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WO2018109887A1 - 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
WO2018109887A1
WO2018109887A1 PCT/JP2016/087306 JP2016087306W WO2018109887A1 WO 2018109887 A1 WO2018109887 A1 WO 2018109887A1 JP 2016087306 W JP2016087306 W JP 2016087306W WO 2018109887 A1 WO2018109887 A1 WO 2018109887A1
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WIPO (PCT)
Prior art keywords
wireless communication
communication device
channel state
csi
communication apparatus
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PCT/JP2016/087306
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English (en)
Japanese (ja)
Inventor
矢野　哲也
剛史 下村
ジヤンミン ウー
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Fujitsu Ltd
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Fujitsu Ltd
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Priority to PCT/JP2016/087306 priority Critical patent/WO2018109887A1/fr
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports

Definitions

  • the present invention relates to a wireless communication device, a wireless communication system, and a wireless communication method.
  • 3GPP Third generation mobile communication system
  • LTE Long Term Evolution
  • 5G fifth generation mobile communication system
  • a technique is known in which user equipment estimates channel state information in a plurality of subframes and sends the lowest channel state information over a plurality of subframes (see, for example, Patent Document 1 below). Also, a technique is known in which an indicator indicating the current value of channel state information is transmitted to a network node when the current value of channel state information changes from a previously transmitted value (for example, Patent Document 2 below). reference.).
  • the data transmission rate control may not be able to follow the channel fluctuation, or the data transmission rate may not match the actual channel state. In some cases, the rate is too low.
  • an object of the present invention is to provide a wireless communication device, a wireless communication system, and a wireless communication method capable of reducing an error rate in data transmission.
  • a first wireless communication apparatus measures a channel state in the own apparatus, and based on a variation state of the measured value of the channel state, the channel A first method for transmitting a report signal including a state measurement value, and a second method for transmitting a report signal including information regarding the channel state measurement value and the time change of the channel state.
  • the control signal received from the first wireless communication apparatus by the second wireless communication apparatus that transmits a control signal indicating a method and a report signal by the selected method and transmits data to the first wireless communication apparatus
  • the first wireless communication device receives a report signal from the first wireless communication device based on the method selected by the first wireless communication device, and based on the received report signal
  • Wireless communication device that performs scheduling of transmission of data, the wireless communication system and wireless communication method is proposed.
  • a second wireless communication device that transmits data to the first wireless communication device is configured to change the channel state based on a variation state of a measured value of the channel state in the first wireless communication device.
  • a method selected from each of the methods including: a first method for transmitting a report signal including a measurement value; and a second method for transmitting a report signal including information regarding the measurement value of the channel state and time variation of the channel state.
  • the control signal is transmitted to the first wireless communication device, the first wireless communication device measures the channel state of the device, receives the control signal from the second wireless communication device, and receives the control signal. Is transmitted to the second wireless communication apparatus, and the second wireless communication apparatus receives and receives the report signal according to the selected method from the first wireless communication apparatus. It said report signal radio communication apparatus that performs scheduling of transmission of data to the first radio communication apparatus based on a wireless communication system and wireless communication method is proposed.
  • the present invention has the effect of reducing the error rate in data transmission.
  • the error rate can be reduced at a transmission rate corresponding to the channel fluctuation state.
  • FIG. 1 is a diagram illustrating an example of a communication system according to the first embodiment.
  • FIG. 2 is a flowchart of an example of a report method selection process performed by the first wireless communication apparatus according to the first embodiment.
  • FIG. 3 is a flowchart of an example of a report method selection process performed by the second wireless communication apparatus according to the first embodiment.
  • FIG. 4 is a flowchart of an example of data reception processing performed by the first wireless communication apparatus according to the first embodiment.
  • FIG. 5 is a flowchart of an example of a data transmission process performed by the second wireless communication apparatus according to the first embodiment.
  • FIG. 6 is a diagram of an example of channel state reporting using the first reporting method by the first wireless communication apparatus according to the first embodiment and data transmission by the second wireless communication apparatus.
  • FIG. 1 is a diagram illustrating an example of a communication system according to the first embodiment.
  • FIG. 2 is a flowchart of an example of a report method selection process performed by the first wireless communication apparatus according to the first embodiment.
  • FIG. 7 is a diagram illustrating an example of channel state reporting using the second reporting method by the first wireless communication apparatus according to the first embodiment and data transmission by the second wireless communication apparatus.
  • FIG. 8 is a diagram of an example of the first wireless communication apparatus according to the first embodiment.
  • FIG. 9 is a diagram of an example of the second wireless communication apparatus according to the first embodiment.
  • FIG. 10 is a diagram of an example of a hardware configuration of the first wireless communication device and the second wireless communication device according to the first embodiment.
  • FIG. 11 is a diagram illustrating an example of calculation of the change amount of CSI based on the measured values of CSI for the past two times by the first wireless communication apparatus according to the first embodiment.
  • FIG. 12 is a diagram illustrating another example of the calculation of the change amount of CSI based on the measured values of CSI for the past two times by the first wireless communication apparatus according to the first embodiment.
  • FIG. 13 is a diagram illustrating an example of calculation of a change amount of CSI based on measured values of CSI for the past N times by the first wireless communication apparatus according to the first embodiment.
  • FIG. 14 is a diagram illustrating another example of calculation of the CSI change amount based on the past N CSI measurement values by the first wireless communication apparatus according to the first embodiment.
  • FIG. 15 is a diagram of an example of a channel state report by the first wireless communication apparatus according to the second embodiment.
  • FIG. 16 is a diagram illustrating another example of the channel state report by the first wireless communication apparatus according to the second embodiment.
  • FIG. 17 is a flowchart of an example of data reception processing by the first wireless communication apparatus according to the second embodiment.
  • FIG. 18 is a flowchart of an example of data transmission processing by the second wireless communication apparatus according to the second embodiment.
  • FIG. 19 is a diagram of an example of a channel state report by the first wireless communication apparatus according to the third embodiment.
  • FIG. 20 is a flowchart of an example of data reception processing by the first wireless communication apparatus according to the third embodiment.
  • FIG. 21 is a diagram of an example of calculation of the change amount of the CSI change amount by the first wireless communication apparatus according to the fourth embodiment.
  • FIG. 22 is a diagram of an example of channel state estimation performed by each wireless communication device according to the fifth embodiment.
  • FIG. 23 is a diagram illustrating an example of a channel state report by the first wireless communication apparatus according to the sixth embodiment.
  • FIG. 24 is a flowchart of an example of data reception processing by the first wireless communication apparatus according to the sixth embodiment.
  • FIG. 25 is a flowchart of another example of the data reception process performed by the first wireless communication apparatus according to the sixth embodiment.
  • FIG. 26 is a diagram illustrating an example of a channel state report by the first wireless communication apparatus according to the seventh embodiment.
  • FIG. 27 is a flowchart of an example of data reception processing by the first wireless communication apparatus according to the seventh embodiment.
  • FIG. 1 is a diagram illustrating an example of a communication system according to the first embodiment.
  • the communication system 100 according to the first embodiment includes a first wireless communication device 110 and a second wireless communication device 120.
  • the first wireless communication device 110 receives data wirelessly transmitted from the second wireless communication device 120.
  • the data transmitted from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 is user data transmitted by U-Plane, for example.
  • the first wireless communication device 110 can be applied to a wireless terminal
  • the second wireless communication device 120 can be applied to a wireless base station.
  • the wireless terminal is a mobile station such as a 3GPP UE (User Equipment: user terminal).
  • the radio base station is various base stations such as eNB (evolved Node B) of 3GPP, for example.
  • the first wireless communication apparatus 110 includes, for example, a measurement unit 111, a selection unit 112, and a transmission unit 113.
  • the first wireless communication device 110 may include a receiving unit 114.
  • the measurement unit 111 measures the channel state in the first wireless communication apparatus 110 (self apparatus). Then, the measurement unit 111 notifies the selection unit 112 and the transmission unit 113 of the measurement result of the channel state in the first wireless communication apparatus 110.
  • the channel state in the first wireless communication device 110 is a channel state between the first wireless communication device 110 and the second wireless communication device 120, for example.
  • the channel state is, for example, CSI (Channel State Information) indicating the state of the wireless channel through which the signal passes.
  • CSI Channel State Information
  • CSI indicates at least one of, for example, received signal power, SINR, CQI, MCS level, and interference amount.
  • SINR Signal to Interference and Noise Ratio
  • CQI is an identifier representing a modulation and coding scheme that can be transmitted with the measured SINR.
  • MCS Modulation and Coding Scheme
  • the interference level is the amount of interference signal included in the received signal.
  • the selection unit 112 selects one of the methods including the first method and the second method based on the fluctuation state of the measurement value of the channel state indicated by the measurement result notified from the measurement unit 111. Then, the selection unit 112 notifies the transmission unit 113 of the selected method.
  • the first method is a method of transmitting a report signal including a measured value of the channel state to the second wireless communication apparatus 120.
  • the measurement value of the channel state included in the report signal in the first method is the lowest value among the measurement values obtained by the measurement unit 111, for example.
  • the measurement value of the channel state included in the report signal in the first method may be the measurement value (latest measurement value) obtained at the end of the measurement values obtained by the measurement unit 111.
  • the second method is a method of transmitting a report signal including information regarding a channel state measurement value and a channel state temporal change to the second wireless communication apparatus 120.
  • the fluctuation state of the measurement value of the channel state is, for example, the frequency (change rate) at which the change direction (increase or decrease) of the measurement value of the channel state changes.
  • the selection unit 112 selects the first method when the change direction of the channel state measurement value is high, and selects the second method when the change direction of the channel state measurement value is low. select. A method for determining the variation state of the measured value of the channel state will be described later.
  • the transmission unit 113 generates a control signal indicating the method notified from the selection unit 112. Then, the transmission unit 113 wirelessly transmits the generated control signal to the second wireless communication apparatus 120. In addition, the transmission unit 113 generates a report signal based on the method notified from the selection unit 112 based on the measurement result notified from the measurement unit 111. Then, the transmission unit 113 wirelessly transmits the generated report signal to the second wireless communication device 120.
  • the transmission unit 113 when the selection unit 112 selects the first method, the transmission unit 113 generates a report signal including the lowest value of the channel state based on the measured value of the channel state and wirelessly transmits the report signal to the second wireless communication apparatus 120. To do. Further, when the second method is selected by the selection unit 112, the transmission unit 113 generates a report signal including information on the channel state measurement value and the channel state temporal change, and wirelessly transmits the report signal to the second wireless communication apparatus 120. Send.
  • the report signal according to the first method does not include information regarding the channel state time change included in the report signal according to the second method. That is, the report signal according to the first method includes information indicating the channel state, while the report signal according to the second method includes information regarding the temporal change of the channel state in addition to the information indicating the channel state. For this reason, the report signal according to the first method and the report signal according to the second method have different data formats such as the number of bits. Therefore, the transmission unit 113 transmits a control signal indicating the reporting method to the second wireless communication apparatus 120, so that the second wireless communication apparatus 120 can determine the data format of the report signal and receive the report signal. become.
  • the transmission of the report signal is, for example, for transmitting PUCCH or other control information (Physical) channels can be used.
  • PUCCH is an abbreviation for Physical Uplink Control Channel (physical uplink control channel).
  • a (physical) channel for data transmission such as PUSCH (Physical Uplink Shared Channel: physical uplink shared channel) may be used.
  • PUSCH Physical Uplink Shared Channel: physical uplink shared channel
  • the minimum value of the channel state included in the report signal by the first method is, for example, the minimum value of the measured value of the channel state in the past predetermined period. As a result, a report signal indicating the lowest possible channel state can be generated by simple processing.
  • the minimum value of the channel state included in the report signal by the first method may be the minimum value of the predicted value of the channel state in the future period based on the measured value of the channel state in the past predetermined period.
  • the predicted value of the channel state can be calculated, for example, by polynomial interpolation (Nth order interpolation) based on the measured value of the channel state in the past period.
  • the predicted value of the channel state is not limited to polynomial interpolation, and can be calculated, for example, by a method using a sine wave described later.
  • the future period is a period from the present to the next periodic timing, for example, when the first wireless communication apparatus 110 transmits a report signal at a periodic timing.
  • wireless communication apparatus 110 transmits a report signal next can be estimated, and it can notify to the 2nd radio
  • the measurement value included in the report signal by the second method is, for example, the measurement value obtained at the end of the measurement values obtained by the measurement unit 111 (latest measurement value).
  • the information regarding the time change of the channel state included in the report signal by the second method is information based on a plurality of measurement values obtained by measuring the channel state a plurality of times by the measurement unit 111, for example.
  • the information regarding the channel state change over time is the rate of change (change amount) of the channel state over time, that is, the rate of change of the channel state over time.
  • the second wireless communication device 120 includes a receiving unit 121 and a control unit 122.
  • the second wireless communication device 120 may include a transmission unit 123.
  • the receiving unit 121 receives a control signal transmitted from the first wireless communication apparatus 110.
  • the reception unit 121 receives a report signal transmitted from the first wireless communication apparatus 110 based on a report method indicated by the received control signal. For example, the reception unit 121 receives the report signal by determining the data format of the report signal transmitted from the first wireless communication apparatus 110 based on the report method indicated by the received control signal. Then, the reception unit 121 outputs the received report signal to the control unit 122.
  • the control unit 122 schedules transmission of data from the second wireless communication device 120 to the first wireless communication device 110 based on the report signal output from the reception unit 121. For example, when the report signal is a report signal according to the first method, the control unit 122 determines from the second radio communication device 120 to the first radio communication device 110 based on the lowest measured value of the channel state indicated by the report signal. Schedule transmission of data to.
  • the control unit 122 uses the measured value of the channel state included in the report signal and the information on the time change of the channel state, and The estimated value of the channel state with one wireless communication apparatus 110 is calculated. For example, the control unit 122 estimates the channel state between the second wireless communication device 120 and the first wireless communication device 110 (predicted value) in a future time resource that can transmit data to the first wireless communication device 110. ) Is calculated. Then, the control unit 122 schedules data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 based on the calculated estimated value of the channel state.
  • the scheduling by the control unit 122 includes, for example, determination of at least one of a modulation scheme and a coding scheme used for data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110.
  • the determination of the modulation scheme and the encoding scheme is, for example, the determination of MCS (Modulation and Coding Scheme: modulation / coding scheme).
  • the scheduling by the control unit 122 includes, for example, determination of the position of the radio resource on the frequency axis and the amount of the radio resource used for data transmission from the second radio communication apparatus 120 to the first radio communication apparatus 110. Also good.
  • the scheduling by the control unit 122 may include, for example, determination of transmission power used for data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110.
  • the second wireless communication apparatus 120 transmits data to the first wireless communication apparatus 110 based on the scheduling result by the control unit 122.
  • the first wireless communication apparatus 110 can select a reporting method from each method including the first method and the second method based on the fluctuation state of the measured value of the channel state.
  • the first method is a method of transmitting a report signal including the lowest value of the channel state based on the measured value of the channel state to the second wireless communication apparatus 120.
  • the second method is a method of transmitting a report signal including information regarding a channel state measurement value and a channel state temporal change to the second wireless communication apparatus 120.
  • wireless communication apparatus 110 can transmit the control signal which shows the selected method, and the report signal by the selected method.
  • the second wireless communication apparatus 120 receives a report signal from the first wireless communication apparatus 110 based on the method selected by the first wireless communication apparatus 110 based on the control signal received from the first wireless communication apparatus 110. Is possible.
  • the second wireless communication device 120 can schedule transmission of data to the first wireless communication device 110 based on the received report signal. Therefore, it is possible to report the measurement result of the channel state according to the channel state fluctuation state between the first wireless communication device 110 and the second wireless communication device 120, and to reduce the error rate in data transmission. Can do.
  • the measurement result of the channel from the first wireless communication device 110 to the second wireless communication device 120 is reported. Can be performed by the first method.
  • the channel state fluctuation state is severe and prediction based on a temporal change in the channel state cannot be followed, data transmission can be performed at a low rate based on the assumed minimum channel state. For this reason, it is possible to suppress an increase in error rate due to failure to follow prediction based on a temporal change in channel state, and to reduce the error rate.
  • the measurement result of the channel from the first wireless communication device 110 to the second wireless communication device 120 Reporting can be done by the second method.
  • the channel state fluctuation state is not severe, data transmission can be performed at a rate based on the channel state predicted using the channel state measurement value and the information on the channel state temporal change. For this reason, it is possible to reduce the data transmission error rate while suppressing a decrease in data transmission efficiency.
  • the channel state can be predicted with high accuracy even if the measurement value is reported less frequently.
  • the second wireless communication device 120 performs scheduling. It is possible to predict the channel state of the variable time resource used for. For this reason, for example, the first radio communication apparatus 110 does not have to report an estimated value of the channel state in each future time resource, so that the efficiency of radio resources for reporting and the power consumption for reporting are reduced. Can be planned. In addition, since it is not necessary to limit the time resource used by second wireless communication apparatus 120 for scheduling, it is possible to suppress a decrease in the degree of freedom of scheduling in second wireless communication apparatus 120.
  • FIG. 1 (Configuration in which the second wireless communication apparatus selects a reporting method and notifies the first wireless communication apparatus of the selection result)
  • the configuration has been described in which the first wireless communication device 110 selects a reporting method and notifies the second wireless communication device 120 of the selection result.
  • the second wireless communication device 120 selects and selects the reporting method.
  • the result may be notified to the first wireless communication apparatus 110.
  • the selection unit 112 illustrated in FIG. 1 is provided in the second wireless communication apparatus 120.
  • the transmission unit 113 of the first wireless communication device 110 transmits the measurement result by the measurement unit 111 to the second wireless communication device 120.
  • This measurement result may be information indicating a measured value of the channel state or information indicating a fluctuation state of the measured value of the channel state.
  • the reception unit 121 of the second wireless communication apparatus 120 receives this measurement result and outputs it to the selection unit 112.
  • the selection unit 112 selects the report method described above based on the measurement result output from the reception unit 121. Then, the second wireless communication device 120 transmits a control signal indicating the reporting method selected by the selection unit 112 to the first wireless communication device 110 by the transmission unit 123.
  • the control signal is transmitted by, for example, transmitting a PDCCH or other control information.
  • a trusted (physical) channel can be used.
  • PDCCH is an abbreviation for Physical Downlink Control Channel (physical downlink control channel).
  • a (physical) channel for data transmission such as PDSCH may be used.
  • PDSCH is an abbreviation for Physical Downlink Shared Channel (physical downlink shared channel).
  • the first wireless communication device 110 receives the control signal transmitted from the second wireless communication device 120 by the receiving unit 114. Then, the reception unit 114 notifies the transmission unit 113 of the received control signal.
  • the transmission unit 113 wirelessly transmits a report signal based on a reporting method indicated by the control signal output from the reception unit of the first wireless communication device 110 to the second wireless communication device 120.
  • the second wireless communication device 120 receives the report signal wirelessly transmitted from the first wireless communication device 110 based on the reporting method selected by the selection unit 112.
  • the measurement result of the channel corresponding to the channel state variation state Reporting is possible. For this reason, it is possible to reduce the error rate in data transmission.
  • FIG. 2 is a flowchart of an example of a report method selection process performed by the first wireless communication apparatus according to the first embodiment.
  • the first wireless communication device 110 on the data receiving side selects the CSI reporting method from the first wireless communication device 110 to the second wireless communication device 120.
  • the first wireless communication apparatus 110 executes, for example, each step shown in FIG. 2 as the reporting method selection process.
  • the first wireless communication device 110 determines whether the first wireless communication device 110 and the second wireless communication device 120 are based on a measured value of CSI between the first wireless communication device 110 and the second wireless communication device 120.
  • the CSI fluctuation speed is determined (step S201). For example, the first wireless communication device 110 determines whether the CSI fluctuation speed between the first wireless communication device 110 and the second wireless communication device 120 is “high speed” or “low speed”.
  • the first wireless communication apparatus 110 determines whether or not the CSI fluctuation speed determined in step S201 is “high speed” (step S202).
  • the fluctuation speed is “high speed” (step S202: Yes)
  • the first wireless communication apparatus 110 selects the first reporting method for reporting the lowest value of the measured CSI value in the past predetermined period (step S203). ), The process proceeds to step S205.
  • the fluctuation speed is “low speed” (step S202: No)
  • the first wireless communication apparatus 110 selects the second reporting method for reporting the measured value of CSI and the amount of change in CSI (step S204).
  • the first wireless communication device 110 notifies the second wireless communication device 120 of the reporting method selected in step S203 or step S204 (step S205), and returns to step S201.
  • the first wireless communication apparatus 110 transmits a control signal indicating the reporting method selected in step S203 or step S204 to the second wireless communication apparatus 120.
  • the process of selecting one of the two reporting methods (the first reporting method and the second reporting method) according to the CSI fluctuation rate in two stages (“high speed” and “low speed”) has been described. It is not limited to such processing. For example, it may be a process of selecting one of three reporting methods according to the CSI fluctuation speed in three stages (for example, “high speed”, “medium speed”, and “low speed”). Similarly, it may be a process of selecting one of four or more reporting methods according to four or more stages of CSI fluctuation speed.
  • the first wireless communication apparatus 110 determines that the fluctuation speed is “high speed” in step S202. Then, the process proceeds to step S203, and the above-described first reporting method is selected. Further, when the fluctuation speed is “medium speed”, the first wireless communication apparatus 110 proceeds to step S204 and selects the second reporting method described above. In addition, when the fluctuation speed is “low speed”, the first wireless communication apparatus 110 reports a CSI measurement value or a measurement value obtained by correcting the CSI measurement value, and does not report a CSI change amount. Select and move to step S205. In step S205, the first wireless communication apparatus 110 notifies the second wireless communication apparatus 120 of the reporting method selected from the first reporting method, the second reporting method, and the third reporting method.
  • the second wireless communication apparatus 120 does not perform prediction of the future CSI based on the information on the CSI measurement value and the time change of the CSI. It is possible to reduce the processing amount and signal overhead required for reporting.
  • the first wireless communication device 110 can determine the fluctuation speed (fluctuation state) based on the number of times of switching within a predetermined time of the magnitude relationship between the measured value of the CSI and the predetermined value.
  • the switching of the magnitude relationship between the CSI measurement value and the predetermined value is, for example, switching from the CSI measurement value ⁇ the predetermined value state to the CSI measurement value> the predetermined value state, or the CSI measurement value> predetermined value.
  • the predetermined value for example, a median value of CSI measurement values, an average value of past CSI measurement values, or the like can be used.
  • the predetermined time is, for example, a period of a fixed time going back from the present.
  • the first wireless communication apparatus 110 determines two-stage fluctuation speeds of “high speed” and “low speed”. For example, the first wireless communication apparatus 110 determines that the fluctuation speed is “high speed” when the number of switching times within a predetermined time in the magnitude relationship between the CSI measurement value and the predetermined value is equal to or greater than the predetermined number. Further, the first wireless communication apparatus 110 determines that the fluctuation speed is “low speed” when the number of switching times within a predetermined time in the magnitude relationship between the measured value of the CSI and the predetermined value is less than the predetermined number.
  • the first wireless communication apparatus 110 determines three-stage fluctuation speeds of “high speed”, “medium speed”, and “low speed”. For example, the first wireless communication apparatus 110 determines that the fluctuation speed is “high speed” when the number of switching times within a predetermined time of the magnitude relationship between the CSI measurement value and the predetermined value is equal to or greater than the predetermined first number. judge. In addition, the first wireless communication device 110 has a fluctuation speed of less than the first number and greater than or equal to the predetermined second number when the number of switchings within a predetermined time of the magnitude relationship between the measured value of the CSI and the predetermined value is less than the first number. It is determined that the speed is “medium speed”.
  • the second number is less than the first number.
  • the first wireless communication device 110 determines that the fluctuation speed is “low speed” when the number of switching times within a predetermined time of the magnitude relationship between the measured value of the CSI and the predetermined value is less than the second number. To do.
  • the first wireless communication apparatus 110 can determine the fluctuation speed (fluctuation state) based on the number of switching times within a predetermined time in the change direction of the CSI measurement value.
  • the first new CSI measurement value is CSI_1
  • the second new CSI measurement value is CSI_2.
  • the change direction of the measurement value of CSI is switched from the state of CSI_1 ⁇ CSI_2 to the state of measurement value of CSI_1> CSI_2, or from the state of CSI_1> CSI_2 to the state of CSI_1 ⁇ CSI_2.
  • the change direction of the CSI measurement value is not limited to the change direction based on the first new CSI measurement value and the second new CSI measurement value.
  • the change direction of the CSI measurement value may be a change direction determined based on the past three or more CSI measurement values.
  • the first wireless communication apparatus 110 determines two-stage fluctuation speeds of “high speed” and “low speed”. For example, the first wireless communication apparatus 110 determines that the fluctuation speed is “high speed” when the number of switching times within a predetermined time in the change direction of the CSI measurement value is equal to or greater than the predetermined number. Also, the first wireless communication apparatus 110 determines that the fluctuation speed is “low speed” when the number of switching times within a predetermined time in the changing direction of the CSI measurement value is less than the predetermined number.
  • the first wireless communication apparatus 110 determines three-stage fluctuation speeds of “high speed”, “medium speed”, and “low speed”. For example, the first wireless communication apparatus 110 determines that the fluctuation speed is “high speed” when the number of switching times within a predetermined time in the changing direction of the CSI measurement value is equal to or greater than the predetermined first number. Further, the first wireless communication device 110 has a “medium speed” when the number of switching times within a predetermined time in the direction of change of the CSI measurement value is less than the first number and greater than or equal to the predetermined second number. Is determined. The second number is less than the first number. Also, the first wireless communication apparatus 110 determines that the fluctuation speed is “low speed” when the number of switching times within a predetermined time in the direction of change of the CSI measurement value is less than the second number.
  • FIG. 3 is a flowchart of an example of a report method selection process performed by the second wireless communication apparatus according to the first embodiment.
  • the second wireless communication device 120 on the data transmission side selects the CSI reporting method from the first wireless communication device 110 to the second wireless communication device 120.
  • the second wireless communication apparatus 120 executes, for example, each step shown in FIG. 3 as the report method selection process.
  • the second wireless communication device 120 determines the variation rate of CSI between the first wireless communication device 110 and the second wireless communication device 120 based on the report from the first wireless communication device 110 (step S301). ). For example, the second wireless communication apparatus 120 determines whether the CSI fluctuation speed between the first wireless communication apparatus 110 and the second wireless communication apparatus 120 is “high speed” or “low speed”. A method for determining the CSI fluctuation speed will be described later.
  • the second wireless communication device 120 receives the control signal indicating the variation rate of CSI between the first wireless communication device 110 and the second wireless communication device 120 from the first wireless communication device 110, thereby changing the CSI. Determine the speed.
  • the second wireless communication device 120 may receive a control signal indicating a CSI measurement result between the first wireless communication device 110 and the second wireless communication device 120 from the first wireless communication device 110. In this case, the second wireless communication device 120 determines the CSI fluctuation speed by a calculation based on the received measurement result.
  • the second wireless communication apparatus 120 determines whether or not the fluctuation speed of the CSI determined in step S301 is “high speed” (step S302).
  • the fluctuation speed is “high speed” (step S302: Yes)
  • the second wireless communication apparatus 120 selects the first reporting method for reporting the lowest CSI measurement value in a predetermined period in the past (step S303). ), The process proceeds to step S305.
  • the fluctuation speed is not “high speed” (step S302: No)
  • the second wireless communication apparatus 120 selects the second reporting method for reporting the measured value of CSI and the amount of change in CSI (step S304).
  • the second wireless communication apparatus 120 instructs the first wireless communication apparatus 110 about the reporting method selected in step S303 or step S304 (step S305), and returns to step S301.
  • the second wireless communication apparatus 120 transmits a control signal indicating the reporting method selected in step S303 or step S304 to the first wireless communication apparatus 110.
  • the first wireless communication apparatus 110 sends a control signal indicating the CSI fluctuation rate to the second wireless communication apparatus 120 or measures CSI.
  • a control signal indicating the result is periodically transmitted.
  • the second wireless communication apparatus 120 selects the CSI reporting method as shown in FIG. 3, as described above, there are three or more reporting methods according to the CSI fluctuation speed of three or more stages. It is good also as a process which selects either.
  • FIG. 4 is a flowchart of an example of data reception processing performed by the first wireless communication apparatus according to the first embodiment.
  • two types of reporting methods (first reporting method and first reporting method) are selected according to the CSI fluctuation speed in two stages (“high speed” and “low speed”) by the reporting method selection process shown in FIG. (2) Reporting method) will be described.
  • the first wireless communication apparatus 110 executes, for example, each step shown in FIG. 4 as the data reception process.
  • the first wireless communication device 110 determines whether or not it is the periodic CSI reporting timing of the device itself (step S401).
  • the periodic CSI reporting timing may be, for example, a reporting timing that the second wireless communication apparatus 120 instructs in advance to the first wireless communication apparatus 110, or the first wireless communication apparatus 110 determines the reporting timing. It may be the timing for reporting to the second wireless communication apparatus 120. Further, the periodic CSI report timing may be a known report timing (for example, every subframe or every several subframes) in the first radio communication apparatus 110 and the second radio communication apparatus 120.
  • step S401 when it is not the periodic CSI reporting timing (step S401: No), the first wireless communication apparatus 110 proceeds to step S405.
  • step S401: Yes the first wireless communication apparatus 110 determines whether or not the selected CSI reporting method is the first reporting method (step S402). ).
  • the selected CSI reporting method in step S402 is the first wireless communication apparatus in step S203 or step S204 shown in FIG. 110 is the last selected reporting method.
  • the second wireless communication apparatus 120 executes the reporting method selection process shown in FIG. 3
  • the selected CSI reporting method is changed from the second wireless communication apparatus 120 to the first in step S305 shown in FIG. This is a reporting method last instructed to the wireless communication apparatus 110.
  • step S402 when the reporting method is the first reporting method (step S402: Yes), the first wireless communication device 110 transmits a report signal indicating the lowest CSI measurement value to the second wireless communication device 120. (Step S403), the process proceeds to Step S405.
  • the reporting method is the second reporting method (step S402: No)
  • the first wireless communication apparatus 110 indicates the latest measured value of CSI and the amount of change in CSI based on past measured values of CSI.
  • a report signal is transmitted to the 2nd radio
  • the latest measured value of CSI is a measured value a0 described later.
  • the change amount of CSI is, for example, a change amount a1 described later.
  • the first wireless communication device 110 determines whether or not it has received a control signal addressed to itself from the second wireless communication device 120 (step S405).
  • This control signal is a signal including control information for notifying transmission of data from the second wireless communication apparatus 120 to the first wireless communication apparatus 110, for example.
  • the control signal has not been received (step S405: No)
  • the first wireless communication device 110 returns to step S401.
  • step S405 when a control signal is received (step S405: Yes), the first wireless communication device 110 receives data from the second wireless communication device 120 based on the received control signal (step S406). The process returns to step S401.
  • the first wireless communication device 110 uses the second wireless communication device with the lowest CSI measurement value at the periodic reporting timing. Report to 120. Further, when the selected reporting method is the second reporting method, the first wireless communication apparatus 110 reports, for example, the CSI measurement value and the change amount to the second wireless communication apparatus 120 at a periodic report timing. And the 1st radio
  • FIG. 5 is a flowchart of an example of a data transmission process performed by the second wireless communication apparatus according to the first embodiment.
  • two types of reporting methods first reporting method and first reporting method
  • the second wireless communication apparatus 120 executes, for example, each step shown in FIG. 5 as the data transmission process.
  • the second wireless communication apparatus 120 determines whether or not the periodic CSI reporting timing by the first wireless communication apparatus 110 has come (step S501).
  • step S501 when the report timing has not come (step S501: No), the second wireless communication apparatus 120 proceeds to step S505.
  • step S501: Yes when it is time to report (step S501: Yes), the second wireless communication apparatus 120 determines whether or not the selected CSI reporting method is the first reporting method (step S502).
  • the selected CSI reporting method in step S502 is changed from the first wireless communication apparatus 110 to step S205 shown in FIG. 2 is a reporting method last notified to the wireless communication device 120. Also, the selected CSI reporting method is the same as the second wireless communication device 120 in step S303 or step S304 shown in FIG. 3 when the second wireless communication device 120 executes the reporting method selection process shown in FIG. Is the last selected reporting method.
  • step S502 when the reporting method is the first reporting method (step S502: Yes), the second wireless communication device 120 receives a report signal indicating the lowest CSI measurement value from the first wireless communication device 110. (Step S503), the process proceeds to Step S505.
  • the reporting method is the second reporting method (step S502: No)
  • the second wireless communication device 120 reports the latest measured value of CSI by the first wireless communication device 110 and the amount of change in CSI.
  • a signal is received from the first wireless communication apparatus 110 (step S504).
  • the second wireless communication apparatus 120 derives CSI in a future time resource based on the report signal received in step S503 or step S504 (step S505).
  • Future time resources are, for example, one or more time resources that can be used to transmit data from the second wireless communication device 120 to the first wireless communication device 110.
  • the second radio communication apparatus 120 when the second radio communication apparatus 120 receives the report signal in step S503, the second radio communication apparatus 120 derives the CSI (the lowest value of the measurement value) indicated by the received report signal as the CSI in the future time resource.
  • the second radio communication apparatus 120 when the second radio communication apparatus 120 receives the report signal in step S504, the second radio communication apparatus 120 derives CSI in a future time resource by calculation based on the CSI measurement value and the CSI change amount included in the received report signal. To do.
  • the second wireless communication apparatus 120 performs scheduling based on the CSI derived in step S505 (step S506).
  • Scheduling includes, for example, determination of radio resources, determination of modulation scheme and coding scheme.
  • the determination of radio resources is, for example, determination of the location and amount of resource blocks.
  • the determination of the encoding method is, for example, determination of a coding rate and a transport block size (data size).
  • the second wireless communication apparatus 120 determines whether to transmit data to the first wireless communication apparatus 110 based on the scheduling result of step S506 (step S507). When it is determined that data is not transmitted to the first wireless communication device 110 (step S507: No), the second wireless communication device 120 returns to step S501.
  • step S507 If it is determined in step S507 that data is transmitted to the first wireless communication apparatus 110 (step S507: Yes), the second wireless communication apparatus 120 transmits a control signal to the first wireless communication apparatus 110 (step S508).
  • the control signal transmitted in step S508 is a control signal for notifying transmission of data from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 based on the scheduling result in step S506.
  • the second wireless communication apparatus 120 transmits data to the first wireless communication apparatus 110 based on the scheduling result of step S506 (step S509), and returns to step S501.
  • the second wireless communication apparatus 120 when the selected reporting method is the first reporting method, the second wireless communication apparatus 120 generates a report signal indicating the lowest CSI measurement value at a periodic reporting timing. 1 Receive from the wireless communication device 110. In addition, when the selected reporting method is the second reporting method, the second wireless communication device 120 transmits a report signal indicating the measured value of CSI and the amount of change from the first wireless communication device 110 at a periodic report timing. Receive. Then, second radio communication apparatus 120 performs scheduling based on the received report signal, and transmits data to first radio communication apparatus 110 based on the scheduling result.
  • FIG. 6 is a diagram of an example of channel state reporting using the first reporting method by the first wireless communication apparatus according to the first embodiment and data transmission by the second wireless communication apparatus.
  • the horizontal axis indicates time
  • the vertical axis indicates CSI (channel state).
  • a subframe 601 on the horizontal axis is a unit of time (for example, 1 [ms]) in which CSI measurement and reporting by the first wireless communication apparatus 110 and data transmission by the second wireless communication apparatus 120 can be performed.
  • Times T ( ⁇ 4) to T (1) are successive times in subframe units.
  • the CSI measurement result 602 is a time change of CSI based on CSI between the first wireless communication device 110 and the second wireless communication device 120 measured by the first wireless communication device 110 for each subframe 601.
  • the first wireless communication device 110 reports CSI to the second wireless communication device 120 by the first reporting method at time T (1).
  • the first wireless communication apparatus 110 specifies the lowest value of the CSI measurement value in the predetermined period 603 immediately before the time T (1).
  • the predetermined period 603 includes times T ( ⁇ 4) to T ( ⁇ 0).
  • the measured values CSI ( ⁇ 4) to CSI (0) are CSI measured by the first radio communication apparatus 110 at times T ( ⁇ 4) to T ( ⁇ 0), respectively.
  • the first wireless communication apparatus 110 specifies that the lowest measured value among the measured values CSI ( ⁇ 4) to CSI (0) is the measured value CSI ( ⁇ 4). Then, the first wireless communication apparatus 110 transmits a report signal indicating the specified minimum value (measurement value CSI ( ⁇ 4)) to the second wireless communication apparatus 120 at time T (1), thereby measuring the minimum value (measurement). The value CSI ( ⁇ 4)) is reported to the second wireless communication apparatus 120.
  • the second radio communication device 120 uses the first radio communication after the time T (1), for example, to estimate the CSI between the second radio communication device 120 and the first radio communication device 110 at the time T (4).
  • the lowest value (measured value CSI ( ⁇ 4)) reported from the apparatus 110 is used.
  • second radio communication apparatus 120 performs scheduling of data to be transmitted to first radio communication apparatus 110 based on the estimated value of CSI at time T (4), that is, measurement value CSI ( ⁇ 4).
  • measurement value CSI ( ⁇ 4) data transmission to the first wireless communication apparatus 110 is performed.
  • the transmission of the report signal from the first wireless communication apparatus 110 to the second wireless communication apparatus 120 can be realized, for example, by assigning in advance a dedicated resource of the first wireless communication apparatus 110 for transmitting the report signal. . This eliminates a collision between the report signal from the first wireless communication apparatus 110 and another signal (for example, a report signal from another wireless communication apparatus), thereby reducing error in the report signal.
  • the transmission of the report signal from the first wireless communication device 110 to the second wireless communication device 120 is performed by, for example, preallocating contention resources for a plurality of wireless communication devices including the first wireless communication device 110 to transmit the report signal. Can be realized. Thereby, it is possible to reduce the resource consumption in the transmission of the report signal.
  • FIG. 7 is a diagram illustrating an example of channel state reporting using the second reporting method by the first wireless communication apparatus according to the first embodiment and data transmission by the second wireless communication apparatus.
  • the horizontal axis indicates time
  • the vertical axis indicates CSI (channel state).
  • Times T ( ⁇ 1) to T (4) are consecutive times in subframe units.
  • the first wireless communication apparatus 110 reports CSI to the second wireless communication apparatus 120 by the second reporting method at time T (1).
  • the measured value a0 is CSI (intercept) measured by the first wireless communication apparatus 110 at time T (0).
  • the change amount a1 is a change amount (gradient) of CSI per time calculated by the first wireless communication apparatus 110 based on a plurality of past CSI measurement results.
  • the first wireless communication device 110 transmits a report signal including the measurement value a0 and the change amount a1 to the second wireless communication device 120 at time T (1) immediately after time T (0), thereby measuring the measurement value a0 and The change amount a1 is reported to the second wireless communication apparatus 120.
  • the second wireless communication device 120 uses the first CSI estimated value between the second wireless communication device 120 and the first wireless communication device 110 at a time after the time T (1), for example, T (4), as the first value. Calculation is performed using the measured value a0 and the change amount a1 reported from the wireless communication apparatus 110.
  • the predicted CSI characteristic 702 is CSI in each time interval predicted by the measured value a0 (intercept) and the change amount a1 (slope) reported by the first wireless communication apparatus 110 to the second wireless communication apparatus 120.
  • Second wireless communication apparatus 120 calculates an estimated value of CSI between second wireless communication apparatus 120 and first wireless communication apparatus 110 at time T (4) based on predicted CSI characteristic 702.
  • the time difference t is a difference between time T (0) and time T (4) (elapsed time from T (0)).
  • the second wireless communication apparatus 120 calculates an estimated value of CSI between the second wireless communication apparatus 120 and the first wireless communication apparatus 110 at time T (4) by calculating a1 * t + a0. Then, second wireless communication apparatus 120 performs scheduling of data to be transmitted to first wireless communication apparatus 110 based on the estimated CSI value at calculated time T (4), and first wireless communication apparatus at time T (4). Data transmission to the communication device 110 is performed.
  • the first wireless communication device 110 May notify the second wireless communication apparatus 120 of this time difference.
  • the second wireless communication apparatus 120 receives the time difference notified from the first wireless communication apparatus 110, the time T (1) when the report from the first wireless communication apparatus 110 is performed, and the time T when data transmission is performed. Based on (4), the time difference t can be calculated.
  • FIG. 8 is a diagram of an example of the first wireless communication apparatus according to the first embodiment.
  • the first wireless communication apparatus 110 includes, for example, a reception antenna 811, an RF reception unit 812, an ADC 813, a demodulation unit 814, a measurement unit 815, and a decoding unit 816. And comprising.
  • the first wireless communication apparatus 110 includes, for example, a control unit 820, an encoding unit 831, a modulation unit 832, a DAC 833, an RF transmission unit 834, and a transmission antenna 835.
  • ADC is an abbreviation for Analog / Digital Converter.
  • the DAC is an abbreviation for Digital / Analog Converter.
  • RF is an abbreviation for Radio Frequency.
  • the receiving antenna 811 receives a signal wirelessly transmitted from another wireless communication device such as the second wireless communication device 120. Then, the receiving antenna 811 outputs the received signal to the RF receiving unit 812.
  • the RF reception unit 812 performs RF reception processing on the signal output from the reception antenna 811.
  • the RF reception processing by the RF receiver 812 includes, for example, amplification and frequency conversion from a high frequency band to a baseband.
  • the RF reception unit 812 outputs the signal subjected to the RF reception process to the ADC 813.
  • the ADC 813 converts the signal output from the RF receiving unit 812 from an analog signal to a digital signal. Then, the ADC 813 outputs the signal converted into the digital signal to the demodulation unit 814.
  • the demodulator 814 demodulates the signal output from the ADC 813. Demodulation section 814 then outputs the demodulated signal to measurement section 815 and decoding section 816.
  • the measuring unit 815 measures the channel state based on the signal output from the demodulating unit 814. For example, the measurement unit 815 measures CSI based on RS (Reference Signal) from the second wireless communication device 120 included in the signal output from the demodulation unit 814. Then, the measurement unit 815 outputs the CSI measurement value to the control unit 820.
  • the decoding unit 816 decodes the signal output from the demodulation unit 814. Then, the decoding unit 816 outputs the signal obtained by the decoding to the control unit 820.
  • the control unit 820 controls the wireless communication by the first wireless communication device 110, for example, by an upper layer of layer 2 or higher. For example, the control unit 820 outputs the data output from the decoding unit 816 to the upper processing unit in the first wireless communication apparatus 110. In addition, the control unit 820 generates the above-described report signal based on the CSI measurement value output from the measurement unit 815.
  • the control unit 820 determines the second wireless communication apparatus based on the CSI measurement value output from the measurement unit 815. Select the CSI reporting method to 120. Then, the control unit 820 generates a control signal indicating the selected reporting method. In addition, the control unit 820 generates a CSI report signal based on the selected reporting method.
  • the control unit 820 uses the CSI selected by the second wireless communication apparatus 120 from the data output from the decoding unit 816. A control signal indicating the reporting method is obtained. Then, the control unit 820 generates a CSI report signal based on the report method indicated by the acquired control signal.
  • control unit 820 outputs a signal to be transmitted to another wireless communication device such as the second wireless communication device 120 to the encoding unit 831.
  • the signal output from the control unit 820 to the encoding unit 831 includes the above-described report signal or control signal generated by the control unit 820, data output from an upper processing unit in the first wireless communication apparatus 110, and the like. .
  • the encoding unit 831 encodes the signal output from the control unit 820. Then, the encoding unit 831 outputs the signal obtained by the encoding to the modulation unit 832.
  • the modulation unit 832 performs modulation based on the signal output from the encoding unit 831. Then, the modulation unit 832 outputs a signal obtained by the modulation to the DAC 833.
  • the DAC 833 converts the signal output from the modulation unit 832 from a digital signal to an analog signal. Then, the DAC 833 outputs the signal converted into the analog signal to the RF transmission unit 834.
  • the RF transmission unit 834 performs RF transmission processing on the signal output from the DAC 833.
  • the RF transmission processing by the RF transmission unit 834 includes, for example, frequency conversion and amplification from the baseband to the high frequency band.
  • the RF transmission unit 834 outputs the signal subjected to the RF transmission process to the transmission antenna 835.
  • the transmission antenna 835 wirelessly transmits the signal output from the RF transmission unit 834 to another wireless communication device such as the second wireless communication device 120.
  • FIG. 9 is a diagram of an example of the second wireless communication apparatus according to the first embodiment.
  • the second wireless communication apparatus 120 includes, for example, a reception antenna 911, an RF reception unit 912, an ADC 913, a demodulation unit 914, and a decoding unit 915.
  • the second wireless communication apparatus 120 includes, for example, a control unit 921, a CSI derivation unit 922, a scheduler 923, an encoding unit 931, a modulation unit 932, a DAC 933, an RF transmission unit 934, and a transmission antenna 935. And comprising.
  • the receiving antenna 911 receives a signal wirelessly transmitted from another wireless communication device such as the first wireless communication device 110. Then, the reception antenna 911 outputs the received signal to the RF reception unit 912.
  • the RF receiver 912 performs RF reception processing on the signal output from the receiving antenna 911.
  • the RF reception processing by the RF receiver 912 includes, for example, amplification and frequency conversion from a high frequency band to a baseband.
  • the RF receiver 912 outputs the signal subjected to the RF reception process to the ADC 913.
  • the ADC 913 converts the signal output from the RF receiver 912 from an analog signal to a digital signal. Then, the ADC 913 outputs the signal converted into the digital signal to the demodulation unit 914.
  • the demodulator 914 demodulates the signal output from the ADC 913. Demodulation section 914 then outputs the demodulated signal to decoding section 915.
  • the decoding unit 915 decodes the signal output from the demodulation unit 914. Then, the decoding unit 915 outputs a signal obtained by the decoding to the control unit 921.
  • the control unit 921 controls the wireless communication by the second wireless communication device 120 by, for example, an upper layer of layer 2 or higher.
  • the control unit 921 outputs the data included in the signal output from the decoding unit 915 to the upper processing unit in the second wireless communication apparatus 120.
  • the control unit 921 uses the CSI selected by the first wireless communication apparatus 110 from the data output from the decoding unit 915. A control signal indicating the reporting method is obtained. And the control part 921 acquires the report signal from the 1st radio
  • the control unit 921 performs CSI by the first wireless communication apparatus 110 included in the data output from the decoding unit 915. Get the measurement result. Further, the control unit 921 selects a CSI reporting method from the first wireless communication apparatus 110 to the second wireless communication apparatus 120 based on the acquired measurement result. Then, the control unit 921 generates a control signal indicating the selected reporting method.
  • control unit 921 outputs a signal to be transmitted to another wireless communication device such as the first wireless communication device 110 to the encoding unit 931.
  • the signal output from the control unit 921 to the encoding unit 931 includes the above-described control signal generated by the control unit 921 and data output from a higher-level processing unit in the second wireless communication apparatus 120.
  • control unit 921 outputs the report signal from the first wireless communication apparatus 110 included in the signal output from the decoding unit 915 to the CSI deriving unit 922. In addition, the control unit 921 notifies the CSI deriving unit 922 of the reporting method selected by the first wireless communication device 110 or the second wireless communication device 120. The control unit 921 controls scheduling in the scheduler 923.
  • the CSI deriving unit 922 uses the CSI measurement value indicated by the report signal output from the control unit 921 to estimate the CSI. The value is output to the scheduler 923.
  • the CSI deriving unit 922 performs the second wireless communication from the first wireless communication device 110 in the future time resource based on the report signal output from the control unit 921. An estimate of the CSI for wireless transmission to device 120 is calculated. Also, the CSI deriving unit 922 may calculate each estimated value of CSI in a plurality of future time resources. Then, the CSI deriving unit 922 outputs the calculated estimated CSI value to the scheduler 923.
  • the scheduler 923 performs data transmission scheduling from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 based on the estimated CSI value output from the CSI deriving section 922 according to the control from the control section 921. Then, the scheduler 923 notifies the encoding unit 931 of the scheduling result.
  • the result of scheduling includes, for example, radio resources used for data transmission from the second radio communication apparatus 120 to the first radio communication apparatus 110, MCS, transmission power, and the like.
  • the radio resource is, for example, a time resource, a frequency resource, or a combination of a time resource and a frequency resource.
  • the encoding unit 931 encodes the signal output from the control unit 921 based on the scheduling result notified from the scheduler 923. Then, the encoding unit 931 outputs a signal obtained by the encoding to the modulation unit 932.
  • the modulation unit 932 performs modulation based on the signal output from the encoding unit 931. Then, the modulation unit 932 outputs a signal obtained by the modulation to the DAC 933.
  • the DAC 933 converts the signal output from the modulation unit 932 from a digital signal to an analog signal. Then, the DAC 933 outputs the signal converted into the analog signal to the RF transmission unit 934.
  • the RF transmission unit 934 performs RF transmission processing on the signal output from the DAC 933.
  • the RF transmission processing by the RF transmission unit 934 includes, for example, frequency conversion from the baseband band to the high frequency band and amplification.
  • the RF transmission unit 934 outputs the signal subjected to the RF transmission process to the transmission antenna 935.
  • the transmission antenna 935 wirelessly transmits the signal output from the RF transmission unit 934 to another wireless communication device such as the first wireless communication device 110.
  • FIG. 10 is a diagram of an example of a hardware configuration of the first wireless communication device and the second wireless communication device according to the first embodiment.
  • each of first radio communication device 110 and second radio communication device 120 can be realized by communication device 1000 shown in FIG. 10, for example.
  • the communication apparatus 1000 includes a processor 1001, a memory 1002, and a wireless communication interface 1003.
  • the processor 1001, the memory 1002, and the wireless communication interface 1003 are connected by, for example, a bus 1009.
  • the processor 1001 is a circuit that performs signal processing, and is, for example, a CPU (Central Processing Unit) that controls the entire communication apparatus 1000.
  • the memory 1002 includes, for example, a main memory and an auxiliary memory.
  • the main memory is, for example, a RAM (Random Access Memory).
  • the main memory is used as a work area for the processor 1001.
  • the auxiliary memory is, for example, a nonvolatile memory such as a magnetic disk, an optical disk, or a flash memory.
  • Various programs for operating the communication device 1000 are stored in the auxiliary memory.
  • the program stored in the auxiliary memory is loaded into the main memory and executed by the processor 1001.
  • processor 1001 and the memory 1002 may be realized by a digital circuit such as an FPGA (Field Programmable Gate Array) or a DSP (Digital Signal Processor).
  • processor 1001 and the memory 1002 may be realized by an LSI (Large Scale Integrated circuit).
  • the wireless communication interface 1003 is a communication interface that performs communication with the outside of the communication device 1000 wirelessly.
  • the wireless communication interface 1003 is controlled by the processor 1001.
  • the demodulation unit 814, the measurement unit 815, the decoding unit 816, the control unit 820, the encoding unit 831, and the modulation unit 832 illustrated in FIG. 8 are realized by the processor 1001, for example.
  • the measurement unit 111 and the transmission unit 113 illustrated in FIG. 1 can be realized, for example, by the processor 1001 controlling the wireless communication interface 1003.
  • the selection unit 112 illustrated in FIG. 1 can be realized by the processor 1001, for example.
  • the demodulation unit 914, the decoding unit 915, the control unit 921, the CSI derivation unit 922, the scheduler 923, the encoding unit 931, and the modulation unit 932 illustrated in FIG. 9 are realized by the processor 1001, for example.
  • the reception unit 121 illustrated in FIG. 1 can be realized by the processor 1001 controlling the wireless communication interface 1003, for example.
  • the control unit 122 illustrated in FIG. 1 can be realized by the processor 1001, for example.
  • the communication apparatus 1000 when the second wireless communication apparatus 120 is a base station and the second wireless communication apparatus 120 is realized by the communication apparatus 1000, the communication apparatus 1000 includes a wired communication interface that performs communication with a host apparatus. May be.
  • the wired communication interface is controlled by the processor 1001.
  • FIG. 11 is a diagram illustrating an example of calculation of the change amount of CSI based on the measured values of CSI for the past two times by the first wireless communication apparatus according to the first embodiment.
  • first wireless communication apparatus 110 measures CSI in each of subframes 601.
  • CSI (-1) is CSI measured by the first wireless communication apparatus 110 at time T (-1).
  • CSI (0) is CSI measured by first radio communication apparatus 110 at time T (0) immediately after time T ( ⁇ 1).
  • the measurement interval T is a time interval between times T ( ⁇ 1) and T (0) when CSI ( ⁇ 1) and CSI (0) are measured.
  • the first wireless communication device 110 transmits the report signal including the measurement value a0 and the change amount a1 to the second wireless communication device 120 at the time T (1) immediately after the time T (0).
  • the a0 and the change amount a1 are reported to the second wireless communication apparatus 120.
  • the predicted CSI characteristic 1121 is CSI in each time interval predicted by the measured value a0 (intercept) and the change amount a1 (slope) that the first wireless communication apparatus 110 reports to the second wireless communication apparatus 120.
  • Second wireless communication apparatus 120 calculates an estimated value of CSI between second wireless communication apparatus 120 and first wireless communication apparatus 110 in a time interval after time T (1) based on predicted CSI characteristic 1121. .
  • the first wireless communication apparatus 110 calculates the change amount a1 by dividing the difference between the measured values of the CSI for the past two times by the difference between the measurement times (measurement interval T), for example. can do.
  • FIG. 12 is a diagram illustrating another example of calculating the change amount of CSI based on the measured values of CSI for the past two times by the first wireless communication apparatus according to the first embodiment.
  • FIG. 12 the same parts as those shown in FIG. In the example illustrated in FIG. 12, a case where the second reporting method for reporting the CSI measurement value and the amount of change is selected as the CSI reporting method will be described.
  • the CSI measurement result 1211 shown in FIG. 12 indicates the CSI by the first radio communication device 110 in each time interval including the time interval after the time T (1) when the first radio communication device 110 reports to the second radio communication device 120. It is a measurement result. As shown in the CSI measurement result 1211, the CSI measurement value after the first wireless communication apparatus 110 reports the measurement value a0 and the change amount a1 is predicted by the predicted CSI characteristic 1121 based on the measurement value a0 and the change amount a1. May be lower than the CSI. In the example illustrated in FIG. 12, the measured value of CSI is lower than the CSI predicted by the predicted CSI characteristic 1121 at time T (4).
  • the value of ⁇ may be a constant value. For example, if the change in CSI is convex upward (while the slope is decreasing), ⁇ is increased or the change in CSI is convex downward (slope If ⁇ is increasing), ⁇ may be decreased. Further, ⁇ may be increased if there is an error in the decoding result of the data received by the first wireless communication apparatus in the past predetermined period.
  • the first wireless communication device 110 transmits the measurement value a0 and the change amount a1 ′ by transmitting a report signal including the measurement value a0 and the change amount a1 ′ to the second wireless communication device 120 at time T (1).
  • the predicted CSI characteristic 1221 is CSI in each time interval predicted by the measured value a0 and the change amount a1 ′ that the first wireless communication apparatus 110 reports to the second wireless communication apparatus 120.
  • the second wireless communication device 120 calculates an estimated CSI value between the second wireless communication device 120 and the first wireless communication device 110 in a time interval after the time T (1) as a predicted CSI characteristic 1221 (a1 ′ * t + a0). ). Thereby, the 2nd radio
  • the configuration in which the first wireless communication apparatus 110 calculates the change amount a1 'has been described the configuration is not limited to such a configuration.
  • FIG. 13 is a diagram illustrating an example of calculation of a change amount of CSI based on measured values of CSI for the past N times by the first wireless communication apparatus according to the first embodiment.
  • the same parts as those shown in FIG. 13 a case where the second reporting method for reporting the CSI measurement value and the amount of change is selected as the CSI reporting method will be described.
  • CSI ( ⁇ 4) is CSI measured by the first wireless communication apparatus 110 at time T ( ⁇ 4).
  • CSI ( ⁇ 3) is CSI measured by first radio communication apparatus 110 at time T ( ⁇ 3) immediately after time T ( ⁇ 4).
  • CSI ( ⁇ 2) is CSI measured by first radio communication apparatus 110 at time T ( ⁇ 2) immediately after time T ( ⁇ 3).
  • CSI ( ⁇ 1) is CSI measured by first radio communication apparatus 110 at time T ( ⁇ 1) immediately after time T ( ⁇ 2).
  • CSI (0) is CSI measured by first radio communication apparatus 110 at time T (0) immediately after time T ( ⁇ 1). That is, CSI ( ⁇ n) is a measurement value n times before the latest measurement value.
  • the measurement interval T is a time interval between times T ( ⁇ 1) and T (0) when CSI ( ⁇ 1) and CSI (0) are measured.
  • the first wireless communication apparatus 110 uses the CSI (0) measured at time T (0) as the measurement value a0 (intercept), as in the example of FIG.
  • the first wireless communication device 110 transmits the report signal including the measurement value a0 and the change amount a1 to the second wireless communication device 120 at the time T (1) immediately after the time T (0).
  • the a0 and the change amount a1 are reported to the second wireless communication apparatus 120.
  • the predicted CSI characteristic 1321 is CSI in each time interval predicted by the measured value a0 and the change amount a1 that the first wireless communication apparatus 110 reports to the second wireless communication apparatus 120.
  • Second wireless communication apparatus 120 calculates an estimated value of CSI between second wireless communication apparatus 120 and first wireless communication apparatus 110 in a time interval after time T (1) based on predicted CSI characteristic 1321. .
  • the first wireless communication apparatus 110 divides the minimum value of the CSI measurement values for the past N times by the difference between the measurement times (measurement interval T), for example. Can be calculated.
  • FIG. 14 is a diagram illustrating another example of calculation of the change amount of CSI based on the measured values of CSI for the past N times by the first wireless communication apparatus according to the first embodiment.
  • FIG. 14 the same parts as those shown in FIG. In the example illustrated in FIG. 12, a case where the second reporting method for reporting the CSI measurement value and the amount of change is selected as the CSI reporting method will be described.
  • the CSI measurement result 1411 shown in FIG. 14 indicates the CSI by the first radio communication device 110 in each time interval including the time interval after the time T (1) when the first radio communication device 110 reports to the second radio communication device 120. It is a measurement result. As shown in the CSI measurement result 1411, the CSI measurement value after the first wireless communication apparatus 110 reports the measurement value a0 and the change amount a1 is predicted by the predicted CSI characteristic 1321 based on the measurement value a0 and the change amount a1. May be lower than the CSI.
  • the first wireless communication device 110 transmits the measurement value a0 and the change amount a1 ′ by transmitting a report signal including the measurement value a0 and the change amount a1 ′ to the second wireless communication device 120 at time T (1).
  • the predicted CSI characteristic 1421 is CSI in each time interval predicted by the measured value a0 and the change amount a1 ′ that the first wireless communication apparatus 110 reports to the second wireless communication apparatus 120.
  • Second radio communication apparatus 120 calculates an estimated value of CSI between second radio communication apparatus 120 and first radio communication apparatus 110 in a time interval after time T (1) based on predicted CSI characteristic 1421. . Thereby, the 2nd radio
  • the configuration in which the first wireless communication apparatus 110 calculates the change amount a1 'has been described the configuration is not limited to such a configuration.
  • the first wireless communication apparatus 110 calculates a difference for each combination of CSI measurement values for the latest N times, not only the difference between measurement values adjacent in measurement time, and measures the lowest value of the calculated difference.
  • the change amount a1 (slope) may be obtained by dividing by the interval T.
  • first radio communication apparatus 110 selects a report method from each method including the first report method and the second report method based on the fluctuation state of the measured value of the channel state. can do.
  • the first reporting method is a method for transmitting a report signal including a measured value (for example, the lowest value) of the channel state to the second wireless communication apparatus 120.
  • the second reporting method is a method of transmitting a report signal including information on channel state measurement values and channel state temporal changes to the second wireless communication apparatus 120.
  • wireless communication apparatus 110 can transmit the control signal which shows the selected method, and the report signal by the selected method.
  • the second wireless communication apparatus 120 receives a report signal from the first wireless communication apparatus 110 based on the method selected by the first wireless communication apparatus 110 based on the control signal received from the first wireless communication apparatus 110. Is possible. In addition, the second wireless communication device 120 can schedule transmission of data to the first wireless communication device 110 based on the received report signal.
  • the measurement result of the channel from the first wireless communication device 110 to the second wireless communication device 120 according to the fluctuation state of the channel state between the first wireless communication device 110 and the second wireless communication device 120 is reported.
  • the error rate in data transmission can be reduced.
  • the first wireless communication apparatus 110 transmits a report signal including a measurement value of the channel state in the own apparatus and information regarding a time change of the channel state in the own apparatus to the second wireless communication. Transmit to device 120. Further, the first wireless communication device 120 uses the channel state measurement value included in the report signal received from the first wireless communication device 110 and the channel state estimation value calculated using the information about the time change. Schedule transmission of data to the communication device.
  • the frequency of reporting measurement values is less than the configuration in which the second radio communication device 120 predicts a change in channel state based on each measurement value of the channel state periodically reported by the first radio communication device 110.
  • the channel state can be predicted with high accuracy.
  • the first wireless communication apparatus 110 includes information indicating any one of a state in which the channel state is deteriorated, a state in which the channel state is constant, and a state in which the channel state is improved as the information regarding the time change of the channel state. It may be transmitted by a report signal.
  • the state where the channel state is deteriorated is, for example, a state where CSI (0) ⁇ CSI ( ⁇ 1), which is the difference between the latest CSI (0) and the previous CSI ( ⁇ 1), is a negative value. It is.
  • the state where the channel state is constant is, for example, a state where CSI (0) ⁇ CSI ( ⁇ 1) which is the difference between the most recent CSI (0) and the previous CSI ( ⁇ 1) is zero.
  • the state in which the channel state is improved is, for example, a state in which CSI (0) ⁇ CSI ( ⁇ 1), which is the difference between the most recent CSI (0) and the previous CSI ( ⁇ 1), is a positive value. It is.
  • the first wireless communication apparatus 110 reports the measured value of the channel state and information indicating that the channel state is in a fixed state or an improved state to the second wireless communication apparatus 120.
  • the second wireless communication apparatus 120 schedules data transmission to the first wireless communication apparatus 110 based on the channel state measurement value reported from the first wireless communication apparatus 110.
  • the first wireless communication apparatus 110 reports the measured value of the channel state and information indicating that the channel state is deteriorated to the second wireless communication apparatus 120.
  • the second wireless communication device 120 calculates a channel state that is deteriorated by a predetermined amount from the measured value of the channel state reported from the first wireless communication device 110, and performs the first wireless communication based on the calculated channel state. Schedule transmission of data to the device 110.
  • the second wireless communication apparatus 120 can perform scheduling of data transmission to the first wireless communication apparatus 110 by predicting deterioration of the channel state. For this reason, it can suppress that the communication quality of the data transmission from the 2nd radio
  • the first wireless communication apparatus 110 may report information indicating whether or not the channel state is deteriorated to the second wireless communication apparatus 120 by a report signal as information regarding the time change of the channel state.
  • first wireless communication apparatus 110 reports a measured value of the channel state and information indicating that the channel state has not deteriorated to second wireless communication apparatus 120.
  • the second wireless communication apparatus 120 schedules data transmission to the first wireless communication apparatus 110 based on the channel state measurement value reported from the first wireless communication apparatus 110.
  • the first wireless communication apparatus 110 reports the measured value of the channel state and information indicating that the channel state is deteriorated to the second wireless communication apparatus 120.
  • the second wireless communication device 120 calculates a channel state that is deteriorated by a predetermined amount from the measured value of the channel state reported from the first wireless communication device 110, and performs the first wireless communication based on the calculated channel state. Schedule transmission of data to the device 110.
  • the second wireless communication apparatus 120 can perform scheduling of data transmission to the first wireless communication apparatus 110 by predicting deterioration of the channel state. For this reason, it can suppress that the communication quality of the data transmission from the 2nd radio
  • the information regarding the time change of the channel state reported by the report signal may be a channel state measurement obtained by a measurement prior to the latest measurement of the channel state reported by the report signal. . That is, the first wireless communication apparatus 110 transmits a report signal including the latest measurement value of the channel state and the measurement value of the channel state obtained by the measurement before the measurement value to the second wireless communication apparatus 120. You may send it.
  • the second wireless communication device 120 predicts a change in the channel state based on the latest measurement value and the past measurement value of the channel state, and the first wireless communication device based on the predicted change in the channel state.
  • the data transmission to 110 is scheduled.
  • the second wireless communication device 120 when the latest measured value is not worse than the past measured value, the second wireless communication device 120 performs scheduling based on the reported latest measured value. In addition, when the latest measured value is worse than the past measured value, the second wireless communication apparatus 120 calculates a channel state that is deteriorated by a predetermined amount from the reported latest measured value, and calculates the calculated channel state. Scheduling based on Second radio communication apparatus 120 estimates the slope of the channel state change from the latest measurement value and the channel state measurement value obtained by the measurement prior to the measurement value, and uses the channel for scheduling The state may be calculated.
  • the information related to the time change of the channel state reported by the report signal may be information that allows the second wireless communication apparatus 120 to identify the CSI change amount.
  • TDD is an abbreviation for Time Division Duplex.
  • the first wireless communication device 110 uses the report signal to indicate the amount of interference (may include noise) in the first wireless communication device 110 and the amount of change in the amount of interference in the first wireless communication device 110 as the second. You may report to the wireless communication apparatus 120.
  • Second radio communication apparatus 120 measures the signal power of the reference signal transmitted from first radio communication apparatus 110. Then, the second wireless communication device 120 performs SINR (signal-to-interference) in data transmission to the first wireless communication device 110 based on the measured value of the signal power and the amount of interference reported from the first wireless communication device 110. And noise power ratio) can be calculated.
  • SINR signal-to-interference
  • the second wireless communication device 120 transmits the first wireless signal from the second wireless communication device 120 based on the amount of change in the measured value of the signal power and the amount of change in the interference amount reported from the first wireless communication device 110.
  • the amount of change in SINR in data transmission to the communication device 110 can be calculated.
  • the information related to the time change of the channel state reported by the report signal may be information indicating the moving speed of the first wireless communication apparatus 110.
  • the channel state CSI, for example, CQI
  • the first wireless communication device 110 transmits a report signal including a CSI measurement value and information indicating the moving speed of the first wireless communication device 110 to the second wireless communication device 120.
  • the second wireless communication apparatus 120 performs scheduling based on the latest measured value reported. Do.
  • the second wireless communication apparatus 120 calculates a channel state that is deteriorated by a predetermined amount from the latest reported measurement value. Then, scheduling is performed based on the calculated channel state.
  • the first wireless communication apparatus 110 receives a report signal including the CSI measurement value and information indicating whether or not the moving speed of the first wireless communication apparatus 110 exceeds a predetermined speed. May be sent to.
  • the predetermined speed is a speed of 0 or more. For example, when the predetermined speed is 0, the information indicating whether or not the moving speed of the first wireless communication device 110 exceeds the predetermined speed is information indicating whether or not the first wireless communication device 110 is moving. .
  • the second wireless communication device 120 performs scheduling based on the latest reported measurement value. I do.
  • the second wireless communication device 120 changes the channel state that is deteriorated by a predetermined amount from the reported latest measured value. The scheduling is performed based on the calculated channel state.
  • FIG. 15 is a diagram of an example of a channel state report by the first wireless communication apparatus according to the second embodiment.
  • the same parts as those shown in FIG. In the example illustrated in FIG. 15, a case will be described in which the first reporting method for reporting the lowest CSI measurement value is selected as the CSI reporting method.
  • the first wireless communication apparatus 110 obtains the minimum value of the measured CSI values for a predetermined period (the last five subframes) at time T (1), which is a periodic report timing. Report to second radio communication apparatus 120. For example, first radio communication apparatus 110 reports CSI ( ⁇ 4) measured at time T ( ⁇ 4) to second radio communication apparatus 120.
  • time T (6) which is the next periodic report timing after time T (1)
  • the lowest CSI measurement value in a predetermined period (the previous five subframes) is reported to second radio communication apparatus 120.
  • the first wireless communication device 110 reports the CSI (3) measured at time T (3) to the second wireless communication device 120.
  • the first wireless communication device 110 reduces the measured CSI to a second wireless communication device when the measured CSI decreases (becomes worse) than the previously reported CSI (3) even at a time other than the periodic report timing. Report to 120.
  • the CSI (8) measured at the time T (8) is lower than the CSI (3) reported immediately before. For this reason, an aperiodic report for reporting CSI (8) to the second wireless communication apparatus 120 is performed at time T (9) immediately after time T (8).
  • the first wireless communication device 110 reports the latest CSI measurement value to the second wireless communication device 120 when the CSI measurement value is worse than the reported measurement value (minimum value). Thereby, even if the measured value of CSI is further deteriorated from the reported measured value (minimum value), the communication quality of data transmission from the second wireless communication device 120 to the first wireless communication device 110 is lower than the reference value. Can be suppressed.
  • the first wireless communication apparatus 110 may predict a future CSI based on a past CSI measurement value. Then, the first wireless communication device 110 reports the latest CSI measurement value to the second wireless communication device 120 when the predicted CSI is worse than the reported measurement value (minimum value). For example, if the first wireless communication apparatus 110 predicts that CSI (8) at time T (8) is worse than reported CSI (3) at time T (7), CSI (8) at time (8). ) To the second wireless communication apparatus 120. Thereby, even if the measured value of CSI is further deteriorated from the reported measured value (minimum value), the communication quality of data transmission from the second wireless communication device 120 to the first wireless communication device 110 is lower than the reference value. Can be suppressed.
  • FIG. 16 is a diagram illustrating another example of the channel state report by the first wireless communication apparatus according to the second embodiment.
  • the same parts as those shown in FIG. In the example illustrated in FIG. 16, a case where the second reporting method for reporting the CSI measurement value and the amount of change is selected as the CSI reporting method will be described.
  • CSI (-1) is CSI measured by the first wireless communication apparatus 110 at time T (-1).
  • CSI (0) is CSI measured by first radio communication apparatus 110 at time T (0).
  • CSI (3) is CSI measured by first radio communication apparatus 110 at time T (3).
  • CSI (4) is CSI measured by first radio communication apparatus 110 at time T (4).
  • Time T (1) immediately after time T (0) is a periodic CSI reporting timing by the first wireless communication apparatus 110.
  • First wireless communication device 110 reports measurement value a0 and change amount a1 based on CSI ( ⁇ 1) and CSI (0) to second wireless communication device 120 at time T (1) (periodic report).
  • the first wireless communication apparatus 110 obtains the change amount a1 by subtracting the margin ⁇ from the slope a1 obtained by dividing the difference between CSI ( ⁇ 1) and CSI (0) by the time interval T. It is assumed that the inclination a1 ′ is reported to the second wireless communication apparatus 120.
  • the first wireless communication device 110 reports the measured value a0 and the change amount a1 reported to the second wireless communication device 120 at time T (1), the measured value of CSI in its own device, and Compare the amount of change. Then, when the amount of change based on the measured value of CSI in the own device is lower (deteriorated) than the amount of change a1 reported to the second wireless communication device 120, the first wireless communication device 110 obtains the latest measured value and amount of change. Report to second radio communication apparatus 120.
  • the CSI measurement result 1611 shown in FIG. 16 is a CSI measurement result by the first wireless communication apparatus 110 in each time interval including a time interval after the time T (1).
  • the slope b1 obtained by dividing the difference between CSI (3) and CSI (4) by the time interval T is lower (becomes worse) than the slope a1 ′ reported to the second wireless communication device 120. (B1 ⁇ a1 ′).
  • b0 CSI (4) as the measured value of CSI at time T (5) immediately after time T (4)
  • the change amount b1 as the change amount of CSI.
  • Time T (5) is a non-periodic timing different from the periodic CSI reporting timing by the first wireless communication apparatus 110.
  • the first wireless communication device 110 reports the latest CSI measurement value b0 and change amount b1 'to the second wireless communication device 120 when the change amount of CSI is worse than the reported change amount. Therefore, even if the change amount of CSI is worse than the reported change amount, it is possible to suppress the communication quality of data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 from being lower than the reference value. it can.
  • FIG. 17 is a flowchart of an example of data reception processing by the first wireless communication apparatus according to the second embodiment.
  • the first wireless communication apparatus 110 according to the second embodiment executes, for example, each step illustrated in FIG. Steps S1701 to S1704 shown in FIG. 17 are the same as steps S401 to S404 shown in FIG.
  • the first wireless communication apparatus 110 determines whether or not the selected CSI reporting method is the first reporting method (step S1705).
  • the reporting method is the first reporting method (step S1705: Yes)
  • the first wireless communication device 110 has the latest measured value of CSI worsened from the CSI that has been reported to the second wireless communication device 120 in the past. It is determined whether or not (step S1706). For example, in the first wireless communication device 110, the difference between the latest measured value of CSI and the CSI that has been reported to the second wireless communication device 120 in the past (the latest measured value ⁇ the reported CSI) is equal to or less than a predetermined value. It is determined whether or not.
  • step S1706 when it has not deteriorated (step S1706: No), the first wireless communication apparatus 110 proceeds to step S1710.
  • step S1706: Yes the 1st radio
  • step S1705 when the reporting method is the second reporting method (step S1705: No), the first wireless communication apparatus 110 proceeds to step S1708. That is, first radio communication apparatus 110 determines whether or not the change amount of CSI based on the latest measurement value of CSI is worse than the change quantity of CSI that has been reported to second radio communication apparatus 120 in the past. (Step S1708).
  • step S1708 when it has not deteriorated (step S1708: No), the first wireless communication apparatus 110 proceeds to step S1710.
  • step S1708: Yes the first wireless communication apparatus 110 outputs a second report signal indicating the latest measured value of CSI and the amount of change in CSI based on the latest measured value of CSI. It transmits to the wireless communication apparatus 120 (step S1709). Then, the first wireless communication apparatus 110 moves to step S1710.
  • Steps S1710 and S1711 shown in FIG. 17 are the same as steps S405 and S406 shown in FIG.
  • the first wireless communication apparatus 110 when using the first reporting method, adds the CSI measurement value to the periodic report timing, and the latest CSI measurement value has already been reported. You may report to the 2nd radio
  • the first wireless communication apparatus 110 when using the second reporting method, adds the CSI measurement value and change amount to the periodic report timing, and the latest CSI change amount has been reported. You may report to the 2nd radio
  • the first wireless communication device 110 uses the second reporting method, the first wireless communication device 110 does not report the measurement value and the change amount to the second wireless communication device 120 once, but does not report at a periodic report timing. The latest change amount may be reported at a timing worse than the reported change amount.
  • the report by the first radio communication apparatus 110 when using the first report method and the second report method has been described, the report by the first radio communication apparatus 110 when using the third report method is, for example, the first report method. This is the same as the report by the first wireless communication apparatus 110 when used.
  • FIG. 18 is a flowchart of an example of data transmission processing by the second wireless communication apparatus according to the second embodiment.
  • the second wireless communication apparatus 120 according to the second embodiment executes, for example, each step illustrated in FIG. Steps S1801 to S1804 shown in FIG. 18 are the same as steps S501 to S504 shown in FIG.
  • step S1803 or step S1804 the second wireless communication apparatus 120 proceeds to step S1805. That is, the second radio communication device 120, when a report signal indicating the latest measured value of CSI and the change amount of CSI is transmitted from the first radio communication device 110 at a non-periodic timing, Is received (step S1805).
  • This report signal is, for example, the report signal transmitted in step S1704 shown in FIG.
  • Step S1806 to S1810 shown in FIG. 18 are the same as steps S505 to S509 shown in FIG. However, in step S1806, the second wireless communication apparatus 120 calculates CSI in a future time resource using the channel state measurement value and the channel state change amount included in the latest report signal among the received report signals. To do.
  • the second wireless communication apparatus 120 when using the first reporting method, adds a report signal indicating a measured value (minimum value) of CSI, for example, to the periodic report timing, in a non-periodic manner. You may receive from the 1st radio
  • the second wireless communication apparatus 120 transmits, for example, a report signal indicating a CSI measurement value and a change amount to the first wireless communication at a non-periodic timing in addition to the periodic reporting timing. You may receive from the apparatus 110.
  • the first wireless communication apparatus 110 uses the latest measured value of CSI and the minimum value of CSI included in the transmitted report signal. Can be compared. And the 1st radio
  • wireless communication apparatus 110 can transmit the newest report signal at the timing different from a periodic timing according to the result of the comparison. For example, the first wireless communication apparatus 110 has the latest measurement value of CSI lower than the minimum value of CSI included in the transmitted report signal, or lower than the minimum value of CSI included in the transmitted report signal. If it is predicted, the latest report signal is transmitted.
  • the communication quality of data transmission from the second wireless communication device 120 to the first wireless communication device 110 becomes the reference value. It is possible to suppress lowering.
  • the first wireless communication device 110 is updated when the rate of temporal change in the channel state measurement value is worse than the rate reported to the second wireless communication device 120. May be transmitted to the second wireless communication apparatus 120. Thereby, it is possible to report when the rate of change in channel state is worse than the rate of change already reported. For this reason, even if the frequency of reports from the first wireless communication apparatus 110 to the second wireless communication apparatus 120 is low, the communication quality of data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 has the reference value. It is possible to suppress lowering.
  • Embodiment 3 The third embodiment will be described with respect to differences from the first and second embodiments.
  • a configuration in which first radio communication apparatus 110 transmits a report signal to second radio communication apparatus 120 at a non-periodic timing will be described.
  • FIG. 19 is a diagram of an example of a channel state report by the first wireless communication apparatus according to the third embodiment.
  • parts that are the same as the parts shown in FIG. 7 are given the same reference numerals, and descriptions thereof will be omitted.
  • the second reporting method for reporting the CSI measurement value and the amount of change is selected as the CSI reporting method.
  • the first wireless communication apparatus 110 at time T (1) immediately after time T (0), has a CSI measurement value a0 at time T (0) and before time T (0).
  • the CSI change amount a1 based on the CSI measurement value is reported to the second wireless communication apparatus 120.
  • the predicted CSI characteristic 1911 indicates that the CSI in each time interval predicted by the measured value a0 (intercept) and the change amount a1 (slope) reported by the first wireless communication apparatus 110 to the second wireless communication apparatus 120 at time T (1). It is.
  • the first wireless communication apparatus 110 determines whether or not the measured CSI value after the time T (1) when the measured value a0 and the change amount a1 are reported is worse than the CSI predicted by the predicted CSI characteristic 1911. Then, when the measured value of CSI is worse than the CSI predicted by the predicted CSI characteristic 1911, the first wireless communication device 110 reports the latest measured value a0 and the change amount a1 to the second wireless communication device 120.
  • the CSI measurement result 1921 shown in FIG. 19 is a CSI measurement result by the first wireless communication apparatus 110 in each time interval including a time interval after the time T (1).
  • the CSI measured by the first wireless communication apparatus 110 at time T (4) is lower than the estimated value of CSI at time T (4) based on the predicted CSI characteristic 1911.
  • first wireless communication apparatus 110 reports CSI measured at time T (4) as measurement value a0 at time T (5) immediately after time T (4).
  • the first wireless communication device 110 reports, to the second wireless communication device 120, a change amount based on CSI measured at the latest time including the time T (4) as the change amount a1 at the time T (5). .
  • the first wireless communication apparatus 110 determines that the latest CSI measurement value a0 when the CSI measurement value is worse than the CSI predicted based on the reported measurement value a0 and the change amount a1.
  • the change amount a1 is reported to the second wireless communication apparatus 120. Thereby, even if the measured value of CSI is worse than the predicted CSI based on the reported measured value a0 and the change amount a1, communication of data transmission from the second wireless communication device 120 to the first wireless communication device 110 is performed. It can suppress that quality falls below a standard value.
  • FIG. 20 is a flowchart of an example of data reception processing by the first wireless communication apparatus according to the third embodiment.
  • the first wireless communication apparatus 110 according to the third embodiment executes the steps shown in FIG. 20, for example. Steps S2001 to S2011 shown in FIG. 20 are the same as the steps shown in steps S1701 to S1711 shown in FIG.
  • step S2008 the first wireless communication apparatus 110 determines that the latest measured value of CSI is worse than the estimated value based on the measured value and change amount of CSI that has been reported to the second wireless communication apparatus 120 in the past. Judge whether or not.
  • the first wireless communication apparatus 110 when using the second reporting method, adds the CSI measurement value and the amount of change to the periodic report timing, and the latest CSI measurement value is You may report at the timing worsened from the estimated value based on the reported information.
  • the first wireless communication device 110 after reporting the measured value and change amount of CSI once to the second wireless communication device 120, the first wireless communication device 110 does not report at the periodic reporting timing, and the latest measured value of CSI is You may report at the timing worsened from the estimated value based on the reported information.
  • the process by the second wireless communication apparatus 120 according to the third embodiment is the same as, for example, each step shown in FIG.
  • the first wireless communication device 110 may predict that the CSI measurement value is worse than the CSI predicted based on the reported measurement value a0 and the change amount a1. For example, when the first wireless communication device 110 reports the measurement value a0 and the change amount a1 to the second wireless communication device 120, the estimated value of CSI based on the reported measurement value a0 and change amount a1 and the measurement of CSI by the own device. The difference from the value is calculated periodically (for example, every subframe).
  • the latest CSI measurement value a0 and the change amount a1 are set to the second radio. It is possible to report to the communication device 120.
  • the difference (measured value of CSI) ⁇ (estimated value of CSI) increases when the time T (0) is shifted to time T (1).
  • the difference (measured value of CSI) ⁇ (estimated value of CSI) increases.
  • the first wireless communication apparatus 110 predicts that the measured value of CSI is worse than the CSI predicted based on the reported measured value a0 and the change amount a1 at time T (3), and the latest CSI The measured value a0 and the change amount a1 are reported to the second wireless communication apparatus 120.
  • the change amount a1 can be reported to the second wireless communication apparatus 120. For this reason, it can suppress that the communication quality of the data transmission from the 2nd radio
  • the first wireless communication apparatus 110 calculates the difference between the measured CSI value and the estimated CSI value calculated using the measured CSI value and the amount of change included in the transmitted report signal. .
  • wireless communication apparatus 110 can estimate that the measured value of CSI deteriorates from the estimated value of CSI based on the temporal variation
  • the channel state measurement value at a certain time is calculated using the CSI measurement value and the change amount included in the transmitted report signal. If it becomes worse than the value, the latest report signal can be transmitted. Thereby, it is possible to report when the measured value of the channel state is worse than the channel state predicted from the reported information. For this reason, even if the frequency of reports from the first wireless communication apparatus 110 to the second wireless communication apparatus 120 is low, the communication quality of data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 has the reference value. It is possible to suppress lowering.
  • the first wireless communication apparatus 110 calculates the difference between the measured value of the channel state and the estimated value of the channel state calculated using the measured value and change amount of the CSI included in the transmitted report signal.
  • the prediction can be performed based on the calculated change amount of the difference. Thereby, it can report before the measured value of a channel state deteriorates from the channel state estimated from reported information. For this reason, even if the frequency of reports from the first wireless communication apparatus 110 to the second wireless communication apparatus 120 is low, the communication quality of data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 has the reference value. It is possible to suppress lowering.
  • the first wireless communication device 110 may calculate the error rate based on a response signal (ACK / NACK) generated based on the decoding result of the data received from the second wireless communication device 120. Then, the first wireless communication device 110 may transmit a report signal based on the latest measured CSI value to the second wireless communication device 120 when the calculated error rate exceeds the reference value.
  • ACK / NACK response signal
  • first wireless communication apparatus 110 transmits information on the time change of the channel state to the second wireless communication apparatus 120 in addition to the measurement value of the channel state and the information on the time change of the channel state.
  • the configuration to be reported will be described.
  • FIG. 21 is a diagram of an example of calculation of the change amount of the CSI change amount by the first wireless communication apparatus according to the fourth embodiment.
  • the same parts as those shown in FIG. 21 a case where the second reporting method for reporting the CSI measurement value and the change amount is selected as the CSI reporting method will be described.
  • CSI ( ⁇ 2) is CSI measured by the first wireless communication apparatus 110 at time T ( ⁇ 2).
  • CSI ( ⁇ 1) is CSI measured by first radio communication apparatus 110 at time T ( ⁇ 1).
  • CSI (0) is CSI measured by first radio communication apparatus 110 at time T (0).
  • the estimated value CSI (t) of the CSI at a future time t can be approximated by the following equation (1), for example.
  • the first wireless communication device 110 solves the following simultaneous equation (2), for example.
  • the first wireless communication apparatus 110 obtains the intercept a0, the first-order coefficient a1 (slope or change amount) and the second-order coefficient a2 (slope of inclination or change amount of change) shown in the following equation (3). Obtainable.
  • the first radio communication apparatus 110 reports the obtained intercept a0, the first-order coefficient a1, and the second-order coefficient a2 to the second radio communication apparatus 120 at time T (1) immediately after time T (0). .
  • the second wireless communication apparatus 120 uses the intercepts a0 and 1 reported from the first wireless communication apparatus 110 to estimate the CSI between the second wireless communication apparatus 120 and the first wireless communication apparatus 110 at a future time t. It calculates based on the following coefficient a1 and secondary coefficient a2, and said (1) Formula.
  • the approximate curve 2111 is CSI in each time interval predicted by the intercept a0, the first-order coefficient a1, the second-order coefficient a2, and the above equation (1).
  • the second wireless communication apparatus 120 calculates an estimated value of CSI between the second wireless communication apparatus 120 and the first wireless communication apparatus 110 at time t based on the approximate curve 2111.
  • the measured value of CSI by the first wireless communication device 110 may be worse than the CSI predicted by the approximate curve 2111.
  • the first wireless communication apparatus 110 may report to the second wireless communication apparatus 120 by including a margin in at least one of the primary coefficient a1 and the secondary coefficient a2.
  • the second wireless communication device 120 may determine that the first-order coefficient a1 ′ and the second-order coefficient a2 ′ are based on the intercept a0, the first-order coefficient a1, and the second-order coefficient a2 reported from the first wireless communication apparatus 110. May be calculated.
  • first radio communication apparatus 110 includes a channel state measurement value, information on a channel state time change, and information on a channel state time change time change.
  • a report signal is transmitted to the second wireless communication apparatus 120.
  • the second-order coefficient a2 has been described in the above example, but it is not limited to such a configuration.
  • the information regarding the time change of the channel state time change is information indicating whether or not a value indicating the time change of the channel state (for example, the first-order coefficient a1) is temporally changing (for example, worsening). Also good.
  • the second wireless communication device 120 reports the latest measured value and change. Scheduling is performed based on the channel state calculated from the quantity.
  • the second wireless communication device 120 reports the latest measured value and change. A channel state that is deteriorated by a predetermined amount from the channel state calculated from the amount is calculated. Then, the second wireless communication device 120 performs scheduling based on the calculated channel state.
  • the channel state is badly estimated and scheduling is performed, and the communication quality of data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 is the reference value. Can be suppressed.
  • FIG. 22 is a diagram of an example of channel state estimation performed by each wireless communication device according to the fifth embodiment.
  • the same parts as those shown in FIG. for example, as shown at time T (3) in FIG. 22, the channel state 2201 calculated from the reported measurement value and the amount of change is more than the lowest value 2202 of the actual channel state value. It can be quite bad.
  • the report signal transmitted by the first wireless communication apparatus 110 may include the minimum value 2203 of the channel state within a predetermined period in the past. For example, the lowest value 2203 measured at time T ( ⁇ 6) is included in the report signal at time T ( ⁇ 3). Then, when the calculated channel state 2201 becomes worse than the above-mentioned minimum value 2203, the second radio communication apparatus 120 may perform scheduling by replacing the calculated channel state 2201 with the above-described minimum value 2203. .
  • FIG. 23 is a diagram illustrating an example of a channel state report by the first wireless communication apparatus according to the sixth embodiment.
  • the same parts as those shown in FIG. 23 a case will be described in which the third reporting method for reporting CSI measurement values is selected as the CSI reporting method.
  • CSI (1) at time T (1) is higher (better) than CSI (0) at time T (0) immediately before. For this reason, the first wireless communication apparatus 110 reports the CSI (1) of the immediately preceding time T (1) to the second wireless communication apparatus 120 at the time T (2).
  • CSI (6) at time T (6) is lower (bad) than CSI (5) at time T (5) immediately before.
  • the first wireless communication apparatus 110 subtracts CSI (6) ⁇ obtained by subtracting the CSI (6) of the immediately preceding time T (6) by a predetermined margin ⁇ ( ⁇ > 0) at time T (7). Report to second radio communication apparatus 120.
  • CSI (6) ⁇ estimated in a worsening direction than CSI (6) can be reported to second radio communication apparatus 120.
  • the CSI (11) at the time T (11) is lower (bad) than the CSI (10) at the previous time T (10). Therefore, the first wireless communication apparatus 110 subtracts CSI (11) ⁇ obtained by subtracting the CSI (11) of the immediately preceding time T (11) by a predetermined margin ⁇ ( ⁇ > 0) at time T (12). Report to second radio communication apparatus 120. As a result, CSI (11) ⁇ estimated in a worsening direction than CSI (11) can be reported to second radio communication apparatus 120.
  • FIG. 24 is a flowchart of an example of data reception processing by the first wireless communication apparatus according to the sixth embodiment.
  • there are three reporting methods first reporting method, second reporting method, and second reporting method
  • the first wireless communication apparatus 110 executes, for example, each step shown in FIG. 24 as the data reception process.
  • Steps S2401 to S2403 shown in FIG. 24 are the same as steps S401 to S403 shown in FIG. After step S2403, the first wireless communication apparatus 110 proceeds to step S2409. In step S2402, when the reporting method is not the first reporting method (step S2402: No), the first wireless communication apparatus 110 determines whether or not the selected CSI reporting method is the second reporting method ( Step S2404).
  • step S2404 when the reporting method is the second reporting method (step S2404: Yes), the first wireless communication apparatus 110 proceeds to step S2405.
  • Step S2405 is the same as step S404 shown in FIG. Following step S2405, the first wireless communication apparatus 110 proceeds to step S2409.
  • step S2404 when the reporting method is the third reporting method (step S2404: No), first radio communication apparatus 110 determines whether or not CSI is decreasing (step S2406). For example, the first wireless communication apparatus 110 determines whether or not the difference between the latest CSI measurement value and the CSI measurement value immediately before the latest CSI is equal to or less than a predetermined value.
  • step S2406 when the CSI is decreasing (step S2406: Yes), the first wireless communication apparatus 110 proceeds to step S2407. That is, the first radio communication apparatus 110 transmits a report signal indicating the CSI measurement value ⁇ obtained by subtracting the latest CSI measurement value by a predetermined margin ⁇ ( ⁇ > 0) to the second radio communication apparatus 120 ( Step S2407) and the process proceeds to Step S2409. If CSI is not decreasing (step S2406: No), first wireless communication apparatus 110 transmits a report signal indicating the latest measured value of CSI to second wireless communication apparatus 120 (step S2408), and proceeds to step S2409. Transition.
  • Steps S2409 and S2410 shown in FIG. 24 are the same as steps S405 and S406 shown in FIG.
  • first wireless communication apparatus 110 subtracts the latest measured value of CSI by a predetermined margin ⁇ ′ ( ⁇ ′> 0) ⁇
  • a report signal indicating ⁇ ′ may be transmitted to the second wireless communication apparatus 120.
  • the margin ⁇ ′ in this case is a margin smaller than the margin ⁇ in step S2407.
  • FIG. 25 is a flowchart of another example of the data reception process performed by the first wireless communication apparatus according to the sixth embodiment.
  • there are three reporting methods (first reporting method, second reporting method, and second reporting method) according to the CSI fluctuation speed in three stages (“high speed”, “medium speed”, and “low speed”). The case where any one of (3 reporting methods) is selected will be described.
  • the first wireless communication apparatus 110 executes, for example, each step shown in FIG. 25 as the data reception process.
  • Steps S2501 to S2505 shown in FIG. 25 are the same as steps S2401 to S2405 shown in FIG. However, the first wireless communication apparatus 110 proceeds to step S2508 after steps S2503 and S2505.
  • Step S2507 the first radio communication apparatus 110 transmits a report signal indicating the CSI measurement value ⁇ obtained by subtracting the latest CSI measurement value by the margin ⁇ calculated in step S2506 to the second radio communication apparatus 120 ( Step S2507) and the process proceeds to Step S2508.
  • Steps S2508 and S2509 shown in FIG. 25 are the same as steps S405 and S406 shown in FIG.
  • the first wireless communication device 110 reports the CSI obtained by subtracting the CSI measurement value to the second wireless communication device 120 in accordance with the state of decrease in the CSI measurement value.
  • wireless communication apparatus 120 can perform scheduling supposing that CSI worsens. For this reason, even if the CSI in each time interval after time T (1) becomes, for example, the CSI measurement result 1211, the communication quality of data transmission from the second wireless communication device 120 to the first wireless communication device 110 is the reference. It can suppress falling below a value.
  • the first wireless communication apparatus 110 when the third reporting method is used, the first wireless communication apparatus 110 includes the CSI measurement value corrected in the deterioration direction according to the change state of the CSI measurement value.
  • a report signal can be transmitted. For example, when the CSI measurement value is decreasing (deteriorating), the first wireless communication apparatus 110 transmits a report signal including the CSI measurement value that is lower than the actual CSI measurement value (for example, FIG. 24). Moreover, when the measured value of CSI is not decreasing, the first wireless communication apparatus 110 transmits a report signal including the actual measured value of CSI (see, for example, FIG. 24). Alternatively, the first wireless communication apparatus 110 transmits a report signal including a CSI measurement value that is lower than the actual CSI measurement value in accordance with the degree of decrease in the CSI measurement value (see, for example, FIG. 25).
  • the third reporting method is used, so that the future CSI is not predicted based on the CSI measurement value and the information on the time change of the CSI, and the processing amount in the second radio communication apparatus 120 Can be reduced. Further, the communication quality of data transmission from the second wireless communication apparatus 120 to the first wireless communication apparatus 110 is corrected to the reference value by correcting the CSI measurement value to be reported in a worsening direction according to the change state of the CSI measurement value. Can be suppressed.
  • FIG. 26 is a diagram illustrating an example of a channel state report by the first wireless communication apparatus according to the seventh embodiment.
  • the same parts as those shown in FIG. In the example illustrated in FIG. 26, a case will be described in which the first reporting method for reporting the lowest CSI measurement value is selected as the CSI reporting method.
  • time T (6) is a periodic report timing.
  • the first wireless communication apparatus 110 from the time T (6) to the next of the time T (6), based on the measured value of CSI in a predetermined period (previous 5 subframes) immediately before the time T (6).
  • the minimum value of the measured value of CSI in the period up to the periodic reporting timing is predicted.
  • a periodic report timing next to time T (6) is set as time T (11).
  • the first wireless communication apparatus 110 performs a period from time T (6) to time T (11) based on CSI (1) to CSI (5) at time T (1) to T (5).
  • the lowest CSI measurement value at 2601 is predicted.
  • the first wireless communication device 110 transmits the report signal including the lowest predicted CSI measurement value to the second wireless communication device 120 at the time T (6), so that the predicted CSI measurement value is The lowest value is reported (predicted report) to the second wireless communication apparatus 120.
  • the first wireless communication apparatus 110 can predict the minimum value of the CSI measurement value in the period 2601 by Nth-order interpolation (for example, fourth-order interpolation).
  • the first wireless communication apparatus 110 can calculate a 4 , a 3 , a 2 , a 1 , and a 0 by solving the generated five equations as simultaneous equations.
  • various methods such as a least square method can be used.
  • the first wireless communication apparatus 110 uses the equation obtained by substituting the calculated a 4 , a 3 , a 2 , a 1 , and a 0 into the above equation (2), thereby obtaining an equation with x and y as variables. Obtainable. And the 1st radio
  • wireless communication apparatus 110 can obtain the predicted value y of CSI in the future time by substituting the future time for x of the obtained formula.
  • the first wireless communication apparatus 110 substitutes the times T (6) to T (13) included in the period 2601 into the equations, respectively, so that CSI (6) to T (13) at the times T (6) to T (13) A predicted value of CSI (13) can be obtained. Then, the first wireless communication apparatus 110 can predict the minimum value of the CSI measurement value in the period 2601 by specifying the minimum value of the obtained CSI prediction value.
  • Nth order interpolation based on CSI measurement values of the past N + 1 subframes is used. be able to. N is 1 or N is an integer of 2 or more. In general, when using the measured values of the past N + 1 subframes, it is possible to perform prediction using an equation of the Nth order or less using the least square method.
  • the first wireless communication apparatus 110 may approximate the time change of the past CSI measurement value by a combination of a plurality of sine waves and predict a future CSI measurement value by the combination of the approximate sine waves.
  • the first wireless communication apparatus 110 includes a plurality of sine waves whose sum of a plurality of sine waves is closest to a time change of CSI based on times T (1) to T (5) and CSI (1) to CSI (5). Calculate each characteristic of the wave.
  • the characteristics of the sine wave include, for example, amplitude, phase, and frequency.
  • the first wireless communication apparatus 110 approximates the time change of the past CSI measurement value by the following equation (5), and for each sine wave, the amplitude (A n ), frequency (f n ), and phase ( By estimating ⁇ n ), future CSI measurements can be predicted.
  • t represents time
  • c (t) represents the channel state (CSI) at time (t).
  • FIG. 27 is a flowchart of an example of data reception processing by the first wireless communication apparatus according to the seventh embodiment.
  • the reporting method selection process shown in FIG. 2 or 3 performs two reporting methods (first reporting method and first reporting method) according to the CSI fluctuation rate in two stages (“high speed” and “low speed”). (2) Reporting method) will be described.
  • the first wireless communication apparatus 110 executes, for example, each step shown in FIG. 27 as the data reception process.
  • Steps S2701 to S2706 shown in FIG. 27 are the same as steps S401 to S406 shown in FIG. However, in step S2703, the first wireless communication apparatus 110 transmits a report signal indicating the lowest CSI predicted value in a future period to the second wireless communication apparatus 120.
  • the future period is, for example, a period from the present to the next periodic CSI reporting timing.
  • the first wireless communication apparatus 110 determines the predicted value of CSI in the future period based on the measured value of CSI in the past predetermined period.
  • a report signal including the lowest value can be transmitted.
  • the lowest possible channel state can be predicted and notified to the second wireless communication apparatus 120.
  • the example in which the first wireless communication device 110 is applied to a wireless terminal and the second wireless communication device 120 is applied to a wireless base station has been described.
  • the first wireless communication device 110 and the second wireless communication device are described.
  • the application destination of the communication device 120 is not limited to these.
  • the second wireless communication device 120 may be a wireless terminal that performs terminal-to-terminal communication with the first wireless communication device 110.
  • the first wireless communication device 110 and the second wireless communication device 120 may be provided in different vehicles, and wireless communication between the vehicles may be realized.
  • automobile communication requirements require high reliability such as a residual error rate of 10 ⁇ 5 and low delay.
  • the error rate in data transmission is reduced, thereby reducing the delay associated with retransmission and realizing high reliability and low delay. be able to.
  • the second wireless communication device 120 calculates the relative speed between the first wireless communication device 110 and the own device based on the moving speed of the first wireless communication device 110 and the moving speed of the own device. . Then, the second wireless communication device 120 converts the calculated relative speed into a rate of change in channel state over time, and estimates a future channel state based on the converted rate.
  • wireless communication between vehicles is not limited to wireless communication associated with automatic driving of a vehicle, and may be wireless communication that transmits information such as traffic jam information and brake information to assist driving by a driver.
  • the wireless communication device As described above, according to the wireless communication device, the wireless communication system, and the wireless communication method, it is possible to reduce the error rate in data transmission.
  • URLLC is an investigation theme for applications such as automatic driving and remote control.
  • URLLC is an abbreviation for Ultra-Reliable and Low Latency Communications.
  • URLLC requires a packet residual error rate of 10 ⁇ 5 for 1 to 2 transmissions.
  • the latest request requires a residual error rate of 10 ⁇ 5 after a maximum of one retransmission.
  • link adaptation including CSI reporting and outer loop control is known in conventional technologies such as LTE.
  • the CSI reports in link adaptation include periodic reports and aperiodic reports.
  • LTE periodic reporting it is possible to report a period of 2 [ms] at the shortest.
  • the feedback amount per time is small.
  • non-periodic report a report is made in response to a request from the network, and the amount of information that can be reported is larger than the periodic report.
  • the correction amount (margin) of CSI when converting from CSI to MCS is adjusted.
  • the error rate is, for example, BLER (BLOCK Error Ratio: block error rate).
  • the channel state may have already fluctuated (deteriorated), and the target error rate may not be obtained. For this reason, in high-reliability communication such as URLLC, the target BLER is small, so there are cases where the margin update by outer loop control is not in time.
  • the CSI time fluctuation Information about can be reported.
  • the CSI can be corrected over time, and even when there is a CSI fluctuation. The desired error rate can be satisfied.
  • a report signal including the minimum CSI value based on the CSI measurement value can be transmitted.
  • a report signal indicating the lowest possible CSI is transmitted to suppress a decrease in the error rate. be able to.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un premier dispositif de communication sans fil (110) qui, sur la base d'un 'état de fluctuation de valeurs de mesure concernant un état de canal, envoie : des signaux de commande indiquant un procédé sélectionné parmi une variété de procédés comprenant un premier procédé et un second procédé ; et des signaux de rapport à l'aide du procédé sélectionné. L'invention concerne également un second dispositif de communication sans fil (120) qui envoie des données au premier dispositif de communication sans fil (110) et qui reçoit un signal de rapport à l'aide du procédé sélectionné par le premier dispositif de communication sans fil (110) de la part du premier dispositif de communication sans fil (110), en fonction d'un signal de commande reçu de la part du premier dispositif de communication sans fil (110). De plus, le second dispositif de communication sans fil (120) programme une transmission de données au premier dispositif de communication sans fil (110) en fonction du signal de rapport reçu.
PCT/JP2016/087306 2016-12-14 2016-12-14 Dispositif de communication sans fil, système de communication sans fil et procédé de communication sans fil Ceased WO2018109887A1 (fr)

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
CN112703759A (zh) * 2018-09-17 2021-04-23 上海诺基亚贝尔股份有限公司 装置、方法和计算机程序

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JP2009049540A (ja) * 2007-08-14 2009-03-05 Ntt Docomo Inc ユーザ装置、基地局及びチャネル品質情報報告方法
JP2009528710A (ja) * 2005-12-22 2009-08-06 クゥアルコム・インコーポレイテッド 無線通信システムにおける情報の効率的なレポーティング
JP2010114517A (ja) * 2008-11-04 2010-05-20 Ntt Docomo Inc 移動端末装置及び無線基地局装置

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JP2009528710A (ja) * 2005-12-22 2009-08-06 クゥアルコム・インコーポレイテッド 無線通信システムにおける情報の効率的なレポーティング
JP2009049540A (ja) * 2007-08-14 2009-03-05 Ntt Docomo Inc ユーザ装置、基地局及びチャネル品質情報報告方法
JP2010114517A (ja) * 2008-11-04 2010-05-20 Ntt Docomo Inc 移動端末装置及び無線基地局装置

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CN112703759A (zh) * 2018-09-17 2021-04-23 上海诺基亚贝尔股份有限公司 装置、方法和计算机程序

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