Technical field

[0001]

　The present invention relates to a base station apparatus, terminal apparatus, according to a wireless communication system, and communication method.

BACKGROUND

[0002]

　Current network, the traffic of the mobile terminal (smartphone, Future phone, etc.) account for a majority of the network of resources. In addition, traffic to the mobile terminal use is, there is a tendency to continue to increase in the future.

[0003]

　On the other hand, IoT (Internet of things) service (e.g., transportation systems, smart meter, the monitoring system of the apparatus, etc.) in accordance with the development of, are required to correspond to the services with diverse requirements. Therefore, in addition to the next generation (e.g., 5G (fifth generation mobile communications)) In the communication standard, 4G standard techniques (4th generation mobile communication) (for example, Non-Patent Documents 1 to 11), further high data rate reduction, large capacity, a technology to achieve low latency reduction is required. Note that the next generation communication standard, has been studied by 3GPP Working Group (e.g., TSG-RAN WG1, TSG-RAN WG2, etc.). (Non-Patent Documents 12-18)

[0004]

　Furthermore, in order to meet the various services, the 5G, eMBB (Enhanced Mobile Broadband), mMTC (massive Machine Type Communications), URLLC (Ultra-Reliable and Low Latency Communication) many use cases that are classified as such It is assumed to support.

[0005]

　In such LTE (fourth generation communication system), hybrid automatic repeat request in order to achieve efficient data transmission (HARQ: Hybrid automatic repeat request) technique is employed. In HARQ, the receiving apparatus, for example, the retransmission of the data that could not be decoded correctly in the process of layer 1 protocol of the LTE, etc., and requests the device on the transmission side. Device on the transmitting side, the data retransmission is required, transmitting a retransmission data corresponding to the not properly decoded in the receiver data. The receiving device decodes the data by combining and could not be decoded correctly data and retransmitted data. Thus, highly efficient and highly accurate retransmission control is realized. The receiving device, when data can correctly decode transmits the ACK information to the transmitting device, when it does not decrypt the data correctly, transmits the NACK information to the transmitting device.

[0006]

　Incidentally, in the current LTE wireless communication system, for example, with respect to the 14 symbols TTI (Transmission Time Interval), the feedback information of one bit representing the ACK / NACK is notified. Further, in 3GPP meetings, code block group feedback information indicating the ACK / NACK (CBG: Code Block Group) method of notification is agreed for each (non-patent document 13). In this case, feedback information for each code block group is one bit. Further, the number of symbols constituting the code block group, for example, or less 14 symbols.

CITATION

Patent Document

[0007]

Patent Document 1: JP 2012-165391 Patent Publication
JP 2: WO2016 / 175029 Patent Publication

Non-patent literature

[0008]

Non-Patent Document 1: 3GPP TS 36.211 V14.2.0 (2017-03 )
Non-Patent Document 2: 3GPP TS 36.212 V14.2.0 (2017-03 )
Non-Patent Document 3: 3GPP TS 36.213 V14.2.0 (2017-03 )
Non-Patent Document 4: 3GPP TS 36.300 V14.2.0 (2017-03 )
non-Patent Document 5: 3GPP TS 36.321 V14.2.0 (2017-03 )
non-Patent Document 6: 3GPP TS 36.322 V14.0.0 (2017-03 )
non-Patent Document 7 : 3GPP TS 36.323 V14.2.0 (2017-03)
non-Patent Document 8: 3GPP TS 36.331 V14.2.0 (2017-03 )
non-Patent Document 9: 3GPP TS 36.413 V14.2.0 (2017-03 )
non-Patent Document 10: 3GPP TS 36.423 V14.2.0 (2017-03)
non-Patent Document 11: 3GPP TS 36.425 V14.0.0 (2017-03 )
non-Patent Document 12: 3GPP TR 38.801 V14.0.0 (2017-03 )
non-Patent Document 13: 3GPP TR 38.802 V14.0.0 (2017-03)
non-Patent Document 14: 3GPP TR 38.803 V14.0.0 (2017-03 )
non-Patent Document 15: 3GPP TR 38.804 V14.0.0 (2017-03 )
non-Patent Document 16: 3GPP TR 38.900 V14. 2.0 (2016-12)
non-Patent Document 17: 3GPP TR 38.912 V14.0.0 (2017-03 )
non-Patent Document 18: 3GPP TR 38.913 V14.0.0 (2017-03 )

Summary of the Invention

Problems that the Invention is to Solve

[0009]

　In the method of notifying the feedback information indicating the ACK / NACK for each code block group (CBG), believed to use the same or more number of bits with the current method. Therefore, in the decoding of the feedback information indicating the ACK / NACK, it can be affected by the decoding error increases. Therefore, a method to reduce the influence of decoding error in covered for decoding feedback information indicating the ACK / NACK is required.

[0010]

　The purpose according to one aspect of the present invention, ACK / NACK decoding error base station device capable of reducing the influence of the feedback information indicating the terminal device is to provide a wireless communication system, and communication method .

Means for Solving the Problems

[0011]

　One base station apparatus according to one embodiment of the present invention includes a first transmission unit that transmits the transmission block including a plurality of bit column blocks to the terminal, receiving from the terminal, the plurality of bit strings blocks correctly received by each of the terminal a decoding unit for decoding an acknowledgment signal indicating whether it is, on the basis of the decoded confirmation signal by the decoding unit, and detects a bit string blocks not correctly received by the terminal among the plurality of bit strings block includes a retransmission control unit for generating a control signal for controlling the reception processing of the terminal, and a second transmission unit that transmits the control signal to the terminal. It said first transmission section retransmits the detected bit string block by the retransmission control unit to the terminal.

The invention's effect

[0012]

　According to the above aspects, it is possible to reduce the influence of decoding error of the feedback information indicating the ACK / NACK.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]

FIG. 1 is a diagram showing an example of HARQ.
Is a diagram illustrating an example of a frame transmitted in [2] Wireless communication systems.
3 is a diagram showing an example of a transmission and the retransmission of the code block group.
4 is a diagram illustrating an example of downlink control information.
It is a diagram illustrating an example of FIG. 5A] CBG indicator (CBG-I).
It is a diagram showing another example of FIG. 5B] CBG indicator (CBG-I).
6 is a block diagram showing an example of a function of the base station.
7 is a block diagram showing an example of the functionality of the terminal device.
Is a flowchart illustrating an example of the processing of FIG. 8 terminal.
9 is a diagram showing an example of HARQ sequence.
It is a diagram showing another example of FIG. 10] HARQ sequence.
11 is a diagram showing a configuration example of a downlink control information.
It is a diagram illustrating an example of HARQ that uses FIG. 12 buffer information.
Is a diagram showing another example of a control signal for detecting a decoding error in FIG. 13 the feedback signal.
14 is a diagram showing an example of a HARQ of a second embodiment.
15 is a diagram showing an example of a HARQ of a third embodiment.
16 is a diagram showing an example of a HARQ of the fourth embodiment.

DESCRIPTION OF THE INVENTION

[0014]

　Wireless communication system according to an embodiment of the present invention, the base station (eNB: enhanced node B) 1 and the terminal device: including (UE user equipment) 2. However, the base station 1 is not limited to the eNB. Further, the base station 1 and the terminal device 2, the hybrid automatic repeat request: it is possible to perform (HARQ Hybrid Automatic repeat request).

[0015]

　Figure 1 shows an example of a hybrid automatic repeat request. In this example, data to be transmitted from the base station 1 to the terminal device 2 is stored in the transport block TB. Transport block TB stores a plurality of code blocks Group CBG. In the example shown in FIG. 1, the transport block TB stores four code block group CBG # 1 ~ CBG # 4. Moreover, each code block group CBG stores one or more code blocks CB. In the example shown in FIG. 1, each code block group CBG stores four code blocks CB.

[0016]

　Note that the transport block TB is an example of a "transport block". Each code block group CBG is an example of a "bit string block". Each code block is an example of the "data unit".

[0017]

　Each code block CB, CRC (cyclic redundancy check) are added. CRC is an example of an error detection code. Therefore, the terminal device 2 can detect the presence or absence of an error for each code block CB. The terminal device 2 determines for each code block group CBG, whether or not receive data correctly.

[0018]

　Terminal device 2 generates an acknowledgment signal indicating whether or not data can be received correctly. Confirmation signal represents an ACK or NACK for each code block group CBG. ACK represents that the code block group CBG is correctly received, NACK indicates that the code block group CBG was not received correctly. Therefore, the reception result of each code block group CBG (ACK / NACK) is represented by 1 bit. The terminal device 2 transmits the confirmation signal to the base station 1. That is, the receiving state for each code block group CBG fed back from the terminal device 2 to the base station 1. In the following description, it may be referred to as the confirmation signal feedback signal (or, ACK / NACK signal) and.

[0019]

　In the example shown in FIG. 1, an error in the code block group CBG # 2 is detected. Therefore, the terminal device 2 transmits the feedback signal "A, N, A, A 'to the base station 1. "A" represents the ACK, "N" represents a NACK.

[0020]

　The base station 1 receives this feedback signal, recognizes that the terminal apparatus 2 can not correctly receive the code block group CBG # 2. Then, the base station 1 retransmits the code block group CBG # 2 to the terminal device 2. The terminal device 2 uses the retransmitted code block group CBG # 2, to reproduce the data stored in the code block group CBG # 2.

[0021]

　Transport block TB or code block group CBG, in this example, is transmitted using the frame shown in FIG. The length of the frame is 10 milliseconds. The frame is composed of 10 sub-frames. That is, the length of the sub-frame is 1 ms.

[0022]

　Subframe, in this embodiment, it consists of 14 OFDM symbols. The sub-frame is composed of two slots. That is, each slot includes seven OFDM symbols. Subframe may transmit signals using different sub-carrier frequencies. Subcarrier, for example, it is arranged at 15kHz intervals.

[0023]

　Figure 3 shows an example of the transmission and the retransmission of the code block group CBG. In this example, one transport block TB is transmitted by one slot. Transport block TB stores four code block group CBG # 1 ~ CBG # 4. At the beginning of each slot, the control channel for transmitting is arranged to control information.

[0024]

　Transport block TB # A is transmitted from the base station 1 to the terminal device 2 according to a time slot N. Here, the terminal device 2 and that could not be correctly received code block group CBG # 2, CBG # 3. In this case, the terminal device 2 transmits the feedback signal "A, N, N, A" to the base station 1.

[0025]

　The base station 1 performs the retransmission processing based on the feedback signal. However, the base station 1, the decoding error of the feedback signal may be generated. In the example shown in FIG. 3, the decoding error has occurred in the second bit of the feedback signal. In this case, even though the code block group CBG # 2 has not been correctly received by the terminal device 2, the base station 1 recognizes that the code block group CBG # 2 is correctly received by the terminal apparatus 2. Then, the base station 1 retransmits only the sign block group CBG # 3 to the terminal device 2. That is, the code block group CBG # 2 is not retransmitted. Note that the code block group CBG # 3, for example, are retransmitted to the terminal device 2 by using a specific sub-channel slot N + k.

[0026]

　In this case, the terminal device 2, a layer higher than the MAC layer HARQ is implemented (e.g., RLC layer) is used to request retransmission of the code block group CBG # 2 to the base station 1. Therefore, as compared with the retransmission by HARQ, the time required to receive the transport block TB becomes longer. This problem is particularly important when the large size of the transport block TB.

[0027]

　Also, in the LTE, ACK / NACK bits are transmitted for each subframe. In the example shown in FIG. 1 with respect to this, ACK / NACK bits are transmitted in each code block group CBG. Therefore, the probability of decoding error of the feedback signal is generated becomes high. Therefore, the wireless communication system ACK / NACK bits are transmitted in each code block group CBG preferably has a function of suppressing the influence of decoding error.

[0028]

　
　In order to address the above problems, CBG indicator from the base station 1 to the terminal device 2 (CBG-I: code block group indicator) is transmitted. CBG indicator, downlink control information: transmitted (DCI downlink control information) is inserted into of from the base station 1 to the terminal device 2. Downlink control information controls a downlink for transmitting signals from the base station 1 to the terminal device 2. Accordingly, downlink control information, as shown in FIG. 4, including MCS information and the redundancy version (RV) information. MCS information specifies a modulation scheme and coding scheme, and the like. Incidentally, the downlink control information DCI, in the example shown in FIG. 3, is arranged in the control channel region of each slot.

[0029]

　5A shows an example of CBG indicator (CBG-I). CBG-I represents the feedback signal decoded in the base station 1. Thus, each bit of CBG-I indicates whether the code block group CBG is correctly received corresponding in the terminal apparatus 2. For example, the first bit of the CBG-I, the terminal device indicates whether the code block group CBG # 1 was received correctly in the 2, the second bit of CBG-I is the code block group CBG # 2 in the terminal device 2 indicating whether correctly received. However, as described above, upon receiving a feedback signal at the base station 1, the decoding error may occur. Then, in the bit decoding error has occurred, the value of CBG-I will be different from the corresponding value of the feedback signal transmitted from the terminal apparatus 2.

[0030]

　When CBG-I (i.e., the feedback signal decoded in the base station 1) is "0000", the base station 1, all of the code block group CBG # 1 ~ CBG # 4 is correctly received at the terminal apparatus 2 It determines that. In this case, the base station 1 without retransmitting the code block group CBG, transmits a new transport block TB to the terminal apparatus 2.

[0031]

　When CBG-I is "0001" - "1110", the base station 1, the code block group CBG "1" corresponds to the bits set (i.e., code block group specified by CBG-I CBG) has determined that was not correctly received by the terminal apparatus 2. In this case, the base station 1 retransmits the code block group CBG designated by CBG-I to the terminal device 2. For example, when the CBG-I is "0001", the base station 1 retransmits the code block group CBG # 4 to the terminal device 2. Alternatively, when the CBG-I is "1110", the base station 1 retransmits the code block group CBG # 1, CBG # 2, CBG # 3 to the terminal device 2.

[0032]

　When CBG-I is "1111", the base station 1 determines that all of the code block group CBG # 1 ~ CBG # 4 has not been correctly received by the terminal apparatus 2. In this case, the base station 1 retransmits the transport block TB to the terminal apparatus 2. Terminal device 2 determines based on the CBG-I received from the base station 1, whether the feedback signal in the base station 1 is decoded correctly. That is, the terminal device 2, based on the CBG-I received from the base station 1, determines the presence or absence of decoding error of the feedback signal at the base station 1. In this case, the terminal device 2 compares the CBG-I received from the feedback signal and the base station 1 that has transmitted to the base station 1. And, if the all of the feedback signal in the bit and CBG-I they match each other, the terminal device 2 judges that the decoding error no. Meanwhile, when there is a bit which does not coincide with each other between the feedback signal and CBG-I, the terminal device 2 determines that decoding errors in the base station 1 occurs.

[0033]

　5B shows another example of CBG indicator (CBG-I). Figure 5B, CBG-I number of bits representing the is an example when fewer than the number of groups of CBG. Each bit in the examples as well as CBG-I shown in FIG. 5A, indicates whether the code block group CBG is correctly received corresponding in the terminal apparatus 2. However, CBG-I the number of bits and the CBG number of groups is different. Therefore, for example, by considering the probability or the like of the combination generated retransmission representing a retransmission CBG-I.

[0034]

　When CBG-I is "000", the base station 1 determines that all of the code block group CBG # 1 ~ CBG # 4 has been correctly received at the terminal apparatus 2. In this case, the base station 1 without retransmitting the code block group CBG, transmits a new transport block TB to the terminal apparatus 2.

[0035]

　When CBG-I is "001" - "110", the base station 1, the code block group CBG (i.e., code block group CBG designated by CBG-I) and has not been correctly received by the terminal apparatus 2 judge. In this case, the base station 1 retransmits the code block group CBG designated by CBG-I to the terminal device 2. For example, when the CBG-I is "001", the base station 1 retransmits the code block group CBG # 1 to the terminal device 2. When CBG-I is "010", the base station 1 retransmits the code block group CBG # 2 to the terminal device 2. When CBG-I is "011", the base station 1 retransmits the code block group CBG # 3 to the terminal device 2. When CBG-I is "100", the base station 1 retransmits the code block group CBG # 4 to the terminal device 2. When CBG-I is "101", the base station 1 retransmits the code block group CBG # 1, CBG # 2, CBG # 3 to the terminal device 2. When CBG-I is "110", the base station 1 retransmits code block group CBG # 2, CBG # 3, the CBG # 4 to the terminal device 2.

[0036]

　When CBG-I is "111", the base station 1 determines that all of the code block group CBG # 1 ~ CBG # 4 has not been correctly received by the terminal apparatus 2. In this case, the base station 1 retransmits the transport block TB to the terminal apparatus 2.

[0037]

　Incidentally, if otherwise, to the case described above, and transmits the CBG-I which contain a combination of appropriate among the above combinations. For example, the terminal device 2, if specified by CBG-I to the retransmitted code block group CBG # 1, CBG # 2, transmits the CBG-I as "101". In this case, the base station 1 retransmits the code block group CBG # 1, CBG # 2, CBG # 3 to the terminal device 2.

[0038]

　Bit representation shown in FIG. 5B is an example, CBG-I number of bits may be changed bit representation of CBG-I taking into account the number of groups such as the code block group CBG. Also, the bit representation of CBG-I, it is preferable to consider a high probability of retransmission occurs combinations.

[0039]

　Figure 6 is a block diagram showing an example of the functionality of the base station 1. Base station 1, the data signal generating section 11, a buffer 12, the control signal generation unit 13, IFFT circuit 14, CP adding unit 15, RF transmission unit 16, RF receiver 17, CP removing section 18, FFT circuit 19, a data signal comprise a demodulator 20, a control signal demodulator 21, a scheduler 22, HARQ controller 23.

[0040]

　Data signal generating unit 11 generates a data signal to be transmitted to the terminal apparatus 2. At this time, the data signal generator 11 generates a data signal according to the schedule information generated by the scheduler 22. The data signal generated by the data signal generating section 11 is temporarily stored in the buffer 12. The data signal generation unit 11, a data signal stored in the buffer 12 can be retransmitted to the terminal device 2 in response to an instruction from the HARQ controller 23. Control signal generating unit 13 generates a control signal to be transmitted to the terminal apparatus 2. At this time, the control signal generator 13 generates control signals according to the schedule information generated by the scheduler 22. Downlink control information DCI is generated by the control signal generating unit 13.

[0041]

　IFFT circuit 14, the IFFT operation to generate a time domain signal from the control signal generated by the data signal and the control signal generating unit 13 is generated by the data signal generating unit 11. CP adding unit 15, a cyclic prefix to the time domain signal output from the IFFT circuit 14 (CP: Cyclic Prefix) adding. Cyclic prefix is ​​inserted into an OFDM signal in order to suppress multipath fading. RF transmitting section 16 generates an RF modulated signal from a time domain signal cyclic prefix is ​​added, and outputs the RF modulated signal via an antenna. Incidentally, RF transmitter 16 transmits the signal may comprise a frequency converter for up-converting the RF bands.

[0042]

　RF receiver 17 receives a radio signal transmitted from the terminal apparatus 2. Incidentally, RF receiver 17 may be provided with a frequency converter for down-converting the received signal in the RF band. CP removing section 18 removes the cyclic prefix from the received signal. FFT circuit 19, the FFT operation to convert the received signal to cyclic prefix has been removed into the frequency domain signal. That is, the received signal is separated for each subcarrier.

[0043]

　Data signal demodulator 20 demodulates and decodes the data signal included in the received signal. That is, data transmitted from the terminal device 2 is reproduced. Control signal demodulator 21 demodulates and decodes the control signal included in the received signal. That is, the control information transmitted from the terminal apparatus 2 is played. Feedback signal transmitted from the terminal device 2 (ACK / NACK bits) is reproduced by the control signal demodulator 21.

[0044]

　The scheduler 22, based on the control information received from the terminal apparatus 2, determines the allocation of the predetermined radio resources available for communication between the base station 1 and the terminal apparatus 2. Radio resource, as shown in FIG. 2, includes a frequency resource and time resource. That is, the scheduler 22 may assign sub-carriers and symbols for transmission signal (data signal and control signal). Then, the scheduler 22 generates schedule information indicating the allocation of radio resources.

[0045]

　HARQ controller 23 performs retransmission control based on the feedback signal reproduced by the control signal demodulator 21. That is, when the code block group CBG wanted correctly received at the terminal apparatus 2 is detected, HARQ controller 23 gives an instruction to retransmit the code block group CBG the data signal generating unit 11. Further, HARQ controller 23, based on the feedback signal reproduced by the control signal demodulator 21, to generate the CBG-I described above. Incidentally, CBG-I is inserted into the downlink control information DCI by the control signal generating unit 13 is transmitted to the terminal device 2.

[0046]

　Data signal generating section 11, the control signal generation unit 13, IFFT circuit 14, FFT circuit 19, a data signal demodulator 20, some or all of the control signal demodulator 21, a scheduler 22, HARQ controller 23, for example, and the processor element It is realized by a processor system including a memory. Alternatively, the data signal generating section 11, the control signal generation unit 13, IFFT circuit 14, FFT circuit 19, a data signal demodulator 20, some or all of the control signal demodulator 21, a scheduler 22, HARQ controller 23, digital signal processing it may be realized by a circuit.

[0047]

　Figure 7 is a block diagram showing an example of the functionality of the terminal device 2. Terminal device 2, RF receiver 31, CP removing section 32, FFT circuit 33, a data signal demodulator 34, a buffer 35, the error detection unit 36, the control signal demodulator 37, a scheduler 38, the data signal generating section 39, HARQ controller 40, includes a CRC adding section 41, the control signal generation unit 42, IFFT circuit 43, CP adding section 44, RF transmission unit 45.

[0048]

　RF receiving unit 31 receives a radio signal transmitted from the base station 1. Incidentally, RF receiving unit 31 may include a frequency converter for down-converting the received signal in the RF band. CP removing section 32 removes the cyclic prefix from the received signal. FFT circuit 33 converts the FFT operation, the received signal cyclic prefix has been removed into the frequency domain signal. That is, the received signal is separated for each subcarrier.

[0049]

　Data signal demodulator 34 demodulates and decodes the data signal included in the received signal. That is, data transmitted from the base station 1 is reproduced. Buffer 35 temporarily stores the data signal included in the received signal. The data signal demodulator 34 may reproduce data from the data signals retransmitted from the data signal and the base station 1 is stored in the buffer 35. In this case, for example, soft-combining (soft combining) is performed. The error detector 36 uses the CRC, detecting an error in data reproduced by the data signal demodulator 34. In this case, the error detection unit 36 ​​detects, for example, an error in each code block CB.

[0050]

　Control signal demodulator 37 demodulates and decodes the control signal included in the received signal. That is, the control information to be transmitted is reproduced from the base station 1. Downlink control information transmitted from the base station 1 DCI is reproduced by the control signal demodulator 37. When downlink control information DCI includes CBG-I is, CBG-I is also reproduced by the control signal demodulator 37.

[0051]

　The scheduler 38, based on the control information received from the base station 1 determines the assignment of predetermined radio resources available for communication between the base station 1 and the terminal apparatus 2. Then, the scheduler 38 generates schedule information indicating the allocation of radio resources.

[0052]

　Data signal generating unit 39 generates a data signal to be transmitted to the base station 1. At this time, the data signal generator 39 generates a data signal according to the schedule information generated by the scheduler 38.

[0053]

　HARQ controller 40 generates a feedback signal based on the detection result by the error detection unit 36. Feedback signal, as described above, the data of each code block group CBG indicating whether correctly received by the terminal device 2, respectively. Further, HARQ controller 40 determines by comparing the CBG-I received from the generated feedback signal and the base station 1, the feedback signal whether it is correctly decoded at the base station 1. That, HARQ controller 40 can detect the decoding error of the feedback signal at the base station 1. Incidentally, when the decoding error of the feedback signal at the base station 1 is detected, the terminal apparatus 2 may transmit the correct feedback signal to the base station 1. CRC adding unit 41, if necessary, adds a CRC to the feedback signal.

[0054]

　Control signal generating unit 42 generates a control signal to be transmitted to the base station 1. At this time, the control signal generation unit 42 generates a control signal according to the schedule information generated by the scheduler 38.

[0055]

　IFFT circuit 43, the IFFT operation to generate a time domain signal from the control signal generated by the data signal and the control signal generating unit 42 is generated by the data signal generating section 39. CP adding section 44 adds a cyclic prefix to the time domain signal output from the IFFT circuit 43. RF transmitting section 45 generates an RF modulated signal from a time domain signal cyclic prefix is ​​added, and outputs the RF modulated signal via an antenna. Incidentally, RF transmission unit 45 transmits the signal may comprise a frequency converter for up-converting the RF bands.

[0056]

　FFT circuit 33, a data signal demodulator 34, error detector 36, the control signal demodulator 37, a scheduler 38, the data signal generating section 39, HARQ controller 40, CRC adding unit 41, one control signal generation unit 42, IFFT circuit 43 part or all, for example, implemented by a processor system including a processor element and memory. Alternatively, FFT circuit 33, a data signal demodulator 34, error detector 36, the control signal demodulator 37, a scheduler 38, the data signal generating section 39, HARQ controller 40, CRC adding section 41, the control signal generation unit 42, IFFT circuit 43 some or all of, may be implemented by a digital signal processing circuit.

[0057]

　Figure 8 is a flow chart illustrating an example of processing of the terminal device 2. This flowchart shows processing relating to hybrid automatic repeat request downlink.

[0058]

　In S1, the terminal apparatus 2 receives a transport block TB from the base station 1. Transport block TB stores a plurality of code blocks Group CBG. In S2, the error detector 36 detects errors in each code block group CBG. That is, the error detector 36 determines whether it has received each code block group CBG correctly.

[0059]

　In S3, HARQ controller 40 generates a feedback signal based on the detection result by the error detection unit 36. In this example, 1 bit is assigned to each code block group CBG. Setting this time, the bit corresponding to the code block group CBG an error is detected is set to "1 (NACK)", the bit corresponding to the code block group CBG an error is not detected in the "0 (ACK)" It is. The terminal device 2 transmits the generated feedback signal to the base station 1.

[0060]

　The base station 1 receives the feedback signal, to generate a corresponding CBG-I is transmitted to the terminal device 2. Therefore, the terminal apparatus 2, at S4, receives the CBG-I corresponding to the feedback signal transmitted by S3. CBG-I, in this example, is generated by decoding the feedback signal in the base station 1. Therefore, when there is no decoding error, the feedback signal and CBG-I are the same to each other. The base station 1, if necessary, retransmit one or more code block groups CBG to the terminal device 2. Therefore, when the base station 1 retransmits the code block group CBG, the terminal device 2, in S4, receives the CBG-I and retransmitted code block group CBG.

[0061]

　In S5 ~ S7, HARQ controller 40 compares the feedback signal and CBG-I. Here, the state each bit are all "zero" of the feedback signal represents the state in which no error is detected in S2. In this case, the terminal device 2 does not require retransmission data. The state of the feedback signal and CBG-I coincide with each other, represents a state in which the decoding error has not occurred in the feedback signal at the base station 1. Therefore, when each bit of the feedback signal and CBG-I are all "zeros" are (S5: Yes), the retransmission control is not executed, the processing of the terminal apparatus 2 returns to S1.

[0062]

　Each bit of the feedback signal are all "zero", and, when the CBG-I includes "1" (S6: Yes), HARQ controller 40 includes a decoding error of the feedback signal is generated at the base station 1 judge. In this case, HARQ controller 40, in S8, the feedback signal previously transmitted again to the base station 1. However, in this case, each bit of the feedback signal is all because "zero", the terminal device 2 does not require the retransmission data. Therefore, the terminal device 2 also receives the retransmission data from the base station 1, ignore the retransmission data. Thereafter, the processing of the terminal apparatus 2 returns to S4.

[0063]

　Each bit of CBG-I are all "zero", and, when the feedback signal comprises a "1" (S7: Yes), HARQ controller 40 includes a decoding error of the feedback signal is generated at the base station 1 judge. In this case, HARQ controller 40, in S8, the feedback signal previously transmitted again to the base station 1. However, in this case, since the feedback signal contains "1", the terminal device 2 requires retransmission data. Therefore, a feedback signal containing "1", again, by sending to the base station 1, the terminal device 2 is able to request retransmission of the data necessary for the base station 1. Thereafter, the processing of the terminal apparatus 2 returns to S4.

[0064]

　The feedback signal comprises a "1", and, when CBG-I also include "1" (S7: No), the terminal device 2 requires retransmission data, also, the base station 1 retransmits the code block group . Therefore, the terminal apparatus 2, at S9, performs reception processing of retransmission data. At this time, the terminal apparatus 2 may play data from the data signals retransmitted from the data signal and the base station 1 is stored in the buffer 35. Alternatively, the terminal device 2, without using a data signal stored in the buffer 35 may play the data from the retransmitted data signal from the base station 1.

[0065]

　9 to 10 show an example of a sequence of hybrid automatic repeat request. In this example, the transport block TB stores four code block group CBG # 1 ~ CBG # 4.

[0066]

　In the case shown in FIG. 9, the downlink control information DCI and transport block TB # A is transmitted from the base station (eNB) 1 to the terminal device (UE) 2. Then, the terminal apparatus 2 receives a transport block TB # A utilizing a downlink control information DCI. Here, the code block group CBG # 1, CBG # is 4 has been received correctly, the code block group CBG # 2, CBG # 3 is assumed to have not been received correctly. In this case, the terminal device 2 transmits a feedback signal "0110" to the base station 1.

[0067]

　The base station 1 decodes the feedback signal received from the terminal apparatus 2. In this example, the feedback signal is assumed to be decoded correctly. In this case, the base station 1 recognizes that the code block group CBG # 2, CBG # 3 was not received correctly in the terminal apparatus 2. Then, the base station 1 transmits to the terminal device 2 generates a CBG-I "0110". Incidentally, CBG-I is set in the downlink control information DCI. Further, the base station 1 retransmits the code block group CBG # 2, CBG # 3 to the terminal device 2.

[0068]

　Terminal 2 receives the code block group CBG # 2, CBG # 3 retransmitted by the base station 1. Here, the code block group CBG # 2, CBG # 3 is assumed to have been correctly received. In this case, the terminal device 2 transmits a feedback signal "0000" to the base station 1.

[0069]

　The base station 1 decodes the feedback signal received from the terminal apparatus 2. As a result, the base station 1, the code block group CBG # 1 ~ CBG # 4 recognizes that all correctly received by the terminal apparatus 2. Then, the base station 1 transmits to the terminal device 2 generates a CBG-I "0000". At this time, the base station 1 may transmit the following transport block TB to the terminal apparatus 2.

[0070]

　Thus, the terminal device 2 is able to request retransmission of the data necessary for the base station 1 by using the feedback signal. Incidentally, when the CBG-I includes "1", the base station 1 retransmits the corresponding data to the terminal device 2. On the other hand, each bit of CBG-I all the time is "zero", the base station 1 does not perform the retransmission, and sends the new data to the terminal device 2. That, CBG-I may also be used as an indicator indicating whether to transmit new data. That, CBG-I may also be used as a NDI for the transport block TB (New Data Indicator).

[0071]

　Similar to the case shown in FIG. 9, in the case shown in FIG. 10, the feedback signal "0110" is transmitted to the base station 1 from the terminal apparatus 2. However, decoding error of the feedback signal is generated at the base station 1. In this example, decoding error occurs in the third bit of the feedback signal, the feedback signal is decoded is "0100". In this case, the base station 1 recognizes only the code block group CBG # 2 is not received correctly in the terminal apparatus 2. Then, the base station 1 transmits to the terminal device 2 generates a CBG-I "0100". Further, the base station 1 retransmits only the sign block group CBG # 2 to the terminal device 2.

[0072]

　Terminal device 2 compares the CBG-I received from the feedback signal and the base station 1 previously transmitted to the base station 1. In this example, since the feedback signal and CBG-I are different from each other, the terminal apparatus 2 recognizes that the decoding error of the feedback signal is generated at the base station 1. The terminal device 2 receives the code block group CBG # 2 that is retransmitted by the base station 1. Here, the code block group CBG # 2 is assumed to have been correctly received. Therefore, the terminal device 2, the retransmission each time, it is necessary to transmit the HARQ feedback corresponding to all of the code block group CBG.

[0073]

　Then, the terminal device 2 generates a new feedback signal. In this example, the code block group CBG # 2 was received correctly, "zero (ACK)" is given to the second bit of the feedback signal. Meanwhile, the code block group CBG # 3 so was not retransmitted, the terminal device 2, it is necessary to request a code block group CBG # 3 to the base station 1. Therefore, "1 (NACK)" is given to the third bit of the feedback signal.

[0074]

　The base station 1 receives this feedback signal, retransmits the code block group CBG # 3 to the terminal device 2. As a result, the terminal apparatus 2 can reproduce the data from all of the code block group CBG # 1 ~ CBG # 4.

[0075]

　Figure 11 shows a configuration example of a downlink control information DCI. In this example, downlink control information DCI includes a flag bit. Flag bit identifies a retransmission of the transmission or code block group CBG transport block TB.

[0076]

　When the transport block TB is transmitted, the downlink control information DCI includes MCS information, RV information, NDI information, and HARQ information. MCS information indicates etc. TBS (transport block size TB) and the modulation scheme. RV information represents the redundancy version of the HARQ. NDI information indicates whether the data is new data that is stored in the slot.

[0077]

　When the code block group CBG is retransmitted, TBS is the same as the size of the transport block TB previously sent. Further, in the initial transmission and the retransmission of the code block group CBG transport block TB, it is possible to transmit data at the same modulation scheme. Therefore, when the code block group CBG is retransmitted, as compared to when the transport block TB is transmitted, it is possible to reduce the number of bits of the MCS information.

[0078]

　Further, it is possible in the initial transmission and the retransmission of the code block group CBG transport blocks TB, using the same redundancy version. Therefore, when the code block group CBG is retransmitted may delete the RV information.

[0079]

　Further, as described above, CBG-I may be data in a slot indicates whether new data or not. That is, the state each bit of CBG-I are all "zero" represents the initial transmission of new data. Therefore, when the code block group CBG is retransmitted may delete the NDI information.

[0080]

　Thus, when the code block group CBG is retransmitted, as compared to when the transport block TB is transmitted, it is possible to reduce the number of bits of some information area. Then, CBG-I is transmitted by using the bits to be reduced in this way. Accordingly, without increasing the number of bits of the downlink control information DCI, it can transmit CBG-I. In other words, as when the transport block TB is transmitted, between when the code block group CBG is retransmitted, the number of bits of the downlink control information DCI (the length of the downlink control information DCI) in the same it can.

[0081]

　The terminal device 2, when receiving the retransmitted code block group CBG, depending on the application or use case, it is possible to use the data signals stored in the buffer 35. For example, when the transport block TB is transmitted only eMBB data, a method for reproducing data by soft combining the data signal is retransmitted and the data signal stored in the buffer 35 is preferred. Alternatively, when the eMBB data and URLLC data in the slot are multiplexed, a method of reproducing data from the retransmitted data signal without using a data signal stored in the buffer 35 is preferred. Accordingly, the base station 1, in addition to the CBG-I, the buffer information specifying whether to use the data signals stored in the buffer 35 may be transmitted to the terminal device 2.

[0082]

　Figure 12 shows an example of a hybrid automatic repeat request using the buffer information. According to this method, the base station 1, the terminal device 2 can indicate whether the data is reproduced using a data signal stored in the buffer 35. For example, a CBG-I is "0001", when the buffer information is "0", the base station 1 retransmits the code block group CBG # 4. The terminal device 2 reproduces the data from the code block group CBG # 4 of the data signal and the retransmitted code block group CBG # 4 stored in the buffer 35. On the other hand, a CBG-I is "0001", when the buffer information is "1", the terminal device 2, deletes the data signals of the code block group CBG # 4 from the buffer 35, retransmitted code block to reproduce the data from the group CBG # 4.

[0083]

　Further, in the above embodiment, the base station 1 generates CBG-I by decoding the feedback signal received from the terminal apparatus 2. Then, CBG-I is used the decoding error of the feedback signal as a control signal for detecting the terminal device 2. However, the control signal for detecting a decoding error of the feedback signal is not limited to the CBG-I described above.

[0084]

　Figure 13 shows another example of a control signal for detecting a decoding error of the feedback signal. In this example, CBG-NDI instead of CBG-I (CBG-new data indicator) is notified from the base station 1 to the terminal device 2. CBG-NDI is generated by inverting the logic of each bit of the decoded feedback signal in the base station 1. Further, each bit of CBG-NDI, the corresponding code block group CBG indicating whether a new data. That is, "1" represents a state in which the new data is transmitted by the corresponding code block group CBG, "zero" represents the state in which the data of the corresponding code block group CBG is retransmitted. Then, the base station 1 performs transmission / retransmission of the code block group CBG according CBG-NDI.

[0085]

　Terminal device 2 can be based on the feedback signal and CBG-NDI, to detect a decoding error of the feedback signal at the base station 1. Here, CBG-NDI is generated by inverting the logic of each bit of the decoded feedback signal in the base station 1. Therefore, the terminal device 2, by comparing the signal and the feedback signal obtained by inverting the logic of each bit of the CBG-NDI, can detect the decoding error of the feedback signal.

[0086]

　Thus, even the method shown in FIG. 13, the terminal device 2 can detect the decoding error of the feedback signal at the base station 1. Further, when each bit of CBG-NDI are all "1", the base station 1 transmits new transport block TB. Therefore, CBG-NDI can also be used as information indicating whether the transport block TB to store new data.

[0087]

　
　In the second embodiment, the error detection code or error correction code is added to each bit of the feedback signal transmitted from the terminal device 2 to the base station 1. As an example, CRC is added to each bit of the feedback signal.

[0088]

　In the example shown in FIG. 14, the transport block TB stores a plurality of code block group CBG # 1 ~ CBG # N. Each code block group CBG consists m code blocks CB. In this case, the terminal apparatus 2 receives a transport block TB, to generate a feedback signal FB1 ~ FBN corresponding to the code block group CBG # 1 ~ CBG # N. Feedback signal FB1 ~ FBN, respectively, indicating whether the code block group CBG # 1 ~ CBG # N has been received correctly by the terminal apparatus 2.

[0089]

　Terminal device 2, as shown in FIG. 13, adds CRC respectively for each bit FB1 ~ FBN feedback signal. Incidentally, CRC is added to each bit of the feedback signal by the CRC adding unit 41 shown in FIG. The terminal device 2 transmits a feedback signal to which the CRC is added to the base station 1. Therefore, the base station 1, when decoding the feedback signal, it is possible to detect a decoding error using the CRC.

[0090]

　Thus, in the second embodiment, CRC is added to each ACK / NACK bits to be transmitted from the terminal device 2 to the base station 1. Accordingly, the base station 1, since the code block group CBG the terminal device 2 requests can be reliably recognized, can be reduced the number of retransmissions.

[0091]

　
　In a third embodiment, the terminal device 2, in addition to the information each code block group CBG indicating whether correctly received, respectively, whether the transport block TB is correctly received information representing to the base station 1. In other words, the feedback signal includes an ACK / NACK bit for the ACK / NACK bit and the transport block TB for each code block group CBG.

[0092]

　In the example shown in FIG. 15, the transport block TB stores a plurality of code block group CBG # 1 ~ CBG # N. In this case, the terminal apparatus 2 receives a transport block TB, to generate the CBG feedback signals FB1 ~ FBN corresponding to the code block group CBG # 1 ~ CBG # N. CBG feedback signal FB1 ~ FBN, respectively, indicating whether the code block group CBG # 1 ~ CBG # N has been received correctly respectively by the terminal apparatus 2. In addition, the terminal device 2 generates a TB feedback signal FB_TB corresponding to the transport block TB. TB feedback signal FB_TB represents whether the transport block TB is correctly received by the terminal apparatus 2. The terminal device 2 transmits the CBG feedback signals FB1 ~ FBN and TB feedback signal FB_TB to the base station 1.

[0093]

　Incidentally, when the code block group CBG # 1 ~ CBG # N are all correctly received, CBG feedback signal FB1 ~ FBN are all "zeros (ACK)", TB feedback signal FB_TB is also at "zero (ACK)" . On the other hand, when at least one of the code block group CBG # 1 ~ CBG # N is not received correctly, TB feedback signal FB_TB is "1 (NACK)."

[0094]

　The base station 1 decodes the CBG feedback signals FB1 ~ FBN and TB feedback signal FB_TB received from the terminal apparatus 2. Then, the base station 1 based on the integrity of their decoding result, detecting a decoding error.

[0095]

　For example, when the code block group CBG # 2 has not been correctly received by the terminal device 2, CBG feedback signal "0100" and TB feedback signal "1" is notified to the base station 1. That is, the terminal device 2 requests the retransmission of the code block group CBG # 2 to the base station 1. Here, it is assumed decoding result by the base station 1 was as follows.
CBG feedback signal: 0100
TB feedback signal: 0

[0096]

　In this case, the base station 1 determines that decoding error has occurred in the second bit or TB feedback signal CBG feedback signal. Then, the base station 1 retransmits the transport block TB to the terminal apparatus 2. Further, it is assumed decoding result by the base station 1 was as follows.
CBG feedback signal: 0000
TB feedback signal: 1

[0097]

　In this case, the base station 1 determines that decoding error has occurred in either the bit or TB feedback signal CBG feedback signal. Then, the base station 1 retransmits the transport block TB to the terminal apparatus 2.

[0098]

　Thus, in the third embodiment, a decoding error of the feedback signal is detected in the base station 1. Then, the base station 1 detects the decoding error of the feedback signal, retransmits the necessary data to the terminal device 2. Therefore, according to the third embodiment, between the base station 1 and the terminal apparatus 2, it may transmit the number of the signal related to the data retransmission is reduced.

[0099]

　
　The number of code blocks CB to be stored in the transport block TB is sometimes less relative to the number of the code block group. That is, depending on the application or use case, when the number of the code block group CBG stored in the transport block TB is M, the number of code blocks CB to be stored in the transport block TB is N (N