WO2008032580A1 - Dispositif de communication, dispositif de détermination de paramètre de modulation, système de communication et procédé de communication - Google Patents

Dispositif de communication, dispositif de détermination de paramètre de modulation, système de communication et procédé de communication Download PDF

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Publication number
WO2008032580A1
WO2008032580A1 PCT/JP2007/066858 JP2007066858W WO2008032580A1 WO 2008032580 A1 WO2008032580 A1 WO 2008032580A1 JP 2007066858 W JP2007066858 W JP 2007066858W WO 2008032580 A1 WO2008032580 A1 WO 2008032580A1
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Prior art keywords
reception quality
information
correction
unit
correspondence
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PCT/JP2007/066858
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English (en)
Japanese (ja)
Inventor
Toshizo Nogami
Takashi Onodera
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Sharp Kabushiki Kaisha
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Publication of WO2008032580A1 publication Critical patent/WO2008032580A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0015—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy
    • H04L1/0019—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy in which mode-switching is based on a statistical approach
    • H04L1/0021—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy in which mode-switching is based on a statistical approach in which the algorithm uses adaptive thresholds
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0026—Transmission of channel quality indication

Definitions

  • the present invention relates to modulation scheme control for selecting one of a plurality of modulation parameters in accordance with the quality of a propagation path.
  • MCS Modulation and Coding Scheme
  • the state of a propagation path is determined by using a preamplifier, which is a known signal inserted in a radio frame, from the reception state to a signal-to-noise power ratio (SNR).
  • a preamplifier which is a known signal inserted in a radio frame, from the reception state to a signal-to-noise power ratio (SNR).
  • SNR signal-to-noise power ratio
  • the ratio is estimated as a value. Furthermore, in subcarrier adaptive modulation communication in the multicarrier transmission scheme, the propagation path state for each subcarrier is estimated, and the modulation parameter is selected for each subcarrier.
  • Non-patent Document 1 a method for selecting a low modulation method has been proposed.
  • Non-patent Document 1 a method has been proposed in which adaptive modulation is applied by estimating the propagation path by using a gutter when the Doppler frequency is low, and the minimum bit rate is selected when the Doppler frequency is high.
  • Patent Document 1 discloses an adaptive modulation radio communication apparatus that uses three types of modulation parameter selection charts having different modulation multi-level numbers and selects a modulation scheme by using the modulation parameter selection chart according to the estimated value of the maximum Doppler frequency fd. Has been.
  • the table for selecting the modulation method in adaptive modulation according to the estimated value of the maximum Doppler frequency fd the degradation of communication quality is reduced when fading fluctuations are large.
  • a known technique is to extrapolate the propagation path information at the time of reception for a plurality of times in the past to the propagation path information at the time of transmission.
  • Fig. 25 shows a method for estimating the propagation path using the first outer casing.
  • the propagation path estimated value 2504 at the k-th transmission is calculated from a straight line 2503 connecting the propagation path value 2501 in the k-1th transmission unit and the propagation path value 2502 in the k-2th transmission unit. Can be sought.
  • Patent Document 1 JP 2003-198426
  • Patent Document 2 Japanese Patent Laid-Open No. 2003-259437
  • Non-Patent Document 1 Mitsuharu Kondo, Takanobu Akiba, Nao Terai, Fumihiro Sunada “A Study on Adaptive Modulation for Commercial Mobile Communications”, IEICE, IEICE Technical Report RCS2001—234, January 2002 , P. 65- 72
  • a modulation parameter selection chart is selected based only on the Doppler frequency, and the modulation method is selected based on the threshold value set in the modulation parameter selection chart.
  • the threshold is corrected in the direction of decreasing the transmission rate, which is the reference for selecting the modulation parameter, and if the difference between the reception quality and the threshold is large, an inefficient modulation method may be selected.
  • the modulation method selected may not be appropriate due to the temporal variation of the reception quality, and the communication quality will deteriorate due to the modulation method selection error. There was something to do.
  • the modulation method is selected based on the estimated propagation path information
  • the propagation path information is estimated based on the temporal variation of the reception quality, and thus the estimated propagation path information is not actually received. It was sometimes different from the quality.
  • the present invention has been made in view of such circumstances, and even in an environment where the propagation path fluctuates, the degradation of communication quality is reduced as compared with the conventional method, and an appropriate transmission rate is achieved.
  • the purpose is to provide a communication device and related technology for selecting.
  • an object is to provide a technique for selecting an appropriate transmission rate in consideration of channel conditions (reception quality) and temporal variations in reception quality.
  • a communication apparatus is a communication apparatus that performs communication using a plurality of channels, and associates reception quality information with modulation parameters. For each channel using the correspondence correction information corrected with the correction width determined based on the reception quality reference value indicating the reference value of the reception quality of the channel and the reception quality fluctuation rate indicating the temporal variation of the reception quality.
  • a modulation parameter determination unit that selects a modulation parameter corresponding to reception quality information is provided.
  • the modulation parameter (transmission rate) corresponding to the reception quality based on the correspondence information.
  • the correction range for correcting the correspondence information is determined based on the reference value of the reception quality of the channel and the temporal fluctuation of the reception quality (reception quality fluctuation rate).
  • the correspondence information is corrected using the correction width. Or the above correction
  • the correspondence correction information is stored and selected. As a result, it becomes possible to select a modulation parameter in consideration of channel conditions and temporal variations in reception quality, and it is possible to reduce deterioration in communication quality.
  • the correction width is a predetermined communication product for each of a plurality of combinations of the reception quality reference value and the reception quality variation rate.
  • V is determined based on correction width information that specifies a value for correcting the correspondence information so as to maintain quality.
  • the correction width is adjusted according to the channel state and the time variation of the reception quality by correcting the correspondence information using the value for correcting the correspondence information so as to satisfy the required communication quality.
  • Modulation parameters can be selected.
  • the modulation parameter can be appropriately selected, and deterioration of communication quality can be reduced.
  • the correction width information is generated by obtaining communication quality characteristics in advance through computer simulations and experiments, and finding a correction width that satisfies the required communication quality.
  • the correspondence relationship information includes a correspondence relationship between reception quality information satisfying a predetermined quality and a modulation parameter when the reception quality variation rate is substantially zero. It is characterized by being set.
  • the correction range for correcting the correspondence information is determined and corrected based on the channel state and the temporal variation in reception quality.
  • the modulation parameter can be appropriately selected, and deterioration of communication quality can be reduced.
  • the modulation parameter determination unit includes the storage unit that stores the correspondence information, and the reception quality criterion described above based on the reception quality information of the plurality of channels.
  • a calculation unit that calculates a value, and a correction width corresponding to a combination of the reception quality reference value calculated by the calculation unit and the reception quality variation rate is determined based on the correction width information, and the determined correction width is used.
  • a correction unit that corrects the correspondence information stored in the storage unit to generate correspondence correction information, and selects a modulation parameter corresponding to the reception quality information of each channel based on the correspondence correction information generated by the correction unit And a modulation parameter selection unit.
  • the modulation parameter corresponding to the channel state and the time fluctuation of the reception quality can be selected, and deterioration of communication quality can be reduced.
  • the modulation parameter determination unit determines a plurality of combinations of the reception quality reference value and the reception quality variation rate based on the correction width information.
  • the reception quality reference value is calculated based on the storage unit that stores a plurality of the correspondence correction information generated in advance using the correction width corresponding to each of the error and the reception quality information of the plurality of channels.
  • Correction that selects one correspondence correction information from the plurality of correspondence correction information stored in the storage unit based on the calculation unit, the reception quality reference value calculated by the calculation unit, and the reception quality variation rate An information selection unit; and a modulation parameter selection unit that selects a modulation parameter corresponding to reception quality information of each channel based on the correspondence correction information selected by the correspondence correction information selection unit.
  • the storage section associates second correspondence information that associates the reception quality information with the modulation parameter when the reception quality variation rate is equal to or greater than a predetermined value.
  • the correction unit selects second correspondence information stored in the storage unit when the reception quality variation rate is equal to or greater than a predetermined value, and based on the selected second correspondence information.
  • the modulation parameter corresponding to the reception quality reference value is selected, and the modulation parameter selection unit determines the modulation parameter selected by the correction unit as the modulation parameter of each channel.
  • the second correspondence information is provided so that the same modulation parameter is used in each channel, and based on the reception quality variation rate.
  • the reception quality fluctuation rate includes a value of a maximum Doppler frequency, a value obtained by multiplying the maximum Doppler frequency and a processing delay time, and reception quality information at different times. Any force of the difference value is used.
  • the time variation of the reception quality is the maximum Doppler frequency value indicating the moving speed of the communication apparatus, the value obtained by multiplying the maximum Doppler frequency and the processing delay time, or the time variation of the reception quality itself. It is possible to acquire it by using one of the difference values of the reception quality information at different times shown, and use one of the acquired values as the reception quality fluctuation rate indicating the temporal fluctuation of the reception quality. As a result, the modulation parameter can be appropriately selected, and deterioration of communication quality can be reduced.
  • a Doppler frequency detection unit that detects the maximum Doppler frequency
  • a processing delay estimation unit that estimates a processing delay time that is required for communication reciprocation
  • the correction unit inputs the maximum Doppler frequency and the processing delay time, acquires the reception quality fluctuation rate from the input maximum Doppler frequency and the processing delay time, and acquires the received reception quality fluctuation rate And a correction width corresponding to the reception quality reference value is determined.
  • the processing delay estimation unit that estimates the processing delay time, it is possible to calculate the reception quality variation rate even in a communication apparatus that performs communication with different packet lengths. Correspondence information can be corrected based on the state and the temporal variation of reception quality. As a result, appropriate modulation parameters can be selected, and communication quality deterioration can be reduced.
  • a time variation of reception quality is detected based on reception quality information of a plurality of channels at different times, and the time variation of the detected reception quality is detected as the reception quality variation. It further comprises a variation rate detection unit that outputs to the correction unit as a rate.
  • the reception quality fluctuation rate can be acquired using the difference due to the temporal fluctuation of the reception quality information instead of the Doppler frequency indicating the moving speed of the communication apparatus.
  • the modulation parameter can be selected based on the temporal variation of the reception quality that is different from the moving speed of the communication apparatus.
  • the reception quality reference value includes average reception quality information obtained by averaging reception quality information in a plurality of channels, a maximum value of reception quality in the plurality of channels, It is characterized by using either the minimum value of the reception quality in multiple channels or the time average value of the reception quality information in any channel.
  • the reception quality reference value is a value that serves as an index indicating the reception quality of a plurality of channels, the average value of reception quality information (for example, SNR) of a plurality of channels, and the reception of a plurality of channels.
  • the expected quality value either the maximum value or the minimum value of the distribution of received quality calculated from the average value of the received quality information is used. As a result, it is possible to select a correction value reflecting the states of a plurality of channels.
  • a modulation parameter determination apparatus is a modulation parameter determination apparatus that determines a modulation parameter according to the reception quality of a channel, and associates reception quality information with modulation parameters. Each channel using the relationship correction information corrected by the correction width determined based on the reception quality reference value indicating the channel reception quality reference value and the reception quality fluctuation rate indicating the time variation of the reception quality. The modulation parameter corresponding to the received quality information is selected.
  • the modulation parameter determination apparatus that selects and adaptively modulates the modulation parameter (transmission rate) according to the reception quality based on the correspondence information, the channel reception quality reference value and the time variation of the reception quality Based on the (reception quality variation rate), a correction range for correcting the correspondence information is determined, and the correspondence information is corrected using the determined correction width.
  • a communication system is a communication system that performs communication by modulating in accordance with each channel state, and includes a reception quality reference value indicating a reference value of reception quality of a channel, and a reception Means for generating correspondence correction information by correcting correspondence information that associates reception quality information with modulation parameters using a correction range determined based on a reception quality fluctuation rate indicating a temporal variation in quality; Means for selecting a modulation parameter corresponding to the reception quality information of each channel based on the created correspondence correction information.
  • the means for acquiring the correspondence correction information as described above for example, 16 and FIG. 23 threshold correction unit and FIG. 17 threshold determination unit
  • means for selecting a modulation parameter based on correspondence correction information for example, the modulation parameter selection unit of FIG. 16, FIG. 17, and FIG. 23
  • the correspondence correction information thus corrected is held and selected.
  • a communication method is a communication method in which communication is performed with modulation in accordance with each channel state, the reception quality reference value indicating the reference value of the reception quality of the channel, and the received product.
  • the correction range is determined based on the reception quality fluctuation rate indicating the temporal variation in quality, and the correspondence information that correlates the reception quality information and the modulation parameter is corrected using the determined correction range to obtain the correspondence correction information.
  • the modulation parameter corresponding to the reception quality information of each channel is selected based on the created correspondence correction information.
  • a reference value of channel reception quality and time variation of reception quality (reception) is determined based on the quality variation rate (for example, S13 in FIG. 7), and the correspondence information is corrected using the determined correction width (for example, S14 in FIG. 7). .
  • the corrected correspondence correction information is held and selected (for example, S23 in FIG. 12).
  • FIG. 17 shows a plurality of threshold value table storage units 406a to 406n.
  • the threshold value table storage unit 406 indicates one or more of the threshold value table storage units 406a to 406n.
  • a description will be given using a communication system (wireless communication system) that uses a plurality of channels and performs communication by performing adaptive modulation according to the reception quality of each channel.
  • a communication system wireless communication system
  • Adaptive modulation is controlled by selecting an appropriate modulation parameter (transmission rate) according to the channel condition. The following terms are used for explanation.
  • the reception quality refers to the reception quality when transmitting from the transmitter to the receiver, that is, the reception quality when the receiver receives the signal transmitted from the transmitter.
  • the receiver since it is assumed that the MCS is controlled for each channel, the receiver measures the reception quality for each channel. Also, the value indicating the reception quality (measurement value or information based on the measurement value) is used as the reception quality information.
  • communication quality refers to the quality of communication as a whole, including the quality of communication data and communication speed.
  • the reception quality reference value indicates a reference value of the reception quality of the channel on the reception side, and an expected value of the reception quality of each channel on the reception side can be used.
  • the quality reference value may be a reception quality average value (average reception quality information) itself obtained by averaging reception quality measurement results in each channel.
  • the average reception quality value may be the average reception quality of each channel or the average value of any channel.
  • the average value may be a value calculated by weight average. Details will be described later.
  • reception quality information value indicating reception quality
  • SINR Signal to Interference plus Noise power Ratio
  • CNR Carrier Power to Noise Power Ratio
  • CINR Carrier Power to Interference Power and Noise Power Ratio
  • RSSI received signal strength indicator
  • the reception quality fluctuation rate is an index representing the magnitude of the temporal fluctuation of the reception quality. Specific examples include the maximum Doppler frequency (f) and the normalized maximum Doppler frequency (f T).
  • the maximum Doppler frequency is the processing delay (round trip time) of the maximum Doppler frequency (f).
  • the “delay time” is sometimes referred to as “processing delay”.
  • any index may be used that represents the magnitude of temporal variation in reception quality. For example, it may be a moving speed of the terminal or a difference value of reception quality at a plurality of times (a difference value of reception quality information at different times). Since the reception quality variation rate is the amount of variation in reception quality due to the processing delay of adaptive modulation, the difference value of reception quality at multiple times is input, but it is used as a parameter.
  • a modulation parameter (hereinafter also referred to as MCS) is a modulation scheme, an error correction coding rate, or a combination thereof, and is a parameter that specifies at least one of the modulation scheme and the coding rate. It is.
  • the modulation parameter is controlled by adaptive modulation in which an appropriate modulation parameter is selected according to the channel state, and is specified based on reception quality information and the like.
  • the modulation parameter is an example of information indicating a transmission rate.
  • Correspondence relationship information is information that specifies a relationship in which the MCS decides when the reception quality is determined, and associates the reception quality with the MCS.
  • the correspondence information is created without considering the temporal variation of the reception quality (the reception quality variation rate is approximately zero).
  • a reception quality fluctuation rate of approximately zero assumes a range in which communication quality does not vary (communication quality has deteriorated! /, Is not judged! /, Range)! /.
  • FIG. 1 shows an example of propagation path characteristics at time t and time t-T.
  • t is an arbitrary time
  • T is a time interval
  • f the maximum Doppler frequency
  • the SNR of the fn channel is! / at time tT, and the tT force that is ⁇ , and ⁇ at time ijt.
  • this time interval T is the length of the processing delay in adaptive modulation, the reception quality ⁇ of the channel of frequency fn at the time of reception quality measurement and the adaptive modulation processing based on the reception quality t—
  • the quality (required communication quality) may not be satisfied.
  • FIG. 2 shows an example of a mechanism in which required quality is not satisfied in adaptive modulation processing.
  • the horizontal axis is SNR, and the vertical axis is MCS.
  • the threshold values for selecting S2, MCS2 and MCS3, and MCS3 and MCS4 are shown.
  • the solid line in the graph of Fig. 2 indicates that MCS1 is selected when the SNR is less than ⁇ , and that the SNR is greater than ⁇ .
  • MCS3 is selected and SNR is ⁇ or more, it means that MCS4 is selected.
  • the MCS that maximizes the transmission rate while satisfying the required quality at each SNR is selected.
  • the correspondence information that associates this threshold value with the MCS is also called a threshold value table.
  • the correspondence relationship information will be described below as a threshold table.
  • the reception quality is ⁇ at time t-T when the reception quality is measured, the required quality is satisfied.
  • the MCS3 with the maximum rate is selected. However, at time t when data is transmitted Since the reception quality is ⁇ , the transmission data to which the selected MCS3 is applied is the required product t
  • FIG. 3 is a diagram showing an example of a function that satisfies the required quality by correcting the correspondence information in the adaptive modulation processing.
  • the MCS2 with the highest rate is selected. Since the reception quality is ⁇ at time t when data is transmitted, the transmission data to which the selected MCS2 is applied satisfies the required quality.
  • the required quality can be maintained by determining the correction range based on the amount of variation. Touch with S.
  • the distribution of SNR at time ijt and the distribution of SNR at time tT are a (t) and a (t -T), respectively, and u and ⁇ are a (t) and a (tT), respectively.
  • u and ⁇ are a (t) and a (tT), respectively.
  • the joint probability density function f normalized by the mean value of each distribution is
  • Equation 1 observes an event with a probability density distribution of a (t), observes u, and observes an event with a probability density distribution of a (t—T), Probability density is calculated.
  • Equation 2 J ⁇ l nj ⁇ ⁇ ) (Equation 2) , where J and I are the 0th order first-order Bessel function and the 0th-order first-order modified Bessel function, respectively.
  • Figure 4 Figure 6 shows an example of the probability density of SNR fluctuations corresponding to the instantaneous SNR.
  • Figure 4 shows the average SNR is OdB
  • Figure 5 shows the average SNR of 10dB
  • Figure 6 shows.
  • the case of B is shown.
  • the probability density of SNR fluctuation relative to the instantaneous SNR when the average SNR is different is calculated using Equation 1 and shown in contour lines.
  • the average SNR increases in the order of Figure 4, Figure 5, and Figure 6.
  • the reception quality variation rate here, the maximum Doppler frequency f is used as an example
  • the probability density value in the figure is indicated by.
  • the instantaneous SNR is the SNR value for a channel at a certain time.
  • the optimum correction width varies depending on the average SNR (reception quality reference value). Also, when the reception quality fluctuation rate changes, the amount of fluctuation of the SNR of each channel changes, so the optimum correction range varies depending on the reception quality fluctuation rate even for the same average SNR. Accordingly, it is possible to generate correspondence information according to the amount of fluctuation in the reception quality of the channel by setting the correction width based on the reception quality fluctuation rate and the average SNR. This makes it possible to select the MCS according to the reception quality of each channel.
  • FIG. 7 shows an example of MCS determination processing for each channel in the present embodiment.
  • the average SNR is calculated (S11), and the reception quality fluctuation rate is detected (S12).
  • a correction width is determined from the calculated average SNR and the detected reception quality fluctuation rate (S13), and the threshold value table (correspondence information) is corrected using the determined correction width (S14).
  • the corrected threshold table (correspondence correction information) is compared with the SNR for each channel, and the MCS for each channel is selected (S15).
  • the correction width information is for each of a plurality of combinations of the reception quality reference value and the reception quality fluctuation rate! /, And required quality (predetermined communication quality) This is information for specifying a value (correction value) for correcting the correspondence information so as to maintain. Therefore, the correction width information is information that sets correction values corresponding to each of a plurality of combinations of the reception quality reference value and the reception quality fluctuation rate, and specifies the means for setting. This information indicates the relationship that the correction range is determined arbitrarily when the reception quality reference value and the reception quality fluctuation rate are determined.
  • FIG. 8 is a diagram showing an example of the correction width information.
  • FIG. 8 shows an example in which correction width information in which values corresponding to each of a plurality of combinations of reception quality reference values and reception quality fluctuation rates are set is held as a table (correction width table).
  • the horizontal axis is the average SNR, and the vertical axis is the reception quality fluctuation rate.
  • the normalized maximum Doppler frequency fT is used as an example of the reception quality fluctuation rate. Normalized maximum Doppler frequency f T
  • the area is divided into a plurality of areas, and correction widths D1 to D25 corresponding to each area are set. It should be noted that here the force described as D1 to D25 is not limited to this number.
  • the plurality of correction widths may be the same value. As a result, in a system with constant processing delay, if the average SNR and f are determined, the correction width (correction value) is
  • an optimal value may be obtained by computer simulation or experiment and stored.
  • the communication quality characteristic with respect to the correction width as shown in FIG. 9 or FIG. 10 is acquired by computer simulation or experiment, and the minimum correction width satisfying the required communication quality is obtained.
  • the packet error rate (PER: Packet Error Rate, hereinafter also referred to as “PER”) is used as the communication quality.
  • 9 and 10 are diagrams showing an example of the relationship between the packet error rate and the correction width.
  • FIG. 9 shows the case where the average SNR is OdB
  • FIG. 10 shows the case where the average SNR is 10 dB.
  • Their respective f T is 10_ 4
  • 10 2, 1 shows the data when the required PER required as required quality
  • the correction width is D1
  • the correction width when the average SNR is OdB and f T is 10_ 2 in D2
  • Correction width when the average SNR is 10dB and f T is a 10- 4 is D6, average SNR is 10 When dB and f T is 10, the correction width is D7, the average SNR is 10 dB, and f T is 1.
  • correction width when is is D8.
  • V / based on the data acquired, correction width information (correction width table) as shown in FIG. 8 may be created.
  • FIG. 8 illustrates the case where the two-dimensional plane is divided into a plurality of rectangular areas, but it is not necessarily required to be rectangular. It is uniquely determined from the average SNR and the reception quality fluctuation rate (f).
  • the specified quality may be satisfied in the propagation path environment of the average SNR and the reception quality fluctuation rate. Any table can be used as long as the correction range can be selected.
  • FIG. 11 is a diagram showing an example of correction width information different from FIG. As in Fig. 8, the horizontal axis is the average SNR, and the vertical axis is fT used as an example of the reception quality fluctuation rate.
  • the two-dimensional plane of the horizontal axis and the vertical axis is divided into a plurality of regions, and unlike the force S, FIG. 8 in which correction values corresponding to each region are set, each region is not rectangular.
  • f T is constant
  • the probability density is calculated in advance using an equation such as Equation 1 and the average SNR and f
  • the correction value may be calculated so as to cover a range in which the probability density is equal to or higher than a predetermined threshold.
  • the area may be divided by this calculation formula, and a fixed correction width may be set for each area. When such a method is used, it is divided into regions that are separated by contour lines indicating mountains.
  • the correction width information may be a method of specifying the correction width by a relational expression or the like that is not limited to the table shown in FIG. 8 or FIG.
  • the correction width information is that the correction width ⁇ is arbitrarily determined when the received quality reference value ⁇ and the received quality fluctuation rate f T are determined.
  • the correspondence relationship information associating the reception quality of each channel with the MCS is represented by the temporal variation (reception quality variation rate) of the reception quality and the reception quality (reception quality reference value). )
  • the transmission rate modulation parameter
  • the transmission rate modulation parameter
  • the correction table is obtained from the average SNR and the reception quality fluctuation rate to correct the threshold table.
  • a description will be given of adaptive modulation control in which a plurality of threshold tables are prepared in advance and the threshold table to be used is determined based on the average SNR and the reception quality fluctuation rate.
  • the correction range is determined based on the average SNR and the reception quality variation rate by the method described in the first embodiment, and the correspondence threshold information is corrected using the determined correction range.
  • a table correspondence correction information
  • a threshold table corresponding to each combination of average SNR and reception quality fluctuation rate is prepared.
  • FIG. 12 shows an example of MCS determination processing for each channel in the present embodiment.
  • the average SNR is calculated (S21), and the reception quality fluctuation rate is detected (S22).
  • a threshold table to be used is selected from threshold table 1 to threshold table k (S23).
  • the selected threshold table is compared with the SNR for each channel, and the MCS for each channel is selected (S24).
  • Figure 13 shows an example of a table (correction information selection table) that identifies the threshold table from the average SNR and the reception quality fluctuation rate.
  • the horizontal axis is the average SNR, and the vertical axis is the reception quality fluctuation rate.
  • the normalized maximum Doppler frequency f ⁇ is used as an example of the quality variation rate.
  • the two-dimensional plane is divided into a plurality of regions, and a threshold table T1 to a threshold table T25 corresponding to each region are set! /.
  • the threshold table T1 to the threshold table T25 correspond to the k threshold tables from the threshold table 1 to the threshold table k shown in FIG. 12, and each threshold table has a correspondence relationship in which the correspondence information is corrected by the correction width. Correction information. That is, in FIG. 8, the correction width is determined based on the average SNR and the reception quality fluctuation rate, but in FIG. 13, the threshold value obtained by correcting the correspondence information with the correction width determined based on the average SNR and the reception quality fluctuation rate.
  • the table correspondence correction information
  • FIG. 13 illustrates the case where the two-dimensional plane is divided into a plurality of rectangular areas, it is not necessarily rectangular.
  • the threshold table is corrected using a correction range uniquely determined from the average SNR and the reception quality fluctuation rate, which is also used in the region division method shown in Fig. 11 and other region division methods, and based on the corrected threshold table. ! / When MCS is selected, any table that can select a correction range that can satisfy the specified quality in the propagation path environment of the average SNR and the reception quality fluctuation rate may be used.
  • the adaptive modulation control of the first embodiment is applied to a multicarrier adaptive modulation system.
  • a multicarrier adaptive modulation system there is one multi-carrier adaptive modulation system! /, Where adaptive modulation is performed for each channel that combines multiple subcarriers.
  • the power explained using the applied system is not limited to this.
  • the present invention can be similarly applied to an MC-CD MA (Multi-Carrier Code Division Multiple Access) adaptive modulation system.
  • the present invention is not limited to a multicarrier system in which a plurality of channels are arranged in the frequency direction.
  • MIMO Multiple Input Multiple Output
  • MIMO Multiple Input Multiple Output
  • Orthogonal Frequency Division Multiplexing with multiple channels arranged in two dimensions of frequency and space
  • the force described assuming an FDD (Frequency Division Duplex) system is not limited to this. Even in a TDD (Time Division Duplex) system, if the propagation path characteristics during reception quality measurement and the propagation path measurement during transmission differ due to processing delay, the communication quality can be reduced by applying the present invention. It can be improved.
  • FDD Frequency Division Duplex
  • FIG. 14 is a block diagram showing an example of the configuration of the transmitter 100 in the present embodiment
  • FIG. 15 is a block diagram showing an example of the configuration of the receiver 200 in the present embodiment.
  • the transmitter 100 corresponds to a base station (communication control device)
  • the receiver 200 corresponds to a terminal (communication terminal device).
  • Transmitter 100 includes encoding unit 101, mapping unit 102, multiple lettuce unit 103, IFFT (Inverse Fast Fourier Transiorm) unit 104, and GI (Guard In terval). Insertion unit 105, D / A (Digital / Analog) conversion unit 106, radio transmission unit 107, adaptive modulation control unit 108, notification information generation unit 109, pilot generation unit 110, radio reception unit 111, A / D (Analog / Digital) conversion unit 112, demultiplexing unit 113, demapping unit 114, decoding unit 115, and antenna unit 116.
  • Receiver 200 includes radio reception unit 201, A / D conversion unit 202, GI removal unit 203, FFT (Fast Fourier Transform) unit 204, demultiplexing unit 205, dematsu Bing unit 206, decoding unit 207, adaptive demodulation control unit 208, reception quality measurement unit 209, f detection
  • Doppler frequency detection unit, variation rate detection unit 301 Doppler frequency detection unit, variation rate detection unit 301, MCS determination unit (modulation parameter determination unit, modulation parameter determination device) 400, report information generation unit 210, encoding unit 211, mapping unit 212, multipletus unit 213, a D / A conversion unit 214, a wireless transmission unit 215, and an antenna unit 216.
  • MCS determination unit modulation parameter determination unit, modulation parameter determination device
  • transmission data is subjected to error correction coding in coding section 101, and the coded bit sequence is mapped to a symbol series for each subcarrier in mapping section 102.
  • encoding section 101 and mapping section 102 are adapted modulation control information sent from adaptive modulation control section 108 (information indicating MCS for each transmission data, for each receiver to which transmission data is transmitted, or for each channel). Based on the above, encoding processing and mapping processing are performed.
  • the multiplex state unit 103 the data symbol sequence output from the mapping unit 102, the symbol sequence for notification information (adaptive modulation control information) output from the notification information generation unit 109, and the pilot output from the pilot generation unit 110 Symbol series are multiplexed.
  • the symbol sequence output from the multiplex state unit 103 is converted into a time domain signal by the IFFT unit 104, and a GI is added by the GI insertion unit 105, whereby an OFDM symbol sequence is generated.
  • the generated OFDM symbol sequence is converted into an analog signal by the D / A converter 108 and transmitted from the wireless transmission unit 107 to the receiver 200 via the antenna unit 116.
  • receiver 200 signal received from transmitter 100 is received by radio reception section 201 via antenna section 216.
  • the analog signal received by radio reception section 201 is converted into an OFDM symbol sequence by A / D conversion section 202, and GI is removed by GI removal section 203.
  • the OFDM symbol sequence from which the GI has been removed is converted into a signal in the frequency domain by the FFT unit 204.
  • the symbol sequence output from the FFT unit 204 is received by the demultiplexing unit 205 as a data symbol sequence, a notification information symbol sequence, and a pilot symbol. And are output to demapping section 206, adaptive demodulation control section 208, and reception quality measurement section 209, respectively.
  • the adaptive demodulation control unit 208 Based on the notification information indicated by the symbol sequence for notification information sent from the demultiplexing unit 205, the adaptive demodulation control unit 208 performs adaptive demodulation control information (per-transmission data or MCS for each channel). Information to the demapping unit 206 and the decoding unit 207.
  • Demapping section 206 demaps the data symbol sequence output from the demultiplexing section 205 based on the adaptive demodulation control information.
  • the bit sequence output from demapping section 206 is subjected to error correction decoding in decoding section 207, and received data is extracted.
  • decoding section 207 performs decoding based on the adaptive demodulation control signal sent from adaptive demodulation control section 208.
  • Reception quality measuring section 209 measures the reception quality for each channel from the pilot symbol sequence separated by demultiplexing section 205. Here, we explain the case of measuring SNR for each channel.
  • the f detection unit 301 detects the maximum Doppler frequency f. Here, reception quality fluctuation
  • Such a method may be used.
  • a method of estimation using a pilot symbol sequence a method of detecting from the moving speed of a terminal, and a method of estimation using fluctuations in reception quality measurement results are conceivable.
  • the processing delay ⁇ is constant and is known in the transmitter 100 and the receiver 200 in the communication system.
  • MCS determination section 400 based on the reception quality measurement result (SNR) measured by reception quality measurement section 209! And f detected by f detection section 301, MCS determination section 400 MCS
  • Report information generation section 210 generates a report information symbol sequence for reporting to transmitter 100 the report information determined here by MCS determination section 400 (in this case, information indicating the MCS for each channel). , And send it to the multiplex lettuce unit 213.
  • the multi-places unit 213 multiplexes the report information symbol sequence on the transmission data encoded and modulated by the encoding unit 211 and the mapping unit 212.
  • D / A conversion of symbol sequence output from multi-lettuce unit 213 The signal is converted into an analog signal by unit 214 and transmitted from radio transmission unit 215 to transmitter 100 via antenna unit 216.
  • signal received from receiver 200 is received by radio reception unit 111 via antenna unit 116.
  • the signal received by the wireless reception unit 111 is converted into a digital signal by the A / D conversion unit 112 and output.
  • the symbol sequence output from the A / D converter 112 is separated into a data symbol sequence and a report information symbol sequence by a demultiplexer 113.
  • the data symbol sequence output from the demultiplexer 113 is subjected to demodulation and error correction decoding processing in the demapping unit 114 and the decoding unit 115, and the received data is extracted.
  • the report information symbol sequence output from demultiplexer 113 is sent to adaptive modulation controller 108.
  • the adaptive modulation control unit 108 transmits to the encoding unit 101 and the mapping unit 102, the adaptive modulation control information for performing adaptive modulation processing based on the report information indicated by the report information symbol sequence. Further, adaptive modulation control section 108 sends adaptive modulation control information to notification information generation section 109, and notification information generation section 109 provides notification information for notifying receiver 200 of notification information (adaptive modulation control information). Generate a symbol series.
  • FIG. 16 is a block diagram illustrating an example of the configuration of the MCS determination unit 400 according to the present embodiment.
  • the MCS determination unit 400 includes a reception quality reference value calculation unit (calculation unit) 401, a threshold correction unit (correction unit) 402, a threshold table storage unit (storage unit) 403, and an MCS selection unit (modulation parameter selection unit) 404. It has.
  • Reception quality reference value calculation section 401 calculates a reception quality reference value based on the reception quality measurement result (SNR) measured by reception quality measurement section 209.
  • SNR reception quality measurement result
  • the plurality of channels for which the reception quality measurement results for calculating the reception quality reference value are measured are not necessarily all channels, but may be a part of the channels. It suffices if a value serving as a parameter that can represent the difference in distribution (in the horizontal axis direction) can be calculated.
  • a description will be given of a configuration in which an average value of reception quality in a plurality of channels is calculated as a reception quality reference value.
  • reception quality reference value can be used as an index indicating the reference value of the reception quality of the channel, the time average value of the reception quality of any channel, etc.
  • the reception quality reference value and other indicators indicating the expected value of the reception quality of the channel can also be parameters that can represent the difference in distribution (in the horizontal axis direction) described with reference to FIGS.
  • the reception quality reference value may be an average value of reception qualities of a plurality of channels other than some channels (excluding SNRs that are extremely different from the SNRs of other channels), or an average. It may be a maximum value, a minimum value, or a weighted average value.
  • a correction width is set in advance, that is, when a correction width table (for example, FIG. 8, FIG. 11, FIG. 13, etc.) is generated (simulation or experiment), when an actual correction width is determined (actual operation) Therefore, it is sufficient that the values used for the reception quality standard values are consistent.
  • the received quality reference value is the average SNR corresponding to the center of the probability distribution and the maximum value corresponding to the right end of the probability distribution ( (Minimum value of reception quality) or the minimum value (minimum value of reception quality) corresponding to the left end of the probability distribution may be used.
  • the reception quality reference value calculation unit 401 extracts the minimum measurement result from the reception quality measurement results and determines the correction width. It is only necessary that the correction values set in advance in simulations and experiments match the indicators used when actually determining the correction values.
  • reception quality reference value calculation section 401 is also referred to as an average reception quality calculation section, a reference value calculation section, and a calculation section.
  • reception quality reference value calculation section 401 is configured to calculate an average SNR based on the SNR measurement result for each channel measured by reception quality measurement section 209. This is not a limitation. For example, it can be obtained from the carrier power and noise power! /, Or by integrating the OFDM signal waveform.
  • threshold correction section 402 Based on the correction width information, threshold correction section 402 combines the average SNR calculated by reception quality reference value calculation section 401 and f (an example of the reception quality variation rate) detected by f detection section 301.
  • a correction range corresponding to the above is determined, and the correspondence information stored in the threshold table storage unit 403 is corrected using the determined correction width to generate a corrected threshold table (correspondence correction information).
  • the correction width information is, for example, corrected as described in the first embodiment.
  • the threshold value correction unit 402 holds (stores) correction width information in a predetermined storage area (accessible storage area), such as a width table (table shown in FIG. 8 as an example) or a relational expression.
  • the threshold value table storage unit 403 is a storage area for storing correspondence information (threshold value table). In this embodiment, the threshold information storage unit 403 stores correspondence information when the reception quality variation rate is zero.
  • the threshold value table storage unit 403 is both a correspondence storage unit and a storage unit.
  • MCS selection section 404 selects a modulation parameter corresponding to the SNR of each channel measured by reception quality measurement section 209 based on correspondence correction information generated by threshold correction section 402.
  • reception quality measurement result (SNR) output from reception quality measurement section 209 is sent to reception quality reference value calculation section 401 and MCS selection section 404.
  • Reception quality reference value calculation section 401 calculates a reception quality reference value (here, average SNR) based on the reception quality measurement result (Sl l).
  • the threshold correction unit 402 is based on the reception quality reference value calculated by the reception quality reference value calculation unit 401 and the f detection result (S 12) detected by the f detection unit 301.
  • the correction width is determined (S13), the threshold value table stored in the threshold value table storage unit 403 is corrected using the determined correction width (S14), and the corrected threshold value table (correspondence correction information) ) Is output.
  • the MCS selection unit 404 compares the corrected threshold value table sent from the threshold correction unit 402 with the reception quality measurement result for each channel, selects and outputs the MCS for each channel (S15). Note that the calculation method of the correction width in the threshold correction unit 402 is the same as the method described in the first embodiment.
  • the correspondence relationship information is corrected based on the temporal variation (reception quality variation rate) of the reception quality and the reception quality (reception quality reference value).
  • the temporal variation reception quality variation rate
  • the reception quality reception quality reference value
  • This makes it possible to select the transmission rate (modulation parameter) according to the reception quality status of each channel, compared to the case where the correspondence information is corrected based only on the temporal variation of the reception quality.
  • Use force S to reduce the deterioration.
  • the MCS determination unit 400 includes the threshold value correction unit 402, the threshold value correction unit 402 calculates the correction width, and corrects the threshold value table.
  • an appropriate threshold value table is selected from a plurality of corrected threshold value table candidates that are not calculated by the MCS determination unit 400.
  • the configuration of the transmitter is the same as that of the transmitter 100 shown in FIG. 14, and the configuration of the receiver is the configuration including the MCS determination unit 440 instead of the MCS determination unit 400 in the receiver 200 of FIG. The configuration is the same.
  • FIG. 17 is a block diagram illustrating an example of the configuration of the MCS determination unit 440 according to the fourth embodiment.
  • the MCS determination unit 440 includes a reception quality reference value calculation unit 401, a threshold determination unit (correction information selection unit) 405, a plurality of threshold table storage units (storage units) 406a to 406n (n is an integer of 2 or more), and MCS A selection unit 404 is provided.
  • Threshold value determination section 405 includes average SNR calculated by reception quality reference value calculation section 401 and f detection section
  • the threshold table storage unit 40 Based on f detected by 301 (an example of the reception quality fluctuation rate), the threshold table storage unit 40
  • One threshold table is selected from a plurality of corrected threshold tables (correspondence correction information) stored in 6.
  • the threshold value determination unit 405 holds a table (also referred to as a correction information selection table or correction information selection information) illustrated as an example in FIG. 13 and performs a correction after correction corresponding to the combination of the average SNR and the reception quality variation rate. Select the threshold table.
  • the threshold value determination unit 405 holds (stores) the correction width selection table in a predetermined storage area (accessible storage area).
  • the threshold table storage unit 406 has a plurality of corrections generated in advance using correction widths corresponding to each of a plurality of combinations of average SNR information and reception quality variation rate! This is a storage area for storing a later threshold table (correspondence correction information).
  • the corrected threshold value table is generated using the same method as in the second embodiment.
  • reception quality measurement result output from reception quality measurement section 209 is sent to reception quality reference value calculation section 401 and MCS selection section 404.
  • Reception quality reference value calculation section 401 calculates a reception quality reference value (here, average SNR) based on the reception quality measurement result (S21).
  • the threshold value determination unit 405 is a received product calculated by the reception quality reference value calculation unit 401. Based on the quality reference value and the f detection result (S22) detected by the f detector 301.
  • One corrected threshold value table is selected from a plurality of corrected threshold value tables stored in the value table storage unit 406 (S23), and the selected corrected threshold value table is output.
  • the MCS selection unit 404 compares the selected corrected threshold value table sent from the threshold value determination unit 405 with the reception quality measurement result for each channel, and selects and outputs the MCS for each channel (S24). Note that the threshold table selection method in the threshold determination unit 405 is the same as the method described in the second embodiment.
  • the receiver includes an f detection unit and an MCS determination unit.
  • the transmitter includes an MCS determination unit and an f detection unit.
  • transmission from the receiver includes an MCS determination unit and an f detection unit.
  • the information indicating the reception quality for each channel is reported rather than the information indicating the MCS for each channel.
  • FIG. 18 is a block diagram showing an example of the configuration of the transmitter 150 in the present embodiment.
  • Transmitter 150 includes code 101, mapping 102, manople lettuce 103, IFFT3 ⁇ 4104, GI insertion unit 105, D / A conversion unit 106, wireless transmission unit 107, adaptive modulation control unit 108, and notification information generation unit 109. , Pilot generation section 110, radio reception section 111, 8/0 conversion section 112, demultiplexing section 113, demapping section 114, decoding section 115, antenna section 116, f detection section 3
  • a transmitter 150 illustrated in FIG. 18 has a configuration in which an f detection unit 301 and an MCS determination unit 400 are added to the transmitter 100 illustrated in FIG.
  • the receiver 200 includes a no-spring receiving unit 201, an A / D conversion unit 202, a GI removal unit 203, an FFT unit 204, a demultiplexing unit 205, a demapping unit 206, a decoding unit 207, and an adaptive demodulation control unit.
  • 20 8 reception quality measurement unit 209, report information generation unit 210, encoding unit 211, mapping unit 212, multiplet unit 213, D / A conversion unit 214, radio transmission unit 215, and antenna unit 216 It comprises.
  • the receiver 250 shown in FIG. 19 is different from the receiver 200 shown in FIG.
  • the MCS determination unit 400 is deleted.
  • the processing from the encoding process of the transmission data in the transmitter 150 to the reception quality measurement in the reception quality measurement unit 209 of the receiver 250 is the same as that in the third embodiment.
  • the reception quality measurement result for each channel measured by reception quality measurement section 209 is sent to report information generation section 210.
  • Report information generation section 210 generates and outputs a report information symbol sequence for reporting report information (information indicating the reception quality measurement result for each channel) to transmitter 150.
  • Multiplexer 213 multiplexes the report information symbol sequence output from report information generator 210 with the transmission data encoded and modulated by encoder 211 and mapping unit 212.
  • the symbol sequence output from the multiplex state unit 213 is converted into an analog signal by the D / A conversion unit 214 and transmitted from the wireless transmission unit 215 to the transmitter 150 via the antenna unit 216.
  • radio receiver 111 receives the signal transmitted from receiver 250 via antenna 116.
  • the signal received by the wireless reception unit 111 is converted into a digital signal by the A / D conversion unit 112 and output.
  • the symbol sequence output from the A / D converter 112 is separated into a data symbol sequence and a report information symbol sequence by a demultiplexer 113.
  • the f detector 301 detects f. Demultiplexing section 113
  • the symbol sequence for report information output is sent to the MCS determination unit 400.
  • the MCS determination unit 400 determines the MCS for each channel from the reception quality measurement result information for each channel indicated by the report information symbol sequence and the f detection result detected by the f detection unit 301.
  • adaptive modulation control section 108 Based on the MCS information for each channel output from MCS determination section 400, adaptive modulation control section 108 sends the adaptive modulation control information for performing adaptive modulation processing to encoding section 101 and mapping 102. Further, adaptive modulation control section 108 sends adaptive modulation control information to notification information generation section 109, and notification information generation section 109 provides notification information (adaptive modulation control). Information) is generated for notifying the receiver 250 of the information).
  • MCS determination section 400 is the same as that described with reference to FIG. 18 illustrates the configuration using the MCS determination unit 400 illustrated in FIG. 16, but the MCS determination unit 440 illustrated in FIG. 17 can also be used.
  • the manner of correcting the correspondence information has been described.
  • the reception quality fluctuation rate (fT) becomes very large, and there is no propagation path characteristic at time t and time t-T.
  • throughput may be higher when uniform MCS is used for all channels than when adaptive modulation is applied for each channel by applying a correction width.
  • the time variation of the reception quality increases, and a predetermined MCS is used without correcting the correspondence information.
  • FIG. R1 is based on the average SNR and f when the average SNR is 10 dB.
  • R2 is the throughput characteristics when the MCS is the same for all channels and the maximum rate MCS that satisfies the required quality is selected when the average SNR is 10 dB. Note that the MCS is uniform for all channels, and the maximum rate MCS that satisfies the required quality is the average SNR and uniform MCS as shown in Figure 21. Selection may be made using a corresponding threshold table.
  • FIG. 21 is a diagram showing an example of correspondence information used in the present embodiment. In Fig. 20, at the intersection 7] of R1 and R2, the efficiency of adaptive modulation for each channel is high on the left side, and the efficiency deterioration due to the increase in correction width is large on the right side.
  • the threshold value table storage unit 403 includes second correspondence information (for example, the threshold value shown in FIG. Table).
  • the threshold correction unit 402 selects the second correspondence information instead of the process of correcting the correspondence information when the reception quality fluctuation rate is equal to or higher than a predetermined value, and based on the selected second correspondence information.
  • the modulation parameter corresponding to the average SNR is selected and notified to the modulation parameter selection unit 404.
  • Modulation parameter selection section 404 determines the modulation parameter selected by threshold correction section 402 as the modulation parameter for each channel. The same applies to the MCS determination unit 470 shown in FIG.
  • the second threshold correspondence information is stored in one of the threshold table storage units 406.
  • the threshold value determination unit 405 selects the second correspondence information when the reception quality variation rate is equal to or greater than a predetermined value, and selects the modulation parameter corresponding to the average SNR based on the selected second correspondence information. Select and notify modulation parameter selection section 404.
  • Modulation parameter selection section 404 determines the modulation parameter selected by threshold correction section 402 as the modulation parameter for each channel.
  • the threshold value determination unit 405 may set the correction width selection table so that the second correspondence information is selected.
  • the same MCS is selected for each channel based on the average SNR, so that the MCS corresponding to the reception quality of the plurality of channels as a whole is selected. To improve throughput. Can do.
  • the processing delay is variable.
  • the present invention is applied to a system having a variable packet length as an example of a system having a variable processing delay.
  • FIG. 22 is a block diagram showing an example of the configuration of the receiver 270 in the seventh embodiment.
  • the receiver 270 has a configuration in which a processing delay estimation unit 271 is added to the receiver 200 of FIG. Note that the transmitter uses the transmitter 100 of FIG. 14, but the notification information generation unit 109 generates notification information that notifies packet length information in addition to the adaptive modulation control information.
  • Multiplexer 103 includes a data symbol sequence output from mapping section 102, a notification information (adaptive modulation control information and packet length information) symbol sequence output from notification information generation section 109, a pilot generation section
  • the pilot symbol system ⁇ IJ output from is multiplexed. Thereafter, the symbol sequence output from the multiplex state unit 103 is converted into an analog signal, and the process of transmitting from the wireless transmission unit 107 to the receiver 270 via the antenna unit 116 is the same.
  • receiver 270 the process from reception of a signal transmitted from transmitter 100 by radio reception section 201 to conversion into a frequency domain signal by FFT section 204 is the same.
  • the symbol sequence output from the FFT unit 204 is separated into a data symbol sequence, a symbol sequence for notification information (adaptive modulation control information and packet length information), and a pilot symbol sequence in a demultiplexing unit 205, and data
  • the symbol sequence is output to demapping section 206
  • the notification information symbol sequence is output to adaptive demodulation control section 208 and processing delay estimation section 271
  • the pilot symbol sequence is output to reception quality measurement section 209.
  • adaptive modulation control information is sent to adaptive demodulation control section 208
  • packet length information is sent to adaptive demodulation control section 208 and processing delay estimation section 271.
  • Adaptive demodulation control section 208 indicates adaptive demodulation control information (indicating MCS for each transmission data or channel) based on the notification information indicated by the symbol sequence for notification information sent from demultiplexer section 205. Information, packet length information) to the demapping unit 206 and the decoding unit 207.
  • Demapping section 206 demaps the data symbol sequence output from demultiplexing section 205 based on adaptive demodulation control information and packet length information.
  • the bit sequence output from demapping section 206 is subjected to error correction decoding in decoding section 207, and received data is extracted.
  • decoding section 207 performs decoding based on the adaptive demodulation control signal and packet length information sent from adaptive demodulation control section 208.
  • Reception quality measuring section 209 measures the reception quality for each channel from the pilot symbol sequence separated by demultiplexing section 205. Here, we will explain the case of measuring SNR for each channel.
  • Processing delay estimation section 271 estimates the processing delay based on the packet length information sent from demultiplexing section 205.
  • the f detector 301 detects f as the reception quality fluctuation rate.
  • the MCS determination unit 400 receives the reception quality measurement result measured by the reception quality measurement unit 209, the processing delay information estimated by the processing delay estimation unit 271 and the f detection unit 301.
  • MCS for each channel is determined based on f detected in step 1, and M for each channel is determined.
  • Information indicating CS is sent to the report information generation unit 210.
  • the report information generation unit 210 After the report information generation unit 210 generates the report information symbol sequence, the converted analog signal is transmitted from the radio transmission unit 215 to the transmitter 100, and the demultiplexing unit 113 reports the data symbol sequence and the report information. The process is the same until the received data is extracted from the data symbol series after being separated into information symbol series. On the other hand, the report information symbol sequence output from the demultiplexing unit 113 is sent to the adaptive modulation control unit 108.
  • Adaptive modulation control section 108 sends adaptive modulation control information to encoding section 101 and mapping section 102 in order to perform adaptive modulation processing based on the report information indicated by the report information symbol sequence. Furthermore, adaptive modulation control section 108 sends adaptive modulation control information to notification information generation section 109. And send packet length information. Notification information generation section 109 generates a notification information symbol sequence for notifying receiver 270 of notification information (adaptive modulation control information and packet length information).
  • FIG. 23 is a block diagram showing an example of the configuration of the MCS determination unit 470 of the present embodiment.
  • the MCS determination unit 470 includes a reception quality reference value calculation unit 401, a threshold correction unit 407, a threshold table storage unit 403, and an MCS selection unit 404.
  • the threshold correction unit 407 uses the f detection result and the processing delay as the reception quality fluctuation rate.
  • the threshold correction unit 407 inputs information for specifying (calculating) the reception quality variation rate that is not the reception quality variation rate itself.
  • the threshold correction unit 407 receives the input f detection result and processing delay estimation result.
  • the threshold correction unit (correction unit) in FIG. 16 or FIG. 23 is the information for specifying (calculating) the reception quality variation rate itself or the reception quality variation rate (information related to the reception quality variation rate).
  • the fluctuation rate related information including any of the above can be input, and the reception quality fluctuation rate can be acquired based on the input fluctuation rate related information.
  • Reception quality reference value calculation section 401 calculates a reception quality reference value (here, average SNR) based on the reception quality measurement result.
  • the threshold correction unit 407 receives the reception quality reference value calculated by the reception quality reference value calculation unit 401, the processing delay T estimated by the processing delay estimation unit 271 and the f detection result detected by the f detection unit 301. Based on the
  • the threshold table stored in the threshold table storage unit 403 is corrected, and a corrected threshold table (correspondence correction information) is output.
  • the MCS selection unit 404 compares the corrected threshold table sent from the threshold correction unit 407 with the reception quality measurement result for each channel, and selects and outputs the MCS for each channel. Note that regarding the calculation method of the correction width in the threshold correction unit 407, the force S is used to use the method described in the first embodiment.
  • the processing delay estimation unit 271 estimates the processing delay T from the downlink packet length.
  • Figure 24 shows downlink and uplink. The state of packet transmission / reception is shown. In FIG. 24, description will be made using an example of a wireless communication system, with a transmitter as a base station and a receiver as a terminal.
  • the downlink packet includes notification information and downlink transmission data
  • the uplink packet includes report information and uplink transmission data.
  • the packet shown in FIG. 24 may include a force S indicating only notification information or report information and data, and pilot symbols or the like may be multiplexed.
  • L is the downlink packet length
  • T is the time required for processing in the terminal.
  • T is the propagation time (shaded area in Figure 24)
  • L is the uplink packet length
  • ⁇ is the base
  • Ch UL BS This is the time required for processing within the ground station.
  • the terminal estimates T by obtaining information about L
  • Processing delay estimation section 271 estimates processing delay (processing delay time) T
  • the base station determines the feedback cycle of the report information, includes the information indicating the feedback cycle in the notification information and notifies the terminal, and the terminal sends the report information to the base station at the feedback cycle notified from the base station.
  • the present invention can be applied by estimating the processing delay based on the feedback period in the processing delay estimation unit.
  • the processing delay is variable, it is possible to detect a temporal variation in reception quality (reception quality variation rate) by estimating the processing delay. .
  • the correspondence information is corrected based on the temporal variation of reception quality (reception quality variation rate) and reception quality (reception quality reference value), thereby reducing communication quality degradation and setting an appropriate transmission rate.
  • the processing delay estimation unit may be arranged in the transmitter.
  • the transmitter transmits a packet transmitted by itself. Length L and received packet length L
  • the transmitter also needs the receiver to process a packet of length L.
  • the transmitter can estimate the processing delay T.
  • the transmitter (base station) determines the reception quality report cycle described in the second half of the sixth embodiment, since the transmitter (base station) itself determines the report cycle, the determined report cycle Processing delay can be calculated based on!
  • the f detector 301 detects f as an example of the reception quality fluctuation rate.
  • the rate of variation in reception quality is not limited to this.
  • the difference value of SNR of each channel at a plurality of times No power.
  • the transmitter or receiver will detect f
  • the fluctuation rate detection unit inputs the SNR of each channel measured by the reception quality measurement unit 209, and calculates the difference value of the SNR by holding the input SNR of each channel for a predetermined time. For example, the SNR measured last time is held in the fluctuation rate detection unit, and the reception quality is calculated by calculating the difference between the SNR measured this time input from the reception quality measurement unit 209 and the previously measured SNR. The rate of change can be obtained.
  • the fluctuation rate detection unit is arranged in the transmitter, the SNR of each channel measured by the reception quality measurement unit 209 of the receiver is input.
  • the difference value of the reception quality information at different times (received) It is also possible to calculate the correction range based on the temporal variation of the actual reception quality and the reception quality of the entire channel (channel state), and the Doppler frequency can be calculated. The same effects as when used can be obtained. In addition, it is possible to grasp the temporal variation of reception quality regardless of the moving speed of the communication device. This makes it possible to select a transmission rate that adapts to the channel state and reduce the degradation of communication quality.
  • the power for explaining the case where the difference value of the reception quality information at different times is used as the reception quality fluctuation rate, and in addition to this, any of the Doppler frequencies (f, f T
  • two indicators may be used.
  • the reception quality fluctuation rate the difference value and the Doppler frequency of the reception quality information can be acquired, and the one with the larger fluctuation rate can be selected and used. In this case, it is determined in advance so that the sizes can be compared by associating the two indices. Alternatively, one of the two indicators can be selected and used depending on the situation. Note that the correction range information is prepared so as to correspond to two indicators (two types are prepared, or a relational expression is set such that one indicator value is associated with the other indicator value). Keep it.
  • the correspondence information is corrected based on the correction range determined based on the channel state (reception quality) and the temporal variation of the reception quality.
  • the average SNR is used as the reception quality reference value, but an index value other than the average SNR may be used as the reception quality reference value.
  • a correction range corresponding to a combination of either the maximum value or the minimum value of reception quality and the reception quality fluctuation rate may be set.
  • the maximum value or the minimum value of the reception quality is used instead of the average SNR.
  • the value used as the reception quality reference value is calculated as the reception quality information power, and the reception quality reference value shown in FIG.
  • the value calculation unit 401 also uses the value used as the reception quality reference value for the reception quality. It will be calculated from the information. For example, if the table (Fig. 8, Fig. 11, Fig. 13) is generated using the maximum value of the reception quality information (SNR) shown in Fig. 4 to Fig. 6, the maximum value of the reception quality measurement result is obtained in S11 of Fig. 7. Will be extracted.
  • SNR reception quality information
  • FIG. 1 is a diagram showing an example of propagation path characteristics at time t and time t-T.
  • FIG. 2 is a diagram showing an example of a mechanism that prevents required quality from being satisfied in adaptive modulation processing.
  • FIG. 3 is a diagram showing an example of a function that satisfies the required quality by correcting the correspondence information in adaptive modulation processing.
  • FIG. 4 shows an example of the probability density of SNR fluctuation corresponding to the instantaneous SNR when the average SNR is OdB.
  • FIG. 5 shows an example of the probability density of SNR fluctuation corresponding to the instantaneous SNR when the average SNR is 10 dB.
  • FIG. 6 shows an example of the probability density of SNR fluctuation corresponding to the instantaneous SNR when the average SNR is 20 dB.
  • FIG. 7 is a diagram showing an example of MCS determination processing for each channel in the first embodiment.
  • FIG. 8 is a diagram showing an example of correction width information.
  • FIG. 9 is a diagram showing an example of the relationship between the packet error rate and the correction width when the average SNR is OdB.
  • FIG. 10 is a diagram showing an example of the relationship between the packet error rate and the correction width when the average SNR is 10 dB.
  • FIG. 11 is a diagram showing an example of correction width information different from FIG.
  • FIG. 12 is a diagram showing an example of MCS determination processing for each channel in the second embodiment.
  • FIG. 13 is a diagram showing an example of a table for specifying a threshold table from an average SNR and a reception quality fluctuation rate.
  • FIG. 14 is a block diagram showing an example of a configuration of a transmitter in a third embodiment.
  • FIG. 15 is a block diagram showing an example of a configuration of a receiver in the third embodiment.
  • FIG. 16 is a block diagram showing an example of the configuration of the MCS determination unit of the third embodiment.
  • FIG. 17 is a block diagram showing an example of the configuration of the MCS determination unit of the fourth embodiment.
  • FIG. 18 A block diagram illustrating an example of a configuration of a transmitter according to the fifth embodiment.
  • [Sen 19] is a block diagram showing an example of a configuration of a receiver in the fifth embodiment.
  • Sono 21 is a diagram showing an example of correspondence information used in the sixth embodiment.
  • FIG. 22 It is a block diagram showing an example of the configuration of the receiver in the seventh embodiment.
  • FIG. 23 is a block diagram showing an example of the configuration of the MCS determination unit of the seventh embodiment.
  • FIG. 24 is a diagram showing an example of packet transmission / reception on the downlink and uplink. 25] This is a diagram showing a method for estimating the propagation path using the primary outer fence as an example of estimating the propagation path information using the outer fence.

Abstract

L'invention a pour objectif de proposer une technologie consistant à réduire une détérioration de qualité de transmission par rapport à des procédés classiques, même dans l'environnement où un canal de propagation fluctue. Ladite technologie consiste également à sélectionner une vitesse de transmission appropriée, notamment à sélectionner une vitesse de transmission appropriée en tenant compte d'un changement de qualité de réception avec le temps et d'une qualité de réception. L'invention concerne un dispositif de communication qui effectue une communication en utilisant une pluralité de canaux. Ledit dispositif de communication est doté d'une section de détermination de paramètre de modulation pour sélectionner (S13) un paramètre de modulation correspondant à des informations de qualité de réception (rapport signal sur bruit - SNR) de chaque canal par l'utilisation d'informations corrigées de relation d'association. Les informations corrigées de relation d'association sont fournies par la détermination d'une plage de correction (S13), selon une valeur de référence de qualité de réception (par exemple, des informations de SNR moyen obtenues en effectuant la moyenne du SNR des canaux) (S11) et une vitesse de fluctuation de la qualité de réception (S12) indiquant une fluctuation de qualité de réception avec le temps, ainsi que par la correction des informations de relation d'association qui associent le SNR avec le paramètre de modulation par l'utilisation de la plage de correction déterminée (S14).
PCT/JP2007/066858 2006-09-14 2007-08-30 Dispositif de communication, dispositif de détermination de paramètre de modulation, système de communication et procédé de communication WO2008032580A1 (fr)

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JP2010278737A (ja) * 2009-05-28 2010-12-09 Advanced Telecommunication Research Institute International 無線通信システム
WO2010150897A1 (fr) * 2009-06-25 2010-12-29 京セラ株式会社 Procédé de calcul de seuil et station de base sans fil
JP2011010039A (ja) * 2009-06-25 2011-01-13 Kyocera Corp 無線基地局及び補正値算出方法
JP2011044943A (ja) * 2009-08-21 2011-03-03 Kddi Corp 符号化方式選択装置、符号化方式選択方法およびプログラム
JP2013141063A (ja) * 2011-12-28 2013-07-18 Panasonic Corp 通信装置、及び通信システム
JP2013211668A (ja) * 2012-03-30 2013-10-10 Kddi R & D Laboratories Inc 移動体通信システム、基地局及び信号伝送システム

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WO2006075547A1 (fr) * 2005-01-11 2006-07-20 Sharp Kabushiki Kaisha Dispositif de commande de modulation adaptative et dispositif de radiocommunication
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WO2006075547A1 (fr) * 2005-01-11 2006-07-20 Sharp Kabushiki Kaisha Dispositif de commande de modulation adaptative et dispositif de radiocommunication
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JP2009267841A (ja) * 2008-04-25 2009-11-12 Kyocera Corp 無線通信システム、無線基地局および無線通信方法
JP2010278737A (ja) * 2009-05-28 2010-12-09 Advanced Telecommunication Research Institute International 無線通信システム
WO2010150897A1 (fr) * 2009-06-25 2010-12-29 京セラ株式会社 Procédé de calcul de seuil et station de base sans fil
JP2011010039A (ja) * 2009-06-25 2011-01-13 Kyocera Corp 無線基地局及び補正値算出方法
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JP2011044943A (ja) * 2009-08-21 2011-03-03 Kddi Corp 符号化方式選択装置、符号化方式選択方法およびプログラム
JP2013141063A (ja) * 2011-12-28 2013-07-18 Panasonic Corp 通信装置、及び通信システム
JP2013211668A (ja) * 2012-03-30 2013-10-10 Kddi R & D Laboratories Inc 移動体通信システム、基地局及び信号伝送システム

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