transmitted by transmit diversity (e.g., beam-cycling and / or precoder-cycling). In this case, the user terminal may assume different transmission schemes for demodulating DCI formats X and Y, respectively.

[0045] (3) When using different RS configurations The user terminal may assume different RS configurations for demodulating DCI format X at the time of initial transmission and DCI format Y at the time of retransmission.

[0046] (4) When using different mapping methods For example, DCI format X at the time of initial transmission may be transmitted using distributed mapping, and DCI format Y for retransmission may be transmitted using localized mapping. In this case, a frequency diversity effect is obtained in the downlink control channel of the initial transmission, and the quality of the initial transmission may be improved. Conversely, DCI format X at the time of initial transmission may be transmitted using localized mapping, and DCI format Y for retransmission may be transmitted using distributed mapping. In this case, the initial transmission is transmitted using optimal resources for each user, but if the transmission is erroneous, a control signal with improved quality can be transmitted by obtaining a frequency diversity effect.

[0047] In addition, information related to the transmission of DCI format X at the time of initial transmission and DCI format Y at the time of retransmission as described above (e.g., at least one of the above (1) resources, (2) transmission scheme, (3) RS configuration, and (4) mapping scheme) may be notified to the user terminal by higher layer signaling (e.g., system information block (SIB) or RRC signaling).

[0048] <Same DCI format> Next, a case where the same DCI format is used between the initial transmission and retransmission will be described. Fig. 5 is a diagram showing another example of the initial transmission and retransmission according to the first aspect. In Fig. 5, it is assumed that the CBG-based retransmission is configured in the user terminal by higher layer signaling. For example, in Fig. 5, it is assumed that the TB includes 3CBG#0 to #2, similarly to Fig. 4. The following description will focus on the differences from Fig. 4.

[0049] In Fig. 5, the radio base station (gNB) transmits DCI in DCI format A for initial transmission, and performs initial transmission of a TB consisting of CBG#0-#2 via a PDSCH. In Fig. 5, in response to a NACK of CBG#2 from the user terminal, the radio base station transmits DCI in DCI format A that is the same as that used in the initial transmission, and retransmits CBG#2 via the PDSCH.

[0050] As shown in Fig. 5, when a common DCI format A is used for the initial transmission and retransmission, it is necessary to notify the user terminal of which CBG is to be retransmitted. For this reason, the common DCI format A for the initial transmission and retransmission includes information indicating the scheduled CBG (CBG information). The CBG information may be a bitmap with a number of bits equal to the number of CBGs in the TB, or may be a binary number indicating the index value of the scheduled CBG.

[0051] For example, as shown in Fig. 5, at the time of initial transmission of a TB including CBG #0 to #2, the CBG information may be a bitmap "111" or may include binary numbers "000", "001", and "010" indicating CBG indexes #0, #1, and #2. At the time of retransmission of CBG #2, the CBG information may be a bitmap "001" or may include binary number "010" indicating CBG index #2.

[0052] Furthermore, as shown in Fig. 5, DCI format A common to the initial transmission and retransmission may include an HPN field value indicating the HPN. Since the HPN is assigned in units of TB (common to CB#0 to #2 constituting the TB), the HPN field of DCI format A may indicate the same HPN (for example, HPN=0 in Fig. 5) at the time of the initial transmission and retransmission.

[0053] Furthermore, DCI format A common to the initial transmission and retransmission includes an identifier (NDI) indicating either the initial transmission or the retransmission. As shown in Fig. 5, the NDI in DCI format A may be toggled in the case of the initial transmission, and may not be toggled in the case of the retransmission. Specifically, the NDI may be set to a value different from the latest value of the same HARQ process in the case of the initial transmission, and may be set to the same value as the latest value of the same HARQ process in the case of the retransmission.

[0054] Furthermore, the DCI format A common to the initial transmission and retransmission may include an RV field indicating the RV of one or more scheduled CBGs. The RV field may be a single field indicating an RV common to one or more scheduled CBGs. Alternatively, the RV field may be provided for each scheduled CBG and may indicate an RV for each CBG.

[0055] As described above, when a common DCI format A is used between the initial transmission and the retransmission, NDI is required to distinguish between the initial transmission and the retransmission. However, since the number of DCI formats that the user terminal monitors (blind decodes) is reduced, the amount of monitoring processing in the user terminal can be reduced.

[0056] Furthermore, when a common DCI format A is used between the initial transmission and the retransmission, even when falling back from CBG-based to TB-based retransmission, there is no need to change the DCI format, so that it is easy to fall back to TB-based retransmission. For example, in FIG. 5, it is possible to fall back to TB-based retransmission by using DCI format A including CBG information indicating that CB#0 to #2 are scheduled and non-toggled NDI.

[0057] In the first aspect, since the DCI format is controlled between the initial transmission and the retransmission, it is possible to appropriately control the TB-based and / or CBG-based transmission (including retransmission) and / or reception.

[0058] (Second aspect) In the second aspect, the control of DCI format (DCI) used for scheduling TB and CBG will be described. In the second aspect, different DCI formats may be used between the case of scheduling TB and the case of scheduling CBG, or the same DCI format may be used. The following mainly describes the differences from the first aspect.

[0059] <Different DCI formats> Fig. 6 is a diagram showing an example of initial transmission and retransmission according to the second aspect. In Fig. 6, it is assumed that CBG-based retransmission is configured in a user terminal by higher layer signaling. For example, in Fig. 6, it is assumed that a TB includes 3CBG#0 to #2, similarly to Fig. 4. The following description will focus on the differences from Fig. 4.

[0060] In Fig. 6, the radio base station (gNB) transmits DCI in DCI format B for TB, and performs initial transmission of TB composed of CBG#0-#2 via PDSCH. In Fig. 6, the radio base station transmits DCI format C for CBG in response to NACK of CBG#2 from the user terminal, and retransmits CBG#2 via PDSCH.

[0061] As shown in Fig. 6, DCI format B is used for scheduling one or more TBs, and therefore does not need to include information (e.g., CBG index) about each CBG constituting the TB. On the other hand, DCI format C is used for scheduling one or more CBGs, and therefore includes information (CBG information) indicating the scheduled CBG. Details of the CBG information are the same as those of DCI format Y in Fig. 4.

[0062] As shown in Fig. 6, DCI format B for TB and DCI format C for CBG may include at least one of an HPN field value indicating an HPN and an RV field value indicating an RV (RV field value). For example, the HPN of DCI formats B and C may indicate an HPN assigned on a TB basis (an HPN common to CBGs #0 to #2). The RV field of DCI format B may indicate an RV of the TB. The RV field of DCI format C may indicate an RV on a TB basis (an RV common to CBGs #0 to #2) or an RV for each CBG.

[0063] When falling back from CBG-based to TB-based retransmission, it is assumed that the retransmission TB is scheduled. That is, when a certain TB is retransmitted based on the CBG, the next retransmission may be based on the TB. For this reason, the DCI format B for the TB may include an NDI indicating the initial transmission or retransmission. The NDI in the DCI format B may be toggled in the case of the initial transmission, and may not be toggled in the case of a retransmission.

[0064] The user terminal may identify whether the DCI schedules a TB or a CBG (whether the DCI is in DCI format B or C) using at least one of (1) the payload of the DCI and (2) the transmission resource.

[0065] (1) When using DCI payload When the payload of DCI differs between DCI formats B and C, the user terminal may identify DCI format B or C based on the payload of the DCI. In this case, which CBG is to be retransmitted may be explicitly indicated by the CBG information in DCI format C.

[0066] (2) When using transmission resources When the transmission resources (eg, search spaces or CORESETs) of DCI differ between DCI formats B and C, the user terminal may identify DCI format B or C based on the transmission resources.

[0067] As described above, when different DCI formats B and C are used between TB scheduling and CBG scheduling, even when falling back from CBG-based to TB-based retransmission (when the next retransmission of data that has been retransmitted based on CBG is to be based on TB), fallback can be easily achieved by simply changing the DCI format. For example, in FIG. 6, by using DCI format B including a non-toggled NDI, the user terminal can recognize (fall back) that the retransmission is a TB-based retransmission.

[0068] <Same DCI format> Next, a case where the same DCI format is used between the case where TB is scheduled and the case where CBG is scheduled will be described. Fig. 7 is a diagram showing another example of initial transmission and retransmission according to the second aspect. In Fig. 7, it is assumed that CBG-based retransmission is configured in the user terminal by higher layer signaling. For example, in Fig. 7, it is assumed that the TB includes 3CBG#0 to #2, similarly to Fig. 4. The following description will focus on the differences from Fig. 5.

[0069] In Fig. 7, the radio base station (gNB) transmits DCI in DCI format D for the TB, and performs an initial transmission of the TB composed of CBG#0-#2 via the PDSCH. In Fig. 7, in response to the NACK of CBG#2 from the user terminal, the radio base station transmits DCI in DCI format D that is the same as the scheduling of the TB in order to schedule CBG#2, and retransmits CBG#2 via the PDSCH.

[0070] As shown in Fig. 7, when the same DCI format D is used for scheduling the TB and for scheduling the CBG, identification information (also called a flag or an identification flag, etc.) indicating whether the TB or the CBG is scheduled is required. For this reason, as shown in Fig. 7, the DCI format D for scheduling the TB may include a flag indicating the TB (e.g., a 1-bit value "0"), and the DCI format D for scheduling the CBG#2 may include a flag indicating the CBG (e.g., a 1-bit value "1").

[0071] Also, in Fig. 7, when DCI format D is used for scheduling CBGs, CBG information indicating which CBGs are scheduled or not may be included in DCI format D. When CBG information is not included in DCI format D, the scheduled CBGs may be indicated implicitly.

[0072] For example, when the scheduled CBG is implicitly indicated, the scheduled CBG may be indicated using at least one of a search space (SS), a Radio Network Temporary Identifier (RNTI), and an aggregation level.

[0073] As described above, when the same DCI format D is used when scheduling the TB and when scheduling the CBG, the number of DCI formats that the user terminal monitors (blindly decodes) is reduced, thereby reducing the amount of monitoring processing in the user terminal.

[0074] Furthermore, even when falling back from CBG-based to TB-based retransmission (when the next retransmission of data that has been retransmitted based on CBG is based on TB), there is no need to change the DCI format, so that fallback can be easily performed. For example, in FIG. 7, by using DCI format D that includes a flag indicating that TB is scheduled and an NDI that is not toggled, the user terminal can recognize (fall back) that the retransmission is a TB-based retransmission.

[0075] In the second aspect, the DCI format is controlled between when scheduling the TB and when scheduling the CBG, so that TB-based and / or CBG-based transmission (including retransmission) and / or reception can be appropriately controlled.

[0076] (Third aspect) In the third aspect, the reception control of the retransmitted CBG according to the cause of the retransmission of the CBG (the cause of the decoding failure in the user terminal) will be described. The retransmission of the CBG (decoding failure) is suitable for the following cases: (1) an error occurs in some CB / CBG in the TB due to thermal noise, interference, or adaptive control error (uncorrelated error), or (2) a transmission other than the data is assigned to a part of the resources assigned to the data, and as a result, a part of the resources assigned to the data is punctured (rewritten). In other words, it is assumed that the cause of the retransmission of the CBG occurs due to these reasons.

[0077] (1) It is assumed that uncorrelated errors in a TB occur in a small number of CBGs (e.g., one CBG) in the TB, for example, during high-speed communication. The user terminal stores a CBG that has failed to be decoded due to uncorrelated errors in a soft buffer. When the CBG is retransmitted, the user terminal may combine the retransmitted CBG with the CBG stored in the soft buffer. Although the CBG stored in the soft buffer contains errors, it is data within the same TB, so that the reception quality can be improved by combining it with the retransmitted CBG.

[0078] On the other hand, (2) puncturing of a part of a TB due to another transmission is assumed to occur, for example, due to preemption caused by a short TTI. Since the CBG that has failed to be decoded due to puncturing is not data in the same TB (it is data of another transmission), combining it with the retransmitted CBG is not effective in improving reception quality. For this reason, when the CBG that has failed to be decoded due to puncturing is stored in the soft buffer, the user terminal discards (also called flushes) the CBG and decodes the retransmitted CBG without combining it with the CBG.

[0079] In this way, it is desirable that the decoding control of the retransmission CBG in the user terminal differs depending on the cause of the CBG retransmission (cause of the decoding failure). For this reason, in the third aspect, the user terminal controls the decoding of the retransmission CBG based on the cause of the CBG retransmission (also called the cause of the decoding failure or the cause of the CBG error, etc.).

[0080] Specifically, when the cause of the retransmission of the CBG is puncture, the user terminal may discard the CBG stored in the soft buffer and decode the retransmitted CBG. On the other hand, when the cause of the retransmission of the CBG is uncorrelated error, the user terminal may combine the CBG stored in the soft buffer and the retransmitted CBG and decode the retransmitted CBG.

[0081] In a third aspect, multiple retransmission CBGs having different retransmission causes may be scheduled using DCI of the same DCI format, or may be scheduled using DCI of different DCI formats, or may be scheduled at different timings.

[0082] <Same DCI format> When a DCI of the same (common) DCI format is used among multiple retransmission CBGs with different retransmission causes, the DCI of the DCI format may include a predetermined field value indicating a retransmission cause for each CBG. The user terminal recognizes the retransmission cause of the CBG based on the predetermined field value. The predetermined field value may be a value of a new field or a value of an existing field (e.g., an RV field).

[0083] <When using a new field> Fig. 8 is a diagram showing an example of a predetermined field indicating a retransmission cause of a CBG according to the third aspect. As shown in Fig. 8, a new 1-bit field (e.g., a retransmission cause field) indicating a retransmission cause for each CBG may be introduced. For example, in Fig. 8, a retransmission cause field value of "0" indicates (2) puncture due to another transmission, and a retransmission cause field value of "1" indicates (1) uncorrelated error.

[0084] When the retransmission cause field value in the DCI is "0", the user terminal discards the CBG in the soft buffer and decodes the retransmission CBG scheduled by the DCI. The CBG in the soft buffer to be discarded may be indicated by the DCI (e.g., a CBG index in the DCI).

[0085] On the other hand, when the retransmission cause field value in the DCI is "1", the user terminal may combine the CBG in the soft buffer with the retransmission CBG scheduled by the DCI, and decode the retransmission CBG. The CBG in the soft buffer to be combined with the retransmission CBG may be indicated by the DCI (e.g., a CBG index in the DCI).

[0086] In addition, the format of the DCI used for scheduling the retransmission CBG may be the same as the format of the DCI used for scheduling the CBG that failed to be decoded, regardless of the cause of the retransmission.

[0087] Also, when a retransmission cause field is introduced, a single RV field common to all CBGs may be provided in the DCI. If the retransmission cause field value is "0", the user terminal may ignore the RV field value in the DCI and assume that the RV of the retransmission CBG is 0. On the other hand, if the retransmission cause field value is "1", the user terminal may assume that the RV field value in the DCI indicates the RV of the retransmission CBG (the RV indicated by the RV field value may be applied to the retransmission CBG).

[0088] In addition, multiple retransmission CBGs indicating different retransmission causes may be scheduled in the same DCI. For example, CBG#0 with a retransmission cause field value of "0" and CBG#X with a retransmission cause field value of "1" may be scheduled by the same DCI.

[0089] As shown in FIG. 8, when a retransmission cause field is newly introduced into DCI, the payload of DCI increases, but decoding control of the retransmission CBG in the user terminal can be easily performed.

[0090] <When using an existing field> Fig. 9 is a diagram showing an example of a predetermined field indicating the cause of retransmission of a CBG according to the third aspect. In Fig. 9, an existing RV field indicates the cause of retransmission of the CBG (the cause of decoding failure or the cause of a CBG error). In this case, an RV field may be provided for each CBG. Fig. 9A shows a 2-bit RV field, and Fig. 9B shows a 1-bit RV field. Note that the number of bits in the RV field is not limited to 1 or 2 bits, and may be 3 bits or more.

[0091] As shown in Figure 9A, the 2-bit RV field value may be associated with the RV value and the CBG retransmission cause. For example, in Figure 9A, the RV field value "00" may indicate RV0 and the retransmission cause is puncture by another transmission, since in the case of puncture, the retransmission CBG is assumed to be RV0. Also, the RV field values ​​"01", "10" and "11" may indicate RV1, RV2 and RV3, respectively, and the retransmission cause is uncorrelated error.

[0092] Similarly, in Figure 9B, a 1-bit RV field value may be associated with an RV value and a retransmission cause of the CBG. For example, in Figure 9B, an RV field value of "0" may indicate RV0 and the retransmission cause is puncture due to another transmission. Also, an RV field value of "1" may indicate either RV1, RV2 or RV3 and the retransmission cause is an uncorrelated error.

[0093] If the RV field value is "00" (FIG. 9A) or "0" (FIG. 9B), the user terminal discards the CBG in the soft buffer and decodes the retransmission CBG scheduled by the DCI. The CBG in the soft buffer to be discarded may be indicated by the DCI (e.g., a CBG index in the DCI).

[0094] On the other hand, when the retransmission cause field value in the DCI is "01", "10" or "11" (FIG. 9A), or "1" (FIG. 9B), the user terminal may combine the CBG in the soft buffer with the retransmission CBG scheduled by the DCI, and decode the retransmission CBG. The CBG in the soft buffer to be combined with the retransmission CBG may be indicated by the DCI (e.g., a CBG index in the DCI).

[0095] In addition, the format of the DCI used for scheduling the retransmission CBG may be the same as the format of the DCI used for scheduling the CBG that failed to be decoded, regardless of the cause of the retransmission.

[0096] In addition, multiple retransmission CBGs indicating different retransmission causes may be scheduled in the same DCI. For example, CBG#0 with an RV field value of "0" and CBG#X with an RV field value of "1" may be scheduled by the same DCI.

[0097] As shown in FIG. 9, when the cause of retransmission of decoding of a CBG is indicated by the RV field value for each CBG, the overhead of DCI can be reduced compared to the case where a new field indicating the cause of retransmission of the CBG is introduced.

[0098] In addition, the user terminal may be instructed by higher layer signaling to change the control of whether to combine or discard the CBG in the soft buffer according to the RV field value. That is, when the control is not configured by higher layer signaling, the user terminal combines the CBG in the soft buffer with the retransmitted CBG regardless of the value of the RV field, and when the control is configured, selects combination or discard according to the value of the RV field. The higher layer signaling may be different from the higher layer signaling that sets the CBG-based retransmission control. In this case, the CBG-based retransmission control can be performed more flexibly. Alternatively, when the CBG-based retransmission control is configured by higher layer signaling, the user terminal may control to select combination or discard according to the value of the RV field. In this case, the overhead of the higher layer signaling can be reduced.

[0099] <Different DCI formats> When DCIs of different DCI formats are used among multiple retransmission CBGs with different retransmission causes, the user terminal recognizes the retransmission cause of the CBG based on the DCI format. DCI format Z1 used for scheduling a retransmission CBG caused by a non-correlated error includes an RV field, and DCI format Z2 used for scheduling a retransmission CBG caused by puncturing by another transmission may not include an RV field.

[0100] The user terminal may be instructed by higher layer signaling to monitor DCI format Z1 and DCI format Z2. That is, when the control is not configured by higher layer signaling, the user terminal monitors DCI format Z1 and DCI format Z2, and selects whether to combine or discard the CBG in the soft buffer and the retransmitted CBG depending on which DCI format is detected. The higher layer signaling may be different from the higher layer signaling that sets the CBG-based retransmission control. In this case, the CBG-based retransmission control can be performed more flexibly. Alternatively, when the CBG-based retransmission control is configured by higher layer signaling, the terminal may perform control to select combination or discard depending on the value of the RV field. In this case, the overhead of the higher layer signaling can be reduced.

[0101] Fig. 10 is a diagram showing an example of scheduling of retransmission CBG according to the third aspect. In Fig. 10, it is assumed that CBG-based retransmission is configured in a user terminal by higher layer signaling. For example, in Fig. 10A, it is assumed that initially transmitted CBG#2 fails to be decoded due to uncorrelated errors. On the other hand, in Fig. 10B, it is assumed that initially transmitted CBG#2 fails to be decoded due to puncturing.

[0102] As shown in Fig. 10A, the retransmission CBG #2 due to the uncorrelated error may be scheduled by DCI format Z1. The DCI format Z1 may include an RV field, and the value of the RV field may indicate an RV common to one or more retransmission CBGs due to the uncorrelated error. For example, in Fig. 10A, the RV field value in DCI format Z1 indicates RV2 applied to the retransmission CBG #2.

[0103] 10A, when the user terminal detects DCI format Z1, it combines the CBG #2 stored in the soft buffer with the retransmission CBG #2 scheduled by DCI format Z1. This makes it possible to improve the reception quality of the retransmission CBG #2.

[0104] 10B, retransmission CBG#2 due to puncturing may be scheduled by DCI format Z2. Since the RV of the retransmission CBG#2 is 0, the DCI format Z2 does not need to include an RV field.

[0105] 10B, when the user terminal detects DCI format Z2, it discards CBG#2 stored in the soft buffer and decodes retransmission CBG#2 scheduled by DCI format Z2. This makes it possible to prevent the retransmission CBG#2 from being combined with data of other communications.

[0106] 10A and 10B, the user terminal may recognize the retransmission cause of the CBG based on the payload of the DCI format. As described above, since it is assumed that the DCI formats Z1 and Z2 have different payloads, the user terminal may identify the retransmission cause of the CBG based on the payload of the DCI format.

[0107] Alternatively, the user terminal may recognize the retransmission cause of the CBG based on the detection resource of the DCI (e.g., the search space and / or CORESET in which the DCI is detected). In this case, the DCI of the DCI formats Z1 and Z2 may be placed in different search spaces and / or different CORESETs.

[0108] <Different timing> When multiple retransmission CBGs with different retransmission causes are scheduled at different timings, the user terminal recognizes the retransmission cause of the CBG based on the timing at which the retransmission CBG is scheduled.

[0109] For example, if a retransmission CBG is scheduled (transmitted) by a certain timing T, the user terminal may recognize that the cause is puncturing due to other communications, and if a retransmission CBG is scheduled after the certain timing T, the user terminal may recognize that the cause is uncorrelated errors.

[0110] Fig. 11 is a diagram showing another example of scheduling of retransmission CBG according to the third aspect. In Fig. 11, it is assumed that CBG-based retransmission is configured in a user terminal by higher layer signaling. For example, in Fig. 11A, it is assumed that decoding of the initially transmitted CBG#2 fails due to puncturing. On the other hand, in Fig. 11B, it is assumed that decoding of the initially transmitted CBG#2 fails due to uncorrelated errors.

[0111] As shown in FIG. 11A, if the retransmission CBG is scaled before a predetermined timing T, the user terminal discards CBG#2 stored in the soft buffer and decodes the retransmission CBG#2.

[0112] The predetermined timing T may be determined based on the feedback timing of the HARQ-ACK. For example, when a CBG that fails to be decoded is received in slot n, the predetermined timing T may be slot n+k (k≧0) that is the same as the feedback timing of the HARQ-ACK, or may be slot n+k+α, where α≧0 and is a predetermined offset with respect to the feedback timing of the HARQ-ACK.

[0113] As shown in Fig. 11A, in the case of a decoding failure due to puncturing, it is assumed that the radio base station retransmits the punctured CBG#2 without waiting for a HARQ-ACK bit from the user terminal. For this reason, if retransmission CBG#2 is scheduled before a predetermined timing T based on the feedback timing of the HARQ-ACK, the user terminal may recognize that the cause of retransmission of CBG#2 is due to puncturing, and discard the CBG#2 stored in the soft buffer.

[0114] On the other hand, as shown in FIG. 11B, when the retransmission CBG is scaled after a predetermined timing T, the user terminal combines the CBG#2 stored in the soft buffer and the retransmission CBG#2, and decodes the retransmission CBG#2.

[0115] As shown in FIG. 11B, in the case of a decoding failure due to an uncorrelated error, when the HARQ-ACK bit from the user terminal indicates NACK, the radio base station retransmits the CBG#2 indicating NACK. Therefore, when the retransmission CBG#2 is scheduled after a predetermined timing T based on the feedback timing of HARQ-ACK, the user terminal recognizes that the retransmission cause of the CBG#2 is due to an uncorrelated error, and may combine the CBG#2 stored in the soft buffer and the retransmission CBG#2.

[0116] As shown in FIGS. 11A and 11B, when the user terminal recognizes the retransmission cause of the CBG based on the timing T at which the retransmission CBG is scheduled, a plurality of retransmission CBGs with different retransmission causes can be scheduled using the DCI in the same DCI format. Note that in FIG. 11, it is not assumed that a plurality of retransmission CBGs with different retransmission causes are scheduled using a single DCI.

[0117] <Discarding of CBG> In the third aspect, it has been described that when the retransmission cause is a puncture, the CBG in the soft buffer is discarded. However, when the retransmission CBG is scheduled, the user terminal may discard (flush) the corresponding CBG in the soft buffer regardless of the retransmission cause.

[0118] The DCI that schedules the retransmission CBG may explicitly or implicitly include the identification information of the retransmission CBG. When the CBG in the soft buffer is discarded regardless of the retransmission cause, the RV field in the DCI that schedules the retransmission CBG may be common to all CBGs in the TB. Also, the RV indicated by the RV field value may be fixed to 0, or the RV field may be omitted.

[0119] Also, the NDI field in the DCI may be common to all CBGs in the TB. As described above, in the case of initial transmission, the NDI is set (toggled) to a value different from the latest value of the same HARQ process, and in the case of retransmission, the NDI is set (not toggled) to the same value as the latest value of the same HARQ process.

[0120] The user terminal may also discard all corresponding CBGs from the soft buffer up to the previous transmission (or retransmission).

[0121] In the third aspect described above, the user terminal controls decoding of the retransmitted CBG based on the cause of retransmission of the CBG, and therefore can prevent erroneous combination of the retransmitted CBG with data of other transmissions due to puncturing.

[0122] (Fourth aspect) In the fourth aspect, fallback control from CBG-based to TB-based retransmission is described.

[0123] When CBG-based retransmission is configured in the user terminal, the user terminal may fall back from CBG-based retransmission to TB-based retransmission based on a predetermined condition. For example, the user terminal may assume that it falls back to TB-based retransmission in at least one of the following cases (1) to (4): (1) When TB-based retransmission is instructed by DCI (2) When DCI is detected by a search space common to one or more user terminals (also called a common search space or a group search space, etc.) (3) A case where the ACKs of all CBGs in the TB are recognized, but a NACK of the TB is recognized (a case where a NACK-to-ACK error occurs in one or more CBGs in the radio base station) (4) When the number of CBGs in the TB at the time of the first transmission is 1

[0124] In addition, in at least one of the above cases (1) to (4), the user terminal may generate and feed back an ACK or NACK based on the decoding result of the entire TB. In addition, when falling back to TB-based retransmission, the user terminal may or may not discard (flush) the TB in the soft buffer.

[0125] In the fourth aspect, CBG-based retransmission falls back to TB-based retransmission based on predetermined conditions, so that appropriate control at the TB level can be performed even when CBG-based retransmission is configured in the user terminal.

[0126] (Wireless communication system) The configuration of a wireless communication system according to the present embodiment will be described below. In this wireless communication system, the wireless communication methods according to the above aspects are applied. Note that the wireless communication methods according to the above aspects may be applied independently or in combination.

[0127] 12 is a diagram showing an example of a schematic configuration of a wireless communication system according to the present embodiment. In the wireless communication system 1, carrier aggregation (CA) and / or dual connectivity (DC) can be applied, in which a plurality of basic frequency blocks (component carriers) are integrated into one unit, the system bandwidth (e.g., 20 MHz) of the LTE system. Note that the wireless communication system 1 may be called SUPER 3G, LTE-A (LTE-Advanced), IMT-Advanced, 4G, 5G, FRA (Future Radio Access), NR (New RAT), or the like.

[0128] The wireless communication system 1 shown in Fig. 12 includes a wireless base station 11 that forms a macrocell C1, and wireless base stations 12a to 12c that are arranged in the macrocell C1 and form small cells C2 that are smaller than the macrocell C1. User terminals 20 are arranged in the macrocell C1 and each small cell C2. Different numerologies may be applied between the cells. Numerology refers to a set of communication parameters that characterize the design of a signal in a certain RAT.

[0129] The user terminal 20 can be connected to both the radio base station 11 and the radio base station 12. It is assumed that the user terminal 20 uses a macro cell C1 and a small cell C2 using different frequencies simultaneously by CA or DC. The user terminal 20 can also apply CA or DC using multiple cells (CC) (for example, two or more CCs). The user terminal can also use licensed bands CC and unlicensed bands CC as multiple cells.

[0130] Furthermore, the user terminal 20 can communicate in each cell using time division duplex (TDD) or frequency division duplex (FDD). A TDD cell and an FDD cell may be called a TDD carrier (frame configuration type 2) and an FDD carrier (frame configuration type 1), respectively.

[0131] Also, in each cell (carrier), either a subframe having a relatively long time length (for example, 1 ms) (also called TTI, normal TTI, long TTI, normal subframe, long subframe, slot, etc.) or a subframe having a relatively short time length (also called short TTI, short subframe, slot, etc.) may be applied, or both long subframes and short subframes may be applied. Also, in each cell, subframes of two or more time lengths may be applied.

[0132] Communication between the user terminal 20 and the radio base station 11 can be performed using a carrier (called an existing carrier, legacy carrier, etc.) with a relatively low frequency band (for example, 2 GHz) and narrow bandwidth. On the other hand, a carrier with a relatively high frequency band (for example, 3.5 GHz, 5 GHz, 30 to 70 GHz, etc.) and wide bandwidth may be used between the user terminal 20 and the radio base station 12, or the same carrier as between the user terminal 20 and the radio base station 11 may be used. Note that the configuration of the frequency bands used by each radio base station is not limited to this.

[0133] The wireless base station 11 and the wireless base station 12 (or between two wireless base stations 12) can be configured as a wired connection (e.g., optical fiber conforming to CPRI (Common Public Radio Interface), X2 interface, etc.) or a wireless connection.

[0134] The radio base station 11 and each radio base station 12 are each connected to a higher station device 30, and are connected to a core network 40 via the higher station device 30. The higher station device 30 includes, for example, an access gateway device, a radio network controller (RNC), a mobility management entity (MME), etc., but is not limited to these. Also, each radio base station 12 may be connected to the higher station device 30 via the radio base station 11.

[0135] The radio base station 11 is a radio base station having a relatively wide coverage, and may be called a macro base station, an aggregation node, an eNodeB (eNB), a transmission / reception point, etc. The radio base station 12 is a radio base station having a local coverage, and may be called a small base station, a micro base station, a pico base station, a femto base station, a Home eNodeB (HeNB), a Remote Radio Head (RRH), a transmission / reception point, etc. Hereinafter, when there is no need to distinguish between the radio base stations 11 and 12, they are collectively referred to as the radio base station 10.

[0136] Each user terminal 20 is a terminal compatible with various communication methods such as LTE and LTE-A, and may include not only mobile communication terminals but also fixed communication terminals. In addition, the user terminal 20 can perform terminal-to-terminal communication (D2D) with other user terminals 20.

[0137] In the wireless communication system 1, as a wireless access method, OFDMA (orthogonal frequency division multiple access) can be applied to the downlink (DL), and SC-FDMA (single carrier-frequency division multiple access) can be applied to the uplink (UL). OFDMA is a multi-carrier transmission method in which a frequency band is divided into a plurality of narrow frequency bands (subcarriers) and data is mapped to each subcarrier for communication. SC-FDMA is a single-carrier transmission method in which the system bandwidth is divided into bands consisting of one or consecutive resource blocks for each terminal, and multiple terminals use different bands to reduce interference between terminals. Note that the uplink and downlink wireless access methods are not limited to these combinations, and OFDMA may be used in the UL. Also, SC-FDMA can be applied to the sidelink (SL) used for terminal-to-terminal communication.

[0138] In the wireless communication system 1, DL channels include a DL data channel (PDSCH: Physical Downlink Shared Channel, also called DL shared channel, etc.) shared by each user terminal 20, a broadcast channel (PBCH: Physical Broadcast Channel), an L1 / L2 control channel, etc. At least one of user data, higher layer control information, SIB (System Information Block), etc. is transmitted by the PDSCH. Also, MIB (Master Information Block) is transmitted by the PBCH.

[0139] The L1 / L2 control channels include DL control channels (PDCCH (Physical Downlink Control Channel), EPDCCH (Enhanced Physical Downlink Control Channel)), PCFICH (Physical Control Format Indicator Channel), PHICH (Physical Hybrid-ARQ Indicator Channel), etc. Downlink control information (DCI: Downlink Control Information) including scheduling information of PDSCH and PUSCH, etc. are transmitted by PDCCH. The number of OFDM symbols used for PDCCH is transmitted by PCFICH. EPDCCH is frequency division multiplexed with PDSCH, and is used for transmitting DCI, etc., like PDCCH. At least one of PHICH, PDCCH, and EPDCCH can transmit retransmission control information of PUSCH (also called A / N, HARQ-ACK, HARQ-ACK bit, A / N codebook, etc.).

[0140] In the wireless communication system 1, as UL channels, a UL data channel (PUSCH: Physical Uplink Shared Channel, also called a UL shared channel, etc.) shared by each user terminal 20, a UL control channel (PUCCH: Physical Uplink Control Channel), a random access channel (PRACH: Physical Random Access Channel), etc. are used. User data and higher layer control information are transmitted by the PUSCH. Uplink control information (UCI: Uplink Control Information) including at least one of retransmission control information (A / N, HARQ-ACK) and channel state information (CSI) of the PDSCH is transmitted by the PUSCH or the PUCCH. A random access preamble for establishing a connection with a cell can be transmitted by the PRACH.

[0141] <Radio base station> 13 is a diagram showing an example of the overall configuration of a radio base station according to this embodiment. The radio base station 10 includes a plurality of transmitting / receiving antennas 101, an amplifier unit 102, a transmitting / receiving unit 103, a baseband signal processing unit 104, a call processing unit 105, and a transmission path interface 106. Note that the radio base station 10 may be configured to include one or more of each of the transmitting / receiving antennas 101, the amplifier unit 102, and the transmitting / receiving unit 103.

[0142] User data transmitted from the radio base station 10 to the user terminal 20 on the downlink is input from the higher-level station device 30 to the baseband signal processing unit 104 via the transmission path interface 106 .

[0143] In the baseband signal processing unit 104, transmission processing such as at least one of PDCP (Packet Data Convergence Protocol) layer processing, user data division / combination, RLC (Radio Link Control) layer transmission processing such as RLC retransmission control, MAC (Medium Access Control) retransmission control (e.g., HARQ (Hybrid Automatic Repeat reQuest) processing), scheduling, transmission format selection, channel coding, rate matching, scrambling, inverse fast Fourier transform (IFFT) processing, and precoding processing is performed on the user data, and the data is transferred to the transceiver unit 103. In addition, transmission processing such as channel coding and / or inverse fast Fourier transform is performed on the downlink control signal, and the data is transferred to the transceiver unit 103.

[0144] The transmitting / receiving unit 103 converts the baseband signal output from the baseband signal processing unit 104 after precoding for each antenna into a radio frequency band and transmits it. The radio frequency signal frequency-converted by the transmitting / receiving unit 103 is amplified by the amplifier unit 102 and transmitted from the transmitting / receiving antenna 101.

[0145] The transmitter / receiver, the transmitter / receiver circuit, or the transmitter / receiver device may be configured based on a common understanding in the technical field related to the present invention. Note that the transmitter / receiver 103 may be configured as an integrated transmitter / receiver, or may be configured from a transmitter and a receiver.

[0146] On the other hand, for a UL signal, a radio frequency signal received by a transmitting / receiving antenna 101 is amplified by an amplifier unit 102. A transmitting / receiving unit 103 receives the UL signal amplified by the amplifier unit 102. The transmitting / receiving unit 103 frequency-converts the received signal to a baseband signal and outputs the signal to a baseband signal processing unit 104.

[0147] The baseband signal processing unit 104 performs Fast Fourier Transform (FFT) processing, Inverse Discrete Fourier Transform (IDFT) processing, error correction decoding, MAC retransmission control reception processing, and RLC layer and PDCP layer reception processing on the UL data included in the input UL signal, and transfers the signal to the upper station device 30 via a transmission path interface 106. The call processing unit 105 performs at least one of call processing such as setting and releasing a communication channel, status management of the wireless base station 10, and management of wireless resources.

[0148] The transmission line interface 106 transmits and receives signals to and from the higher-level station device 30 via a predetermined interface. The transmission line interface 106 may also transmit and receive signals (backhaul signaling) to and from the adjacent wireless base station 10 via an inter-base station interface (for example, an optical fiber conforming to CPRI (Common Public Radio Interface), an X2 interface).

[0149] In addition, the transceiver 103 transmits DL signals (e.g., at least one of DCI (DL assignment for scheduling DL data and / or UL grant for scheduling UL data), DL data, and DL reference signals) and receives UL signals (e.g., at least one of UL data, UCI, and UL reference signals).

[0150] Furthermore, the transmitting / receiving unit 103 receives retransmission control information (also referred to as ACK / NACK, A / N, HARQ-ACK, A / N codebook, etc.) of DL signals. The unit of the retransmission control information may be, for example, for each CB, for each CBG, for each TB, or for one or more TBs (ACK or NACK may be indicated for each CB, for each CBG, for each TB, or for one or more TBs). Furthermore, the transmitting / receiving unit 103 may transmit setting information (information indicating a TB base or a CBG base) of the retransmission unit of DL signals and / or UL signals.

[0151] Fig. 14 is a diagram showing an example of a functional configuration of a radio base station according to this embodiment. Fig. 14 mainly shows functional blocks of characteristic parts in this embodiment, and it is assumed that the radio base station 10 also has other functional blocks necessary for wireless communication. As shown in Fig. 14, the baseband signal processing unit 104 includes a control unit 301, a transmission signal generating unit 302, a mapping unit 303, a reception signal processing unit 304, and a measurement unit 305.

[0152] The control unit 301 performs overall control of the radio base station 10. The control unit 301 controls at least one of the generation of DL signals by the transmission signal generation unit 302, the mapping of DL signals by the mapping unit 303, the reception processing (e.g., demodulation) of UL signals by the reception signal processing unit 304, and the measurement by the measurement unit 305, for example.

[0153] Specifically, the control unit 301 determines a modulation scheme and / or a TBS for the DL signal based on a channel quality indicator (CQI) fed back from the user terminal 20. The control unit 301 controls the transmission signal generation unit 302 to encode the DL signal with the TBS and modulate the DL signal with the modulation scheme. Furthermore, when the TBS exceeds a predetermined threshold, the control unit 301 may apply code block partitioning to the DL signal, which divides the TBS into multiple CBs.

[0154] Furthermore, the control unit 301 may control transmission of DCI. Specifically, the control unit 301 may use the same DCI format (format) between the initial transmission and the retransmission or different DCI formats (first aspect, FIGS. 4 and 5). Furthermore, the control unit 301 may use the same DCI format (format) between the case of scheduling the TB and the case of scheduling the CBG or different DCI formats (second aspect, FIGS. 6 and 7).

[0155] Furthermore, the control unit 301 may control the transmission of DCI including a predetermined field value indicating a retransmission cause (third aspect, Figs. 8 and 9). Alternatively, the control unit 301 may use different DCI formats between multiple retransmission CBGs having different retransmission causes (third aspect, Fig. 10). Furthermore, the control unit 301 may schedule multiple retransmission CBGs having different retransmission causes at different timings (third aspect, Fig. 11).

[0156] Furthermore, the control unit 301 may control a fallback from CB-based to TB-based retransmission (fourth aspect).

[0157] Also, the control unit 301 controls the reception processing (e.g., demodulation, decoding, etc.) of the UL signal. For example, the control unit 301 demodulates the UL signal based on the modulation scheme indicated by the MCS index specified in the DCI (UL grant), and determines the TBS based on the TBS index indicated by the MCS index and the number of allocated resource blocks. Based on the determined TBS of the UL data, the control unit 301 determines the number of CBs in the TB and the size of each CB.

[0158] Furthermore, the control unit 301 may control the retransmission of each CBG (or each TB) based on retransmission control information indicating an ACK or NACK for each CBG (or for each TB) from the user terminal 20.

[0159] The control unit 301 can be configured from a controller, a control circuit, or a control device that is described based on common understanding in the technical field related to the present invention.

[0160] The transmission signal generating unit 302 may generate a DL signal (including at least one of DL data, DCI, DL reference signal, and control information by higher layer signaling) based on an instruction from the control unit 301, and output the DL signal to the mapping unit 303.

[0161] The transmission signal generating unit 302 may be a signal generator, a signal generating circuit, or a signal generating device described based on common understanding in the technical field related to the present invention.

[0162] Based on an instruction from the control unit 301, the mapping unit 303 maps the DL signal generated by the transmission signal generation unit 302 to a predetermined radio resource and outputs the DL signal to the transmission / reception unit 103. The mapping unit 303 can be a mapper, a mapping circuit, or a mapping device that is described based on a common understanding in the technical field related to the present invention.

[0163] The reception signal processing unit 304 performs reception processing (e.g., demapping, demodulation, decoding, etc.) of a UL signal transmitted from the user terminal 20. For example, the reception signal processing unit 304 may perform decoding processing on a CB basis in accordance with an instruction from the control unit 301.

[0164] The received signal processing unit 304 performs reception processing (e.g., demapping, demodulation, decoding, etc.) on UL signals (e.g., including UL data signals, UL control signals, and UL reference signals) transmitted from the user terminal 20. Specifically, the received signal processing unit 304 may output the received signals and / or signals after reception processing to the measurement unit 305. Furthermore, the received signal processing unit 304 performs reception processing of UCI based on the UL control channel configuration instructed by the control unit 301.

[0165] The measurement unit 305 may measure the UL channel quality based on, for example, the received power (e.g., Reference Signal Received Power (RSRP)) and / or the received quality (e.g., Reference Signal Received Quality (RSRQ)) of the UL reference signal. The measurement result may be output to the control unit 301.

[0166] <User device> 15 is a diagram showing an example of the overall configuration of a user terminal according to this embodiment. The user terminal 20 includes a plurality of transmitting / receiving antennas 201 for MIMO transmission, an amplifier unit 202, a transmitting / receiving unit 203, a baseband signal processing unit 204, and an application unit 205.

[0167] Radio frequency signals received by the multiple transmitting / receiving antennas 201 are each amplified by an amplifier unit 202. Each transmitting / receiving unit 203 receives the DL signal amplified by the amplifier unit 202. The transmitting / receiving unit 203 frequency-converts the received signal to a baseband signal and outputs the signal to a baseband signal processing unit 204.

[0168] The baseband signal processing unit 204 performs at least one of FFT processing, error correction decoding, and receiving processing such as retransmission control on the input baseband signal. DL data is transferred to the application unit 205. The application unit 205 performs processing related to layers higher than the physical layer and the MAC layer.

[0169] On the other hand, the UL data is input from the application unit 205 to the baseband signal processing unit 204. In the baseband signal processing unit 204, at least one of retransmission control processing (e.g., HARQ processing), channel coding, rate matching, puncturing, discrete Fourier transform (DFT) processing, IFFT processing, etc. is performed on the UL data, and the data is transferred to each transceiver unit 203. As for the UCI (e.g., at least one of A / N of DL signal, channel state information (CSI), and scheduling request (SR)), at least one of channel coding, rate matching, puncturing, DFT processing, IFFT processing, etc. is also performed on the UCI, and the data is transferred to each transceiver unit 203.

[0170] The transmitting / receiving unit 203 converts the baseband signal output from the baseband signal processing unit 204 into a radio frequency band and transmits it. The radio frequency signal frequency-converted by the transmitting / receiving unit 203 is amplified by the amplifier unit 202 and transmitted from the transmitting / receiving antenna 201.

[0171] In addition, the transceiver 203 receives DL signals (for example, at least one of DCI (DL assignment and / or UL grant), DL data, and DL reference signals) and transmits UL signals (for example, at least one of UL data, UCI, and UL reference signals).

[0172] Furthermore, the transmitting / receiving unit 203 transmits retransmission control information of the DL signal. As described above, the unit of the retransmission control information may be, for example, for each CB, for each CBG, for each TB, or for one or more TBs (ACK or NACK may be indicated for each CB, for each CBG, for each TB, or for one or more TBs). Furthermore, the transmitting / receiving unit 203 may receive setting information (information indicating a TB base or a CBG base) of the retransmission unit of the DL signal and / or the UL signal.

[0173] The transceiver unit 203 may be a transmitter / receiver, a transceiver circuit, or a transceiver device that is described based on common understanding in the technical field related to the present invention. The transceiver unit 203 may be configured as an integrated transceiver unit, or may be configured of a transmitter unit and a receiver unit.

[0174] Fig. 16 is a diagram showing an example of a functional configuration of a user terminal according to this embodiment. Fig. 16 mainly shows functional blocks of characteristic parts in this embodiment, and the user terminal 20 is assumed to have other functional blocks necessary for wireless communication. As shown in Fig. 16, the baseband signal processing unit 204 of the user terminal 20 includes a control unit 401, a transmission signal generating unit 402, a mapping unit 403, a reception signal processing unit 404, and a measurement unit 405.

[0175] The control unit 401 performs overall control of the user terminal 20. The control unit 401 controls at least one of the following: generation of a UL signal by a transmission signal generation unit 402, mapping of the UL signal by a mapping unit 403, reception processing of a DL signal by a reception signal processing unit 404, and measurement by a measurement unit 405, for example.

[0176] Specifically, the control unit 401 controls the reception processing (e.g., demodulation, decoding, etc.) of the DL signal based on the DCI (DL assignment). For example, the control unit 401 may control the reception signal processing unit 404 to demodulate the DL signal based on the modulation scheme indicated by the MCS index in the DCI. Furthermore, the control unit 401 determines the TBS based on the TBS index indicated by the MCS index and the number of allocated resource blocks. Based on the determined TBS of the DL data, the control unit 401 determines the number of CBs in the TB and the size of each CB.

[0177] Also, the control unit 401 may monitor (blind decode) DL control channel candidates (search spaces) and control the reception of CBG or TB based on the detected DCI. Specifically, the control unit 401 may assume the same DCI format or different DCI formats between the initial transmission and the retransmission (first aspect, Figs. 4 and 5). Also, the control unit 401 may assume the same DCI format or different DCI formats between the case of scheduling TB and the case of scheduling CBG (second aspect, Figs. 6 and 7).

[0178] Furthermore, the control unit 401 may control the decoding of the retransmitted CBG based on the cause of retransmission of the CBG (also referred to as the cause of decoding failure or the cause of a CBG error, etc.) (third aspect). Specifically, when the cause of retransmission of the retransmitted CBG is puncture due to another transmission, the control unit 401 may discard the CBG stored in the soft buffer. On the other hand, when the cause of retransmission of the retransmitted CBG is not puncture due to another transmission (non-correlated error), the control unit 401 may combine the retransmitted CBG with the CBG stored in the soft buffer.

[0179] Furthermore, the control unit 401 may determine the retransmission cause based on a predetermined field value in a DCI that schedules the retransmission CBG (third aspect, Figs. 8 and 9). Alternatively, the control unit 401 may determine the retransmission cause of the retransmission CBG based on a DCI format used for scheduling the retransmission CBG (third aspect, Fig. 10). Alternatively, the control unit 401 may determine the retransmission cause of the retransmission CBG based on the scheduling timing of the retransmission CBG (third aspect, Fig. 11).

[0180] Also, the control unit 401 may control a fallback from CB-based to TB-based retransmission (fourth aspect). Specifically, the control unit 401 may recognize that the retransmission is a TB-based retransmission when a predetermined condition is satisfied.

[0181] Furthermore, the control unit 401 may control the generation and / or transmission of retransmission control information for DL ​​data. Specifically, the control unit 401 may control the generation and / or transmission of retransmission control information indicating ACK or NACK for each predetermined unit (for example, for each CB or for each CBG). Specifically, the control unit 401 may control the generation of retransmission control information indicating ACK / NACK for each CBG and / or TB based on the result of demodulation and / or decoding (error correction) of each CB.

[0182] Furthermore, the control unit 401 may control the restoration of the TB constituting the DL signal. Specifically, the control unit 401 may perform control so as to restore the TB based on the initially transmitted CB or CBG and / or the retransmitted CB / CBG.

[0183] Furthermore, the control unit 401 may control the reception process of the retransmission CBG based on information on the retransmission CBG included in the DCI (DL assignment). For example, the control unit 401 may control the synthesis process of the data stored in the (soft buffer of) the user terminal 20 and the retransmission CBG based on the CBG index of the retransmission CBG included in the DCI.

[0184] Furthermore, control unit 401 controls generation and transmission processing (e.g., coding, modulation, mapping, etc.) of the UL signal based on the DCI (UL grant). For example, control unit 401 may control transmission signal generation unit 402 to modulate the UL signal based on a modulation scheme indicated by an MCS index in the DCI. Control unit 401 may also control transmission signal generation unit 402 to determine a TBS based on a TBS index indicated by the MCS index and the number of allocated resource blocks, and to code the UL signal based on the TBS.

[0185] The control unit 401 can be configured from a controller, a control circuit, or a control device that is described based on common understanding in the technical field related to the present invention.

[0186] The transmission signal generating unit 402 generates retransmission control information for the UL signal and DL signal (e.g., encoding, rate matching, puncturing, modulation, etc.) based on an instruction from the control unit 401, and outputs the generated information to the mapping unit 403. The transmission signal generating unit 402 can be a signal generator, a signal generating circuit, or a signal generating device described based on a common understanding in the technical field related to the present invention.

[0187] Based on an instruction from the control unit 401, the mapping unit 403 maps retransmission control information of the UL signal and DL signal generated by the transmission signal generation unit 402 to radio resources and outputs the radio resources to the transmission / reception unit 203. The mapping unit 403 can be a mapper, a mapping circuit, or a mapping device that is described based on a common understanding in the technical field related to the present invention.

[0188] The reception signal processing unit 404 performs reception processing (e.g., demapping, demodulation, decoding, etc.) of the DL signal. For example, the reception signal processing unit 404 may perform decoding processing on a CB basis in accordance with an instruction from the control unit 401, and output the decoding result of each CB to the control unit 401.

[0189] The received signal processing unit 404 outputs information received from the radio base station 10 to the control unit 401. The received signal processing unit 404 outputs, for example, broadcast information, system information, higher layer control information based on higher layer signaling such as RRC signaling, L1 / L2 control information (for example, UL grant, DL assignment), and the like to the control unit 401.

[0190] The received signal processing unit 404 can be configured from a signal processor, a signal processing circuit, or a signal processing device that is described based on common understanding in the technical field related to the present invention. Also, the received signal processing unit 404 can configure a receiving unit according to the present invention.

[0191] The measurement section 405 measures the channel state based on a reference signal (for example, CSI-RS) from the radio base station 10, and outputs the measurement result to the control section 401. Note that the measurement of the channel state may be performed for each CC.

[0192] The measurement unit 405 can be composed of a signal processor, a signal processing circuit, or a signal processing device, as well as a measuring device, a measuring circuit, or a measuring device, which are described based on common understanding in the technical field related to the present invention.

[0193] <Hardware configuration> The block diagrams used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of hardware and / or software. The means for realizing each functional block is not particularly limited. That is, each functional block may be realized by one device that is physically and / or logically coupled, or may be realized by two or more devices that are physically and / or logically separated and directly and / or indirectly (e.g., wired and / or wirelessly) connected to each other and these multiple devices.

[0194] For example, the radio base station, the user terminal, and the like in this embodiment may function as a computer that performs processing of the radio communication method of the present invention. Fig. 17 is a diagram showing an example of a hardware configuration of the radio base station and the user terminal according to this embodiment. The above-mentioned radio base station 10 and the user terminal 20 may be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, and the like.

[0195] In the following description, the term "apparatus" may be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the radio base station 10 and the user terminal 20 may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0196] For example, although only one processor 1001 is shown, there may be multiple processors, and processes may be performed by one processor or processes may be performed simultaneously, sequentially, or otherwise on one or more processors, and processor 1001 may be implemented on one or more chips.

[0197] Each function in the radio base station 10 and the user terminal 20 is realized, for example, by loading a specific software (program) onto hardware such as a processor 1001 and a memory 1002, so that the processor 1001 performs calculations and controls at least one of communication by a communication device 1004, and reading and writing of data in the memory 1002 and the storage 1003.

[0198] The processor 1001, for example, operates an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, the above-mentioned baseband signal processing unit 104 (204), call processing unit 105, etc. may be realized by the processor 1001.

[0199] Furthermore, the processor 1001 reads out programs (program codes), software modules, data, etc. from the storage 1003 and / or the communication device 1004 into the memory 1002, and executes various processes in accordance with these. As the programs, programs that cause a computer to execute at least a part of the operations described in the above-mentioned embodiments are used. For example, the control unit 401 of the user terminal 20 may be realized by a control program stored in the memory 1002 and operated by the processor 1001, and other functional blocks may be realized in a similar manner.

[0200] The memory 1002 is a computer-readable recording medium, and may be composed of at least one of, for example, a Read Only Memory (ROM), an Erasable Programmable ROM (EPROM), an Electrically EPROM (EEPROM), a Random Access Memory (RAM), and other suitable storage media. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), and the like. The memory 1002 can store executable programs (program codes), software modules, and the like for implementing a wireless communication method according to one embodiment of the present invention.

[0201] Storage 1003 is a computer-readable recording medium, and may be comprised of at least one of, for example, a flexible disk, a floppy disk, a magneto-optical disk (e.g., a compact disk (CD-ROM (Compact Disc ROM)), a digital versatile disk, a Blu-ray Disc), a removable disk, a hard disk drive, a smart card, a flash memory device (e.g., a card, stick, key drive), a magnetic stripe, a database, a server, or other suitable storage medium. Storage 1003 may be referred to as an auxiliary storage device.

[0202] The communication device 1004 is hardware (transmission / reception device) for performing communication between computers via a wired and / or wireless network, and is also called, for example, a network device, a network controller, a network card, or a communication module. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc., in order to realize, for example, Frequency Division Duplex (FDD) and / or Time Division Duplex (TDD). For example, the above-mentioned transmission / reception antenna 101 (201), amplifier unit 102 (202), transmission / reception unit 103 (203), transmission path interface 106, etc. may be realized by the communication device 1004.

[0203] The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that accepts input from the outside. The output device 1006 is an output device (e.g., a display, a speaker, an LED (Light Emitting Diode) lamp, etc.) that performs output to the outside. The input device 1005 and the output device 1006 may be integrated into one (e.g., a touch panel).

[0204] 17 are connected to each other via a bus 1007 for communicating information. The bus 1007 may be configured as a single bus, or may be configured with different buses between the devices.

[0205] Furthermore, the radio base station 10 and the user terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), etc., and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented by at least one of these pieces of hardware.

[0206] (Modification) In addition, the terms described in this specification and / or terms necessary for understanding this specification may be replaced with terms having the same or similar meanings. For example, a channel and / or a symbol may be a signal (signaling). Also, a signal may be a message. A reference signal may be abbreviated as RS (Reference Signal) and may be called a pilot, pilot signal, etc. depending on the applied standard. Also, a component carrier (CC) may be called a cell, a frequency carrier, a carrier frequency, etc.

[0207] Moreover, a radio frame may be composed of one or more periods (frames) in the time domain. Each of the one or more periods (frames) constituting a radio frame may be called a subframe. Furthermore, a subframe may be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0208] A slot may be composed of one or more symbols (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol) in the time domain. A slot may also be a time unit based on numerology. A slot may also include multiple minislots. Each minislot may be composed of one or more symbols in the time domain.

[0209] A radio frame, a subframe, a slot, a minislot, and a symbol each represent a time unit for transmitting a signal. A radio frame, a subframe, a slot, a minislot, and a symbol may be called by a different name corresponding to each of them. For example, one subframe may be called a transmission time interval (TTI), a plurality of consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. That is, a subframe and / or a TTI may be a subframe (1 ms) in the existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms.

[0210] Here, TTI refers to, for example, the minimum time unit of scheduling in wireless communication. For example, in an LTE system, a radio base station performs scheduling to allocate radio resources (such as a frequency bandwidth and / or transmission power that can be used in each user terminal) to each user terminal in TTI units. The definition of TTI is not limited to this. TTI may be a transmission time unit of a channel-coded data packet (transport block), or may be a processing unit for scheduling and / or link adaptation. When one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit of scheduling. Also, the number of slots (minislots) constituting the minimum time unit of scheduling may be controlled.

[0211] A TTI having a time length of 1 ms may be called a normal TTI (TTI in LTE Rel. 8-12), a normal TTI, a long TTI, a normal subframe, a normal subframe, a long subframe, etc. A TTI shorter than a normal TTI may be called a shortened TTI, a short TTI, a partial or fractional TTI, a shortened subframe, a short subframe, etc.

[0212] A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or more consecutive subcarriers in the frequency domain. In addition, an RB may include one or more symbols in the time domain, and may have a length of one slot, one minislot, one subframe, or one TTI. One TTI and one subframe may each be composed of one or more resource blocks. An RB may also be called a physical resource block (PRB), a PRB pair, an RB pair, etc.

[0213] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0214] The above-mentioned structures of radio frames, subframes, slots, minislots, and symbols are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols included in a slot or minislot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, and the cyclic prefix (CP) length can be changed in various ways.

[0215] In addition, the information, parameters, etc. described in this specification may be expressed as absolute values, may be expressed as relative values ​​from a predetermined value, or may be expressed as corresponding other information. For example, a radio resource may be indicated by a predetermined index. Furthermore, the mathematical expressions using these parameters, etc. may be different from those explicitly disclosed in this specification.

[0216] The names used for parameters etc. herein are not intended to be limiting in any respect. For example, the various channels (e.g., Physical Uplink Control Channel (PUCCH), Physical Downlink Control Channel (PDCCH), etc.) and information elements may be identified by any suitable names, and the various names assigned to these various channels and information elements are not intended to be limiting in any respect.

[0217] The information, signals, etc. described herein may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0218] Furthermore, information, signals, etc. may be output from a higher layer to a lower layer and / or from a lower layer to a higher layer. Information, signals, etc. may be input / output via multiple network nodes.

[0219] Input and output information, signals, etc. may be stored in a specific location (e.g., memory) or managed in a management table. Input and output information, signals, etc. may be overwritten, updated, or added. Output information, signals, etc. may be deleted. Input information, signals, etc. may be transmitted to another device.

[0220] The notification of information is not limited to the aspects / embodiments described in this specification, and may be performed by other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB), etc.), Medium Access Control (MAC) signaling), other signals, or a combination of these.

[0221] The physical layer signaling may be called L1 / L2 (Layer 1 / Layer 2) control information (L1 / L2 control signal), L1 control information (L1 control signal), etc. The RRC signaling may be called an RRC message, for example, an RRC connection setup message, an RRC connection reconfiguration message, etc. The MAC signaling may be notified by a MAC control element (MAC CE (Control Element)), for example.

[0222] In addition, notification of specified information (e.g., notification that "it is X") is not limited to being given explicitly, but may be given implicitly (e.g., by not notifying the specified information or by notifying other information).

[0223] The determination may be made based on a value represented by a single bit (0 or 1), a Boolean value represented as true or false, or by comparing numerical values ​​(e.g., with a predetermined value).

[0224] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0225] Additionally, software, instructions, information, etc. may be transmitted or received over a transmission medium. For example, if the software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave, etc.), these wired and / or wireless technologies are included within the definition of transmission media.

[0226] As used herein, the terms "system" and "network" are used interchangeably.

[0227] In this specification, the terms "base station (BS)", "radio base station", "eNB", "gNB", "cell", "sector", "cell group", "carrier" and "component carrier" may be used interchangeably. A base station may also be called a fixed station, NodeB, eNodeB (eNB), access point, transmission point, reception point, femtocell, small cell, etc.

[0228] A base station can accommodate one or more (e.g., three) cells (also called sectors). When a base station accommodates multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head). The term "cell" or "sector" refers to a part or the entire coverage area of ​​a base station and / or a base station subsystem that provides communication services in this coverage.

[0229] In this specification, the terms "Mobile Station (MS)", "user terminal", "User Equipment (UE)" and "terminal" may be used interchangeably. A base station may also be called a fixed station, NodeB, eNodeB (eNB), access point, transmission point, reception point, femtocell, small cell, etc.

[0230] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

[0231] Furthermore, the radio base station in this specification may be read as a user terminal. For example, each aspect / embodiment of the present invention may be applied to a configuration in which communication between a radio base station and a user terminal is replaced with communication between a plurality of user terminals (D2D: Device-to-Device). In this case, the user terminal 20 may be configured to have the functions of the radio base station 10 described above. Furthermore, "uplink" and / or "downlink" may be read as "side". For example, an uplink channel may be read as a side channel.

[0232] Similarly, the user terminal in this specification may be read as a wireless base station. In this case, the wireless base station 10 may be configured to have the functions of the user terminal 20 described above.

[0233] In this specification, a specific operation that is described as being performed by a base station may be performed by its upper node in some cases. It is clear that in a network consisting of one or more network nodes having a base station, various operations performed for communication with a terminal may be performed by the base station, one or more network nodes other than the base station (such as, but not limited to, an MME (Mobility Management Entity) and an S-GW (Serving-Gateway)), or a combination thereof.

[0234] Each aspect / embodiment described herein may be used alone, in combination, or switched depending on the implementation. In addition, the processing procedures, sequences, flow charts, etc. of each aspect / embodiment described herein may be rearranged unless inconsistent. For example, the methods described herein present elements of various steps in an example order, and are not limited to the particular order presented.

[0235] Each aspect / embodiment described in this specification may be applied to a system using LTE (Long Term Evolution), LTE-Advanced (LTE-A), LTE-Beyond (LTE-B), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), New-RAT (Radio Access Technology), NR (New Radio), NX (New radio access), FX (Future generation radio access), GSM (Registered trademark) (Global System for Mobile communications), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (Registered trademark)), IEEE 802.16 (WiMAX (Registered trademark)), IEEE 802.20, UWB (Ultra-Wide Band), Bluetooth (Registered trademark), or other suitable wireless communication method, and / or a next generation system enhanced based on these.

[0236] As used herein, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0237] As used herein, any reference to an element using a designation such as "first," "second," etc., does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must precede the second element in some way.

[0238] As used herein, the term "determining" may encompass a wide variety of actions. For example, "determining" may be considered to be "determining" calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, database, or another data structure), ascertaining, and the like. "Determining" may also be considered to be "determining" receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in a memory), and the like. "Determining" may also be considered to be "determining" resolving, selecting, choosing, establishing, comparing, and the like. That is, a "judgment" may be considered as "deciding" to take some kind of action.

[0239] As used herein, the terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to one another. The coupling or connection between the elements may be physical, logical, or a combination thereof. As used herein, two elements may be considered to be "connected" or "coupled" to one another by using one or more wires, cables, and / or printed electrical connections, as well as by using electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and light (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0240] When the terms "including," "comprising," and variations thereof are used in the specification or claims, these terms are intended to be inclusive, similar to the term "comprising." Further, when used in the specification or claims, the term "or" is not intended to be an exclusive or.

[0241] Although the present invention has been described in detail above, it is clear to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented in modified and altered forms without departing from the spirit and scope of the present invention as defined by the claims. Therefore, the description in this specification is intended to be illustrative and does not have any limiting meaning on the present invention.

Claims

1. A receiving unit for receiving downlink control information (DCI) including information regarding transmission of a code block group (CBG); A control unit that controls reception of the CBG based on information regarding the transmission of the CBG, The format of the first DCI used for scheduling the CBG to be initially transmitted and the format of the second DCI used for scheduling the CBG to be retransmitted are a common DCI format; A terminal, wherein the first DCI format and the second DCI format include a Hybrid Automatic Repeat reQuest (HARQ) process number field, a new data indicator field, and a redundancy version field that are common to multiple CBGs.

2. The terminal according to claim 1 , wherein the control unit determines a CBG to be retransmitted based on a bitmap corresponding to a CBG index.

3. receiving downlink control information (DCI) including information regarding transmission of code block groups (CBGs); and controlling reception of the CBG based on information regarding the transmission of the CBG; The format of the first DCI used for scheduling the CBG to be retransmitted and the format of the second DCI used for scheduling the CBG to be initially transmitted are a common DCI format; A wireless communication method for a terminal, wherein the first DCI format and the second DCI format include a Hybrid Automatic Repeat reQuest (HARQ) process number field, a new data indicator field, and a redundancy version field that are common to multiple CBGs.

4. A transmitter that transmits downlink control information (DCI) including information regarding transmission of a code block group (CBG); A control unit that controls reception of a HARQ-ACK for the CBG, the HARQ-ACK being transmitted based on information regarding the transmission of the CBG; The format of the first DCI used for scheduling the CBG to be retransmitted and the format of the second DCI used for scheduling the CBG to be initially transmitted are a common DCI format; A base station, wherein the first DCI format and the second DCI format include a Hybrid Automatic Repeat reQuest (HARQ) process number field, a new data indicator field, and a redundancy version field that are common to multiple CBGs.

5. A system having a base station and a terminal, The base station, A transmitter that transmits downlink control information (DCI) including information regarding transmission of a code block group (CBG); A control unit that controls reception of a HARQ-ACK for the CBG, the HARQ-ACK being transmitted based on information regarding the transmission of the CBG; The terminal includes: A receiving unit for receiving the DCI; A control unit that controls reception of the CBG based on information regarding the transmission of the CBG, The format of the first DCI used for scheduling the CBG to be initially transmitted and the format of the second DCI used for scheduling the CBG to be retransmitted are a common DCI format; A system, wherein the first DCI format and the second DCI format include a Hybrid Automatic Repeat reQuest (HARQ) process number field, a new data indicator field, and a redundancy version field that are common to multiple CBGs.

Images