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WO2018123058A1 - Dispositif de communication sans fil, système de communication sans fil et procédé de communication sans fil - Google Patents

Dispositif de communication sans fil, système de communication sans fil et procédé de communication sans fil Download PDF

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Publication number
WO2018123058A1
WO2018123058A1 PCT/JP2016/089198 JP2016089198W WO2018123058A1 WO 2018123058 A1 WO2018123058 A1 WO 2018123058A1 JP 2016089198 W JP2016089198 W JP 2016089198W WO 2018123058 A1 WO2018123058 A1 WO 2018123058A1
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Prior art keywords
data
response signal
wireless communication
nack
unit
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PCT/JP2016/089198
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English (en)
Japanese (ja)
Inventor
矢野　哲也
田中　良紀
ジヤンミン ウー
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富士通株式会社
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Priority to PCT/JP2016/089198 priority Critical patent/WO2018123058A1/fr
Publication of WO2018123058A1 publication Critical patent/WO2018123058A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems

Definitions

  • the present invention relates to a wireless communication device, a wireless communication system, and a wireless communication method.
  • the 5G (5th generation mobile communication) communication standard requires a technology that realizes a higher data rate, larger capacity, lower delay, and larger number of connections in addition to the 4G (4th generation mobile communication) technology. It has been.
  • eMBB Enhanced Mobile BroadBand
  • Massive MTC Machine Type Communications
  • URLLC Ultra-Reliable and Low Latency Communications
  • URLLC is the most difficult use case to be realized.
  • a packet error rate in a wireless section is 10 ⁇ 5 or less.
  • As one method for realizing the ultra-high reliability requirement there is a method of increasing the amount of resources used and making data redundant.
  • radio resources are limited, it is difficult to increase usage resources without limitation.
  • URLLC has a goal of setting the delay of the radio section of the user plane in the uplink and downlink to 0.5 milliseconds or less. This target is a high requirement of less than 1/10 of LTE (Long Term Evolution) 4G wireless system. URLLC is required to satisfy the above two requirements of ultra-high reliability and low delay at the same time.
  • LTE Long Term Evolution
  • LTE (4th generation communication system) and the like adopt a hybrid automatic repeat request (HARQ) technology.
  • HARQ the receiving apparatus requests the transmitting apparatus side to retransmit the data that could not be correctly decoded in the processing of the layer 1 protocol layer such as LTE.
  • the transmission apparatus requests retransmission of data
  • the transmission apparatus transmits the original data that could not be correctly decoded on the reception apparatus side as retransmission data.
  • the data is decoded by combining the data that could not be correctly decoded and the retransmission data corresponding to the retransmission request for the data that could not be correctly decoded.
  • the retransmission request is repeated by the receiving apparatus side sending the retransmission request again to the transmitting apparatus side. May be.
  • communication delay increases as the data for which retransmission requests are repeated increases. For example, in the case of URLLC, it becomes difficult to achieve the packet error rate of 10 ⁇ 5 in the radio section within the target delay time.
  • the disclosed technology has been made in view of the above, and provides a wireless communication device, a wireless communication system, and a wireless communication method capable of suppressing a decrease in communication reliability such as an increase in communication delay
  • the purpose is to do.
  • the wireless communication apparatus includes a reception unit, a determination unit, a selection unit, a modulation unit, and a transmission unit.
  • the receiving unit receives data wirelessly transmitted from another device.
  • the determination unit determines whether or not the received data has been successfully decoded.
  • the selection unit selects ACK (ACKnowledgement) as a response signal to be returned to another device when the determination unit determines that the data decoding is successful, and the determination unit determines that the data decoding has failed To select one of a plurality of NACKs (Negative ACKnowledgement) as a response signal.
  • the modulation unit modulates the response signal selected by the selection unit.
  • the transmission unit wirelessly transmits the response signal modulated by the modulation unit to another device.
  • the modulation unit transmits a response signal so that an ACK symbol is arranged in one area across one of the I axis and the Q axis on the IQ plane. Modulate. Further, when any one of a plurality of NACKs is selected by the selection unit, the modulation unit selects the other region across one axis in the IQ plane by the selection unit along a straight line parallel to the one axis. The response signal is modulated such that the received NACK symbols are arranged.
  • the reliability of communication can be improved.
  • FIG. 1 is a diagram illustrating an example of a wireless communication system.
  • FIG. 2 is a block diagram illustrating an example of a wireless terminal.
  • FIG. 3 is a diagram illustrating an example of the arrangement of symbols in the response signal.
  • FIG. 4 is a diagram illustrating an example of a calculation result of an error rate between ACK and NACK when NACK occurrence probability P NACK is 1%.
  • FIG. 5 is a diagram illustrating an example of a calculation result of an error rate between ACK and NACK when NACK occurrence probability P NACK is 10%.
  • FIG. 6 is a diagram illustrating an example of a calculation result of an error rate between NACK i and NACK j when the occurrence probability P NACK of NACK is 1%.
  • FIG. 1 is a diagram illustrating an example of a wireless communication system.
  • FIG. 2 is a block diagram illustrating an example of a wireless terminal.
  • FIG. 3 is a diagram illustrating an example of the arrangement of symbols in the response signal.
  • FIG. 7 is a diagram illustrating an example of a calculation result of an error rate between NACK i and NACK j when the occurrence probability P NACK of NACK is 10%.
  • FIG. 8 is a diagram illustrating an example of a calculation result of a required SN (Signal-to-Noise ratio) for satisfying a predetermined error rate when the occurrence probability P NACK of NACK is 1%.
  • FIG. 9 is a diagram illustrating an example of a calculation result of a required SN for satisfying a predetermined error rate when the NACK occurrence probability P NACK is 10%.
  • FIG. 10 is a diagram illustrating an example of a calculation result of average signal power.
  • FIG. 11 is a diagram showing an arrangement of ACK and a plurality of NACK symbols in the comparative example.
  • FIG. 12 is a diagram illustrating an example of a calculation result of an error rate from ACK to NACK in the comparative example.
  • FIG. 13 is a diagram illustrating an example of a calculation result of an error rate from NACK to ACK in the comparative example.
  • FIG. 14 is a diagram illustrating an example of a calculation result of an error rate between NACK i and NACK j in the comparative example.
  • FIG. 15 is a diagram illustrating an example of a calculation result of the required SN when a predetermined error rate is satisfied in the comparative example.
  • FIG. 16 is a diagram illustrating an example of a calculation result of the required SN when the error rate from NACK to ACK is 0.01% and the error rate from NACK i to NACK j is 1%.
  • FIG. 12 is a diagram illustrating an example of a calculation result of an error rate from ACK to NACK in the comparative example.
  • FIG. 13 is a diagram illustrating an example of a calculation result of an error rate from
  • FIG. 17 is a diagram illustrating another example of the arrangement of ACK and NACK symbols.
  • FIG. 18 is a diagram illustrating another example of arrangement of each symbol of ACK and NACK.
  • FIG. 19 is a diagram illustrating an example of a calculation result of an error rate from ACK to NACK.
  • FIG. 20 is a diagram illustrating an example of a calculation result of an error rate from NACK to ACK.
  • FIG. 21 is a diagram illustrating an example of the calculation result of the error rate from NACK i to NACK j .
  • FIG. 22 is a block diagram illustrating an example of a radio base station.
  • FIG. 23 is a diagram illustrating an example of a correspondence table in the first embodiment.
  • FIG. 24 is a flowchart illustrating an example of the operation of the wireless terminal according to the first embodiment.
  • FIG. 25 is a flowchart illustrating an example of the operation of the radio base station according to the first embodiment.
  • FIG. 26 is a diagram illustrating an example of a method for transmitting additional information according to the second embodiment.
  • FIG. 27 is a diagram illustrating an example of the transmission timing of NACK and additional information.
  • FIG. 28 is a diagram illustrating an example of a correspondence table in the second embodiment.
  • FIG. 29 is a flowchart illustrating an example of the operation of the wireless terminal according to the second embodiment.
  • FIG. 30 is a flowchart illustrating an example of the operation of the radio base station according to the second embodiment.
  • FIG. 1 is a diagram illustrating an example of a wireless communication system 10.
  • the radio communication system 10 includes a radio base station 20 and a radio terminal 30. Note that the radio communication system 10 may include a plurality of radio base stations 20 and a plurality of radio terminals 30.
  • the radio communication system 10 is a mobile communication system such as LTE.
  • the radio base station 20 and the radio terminal 30 are examples of radio communication devices.
  • the radio base station 20 includes a communication interface 21, a processor 22, a memory 23, a radio communication circuit 24, and an antenna 25.
  • the communication interface 21 is connected to the core network 11, receives data transmitted via the core network 11, outputs the data to the processor 22, and outputs data output from the processor 22 to the core network 11.
  • the processor 22 includes, for example, a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or a DSP (Digital Signal Processor). Based on the signal output from the communication interface 21, the processor 22 generates a transmission signal to be transmitted to the wireless terminal 30 and outputs the generated transmission signal to the wireless communication circuit 24. Further, the processor 22 generates a transmission signal including retransmission data for data that has failed to be decoded in the wireless terminal 30 and outputs the generated transmission signal to the wireless communication circuit 24. Further, the processor 22 generates a signal to be transmitted to the core network 11 based on the reception signal output from the wireless communication circuit 24, and outputs the generated signal to the communication interface 21.
  • a CPU Central Processing Unit
  • FPGA Field Programmable Gate Array
  • DSP Digital Signal Processor
  • the memory 23 includes, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores information used by the processor 22 to execute processing.
  • the processor 22 executes predetermined processing using information read from the memory 23.
  • the wireless communication circuit 24 performs processing such as up-conversion, quadrature modulation, and amplification on the transmission signal output from the processor 22, and wirelessly transmits the processed transmission signal to the space via the antenna 25.
  • the wireless communication circuit 24 performs processing such as amplification, orthogonal demodulation, and down-conversion on the received signal received via the antenna 25 and outputs the processed received signal to the processor 22.
  • the wireless terminal 30 includes an antenna 31, a wireless communication circuit 32, a processor 33, and a memory 34.
  • the wireless communication circuit 32 performs processing such as up-conversion, orthogonal modulation, and amplification on the transmission signal output from the processor 33 and wirelessly transmits the processed transmission signal to the space via the antenna 31.
  • the radio communication circuit 32 performs processing such as amplification, quadrature demodulation, and down-conversion on the reception signal received via the antenna 31 and outputs the processed reception signal to the processor 33.
  • the wireless communication circuit 32 is an example of a transmission unit.
  • the processor 33 includes a CPU, FPGA, DSP, or the like, for example, and determines whether or not the data transmitted from the radio base station 20 has been successfully decoded based on the received signal output from the radio communication circuit 32. When the data transmitted from the radio base station 20 is successfully decoded, the processor 33 generates a transmission signal including ACK, outputs the generated transmission signal to the radio communication circuit 32, and based on the data successfully decoded. To execute a predetermined process.
  • the processor 33 if the decoding of the data transmitted from the radio base station 20 fails, the processor 33 generates a transmission signal including NACK and outputs the generated transmission signal to the radio communication circuit 32. Then, the processor 33 tries to decode the data again based on the retransmission data transmitted from the radio base station 20 and the data that failed to be decoded.
  • the memory 34 includes, for example, a RAM or a ROM, and stores a program, data, and the like for the processor 33 to realize each function.
  • the processor 33 implements various functions based on a program read from the memory 34 and the like.
  • FIG. 2 is a block diagram illustrating an example of the wireless terminal 30.
  • the wireless terminal 30 includes a reception BB (BaseBand) processing unit 330, a determination unit 331, a measurement unit 332, a response signal generation unit 333, a transmission BB (BaseBand) processing unit 334, and a re-decoding unit 335.
  • Each function of the reception BB processing unit 330, the determination unit 331, the measurement unit 332, the response signal generation unit 333, the transmission BB processing unit 334, and the re-decoding unit 335 executes a program read from the memory 34 by the processor 33. It is realized by.
  • the reception BB processing unit 330 performs error correction decoding or the like for each block of a predetermined unit on the reception signal output from the wireless communication circuit 32 and restores data transmitted from the wireless base station 20. Then, the reception BB processing unit 330 outputs the restored data to the determination unit 331.
  • the reception BB processing unit 330 is an example of a reception unit.
  • the determination unit 331 determines whether or not the data has been successfully decoded by determining whether or not the data output from the reception BB processing unit 330 or the re-decoding unit 335 includes an error.
  • the determination unit 331 determines, for example, whether or not an error is included in the restored data using an error detection code such as a CRC (Cyclic Redundancy Check) code included in the data. If it is determined that the data has been successfully decoded, the determination unit 331 notifies the response signal generation unit 333 that the data has been successfully decoded.
  • the successfully decoded data is sent to a processing block (not shown), and a predetermined process based on the data is performed.
  • the determining unit 331 notifies the response signal generating unit 333 of the data decoding failure and outputs the data that has failed to be decoded to the re-decoding unit 335.
  • the re-decoding unit 335 holds the data that has been output from the determination unit 331 and failed to be decoded. Then, when the retransmission data is output from the reception BB processing unit 330, the re-decoding unit 335 restores the data using the retransmission data and the held data. Then, the re-decoding unit 335 outputs the restored data to the determination unit 331. Note that the function of the re-decoding unit 335 may be realized by the decoding function of the reception BB processing unit 330.
  • the measuring unit 332 measures an index indicating the quality of the reception environment based on the reception signal output from the wireless communication circuit 32.
  • the index indicating the quality of the reception environment include CQI (Channel Quality Indicator), SINR (Signal-to-Interference plus Noise power Ratio), RSSI (Received Signal Strength Indicator), and the like.
  • the measurement unit 332 outputs a measured value of an index indicating the quality of the reception environment to the response signal generation unit 333.
  • the response signal generation unit 333 generates a response signal indicating ACK when the determination unit 331 is notified of successful data decoding. Then, the response signal generation unit 333 outputs the generated response signal to the transmission BB processing unit 334.
  • the response signal generation unit 333 is an example of a selection unit.
  • the response signal generation unit 333 acquires a measurement value of an index indicating the quality of the reception environment from the measurement unit 332. Then, the response signal generation unit 333 selects one NACK from a plurality of different NACKs according to the quality level of the reception environment indicated by the measurement value acquired from the measurement unit 332. In the present embodiment, the response signal generation unit 333 selects one NACK from the three different NACKs 1 to 3. Then, the response signal generation unit 333 generates a response signal indicating the selected NACK. Then, the response signal generation unit 333 outputs the generated response signal to the transmission BB processing unit 334.
  • the transmission BB processing unit 334 modulates the response signal output from the response signal generation unit 333. Then, the transmission BB processing unit 334 maps the modulated response signal to, for example, an uplink control channel resource and outputs the mapped response signal to the radio communication circuit 32.
  • the uplink control channel is, for example, PUCCH (Physical Uplink Control Channel).
  • PUCCH Physical Uplink Control Channel
  • the modulated response signal may be mapped to the channel resource.
  • the uplink user data channel is, for example, PUSCH (Physical Uplink Shared Channel).
  • the transmission BB processing unit 334 is an example of a modulation unit.
  • FIG. 3 is a diagram illustrating an example of the arrangement of symbols in the response signal.
  • the transmission BB processing unit 334 when the response signal is ACK, the transmission BB processing unit 334 has an ACK symbol in one area across one of the I axis and the Q axis on the IQ plane that is the complex coordinate plane. Modulate the response signal to be placed.
  • the transmission BB processing unit 334 when the response signal is ACK, the transmission BB processing unit 334, for example, as illustrated in FIG. 3, a region where the I component is positive across the Q axis (that is, the first quadrant and the first quadrant of the IQ plane).
  • the response signal is modulated so that an ACK symbol is arranged on the I axis.
  • the amplitude of the ACK symbol is defined as a.
  • the transmission BB processing unit 334 when the response signal is one of a plurality of NACKs, the transmission BB processing unit 334 extends along the straight line parallel to one axis in the other region across one axis in the IQ plane.
  • the response signal is modulated so that NACK symbols are arranged.
  • the transmission BB processing unit 334 has a region where the I component is negative across the Q axis (that is, on the IQ plane).
  • the response signal is modulated such that the NACK symbol is arranged on the straight line 40 that passes through the coordinates of -a on the I axis in the second quadrant and third quadrant areas). For example, as shown in FIG.
  • the radio base station 20 that has received the response signal can determine whether or not the response signal is ACK by determining whether or not the amplitude of the I component of the response signal is positive.
  • the plurality of NACK1 to 3 NACK symbols are arranged in the direction along the straight line 40 so that the intervals between adjacent NACK symbols are equal.
  • the Q component of the NACK1 symbol is + 2b
  • the Q component of the NACK2 symbol is 0,
  • the Q component of the NACK3 symbol is -2b.
  • the symbol interval is 2b.
  • the transmission BB processing unit 334 performs BPSK (Binary Phase Shift Keying) modulation of the response signal with ACK and NACK in the I-axis direction, and further NACK is ternary in the Q-axis direction according to the values of NACK1 to NACK3.
  • BPSK Binary Phase Shift Keying
  • NACK is ternary in the Q-axis direction according to the values of NACK1 to NACK3.
  • PAM modulation Pulse Amplitude Modulation
  • the radio base station 20 that has received the response signal determines whether or not the amplitude of the Q component of the response signal is greater than + b. Whether or not it is NACK1 can be determined.
  • the radio base station 20 that has received the response signal determines whether the amplitude of the Q component of the response signal is smaller than + b and larger than ⁇ b when the amplitude of the I component of the received signal is negative. Thus, it can be determined whether or not the response signal is NACK2.
  • the radio base station 20 determines whether or not the amplitude of the Q component of the response signal is smaller than ⁇ b. It can be determined whether or not it is NACK3.
  • the radio base station 20 determines whether the response signal is ACK or NACK 1 to 3 based on the amplitudes of the I component and Q component of the response signal. Can be determined. Therefore, the response signal determination circuit can be configured simply.
  • the amplitude of the NACK1 and NACK3 symbols is ⁇ (a 2 + 4b 2 ), and the power of the NACK1 and NACK3 symbols is (a 2 + 4b 2 ). is there.
  • the amplitude of the symbols of the ACK and NACK2 are a, power of the symbol of the ACK and NACK2 is a 2. Therefore, the power of the NACK1 and NACK3 symbols is greater than the power of the ACK symbols.
  • actual communication is often performed in a state where the occurrence probability of NACK is not so high, and the occurrence frequency of NACK is much lower than the occurrence frequency of ACK. Therefore, even if there is a symbol having an amplitude larger than that of the ACK symbol among the plurality of NACK symbols, the power consumption does not increase so much in the entire communication.
  • the radio terminal 30 transmits one of the three types of NACKs to the radio base station 20 according to the quality level of the reception environment when data decoding fails.
  • the NACK symbol with the highest occurrence frequency among the three types of NACKs as NACK2 on the I axis.
  • the power of NACK2 is a 2, smaller than a power of NACK1 and NACK2 (a 2 + 4b 2) . Therefore, it is possible to further suppress an increase in power consumption when viewed over the entire communication.
  • an error rate P (ACK ⁇ NACK) that is a rate of ACK being mistaken as any NACK, and an error rate P (NACK ⁇ ACK) that is a rate at which any NACK is mistaken as ACK are: For example, it is expressed as the following formula (1).
  • an error rate P (NACK i ⁇ NACK i ⁇ j ), which is a rate of mistaking one NACK i as another NACK j (j ⁇ i), is expressed by, for example, the following equation (2).
  • the average power S of the response signal is expressed as the following equation (3), for example.
  • the coordinates of the ACK symbol on the IQ plane are (+ a, 0), the coordinates of the NACK1 symbol are ( ⁇ a, + 2b), and the coordinates of the NACK2 symbol are ( ⁇ a, 0). 0), the coordinates of the NACK3 symbol are ( ⁇ a, ⁇ 2b).
  • N noise power
  • N 2 ⁇ 2 .
  • Erfc (x) is a complementary error function of x.
  • FIG. 4 is a diagram illustrating an example of a calculation result of an error rate between ACK and NACK when NACK occurrence probability P NACK is 1%.
  • FIG. 5 is a diagram illustrating an example of a calculation result of an error rate between ACK and NACK when NACK occurrence probability P NACK is 10%.
  • FIG. 6 is a diagram illustrating an example of a calculation result of an error rate between NACK i and NACK j when the occurrence probability P NACK of NACK is 1%.
  • FIG. 7 is a diagram illustrating an example of a calculation result of an error rate between NACK i and NACK j when the occurrence probability P NACK of NACK is 10%.
  • the error rate tends to increase as the NACK occurrence probability P NACK increases. Also, the error rate tends to decrease as the value of b is increased.
  • FIGS. 8 and 9 The required SNs for satisfying the predetermined error rate are summarized as shown in FIGS. 8 and 9, for example.
  • FIG. 8 is a diagram illustrating an example of a calculation result of a required SN for satisfying a predetermined error rate when the occurrence probability P NACK of NACK is 1%.
  • FIG. 9 is a diagram illustrating an example of a calculation result of a required SN for satisfying a predetermined error rate when the NACK occurrence probability P NACK is 10%.
  • the required SN for setting the error rate between ACK and NACK to a predetermined value and the error rate between different NACKs to a predetermined value is a large value of b with respect to a. Varies depending on the situation. Therefore, the size of b with respect to a is determined according to the target required SN. For example, in FIG. 8, when the ratio of b to a is about 0.66, the required SN in which the error rate between ACK and NACK is 0.01% and the required SN in which the error rate between NACK is 1%. Both are about 8.4 dB. For example, in FIG. 9, when the ratio of b to a is about 0.66, the required SN where the error rate between ACK and NACK is 0.01% and the error rate between NACK is 1%. The required SN is both about 8.8 dB.
  • FIG. 10 is a diagram illustrating an example of a calculation result of average signal power.
  • the average power increases as the size of b with respect to a increases.
  • the average power increase rate increases. If the probability P NACK of NACK is 10% when the magnitude of b and size the same order of a, the size of b is compared with the case of 0, the average power is increased by about 27%.
  • the occurrence probability P NACK of NACK is 1%, if the size of b is about the same as the size of a, the average power increases by about 3% compared to the case where the size of b is 0. Stay.
  • the lower the NACK occurrence probability P NACK the lower the average power increase.
  • a response is made so that the ACK symbol and the NACK 1 to 3 symbols are arranged on the circumference of the radius A centered on the origin O on the IQ plane.
  • an ACK symbol and a NACK1 symbol are arranged on the Q axis.
  • NACK3 is arranged on the circumference of the angle ⁇ ° from the I axis
  • NACK2 is arranged on the circumference of the angle ⁇ ° from the I axis.
  • the comparative example is a modulation method described in “Performance of Asymmetric QPSK Modulation for Multi-Level ACK / NACK in LTE Uplink” (European Wireless 2014; 20th European Wireless Conference, Pages: 814-819).
  • an error rate P (ACK ⁇ NACK), which is a rate at which ACK is mistaken as any NACK, is expressed by, for example, the following equation (4).
  • an error rate P (NACK ⁇ ACK), which is a rate at which any NACK is mistaken as ACK, is expressed by, for example, the following equation (5).
  • an error rate P (NACK i ⁇ NACK i ⁇ j ), which is a ratio of mistaking one NACK i as another NACK j (i ⁇ j), is represented by the following equation (6), for example. It is expressed in
  • FIG. 12 is a diagram illustrating an example of a calculation result of an error rate from ACK to NACK in the comparative example.
  • FIG. 13 is a diagram illustrating an example of a calculation result of an error rate from NACK to ACK in the comparative example.
  • FIG. 14 is a diagram illustrating an example of a calculation result of an error rate between NACK i and NACK j in the comparative example.
  • the error rate between ACK and NACK decreases. This is because the distance between the ACK symbol and the NACK2 and NACK3 symbols increases on the IQ plane as the angle ⁇ increases.
  • the error rate between different NACKs deteriorates as the angle ⁇ increases. This is because the distance between adjacent NACKs becomes shorter in the IQ plane as the angle ⁇ increases.
  • FIG. 15 is a diagram illustrating an example of a calculation result of the required SN when a predetermined error rate is satisfied in the comparative example.
  • the required SN for setting the error rate between ACK and NACK to a predetermined value and setting the error rate between different NACKs to a predetermined value is a large angle ⁇ . Varies depending on the situation. For example, in FIG. 15, when the angle ⁇ is about 22 °, both the required SN in which the error rate between ACK and NACK is 0.01% and the required SN in which the error rate between NACK is 1% are both It is about 9.7 dB.
  • FIG. 16 is a diagram illustrating an example of a calculation result of the required SN when the error rate from NACK to ACK is 0.01% and the error rate from NACK i to NACK j is 1%.
  • the required SN for achieving both an error rate of 0.01% between ACK and NACK and an error rate of 1% between NACKs is approximately 9.7 dB in the comparative example. Then, it becomes about 8.4 to 8.8 dB.
  • the modulation method of the present embodiment can achieve the same error rate as the comparative example with a lower average SN than the modulation method of the comparative example. Also, the modulation method of this embodiment can achieve a lower error rate than the modulation method of the comparative example under the same average SN conditions.
  • FIG. 16 also describes the required SNs when binary NACK is used (BPSK + BPSK) and when quaternary NACK is used (BPSK + 4PAM).
  • the response signal has a symbol arrangement as shown in FIG. 17, for example.
  • the response signal when the response signal is NACK1 or 2, the NACK symbol is placed on the straight line 40 that passes through the ⁇ a coordinate on the I axis, in which the I component is negative across the Q axis.
  • the response signal is modulated to be arranged.
  • the IQ plane coordinates of NACK1 are ( ⁇ a, + b), for example, and the IQ plane coordinates of NACK2 are ( ⁇ a, ⁇ b), for example.
  • the interval between adjacent NACK symbols is 2b, for example.
  • the response signal has a symbol arrangement as shown in FIG. 18, for example.
  • the response signal when the response signal is any one of NACK1 to NACK4, it is a region where the I component is negative across the Q axis, and the NACK is on the straight line 40 passing through the -a coordinate on the I axis.
  • the response signal is modulated such that the symbols are arranged.
  • the IQ plane coordinates of NACK1 are, for example, ( ⁇ a, + 3b)
  • the IQ plane coordinates of NACK2 are, for example, ( ⁇ a, + b)
  • the IQ plane coordinates of NACK3 are, for example, ( ⁇ a, + 3b).
  • the IQ plane coordinates of NACK4 are, for example, (-a, -3b).
  • the interval between adjacent NACK symbols is 2b, for example.
  • the required SN for achieving both an error rate of 0.01% between ACKs and NACK and an error rate of 1% between NACKs is about 8. It can be seen that it is 4 to 8.5 dB.
  • the required SN for achieving both an error rate of 0.01% between ACKs and NACK and an error rate of 1% between NACKs is about 8.4 to 9.2 dB.
  • an error rate comparable to that of the comparative example can be achieved with an average SN lower than that of the modulation method of the comparative example.
  • the number of NACKs can be increased as compared with the modulation method of the comparative example under the same average SN condition.
  • FIG. 19 is a diagram illustrating an example of a calculation result of an error rate from ACK to NACK.
  • FIG. 20 is a diagram illustrating an example of a calculation result of an error rate from NACK to ACK.
  • FIG. 21 is a diagram illustrating an example of the calculation result of the error rate from NACK i to NACK j .
  • comparison is made at a required SN that achieves both an error rate of 0.01% between ACK and NACK and an error rate of 1% between NACKs.
  • a lower error rate than the comparative example can be achieved with the same multi-level number of NACK as in the example.
  • an error rate lower than that of the comparative example can be achieved even when the number of multilevel NACKs is smaller than that of the comparative example and when the number of multilevel NACKs is larger than that of the comparative example.
  • the modulation method of the comparative example it is determined whether the response signal is ACK or NACK 1 to 3 depending on which boundary line 41 set on the IQ plane is located in the response signal symbol. The This complicates the response signal determination circuit.
  • the modulation method of the present embodiment it is possible to determine whether the response signal is ACK or NACK 1 to 3 based on the amplitudes of the I component and Q component of the response signal. For this reason, in this embodiment, the response signal determination circuit can be simplified in comparison with the comparative example.
  • FIG. 22 is a block diagram illustrating an example of the radio base station 20.
  • the radio base station 20 includes a scheduler 220, a determination unit 221, a reception BB processing unit 222, a buffer 223, a retransmission data generation unit 224, a transmission data processing unit 225, and a transmission BB processing unit 226.
  • Each function of the scheduler 220, the determination unit 221, the reception BB processing unit 222, the buffer 223, the retransmission data generation unit 224, the transmission data processing unit 225, and the transmission BB processing unit 226 is a program read from the memory 23 by the processor 22. It is realized by executing.
  • the reception BB processing unit 222 performs error correction decoding on the reception signal output from the wireless communication circuit 24 for each block of a predetermined unit, and restores data transmitted from the wireless terminal 30. Then, the reception BB processing unit 222 outputs the restored data to a reception data processing unit (not shown).
  • the reception BB processing unit 222 performs quadrature demodulation on the block including the response signal, and outputs I component and Q component signals to the determination unit 221.
  • the reception BB processing unit 222 is an example of a reception unit.
  • the determination unit 221 determines whether the response signal is ACK or NACK 1 to 3 based on the amplitudes of the I component and Q component of the response signal output from the reception BB processing unit 222. In the present embodiment, the determination unit 221 determines whether or not the response signal is ACK by determining whether or not the amplitude of the I component is positive. When the amplitude of the I component is negative, that is, when the response signal is not ACK, the determination unit 221 determines whether the response signal is NACK 1 to 3 based on the amplitude of the Q component. judge. The determination unit 221 outputs the determination result to the scheduler 220 and the retransmission data generation unit 224.
  • the scheduler 220 instructs the retransmission data generation unit 224 about the transmission timing of the retransmission data.
  • the transmission data processing unit 225 generates transmission data based on the signal output from the communication interface 21. Then, transmission data processing section 225 outputs the generated transmission data to buffer 223 and transmission BB processing section 226.
  • the buffer 223 holds the transmission data output from the transmission data processing unit 225.
  • the buffer 223 is an example of a holding unit.
  • the transmission BB processing unit 226 performs processing such as baseband modulation and multiplexing on the transmission data output from the retransmission data generation unit 224 and the retransmission data output from the transmission data processing unit 225. Then, the transmission BB processing unit 226 outputs the processed transmission signal to the wireless communication circuit 24.
  • the transmission BB processing unit 226 is an example of a transmission unit.
  • the retransmission data generation unit 224 acquires the transmission data held in the buffer 223 when the determination result of the response signal by the determination unit 221 is any one of NACK1 to NACK3. Then, the retransmission data generation unit 224 generates retransmission data based on the transmission data acquired from the buffer 223 with reference to, for example, the correspondence table 50 illustrated in FIG. In the present embodiment, the retransmission data generation unit 224 holds the correspondence table 50. Note that the processing such as encoding and modulation performed by the retransmission data generation unit 224 may be executed by a functional unit that performs encoding and modulation included in the transmission BB processing unit 226.
  • the scheduler 220 may read MCS and transmission power parameters from the correspondence table 50 and pass them to the transmission BB processing unit 226. Further, when only a part of the data before encoding is retransmitted, the retransmission data generation unit 224 extracts the part of the data from the buffer 223 and passes it to the transmission BB processing unit 226. May be.
  • the encoded retransmission data is held in the buffer 223, the encoding process is omitted at the time of retransmission, and the repetition of encoding at the time of retransmission and the amount of decimation are adjusted according to the NACK level. The form of can also be considered.
  • FIG. 23 is a diagram illustrating an example of the correspondence table 50 according to the first embodiment.
  • the correspondence table 50 is information for generating retransmission data corresponding to each of NACK 1 to 3 in association with transmission information including information on transmission data such as MCS (Modulation and Coding Scheme) of transmission data and transmission power. Store some generated information.
  • transmission information 2 when transmission data is generated based on “transmission information 2”, retransmission data is generated based on “generation information [21]” for NACK1, For NACK2, retransmission data is generated based on “generation information [22]”, and for NACK3, retransmission data is generated based on “generation information [23]”.
  • the retransmission data generation unit 224 refers to the correspondence table 50, and outputs the retransmission data generated based on the transmission data acquired from the buffer 223 to the transmission BB processing unit 226 at the transmission timing instructed by the scheduler 220. In addition, when the determination result of the response signal by the determination unit 221 is ACK, the retransmission data generation unit 224 deletes transmission data corresponding to the ACK from the buffer 223.
  • the retransmission data generation unit 224 is an example of a generation unit.
  • the retransmission data generation unit 224 generates retransmission data according to the type of NACK determined by the determination unit 221 when the determination unit 221 determines that the response signal is NACK.
  • the disclosed technology is not limited to this.
  • the retransmission data generation unit 224 may generate retransmission data in advance for each of the NACKs 1 to 3 with reference to the correspondence table 50 when transmission data is stored in the buffer 223.
  • the retransmission data generation unit 224 transmits the retransmission data corresponding to the determination result from the retransmission data generated in advance from the scheduler 220.
  • the data is output to the transmission BB processing unit 226 at the timing.
  • the retransmission data generation unit 224 can sufficiently secure time for generating retransmission data.
  • FIG. 24 is a flowchart illustrating an example of the operation of the wireless terminal 30 according to the first embodiment. For example, when starting reception of data, the wireless terminal 30 starts the operation illustrated in this flowchart.
  • the wireless terminal 30 receives data transmitted from the wireless base station 20 (S100). Specifically, the wireless communication circuit 32 performs processing such as amplification, orthogonal demodulation, and down-conversion on the reception signal received via the antenna 31 and outputs the processed reception signal to the processor 33.
  • the reception BB processing unit 330 in the processor 33 performs error correction decoding or the like for each block of a predetermined unit on the reception signal output from the wireless communication circuit 32 to restore the data transmitted from the wireless base station 20. . Then, the reception BB processing unit 330 outputs the restored data to the determination unit 331.
  • the wireless terminal 30 determines whether the data has been successfully decoded (S101). Specifically, the determination unit 331 determines whether or not the restored data includes an error using an error detection code such as a CRC code included in the data output from the reception BB processing unit 330. Thus, it is determined whether or not the data has been successfully decoded.
  • an error detection code such as a CRC code included in the data output from the reception BB processing unit 330.
  • the determination unit 331 notifies the response signal generation unit 333 of the successful data decoding.
  • the response signal generation unit 333 generates a response signal indicating ACK, and outputs the generated response signal to the transmission BB processing unit 334 (S104). Then, the transmission BB processing unit 334 executes the process shown in step S105.
  • the determination unit 331 notifies the response signal generation unit 333 of the data decoding failure.
  • the response signal generation unit 333 acquires a measurement value of an index indicating the quality of the reception environment from the measurement unit 332 (S102). Then, the response signal generation unit 333 selects one NACK from the plurality of NACKs 1 to 3 according to the quality level of the reception environment indicated by the measurement value acquired from the measurement unit 332. Then, the response signal generation unit 333 generates a response signal indicating the selected NACK (S103). Then, the response signal generation unit 333 outputs the generated response signal to the transmission BB processing unit 334.
  • the transmission BB processing unit 334 modulates the response signal output from the response signal generation unit 333 (S105). Specifically, when the response signal is ACK, the transmission BB processing unit 334, for example, as illustrated in FIG. 3, the response signal so that the symbol is mapped to the coordinates of (+ a, 0) on the IQ plane. Modulate.
  • the response signal is NACK1
  • the response signal is modulated so that the symbol is mapped to the coordinates of ( ⁇ a, + 2b) on the IQ plane.
  • the response signal is NACK2 for example, as shown in FIG. 3, the response signal is modulated so that the symbol is mapped to the coordinates of ( ⁇ a, 0) on the IQ plane.
  • the response signal is NACK3, for example, as shown in FIG. 3, the response signal is modulated so that symbols are mapped to the coordinates of ( ⁇ a, ⁇ 2b) on the IQ plane.
  • the transmission BB processing unit 334 maps the modulated response signal to, for example, an uplink control channel resource, and outputs the mapped response signal to the wireless communication circuit 32.
  • the wireless communication circuit 32 wirelessly transmits the response signal modulated by the transmission BB processing unit 334 via the antenna 31 (S106).
  • FIG. 25 is a flowchart illustrating an example of the operation of the radio base station 20 according to the first embodiment. For example, when starting the transmission of data, the radio base station 20 starts the operation shown in this flowchart.
  • the wireless base station 20 wirelessly transmits data (S200). Specifically, the transmission data processing unit 225 in the processor 22 generates transmission data based on a signal output from the communication interface 21, and outputs the generated transmission data to the buffer 223 and the transmission BB processing unit 226. .
  • the transmission BB processing unit 226 performs processing such as baseband modulation and multiplexing on the transmission data output from the retransmission data generation unit 224. Then, the transmission BB processing unit 226 outputs the processed transmission signal to the wireless communication circuit 24.
  • the wireless communication circuit 24 performs processing such as up-conversion, orthogonal modulation, and amplification on the transmission signal output from the transmission BB processing unit 226, and wirelessly transmits the processed transmission signal to the space via the antenna 25. To do.
  • the buffer 223 holds the transmission data output from the transmission data processing unit 225 (S201).
  • the determination unit 221 refers to the signal output from the reception BB processing unit 222 and determines whether a response signal has been received (S202).
  • the determination unit 221 determines whether the response signal is ACK based on the amplitudes of the I component and the Q component of the response signal output from the reception BB processing unit 222. (S203). Specifically, the determination unit 221 determines whether or not the response signal is ACK by determining whether or not the amplitude of the I component is positive.
  • the determination unit 221 outputs the determination result to the scheduler 220 and the retransmission data generation unit 224.
  • the retransmission data generation unit 224 deletes the transmission data corresponding to ACK from the buffer 223 (S206).
  • the determination unit 221 determines the response based on the magnitude of the Q component amplitude of the response signal. It is determined whether the signal is NACK1 to NACK3. Then, the determination unit 221 outputs the determination result to the scheduler 220 and the retransmission data generation unit 224.
  • the scheduler 220 instructs the retransmission data generation unit 224 to transmit retransmission data.
  • the retransmission data generation unit 224 acquires transmission data held in the buffer 223. Then, the retransmission data generation unit 224 generates retransmission data based on the transmission data acquired from the buffer 223 with reference to, for example, the correspondence table 50 illustrated in FIG. 23 (S204). Then, retransmission data generation section 224 outputs the generated retransmission data to transmission BB processing section 226 at the transmission timing instructed from scheduler 220.
  • the transmission BB processing unit 226 performs processing such as baseband modulation and multiplexing on the retransmission data output from the retransmission data generation unit 224. Then, the transmission BB processing unit 226 outputs the processed transmission signal to the wireless communication circuit 24.
  • the wireless communication circuit 24 performs processing such as up-conversion, orthogonal modulation, and amplification on the transmission signal output from the transmission BB processing unit 226, and wirelessly transmits the processed transmission signal to the space via the antenna 25. (S205).
  • the radio communication system 10 includes a radio base station 20 and a radio terminal 30.
  • the wireless terminal 30 includes a reception BB processing unit 330, a determination unit 331, a response signal generation unit 333, a transmission BB processing unit 334, and a wireless communication circuit 32.
  • the reception BB processing unit 330 receives data transmitted from the radio base station 20.
  • the determination unit 331 determines whether or not the received data has been successfully decoded.
  • the response signal generation unit 333 selects ACK as a response signal to be returned to the radio base station 20 when the determination unit 331 determines that the data has been successfully decoded.
  • the response signal generation unit 333 selects one of a plurality of NACKs as the response signal.
  • the transmission BB processing unit 334 modulates the response signal selected by the response signal generation unit 333.
  • the wireless communication circuit 32 transmits the response signal modulated by the transmission BB processing unit 334 to the wireless base station 20.
  • the transmission BB processing unit 334 responds so that the ACK symbol is arranged in a region where the I coordinate is positive across the Q axis in the IQ plane. Modulate.
  • the transmission BB processing unit 334 is parallel to the Q axis in a region where the I coordinate is negative across the Q axis on the IQ plane when any one of the plurality of NACKs is selected by the response signal generating unit 333.
  • the response signal is modulated such that the NACK symbols selected by the response signal generation unit 333 are arranged along the straight line.
  • the radio base station 20 includes a reception BB processing unit 222 and a transmission BB processing unit 226.
  • the transmission BB processing unit 226 transmits data to the wireless terminal 30.
  • the reception BB processing unit 222 receives a response signal indicating one of ACK and a plurality of NACKs returned from the wireless terminal 30.
  • the transmission BB processing unit 226 transmits retransmission data created from the data transmitted to the radio terminal 30 to the radio terminal 30 in response to the NACK. To do. Thereby, the radio
  • the distance on the IQ plane from the ACK symbol to the Q axis is equal to the distance on the IQ plane from each of the plurality of NACK symbols to the Q axis.
  • the radio base station 20 can determine whether or not the response signal is ACK by determining whether or not the amplitude of the I component of the response symbol is positive in the IQ plane.
  • a circuit for determining whether or not the response signal is ACK can be simplified.
  • a plurality of NACK symbols are arranged at equal intervals along a straight line parallel to the Q axis on the IQ plane.
  • the radio base station 20 can determine which of the plurality of NACKs is the response signal according to the magnitude of the amplitude of the Q component of the response symbol on the IQ plane.
  • a circuit for identifying a plurality of NACKs can be simplified.
  • the wireless terminal 30 includes a measurement unit 332 that measures the reception environment.
  • the response signal generation unit 333 selects one of a plurality of NACKs according to the reception environment measured by the measurement unit 332.
  • wireless terminal 30 can notify the information regarding the receiving environment in the radio
  • the radio base station 20 can transmit retransmission data that is more likely to be successfully decoded to the radio terminal 30 while suppressing the size of the retransmission data in data retransmission.
  • the radio base station 20 includes a buffer 223 and a retransmission data generation unit 224.
  • the buffer 223 holds the data transmitted to the wireless terminal 30 by the transmission BB processing unit 226. If any NACK is included in the response signal, retransmission data generation section 224 generates retransmission data from the data held in buffer 223 in response to NACK.
  • the transmission BB processing unit 226 transmits the retransmission data generated by the retransmission data generation unit 224 to the radio terminal 30 when NACK is included in the response signal. As a result, the radio base station 20 can retransmit the data that the radio terminal 30 has failed to decode.
  • each of the multi-valued NACKs is associated with a different reception environment in the wireless terminal 30, and reception of the wireless terminal 30 is performed when data decoding fails on the wireless terminal 30 side. NACK corresponding to the environment is notified to the radio base station 20.
  • NACK when data decoding fails on the wireless terminal 30 side, NACK is notified to the wireless base station 20, and information about the reception environment of the wireless terminal 30 is low. The data is transmitted to the radio base station 20 through a channel for transmitting delay data.
  • the wireless terminal 30 of this embodiment includes an antenna 31, a wireless communication circuit 32, a processor 33, and a memory 34.
  • the wireless terminal 30 also includes a reception BB processing unit 330, a determination unit 331, a measurement unit 332, a response signal generation unit 333, a transmission BB processing unit 334, and a re-decoding unit 335.
  • the configuration of the wireless terminal 30 is the same as that of the wireless terminal 30 according to the first embodiment described with reference to FIG. 2 except for the points described below, and thus detailed description thereof is omitted.
  • the response signal generation unit 333 generates a response signal indicating ACK when the determination unit 331 is notified of successful data decoding. Further, when the data decoding failure is notified from the determination unit 331, the response signal generation unit 333 generates a response signal indicating NACK. Then, the response signal generation unit 333 outputs the generated response signal to the transmission BB processing unit 334.
  • the response signal generation unit 333 acquires a measurement value of an index indicating the quality of the reception environment from the measurement unit 332 when the data decoding failure is notified from the determination unit 331. Then, the response signal generation unit 333 converts the acquired measurement value into additional information and outputs it to the transmission BB processing unit 334.
  • the additional information is information obtained by quantizing measured values such as CQI, SINR, and RSSI into a predetermined number of bits.
  • the response signal generation unit 333 converts the measurement value acquired from the measurement unit 332 into, for example, 4-bit additional information and outputs it to the transmission BB processing unit 334. Note that the number of bits of the additional information is not limited to 4 bits, and may be 3 bits or less, or 5 bits or more.
  • the transmission BB processing unit 334 modulates the response signal output from the response signal generation unit 333.
  • the transmission BB processing unit 334 performs BPSK modulation on the response signal, for example.
  • the transmission BB processing unit 334 maps the modulated response signal to, for example, an uplink control channel resource and outputs the mapped response signal to the radio communication circuit 32.
  • the response signal is transmitted to the radio base station 20 via the uplink control channel, for example, as shown in FIG. In FIG. 26, “A” indicates ACK, and “N” indicates NACK.
  • the modulated response signal may be mapped to a resource of a channel for uplink user data.
  • the transmission BB processing unit 334 establishes a channel for low delay data with the radio base station 20.
  • the low delay data channel is, for example, a URLLC channel.
  • the transmission BB processing unit 334 performs processing such as encoding and modulation on the additional information, and converts the processed data into a low-delay data channel.
  • the additional information output from the response signal generation unit 333 is transmitted to the radio base station 20 via a low-delay data channel, for example, as illustrated in FIG.
  • the radio base station 20 when the radio terminal 30 fails to decode the data, the radio base station 20 notifies the additional information to the radio base station 20 together with NACK, so that the radio base station 20 is more likely to succeed in decoding the data.
  • the retransmission data can be transmitted to the wireless terminal 30.
  • the radio terminal 30 transmits the additional information to the radio base station 20 using the low-delay data channel, so that the radio base station 20 can quickly receive the additional information having a larger data amount than the ACK and NACK. be able to.
  • the radio terminal 30 transmits additional information to the radio base station 20, but the transmission timing of the additional information is not necessarily the same as the slot or subframe in which the NACK is transmitted, It may not be transmitted in a subframe.
  • the transmission BB processing unit 334 may transmit the additional information to the radio base station 20 at an arbitrary timing within a range that satisfies the condition that the data retransmission timing in the radio base station 20 is met.
  • ACK and NACK may also be transmitted to the radio base station 20 at an arbitrary timing within a range that satisfies the condition of being in time for the data retransmission timing in the radio base station 20.
  • the radio base station 20 of this embodiment includes a communication interface 21, a processor 22, a memory 23, a radio communication circuit 24, and an antenna 25. Further, the radio base station 20 includes a scheduler 220, a determination unit 221, a reception BB processing unit 222, a buffer 223, a retransmission data generation unit 224, a transmission data processing unit 225, and a transmission BB processing unit 226.
  • the configuration of the radio base station 20 is the same as that of the radio base station 20 according to the first embodiment described with reference to FIG. 22 except for the points described below, and thus detailed description thereof is omitted.
  • the reception BB processing unit 222 establishes a channel for low delay data with the wireless terminal 30. Specifically, the reception BB processing unit 222 establishes a channel for URLLC, for example.
  • the determination unit 221 refers to the signal output from the reception BB processing unit 222 and determines whether a response signal has been received. When the response signal is received, the determination unit 221 determines whether the response signal output from the reception BB processing unit 222 is ACK. In this embodiment, the response signal is BPSK-modulated, for example, and the determination unit 221 determines whether or not the response signal is ACK by determining whether or not the amplitude of the response signal is positive.
  • the determination unit 221 outputs the determination result to the scheduler 220 and the retransmission data generation unit 224.
  • the scheduler 220 instructs the retransmission data generation unit 224 to transmit retransmission data.
  • the retransmission data generation unit 224 acquires the transmission data held in the buffer 223 when the determination result of the response signal by the determination unit 221 is NACK. Then, the retransmission data generation unit 224 generates retransmission data based on the transmission data acquired from the buffer 223 with reference to, for example, the correspondence table 51 illustrated in FIG. In the present embodiment, the retransmission data generation unit 224 holds the correspondence table 51.
  • FIG. 28 is a diagram illustrating an example of the correspondence table 51 in the second embodiment.
  • the correspondence table 51 stores generation information, which is information for generating retransmission data corresponding to each additional information, in association with transmission information including information on transmission data such as MCS and transmission power of transmission data. For example, when the transmission data is generated based on “transmission information 2”, the correspondence table 51 illustrated in FIG. 28 generates retransmission data based on “generation information [21]” for the additional information 1. For additional information 2, it is shown that retransmission data is generated based on “generation information [22]”.
  • the retransmission data generation unit 224 refers to the correspondence table 51 and outputs the retransmission data generated based on the transmission data acquired from the buffer 223 to the transmission BB processing unit 226 at the transmission timing instructed by the scheduler 220. In addition, when the determination result of the response signal by the determination unit 221 is ACK, the retransmission data generation unit 224 deletes transmission data corresponding to the ACK from the buffer 223. Also in this embodiment, the retransmission data generation unit 224 may generate retransmission data corresponding to each additional information in advance before a response signal is returned from the wireless terminal 30.
  • FIG. 29 is a flowchart illustrating an example of the operation of the wireless terminal 30 according to the second embodiment. For example, when the wireless terminal 30 starts communication with the wireless base station 20, the wireless terminal 30 starts the operation shown in this flowchart.
  • the wireless terminal 30 establishes a low-delay data channel with the wireless base station 20 (S120).
  • the radio terminal 30 establishes a URLLC channel, for example, with the radio base station 20.
  • a URLLC channel is established with the radio base station 20 by a control unit (not shown) in the processor 33, for example.
  • the wireless terminal 30 receives data transmitted from the wireless base station 20 (S121).
  • the wireless communication circuit 32 performs processing such as amplification, orthogonal demodulation, and down-conversion on the reception signal received via the antenna 31 and outputs the processed reception signal to the processor 33.
  • the reception BB processing unit 330 in the processor 33 performs error correction decoding or the like for each block of a predetermined unit on the reception signal output from the wireless communication circuit 32 to restore the data transmitted from the wireless base station 20. . Then, the reception BB processing unit 330 outputs the restored data to the determination unit 331.
  • the wireless terminal 30 determines whether the data has been successfully decoded (S122). Specifically, the determination unit 331 determines whether or not the restored data includes an error using an error detection code such as a CRC code included in the data output from the reception BB processing unit 330. Thus, it is determined whether or not the data has been successfully decoded.
  • an error detection code such as a CRC code included in the data output from the reception BB processing unit 330.
  • the determination unit 331 notifies the response signal generation unit 333 of the successful data decoding.
  • the response signal generation unit 333 generates a response signal indicating ACK.
  • the transmission BB processing unit 334 performs encoding and modulation on the response signal generated by the response signal generation unit 333, and outputs the processed signal to the wireless communication circuit 32.
  • the wireless communication circuit 32 wirelessly transmits the response signal output from the transmission BB processing unit 334 via the antenna 31 via the control channel (S127). And the reception BB process part 330 performs the process shown to step S126.
  • the determination unit 331 notifies the response signal generation unit 333 of the data decoding failure.
  • the response signal generation unit 333 generates a response signal indicating NACK.
  • the transmission BB processing unit 334 performs processing such as encoding and modulation on the response signal generated by the response signal generation unit 333. Then, the transmission BB processing unit 334 maps the processed response signal to the control channel and outputs it to the wireless communication circuit 32.
  • the wireless communication circuit 32 wirelessly transmits the response signal output from the transmission BB processing unit 334 via the antenna 31 (S123).
  • the response signal generation unit 333 acquires a measurement value of an index indicating the quality of the reception environment from the measurement unit 332 (S124). Then, the response signal generation unit 333 converts the measurement value acquired from the measurement unit 332 into additional information having a predetermined number of bits. Then, the response signal generation unit 333 outputs the additional information to the transmission BB processing unit 334.
  • the transmission BB processing unit 334 performs processing such as encoding and modulation on the additional information output from the response signal generation unit 333. Then, the transmission BB processing unit 334 maps the processed additional information to the low-delay data channel and outputs it to the wireless communication circuit 32.
  • the wireless communication circuit 32 wirelessly transmits the additional information output from the transmission BB processing unit 334 via the antenna 31 (S125).
  • the reception BB processing unit 330 determines whether or not the communication with the radio base station 20 has ended (S126). If the communication with the radio base station 20 has not ended (S126: No), the reception BB processing unit 330 executes the process shown in step S121 again. On the other hand, when the communication with the radio base station 20 is finished (S126: Yes), the radio terminal 30 finishes the process shown in this flowchart.
  • FIG. 30 is a flowchart illustrating an example of the operation of the radio base station 20 according to the second embodiment. For example, when starting communication with the wireless terminal 30, the wireless base station 20 starts the operation shown in this flowchart.
  • the radio base station 20 establishes a channel for low delay data with the radio terminal 30 (S220).
  • the radio base station 20 establishes, for example, a URLLC channel with the radio terminal 30.
  • a URLLC channel is established with the radio base station 30 by a control unit (not shown) in the processor 22, for example.
  • the wireless base station 20 wirelessly transmits data (S221). Specifically, the transmission data processing unit 225 in the processor 22 generates transmission data based on a signal output from the communication interface 21, and outputs the generated transmission data to the buffer 223 and the transmission BB processing unit 226. .
  • the transmission BB processing unit 226 performs processing such as baseband modulation and multiplexing on the transmission data output from the transmission data processing unit 225. Then, the transmission BB processing unit 226 outputs the processed transmission signal to the wireless communication circuit 24.
  • the wireless communication circuit 24 performs processing such as up-conversion, orthogonal modulation, and amplification on the transmission signal output from the transmission BB processing unit 226, and wirelessly transmits the processed transmission signal to the space via the antenna 25. To do.
  • the buffer 223 holds the transmission data output from the transmission data processing unit 225 (S222).
  • the determination unit 221 refers to the signal output from the reception BB processing unit 222 and determines whether a response signal has been received (S223).
  • the determination unit 221 determines whether the response signal output from the reception BB processing unit 222 is ACK (S224). Then, the determination unit 221 outputs the determination result to the scheduler 220 and the retransmission data generation unit 224.
  • the retransmission data generation unit 224 deletes the transmission data corresponding to the ACK from the buffer 223 (S229). Then, the transmission BB processing unit 226 executes the process shown in step S228.
  • the determination unit 221 receives the additional information through the low-delay data channel established by the reception BB processing unit 222 with the wireless terminal 30. (S225). Then, the determination unit 221 outputs the received additional information to the retransmission data generation unit 224. Further, the scheduler 220 instructs the retransmission data generation unit 224 to transmit retransmission data.
  • the retransmission data generation unit 224 acquires the transmission data held in the buffer 223. Then, the retransmission data generation unit 224 generates retransmission data based on the transmission data acquired from the buffer 223 with reference to, for example, the correspondence table 51 illustrated in FIG. 28 (S226). Then, retransmission data generation section 224 outputs the generated retransmission data to transmission BB processing section 226 at the transmission timing instructed from scheduler 220.
  • the transmission BB processing unit 226 performs processing such as baseband modulation and multiplexing on the retransmission data output from the retransmission data generation unit 224. Then, the transmission BB processing unit 226 outputs the processed transmission signal to the wireless communication circuit 24.
  • the wireless communication circuit 24 performs processing such as up-conversion, orthogonal modulation, and amplification on the transmission signal output from the transmission BB processing unit 226, and wirelessly transmits the processed transmission signal to the space via the antenna 25. (S227).
  • the transmission BB processing unit 226 determines whether or not communication with the wireless terminal 30 has ended (S228). If the communication with the wireless terminal 30 has not ended (S228: No), the transmission BB processing unit 226 executes the process shown in step S221 again. On the other hand, when the communication with the wireless terminal 30 is finished (S228: Yes), the wireless base station 20 finishes the processing shown in this flowchart.
  • the radio communication system 10 includes a radio base station 20 and a radio terminal 30.
  • the wireless terminal 30 includes a reception BB processing unit 330, a determination unit 331, a measurement unit 332, and a wireless communication circuit 32.
  • the reception BB processing unit 330 receives data transmitted from the radio base station 20.
  • the determination unit 331 determines whether or not the received data has been successfully decoded.
  • the radio communication circuit 32 transmits ACK or NACK to the radio base station 20 according to the determination result of the determination unit 331.
  • the measurement unit 332 measures the reception environment.
  • the wireless communication circuit 32 transmits NACK to the wireless base station 20
  • the information regarding the reception environment measured by the measuring unit 332 is obtained from the channel secured with the wireless base station 20 for low-delay data.
  • the radio base station 20 includes a reception BB processing unit 222 and a transmission BB processing unit 226.
  • the transmission BB processing unit 226 transmits data to the wireless terminal 30.
  • the reception BB processing unit 222 receives ACK or NACK returned from the wireless terminal 30 in response to reception of data transmitted from the wireless base station 20 to the wireless terminal 30.
  • the reception BB processing unit 222 further receives information indicating the reception environment in the wireless terminal 30 from the wireless terminal 30 using a channel secured with the wireless terminal 30 for low-delay data.
  • the transmission BB processing unit 226 transmits retransmission data created from data transmitted to the wireless terminal 30 to the wireless terminal 30 according to information indicating the reception environment.
  • wireless communications system 10 can suppress the fall of the reliability of communication, such as the increase in the delay of communication.
  • the radio terminal 30 can cause the radio base station 20 to promptly receive additional information having a larger data amount than ACK and NACK.
  • the case where the wireless terminal 30 returns ACK or NACK to the wireless base station 20 for the data transmitted from the wireless base station 20 has been described as an example, but the disclosed technology is not limited thereto.
  • the technique disclosed in each of the above embodiments can also be applied to the case where the radio base station 20 returns ACK or NACK to the radio terminal 30 for data transmitted from the radio terminal 30.
  • the above-described first and second embodiments can be combined. Specifically, when each of the multi-valued NACKs is associated with a different reception environment in the wireless terminal 30 and data decoding fails on the wireless terminal 30 side, the wireless terminal 30 responds to the reception environment. NACK is notified to the radio base station 20. Further, the radio terminal 30 may transmit more detailed information regarding the reception environment as additional information to the radio base station 20 using a channel established with the radio base station 20 for low-delay data.
  • the case where the number of multi-levels of NACK is 2 to 4 has been described as an example.
  • the disclosed technique is not limited to this, and the number of multi-levels of NACK may be 5 or more.
  • the modulation method of the comparative example shown in FIG. 11 when the multi-level number of NACK is increased, the distance between adjacent NACKs is shortened and the error rate between NACKs is increased.
  • the modulation method of the first embodiment since each NACK symbol is arranged along a straight line 40 parallel to the Q axis, multiple NACK values are maintained while maintaining a distance between adjacent NACKs at a certain value or more. The number can be increased. Therefore, in the modulation method of the first embodiment, it is possible to increase the multi-level number of NACK without increasing the error rate between NACKs.
  • the ACK symbol is arranged on the I axis where the I coordinate is positive, and each NACK symbol is arranged along the straight line 40 parallel to the Q axis.
  • the response signal may be modulated such that an ACK symbol is arranged on the Q axis with a positive Q coordinate, and each NACK symbol is arranged along a straight line parallel to the I axis.
  • each processing block included in the radio base station 20 and the radio terminal 30 in the above-described embodiment can be subdivided into a larger number of processing blocks according to the processing content, or a plurality of processing blocks can be divided into one processing block. Can also be integrated.
  • the processing executed by each processing block may be realized as software processing, or may be realized by dedicated hardware such as ASIC (Application Specific Integrated Circuit).
  • wireless communication system 11 core network 20 wireless base station 21 communication interface 22 processor 220 scheduler 221 determination unit 222 reception BB processing unit 223 buffer 224 retransmission data generation unit 225 transmission data processing unit 226 transmission BB processing unit 23 memory 24 wireless communication circuit 25 Antenna 30 Wireless terminal 31 Antenna 32 Wireless communication circuit 33 Processor 330 Reception BB processing unit 331 Determination unit 332 Measurement unit 333 Response signal generation unit 334 Transmission BB processing unit 335 Re-decoding unit 34 Memory 40 Straight line 50 Correspondence table 51 Correspondence table

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Detection And Prevention Of Errors In Transmission (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un dispositif de communication sans fil qui comprend une unité de réception, une unité de sélection, une unité de modulation et une unité de transmission. L'unité de sélection sélectionne un ACK en tant que signal de réponse lorsqu'il est déterminé que la démodulation des données de réception a réussi, et sélectionne un quelconque d'une pluralité de NACK en tant que signal de réponse lorsqu'il est déterminé que la démodulation des données de réception a échoué. Lorsqu'un ACK est sélectionné par l'unité de sélection, l'unité de modulation module le signal de réponse de sorte que le symbole de l'ACK soit agencé dans une région sur un axe I et un axe Q sur un plan IQ. Lorsqu'un quelconque de la pluralité de NACK est sélectionné par l'unité de sélection, l'unité de modulation module le signal de réponse de sorte que le symbole du NACK sélectionné par l'unité de sélection soit agencé le long d'une ligne droite (40) parallèle à l'axe dans l'autre région à travers ledit axe sur le plan IQ. L'unité de transmission transmet le signal de réponse modulé par l'unité de modulation à un autre dispositif.
PCT/JP2016/089198 2016-12-28 2016-12-28 Dispositif de communication sans fil, système de communication sans fil et procédé de communication sans fil WO2018123058A1 (fr)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008093774A1 (fr) * 2007-02-02 2008-08-07 Panasonic Corporation Appareil de station de base de communications sans fil, appareil de station mobile de communications sans fil et procédé de mappage de signal de réponse dans un protocole arq

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008093774A1 (fr) * 2007-02-02 2008-08-07 Panasonic Corporation Appareil de station de base de communications sans fil, appareil de station mobile de communications sans fil et procédé de mappage de signal de réponse dans un protocole arq

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