JP2008167347A - Wireless receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform wireless communication with much more transmission capacitance and much higher transmission definition. <P>SOLUTION: In the wireless receiver, wireless receiving circuits 23a-23d receive radio signals from a wireless transmitter 100 by means of antennas 21a-24d. A controller 20 calculates an eigenvalue in a specific transmission mode scheme of a MIMO communication system on the basis of a wireless reception signal and refers to a threshold table for eigenvalues to control a wireless transmitter 200 so as to select one modulation scheme between 16QAM and 64QAM and to generate a radio signal using the selected modulation scheme. A threshold value λA2 in switching from 16QAM to QPSK in the threshold table, a threshold value λB1 in switching from QPSK to 16QAM, a threshold value λA3 in switching from 64QAM to 16QAM and a threshold value λB2 in switching from 16QAM to 64QAM are different and ¾λB1-λA2¾ and ¾λB2-λA3¾ are different. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radio receiving apparatus that performs radio communication by adaptively switching radio parameters such as a modulation scheme and an error correction coding scheme with a radio transmitting apparatus.

  In a mobile communication system, a phase modulation method (Phase Shift Keying; hereinafter referred to as PSK) that changes the phase of a carrier according to transmission data, or a quadrature amplitude modulation (Quadrature Amplitude Modulation) that changes the amplitude and phase of a carrier according to transmission data. , QAM)) is used. Each of PSK and QAM includes a plurality of modulation schemes having different amounts of data that can be transmitted in one symbol, that is, the number of modulation levels. For example, PSK includes modulation schemes such as BPSK (Binary PSK, hereinafter referred to as BPSK), QPSK (Quadrature PSK, hereinafter referred to as QPSK), and 8-phase PSK, and the QAM scheme includes modulation schemes such as 16QAM and 64QAM. including. Here, the modulation multilevel number increases in the order of BPSK, QPSK, 8-phase PSK, 16QAM, and 64QAM, and the transmission rate increases. Therefore, if wireless communication is performed using 64QAM, data can be transmitted in a shorter time than when other modulation schemes are used.

  However, when the amount of data that can be transmitted with one symbol increases, the phase and amplitude level between different symbols become close, and therefore, the data is easily affected by multipath such as reflection, transmission, and diffraction. As a result, there is a problem that a reception error occurs in the mobile station, the number of data retransmission requests to the base station increases, and the throughput decreases. In order to solve this problem, an error correction technique such as an error correction coding method for adding redundant information to transmission data is used in the field of wireless communication. However, the number of data retransmission requests from the mobile station to the base station can be reduced by error correction. However, since redundant information is added to the transmission data, the amount of information that can be actually transmitted increases as the error correction coding rate increases. There arises a problem that there is less.

  Patent Document 1 describes an adaptive modulation method in which one modulation method is adaptively selected and used from a plurality of modulation methods having different transmission rates based on channel quality estimated by a mobile station.

Japanese Patent Application Laid-Open No. 2004-23145.

  However, in the adaptive modulation method described in Patent Document 1, when the channel quality fluctuates in the vicinity of the channel quality threshold for switching the modulation method, the modulation method is frequently switched, and the base station and the mobile station There was a problem that discontinuity occurred in communication.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and in a wireless receiver that performs wireless communication by adaptively switching wireless parameters such as a modulation scheme and an error correction coding scheme with a wireless transmitter. An object of the present invention is to provide a wireless receiver capable of stably performing wireless communication having a large transmission capacity and high transmission quality as compared with the above.

A wireless receiver according to a first invention is
Receiving means for receiving at least one wireless signal from the wireless transmission device by a plurality of antennas;
Radio reception comprising: control means for selecting a predetermined radio parameter based on the received radio reception signal and controlling the radio transmission apparatus so as to generate the radio signal using the selected radio parameter In the device
The radio parameter includes at least one of a plurality of different modulation schemes and a plurality of different error correction coding schemes,
A first threshold value of an evaluation value related to the radio reception signal when switching from the second radio parameter to the first radio parameter when the radio parameter includes first, second and third radio parameters; , A second threshold value of the evaluation value related to the radio reception signal when switching from the first radio parameter to the second radio parameter, and the above when switching from the third radio parameter to the second radio parameter The third threshold value of the evaluation value related to the radio reception signal is different from the fourth threshold value of the evaluation value related to the radio reception signal when switching from the second radio parameter to the third radio parameter. A threshold value table that indicates the relationship of the first to fourth threshold values with respect to the first to third wireless parameters. Equipped with a stage,
The magnitude of the difference between the first threshold and the second threshold is set different from the magnitude of the difference between the third threshold and the fourth threshold. ,
The control means calculates an evaluation value related to the radio reception signal based on the received radio reception signal, refers to the threshold value table, and selects the selected radio parameter and the calculated radio reception signal. One of the wireless parameters is selected on the basis of the evaluation value for the wireless parameter.

  In the wireless communication apparatus, the evaluation value is a received power intensity of the wireless reception signal.

In the wireless communication device, the receiving means receives a plurality of wireless signals from the wireless transmission device by a plurality of antennas,
The evaluation value is an eigenvalue in an eigentransmission mode system in a MIMO (Multi-Input Multi-Output) communication system.

A wireless communication apparatus according to a second invention is
Receiving means for receiving a plurality of radio signals from a radio transmitting apparatus by a plurality of antennas;
Radio reception comprising: control means for selecting a predetermined radio parameter based on the received radio reception signal and controlling the radio transmission apparatus to generate the radio signal using the selected radio parameter In the device
The radio parameter includes at least one of a plurality of different modulation schemes and a plurality of different error correction coding schemes,
A first threshold value of an evaluation value related to the radio reception signal when switching from the second radio parameter to the first radio parameter when the radio parameter includes first, second and third radio parameters; , A second threshold value of the evaluation value related to the radio reception signal when switching from the first radio parameter to the second radio parameter, and the above when switching from the third radio parameter to the second radio parameter The third threshold value of the evaluation value related to the radio reception signal is different from the fourth threshold value of the evaluation value related to the radio reception signal when switching from the second radio parameter to the third radio parameter. And stores a plurality of threshold value tables indicating the relationship of the first to fourth threshold values with respect to the first to third wireless parameters. Comprising a storage unit,
The evaluation value is an eigenvalue in an eigentransmission mode scheme in a MIMO (Multi-Input Multi-Output) communication system,
At least one of the magnitude of the difference between the first threshold and the second threshold and the magnitude of the difference between the third threshold and the fourth threshold is the plurality of Of at least two of the threshold tables are different from each other,
The control means calculates the eigenvalue based on the received radio reception signal, detects a time change of the calculated eigenvalue, and determines the plurality of threshold values based on the time change of the detected eigenvalue. Selecting and referring to one threshold table of the tables, and selecting one of the radio parameters based on the selected radio parameter and the calculated eigenvalue; And

  In the wireless communication apparatus, the time variation of the eigenvalue is a fluctuation range within a predetermined period of the eigenvalue.

  In the wireless communication device, the time variation of the eigenvalue is an average value of the eigenvalue within a predetermined period.

  According to the wireless reception device of the first invention, when the wireless parameter includes the first, second, and third wireless parameters, the wireless reception signal when switching from the second wireless parameter to the first wireless parameter is provided. The first threshold value of the evaluation value, the second threshold value of the evaluation value related to the radio reception signal when switching from the first radio parameter to the second radio parameter, and the second value from the third radio parameter A third threshold value of the evaluation value related to the radio reception signal when switching to the radio parameter, and a fourth threshold value of the evaluation value related to the radio reception signal when switching from the second radio parameter to the third radio parameter; Are set to be different from each other, and the magnitude of the difference between the first threshold and the second threshold is different from the magnitude of the difference between the third threshold and the fourth threshold. Storing a threshold value table set so. Further, an evaluation value related to the wireless reception signal is calculated based on the received wireless reception signal, and a wireless communication is performed based on the selected wireless parameter and the calculated evaluation value regarding the wireless reception signal by referring to the threshold value table. One radio parameter is selected from the parameters, and the radio transmission apparatus is controlled to generate a radio signal using the selected radio parameter. Therefore, compared with the prior art, the frequency of communication discontinuity due to switching of wireless parameters is reduced, and wireless communication with a large transmission capacity and high transmission quality can be performed.

  Further, according to the radio receiving apparatus according to the second invention, when the radio parameter includes the first, second and third radio parameters, the MIMO communication for switching from the second radio parameter to the first radio parameter A first threshold of eigenvalues in the eigentransmission mode system in the system, a second threshold of eigenvalues when switching from the first radio parameter to the second radio parameter, and a second from the third radio parameter A plurality of eigenvalue third threshold values for switching to the radio parameter and a fourth eigenvalue threshold value for switching from the second radio parameter to the third radio parameter are different from each other. The threshold table is stored. Here, at least one of the magnitude of the difference between the first threshold and the second threshold and the magnitude of the difference between the third threshold and the fourth threshold is a plurality of The threshold value tables are set to be different from each other between at least two of the threshold value tables. Further, an eigenvalue is calculated based on the received radio reception signal, a time change of the calculated eigenvalue is detected, and a threshold of one of a plurality of threshold tables is detected based on the time change of the detected eigenvalue. A value table is selected and referred to, one radio parameter is selected from a plurality of radio parameters based on the selected radio parameter and the calculated eigenvalue, and a radio signal is used using the selected radio parameter. The wireless transmission device is controlled to generate Therefore, compared to the prior art, even when the eigenvalue changes with time, the frequency of communication discontinuity due to switching of the modulation method does not increase, and wireless communication with high transmission capacity and high transmission quality is performed. Can do.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each following embodiment, the same code | symbol is attached | subjected about the same component.

First embodiment.
FIG. 1 is a block diagram illustrating a configuration of a wireless transmission system including a wireless transmission device 100 and a wireless reception device 200 according to the first embodiment.

  In FIG. 1, a wireless transmission device 100 and a wireless reception device 200 perform wireless communication using a specific transmission mode method in a MIMO (Multi-Input Multi-Output, hereinafter referred to as MIMO) communication system. Hereinafter, the operation principle of the specific transmission mode method in the MIMO communication system will be described. It should be noted that in this specification, mathematical formulas input in an image and mathematical formulas input in a text are mixedly used, and in order to identify each mathematical formula, a series of serial numbers (1) described at the end of each mathematical formula. , (2),... Are referred to as “expression (1), expression (2),.

  A MIMO communication system increases transmission capacity by spatially multiplexing a plurality of signal sequences transmitted simultaneously in the same frequency band by using a plurality of antenna elements in each of a transmitter and a receiver, and performs MIMO decoding. This is a technique for increasing the total transmission rate related to a plurality of signal sequences after conversion processing, and is also referred to as space division multiplexing (SDM).

  When the number of antenna elements of the transmitter is nt and the number of antenna elements of the receiver is nr, the received signal y at the receiver can be expressed by the following equation.

[Equation 1]
y = Hx + w (1)

Here, y representing a received signal is a vector of size nr, each element of which represents a signal received by each antenna element of the receiver. H is a matrix of size nr × nt and is called a channel matrix, and each element H _ij is a propagation coefficient between the j-th antenna element of the transmitter and the i-th antenna element of the receiver, that is, Represents the amount of phase rotation and the amount of amplitude attenuation of signals transmitted and received between these antenna elements. Also, x representing the transmitted signal, the size is a vector of nt, and each element x _i is a signal transmitted from each antenna element of the transmitter, represent signals that are orthogonal to each other. w is a vector of size nr, each element of which represents thermal noise received at each antenna element of the receiver.

  In order to obtain the channel matrix H at the receiver, the receiver stores a predetermined pilot signal x in advance, the transmitter transmits this known pilot signal x to the receiver, and the pilot signal x stored in advance by the receiver. And the channel matrix H is calculated from the equation (1) based on the received signal y (that is, the transmitted pilot signal x).

  Here, when the singular value decomposition (SVD) for the channel matrix H is performed, the following equation is obtained.

In Equation (2), U is a matrix of size nr × nr, Σ is a matrix of size nr × nt, and the element in the i-th row and i-th column is σ _i (0 ≦ i ≦ q). The other elements are 0 matrixes, and V is a matrix of size nt × nt. U _i and v _i are i-th column vectors of matrices U and V, respectively, and are orthogonal to other column vectors. q is the rank of the channel matrix H, and in the following explanation, q = min (nt, nr). A superscript H represents a complex conjugate transpose. Here, the matrix U and V, size is the identity matrix _{I nr} and size nr × nr for matrix _{I nt} of nt × nt satisfy the following equation.

[Equation 2]
U ^H U = I _nr (3)
[Equation 3]
V ^H V = I _nt (4)

  Further, when eigenvalue decomposition (EVD) is performed, the following equation is obtained.

In equation (5), λ _i is the i-th eigenvalue of the channel matrix product HH ^H , and λ _i = σ _i ² . Note that i = 1, 2,..., Q in descending order of eigenvalues.

The vector u _i ^H, the matrix is orthogonal to the other row vectors, which are elements of U ^H, are used to weight the signals transmitted from the respective antenna elements of the transmitter (amplitude and phase), the vector u _i Are orthogonal to other column vectors that are elements of the matrix U, and are used to weight signals received at each antenna element of the receiver. By using weights in this way, orthogonal directivity can be obtained.

Here, from Expression (1), the received signal power is Hx (Hx) ^H = HH ^H xx ^H. The matrix xx ^H represents the transmission signal power. However, since each element of the vector x is a signal orthogonal to each other, the matrix xx ^H is a diagonal matrix diag [x ₁ x ₁ ^* , x ₂ x ₂ ^* , ..., x _q x _q ^* ]. On the other hand, the matrix HH ^H is a diagonal matrix diag [λ ₁ , λ ₂ ,..., Λ _q ]. That is, in the specific transmission mode scheme in the MIMO communication system, the propagation channel includes a maximum of q independent transmission paths (hereinafter, i-th propagation channel is referred to as channel i). Furthermore, it is possible to separate a plurality of propagation paths by using orthogonal weights in the antenna elements of the transmitter and the receiver, and the received signal power in each propagation path at this time is λ _i x _i x _i ^* and Become. When the signals x _i are all equal, the ratio of the received signal power in each channel is the ratio of the eigenvalue λ _i .

  According to the eigen transmission mode method in the MIMO communication system described above, the transmission capacity of the MIMO communication system is given by the following equation.

Here, the SNR is the total transmission signal power-to-noise ratio, that is, SNR / nt = x _i x _i ^* . The unit of C _MIMO is [bit / second / Hz]. On the other hand, in the case of normal one-to-one communication (Single-Input Single-Output: SISO), the transmission capacity is obtained by the following equation.

In Expression (7), h is a propagation coefficient, and the unit of C _SISO is [bit / second / Hz].

For example, in order to simplify the comparison between Expression (6) and Expression (7), hh ^* = λ _i = λ, q = nt, and SNR · λ / nt >> 1. At this time, the transmission capacity of Expression (6) is calculated as follows.

  On the other hand, the transmission capacity of Expression (7) is calculated as follows.

For example, when nt = 4 and SNR · λ = 1024, MIMO transmission capacity C _MIMO = 4 · (10−2) = 32 [bits / second / Hz] and SISO transmission capacity C _SISO = 10 [bits] / Sec / Hz], and it can be seen that the MIMO transmission capacity is higher than the SISO transmission capacity.

As described above, in the MIMO communication system, the directivity orthogonal to each other is allocated to a plurality of signal sequences to spatially multiplex signals to increase the transmission capacity, and thereby the plurality of signal sequences after the MIMO decoding process. The total transmission speed can be increased. Also, according to Equation (6), it is understood that the MIMO transmission capacity increases as the eigenvalue λ _i calculated from the channel matrix H increases.

In FIG. 1, a wireless transmission device 100 includes a controller 10, a MIMO encoding circuit 11, wireless transmission circuits 12a to 12d each including antennas 14a to 14d, and a wireless reception circuit 13 including an antenna 15. Composed. Here, the controller 10 is a controller for controlling the overall operation of the wireless transmission device 100 and each operation of the MIMO encoding circuit 11, the wireless transmission circuits 12a to 12d, and the wireless reception circuit 13. The controller 10 uses the radio receiving circuit 13 and the antenna 15 connected thereto from the radio receiving device 200, which will be described in detail later, and uses the eigenvalue λ _i (i = 1, 2, 3, 4 in this embodiment). ), A vector u _i ^H , and a modulation scheme notification signal including a modulation scheme which is a radio parameter used in each channel, and the received eigenvalue λ _i , vector u _i ^H , and the modulation scheme used in each channel. Based on this, each operation of the MIMO encoding circuit 11 and the wireless transmission circuits 12a to 12d is controlled. Here, the modulation scheme used in each channel is any one of QPSK, 16QAM, or 64QAM.

The MIMO encoding circuit 11 stores a predetermined pilot signal in advance, serially / parallel converts the input transmission data into four transmission signals each having a frame configuration, and performs predetermined transmission for each transmission signal for each frame. A pilot signal is added and output to the radio transmission circuits 12a to 12d. Each of the radio transmission circuits 12a to 12d modulates a carrier wave using either QPSK, 16QAM, or 64QAM according to a transmission signal inputted thereto, generates a modulation signal, and power-amplifies the modulation signal based on an eigenvalue λ _i The amplitude and phase of the modulated signal after power amplification are changed based on the vector u _i ^H , respectively. Further, each of the radio transmission circuits 12a to 12d performs digital / analog conversion on the modulated signal whose amplitude and phase have been changed, and then converts the modulation signal to a radio transmission signal to a high frequency and performs band-pass filtering on the radio transmission signal. And wirelessly transmit to the wireless reception device 200 via the antennas 14a to 14d.

  In FIG. 1, a radio reception apparatus 200 includes a controller 20 including a threshold table memory 26 that stores a threshold table, which will be described in detail later, a MIMO decoding circuit 25, and antennas 21a to 21d. Circuits 23 a to 23 d and a wireless reception circuit 24 including an antenna 22 are configured.

The radio reception circuits 23a to 23d receive the four radio signals from the radio transmission device by the antennas 21a to 21d. Here, the wireless reception circuits 23a to 23d respectively include a band-pass filter that performs predetermined band-pass filtering processing on a wireless reception signal that is a wireless transmission signal received using the antennas 21a to 21d, and band-pass filtering. A high-frequency amplifier that amplifies the subsequent radio reception signal, a mixing circuit that converts the amplified radio reception signal to an intermediate frequency signal having a predetermined intermediate frequency, and predetermined intermediate frequency signal processing for the intermediate frequency signal An intermediate frequency circuit for performing demodulation, a demodulating circuit for demodulating the processed intermediate frequency signal into a demodulated signal using a modulation method used in each channel selected by the controller 20, and MIMO decoding by analog / digital conversion of the demodulated signal And an analog / digital converter for outputting to the conversion circuit 25. Each of the radio reception circuits 23a to 23d performs a predetermined band-pass filtering process on the radio reception signal that is the received radio transmission signal, amplifies the radio reception signal after band-pass filtering, and radio reception after amplification Low-frequency conversion of the signal to an intermediate frequency signal having a predetermined intermediate frequency, predetermined intermediate frequency signal processing is performed on the intermediate frequency signal, and processing is performed using the modulation method used in each channel selected by the controller 20 After demodulating the subsequent intermediate frequency signal into a demodulated signal, the demodulated signal is analog / digital converted and output to the MIMO decoding circuit 25. Further, the MIMO decoding circuit 25 uses the vector u _i calculated by the controller 20 to perform the MIMO encoding process on the four demodulated signals from the radio receiving circuits 23a to 23d, thereby performing four demodulations. The received signal and the transmitted pilot signal are separated from the signal, respectively, and reception data is generated and output based on the four received signals, and the four transmitted pilot signals are output to the controller 20.

The controller 20 is a controller for controlling the overall operation of the wireless transmission device 200 and the operations of the MIMO decoding circuit 25, the wireless reception circuits 23a to 23d, and the wireless transmission circuit 24. The eigenvalue λ _i in the eigentransmission mode scheme in the MIMO communication system is calculated based on the signal, and the selected modulation scheme and the calculated one are calculated with reference to a threshold value table, which will be described in detail later with reference to FIGS. Based on the eigenvalue λ _i , one modulation scheme is selected from each of QPSK, 16QAM, and 64QAM in each channel, and the radio transmission apparatus 100 is controlled to generate a radio signal using the selected modulation scheme. Features.

Here, the controller 20 stores in advance a pilot signal identical to the predetermined pilot signal stored in the MIMO encoding circuit 11, and the MIMO decoding circuit in accordance with the operation principle of the eigentransmission mode method in the MIMO communication system described above. After calculating the channel matrix H for each frame based on the four transmitted pilot signals from 25 and the predetermined pilot signal, the eigenvalue λ _i of the channel matrix product HH ^H is calculated. Next, the controller 20 calculates vectors u _i and u _i ^H by performing singular value decomposition on the calculated channel matrix H. Further, the controller 20 executes a modulation method selection process, which will be described in detail later, for each channel and for each predetermined number of frames. Here, in the modulation method selection process, the controller 20 refers to the threshold value table stored in the threshold value table memory 26 based on the calculated eigenvalue λ _i and determines the modulation method used in each channel. Select one from QPSK, 16QAM and 64QAM. Further, the controller 20 generates a modulation scheme notification signal including the eigenvalue λ _i , the vector u _i ^H , and the modulation scheme used in each selected channel, and uses the radio transmission circuit 24 and the antenna 22 connected thereto. By wirelessly transmitting to the controller 10 of the wireless receiving device 100, the wireless transmitting device 100 is controlled to generate a wireless signal using the selected modulation method. Further, the controller 20 outputs the vector u _i and the modulation scheme used in each channel to the MIMO decoding circuit 25 and the radio reception circuits 23a to 23d.

FIG. 2 is a sequence diagram showing the operation of the wireless transmission system of FIG. In FIG. 2, the MIMO encoding circuit 11 of the wireless transmission device 100 serially / parallel converts input transmission data into four transmission signals each having a frame configuration, and each transmission signal is predetermined for each frame. Are added to the radio transmission circuits 12a to 12d. Each of the radio transmission circuits 12a to 12d modulates a carrier wave using either QPSK, 16QAM, or 64QAM according to a transmission signal inputted thereto, generates a modulation signal, and power-amplifies the modulation signal based on an eigenvalue λ _i The amplitude and phase of the modulated signal after power amplification are changed based on the vector u _i ^H , respectively. Further, each of the radio transmission circuits 12a to 12d performs digital / analog conversion on the modulated signal whose amplitude and phase have been changed, and then converts the modulation signal to a radio transmission signal to a high frequency and performs band-pass filtering on the radio transmission signal. And wirelessly transmit to the wireless reception device 200 via the antennas 14a to 14d.

Further, in FIG. 2, the controller 20 of the wireless reception device 200 calculates a channel matrix H for each frame based on the four transmitted pilot signals from the MIMO decoding circuit 25 and the predetermined pilot signal. After that, the eigenvalue λ _i of the channel matrix product HH ^H is calculated. Thereafter, the controller 20 executes a modulation method selection process, which will be described in detail later, for each channel and for each predetermined number of frames, selects one modulation method to be used for each channel from QPSK, 16QAM, and 64QAM, A controller of radio receiving apparatus 100 using λ _i , vector u _i ^H , and a modulation scheme notification signal including a modulation scheme used in each selected channel, using radio transmission circuit 24 and antenna 22 connected thereto. 10 is transmitted wirelessly.

  Based on the received modulation method notification signal, the controller 10 of the wireless transmission device 100 modulates each of the wireless transmission circuits 12a to 12d using either QPSK, 16QAM, or 64QAM according to the transmission signal to which the carrier wave is input. To control.

  FIG. 3 is a diagram showing an example of the threshold value table stored in the threshold value table memory 26 of FIG. FIG. 4 is a graph showing the relationship between the threshold value λAn and λBn of the threshold value table stored in the threshold value table memory 26 of FIG. 1 and the multi-value level n according to the first embodiment. It is.

The threshold value table of FIG. 3 shows that when the first radio parameter is QPSK, the second radio parameter is 16QAM, and the third radio parameter is 64QAM, the eigenvalue λ _i when switching from 16QAM to QPSK. the threshold Ramudaei2, the threshold λB1 eigenvalues lambda _i when switching from QPSK to 16QAM, the threshold λA3 eigenvalues lambda _i when switching from 64QAM to 16QAM, eigenvalues when switching to 64QAM from 16QAM lambda 11 is a table showing the relationship of threshold values λA2, λB1, λA3, and λB2 with respect to the first to third radio parameters, which are set to be different from the threshold value λB2 of _i .

  In FIG. 3, multi-value levels n (n = 1, 2, 3) are values respectively indicating a plurality of different modulation schemes which are radio parameters used in the radio transmission circuits 12a to 12d in FIG. A higher modulation level n indicates a modulation scheme with a large modulation multi-level number and a large transmission capacity. Here, the modulation scheme having the multi-level level “1” is QPSK, the modulation mode having the multi-level level “2” is 16 QAM, and the modulation mode having the multi-level level “3” is 64 QAM. .

  Here, in the present embodiment, as shown in FIG. 4, the thresholds λAn and λBn are set such that the throughput when transmitting transmission data using a modulation scheme having a multi-level n is a predetermined threshold value. The lower limit eigenvalue λAno and the positive constant D are set so as to satisfy the following two expressions.

[Equation 4]
λA2o <λA2 <λB1 <λA3o <λA3 <λB2 (10)
[Equation 5]
| ΛB1-λA2 | = | λB2-λA3 | = D (11)

  Here, as the threshold λB1 is closer to the lower limit eigenvalue λA2o and the threshold λB2 is closer to the lower limit eigenvalue λA3o, the controller 20 uses a modulation scheme having a higher multi-value level n. In the transmission system, the transmission capacity increases. On the other hand, as the threshold λA2 is larger than the lower limit eigenvalue λA2o and the threshold λA3 is larger than the lower limit eigenvalue λA3o, the controller 20 uses a modulation scheme having a lower multi-value level n. Although the transmission capacity is reduced in the system, the number of switching of the modulation method is minimized.

In the present embodiment, the threshold λA1 at the lowest multilevel level "1" has sufficiently small values eigenvalue lambda _i can not have, for example, "-999", the best multilevel The threshold value λB3 at the activation level “3” is set to have a sufficiently large value that the eigenvalue λ _i cannot have, for example, “999”.

  FIG. 5 is a flowchart showing a modulation method selection process executed by the controller 20 of FIG. 1 according to the first embodiment. Note that the modulation scheme selection processing in FIG. 5 is executed for each channel.

5, first, in step S1, the multi-value level n is set to the initial value “3”, and the threshold values λA3 and λB3 are set from the threshold value table (see FIG. 3) of the threshold value table memory 26. read out. Next, in step S2, it is determined whether or not the eigenvalue λ _i in the current frame is smaller than the threshold value λAn. If YES, the process proceeds to step S3. If NO, the process proceeds to step S5. Further, after subtracting 1 from the multilevel level n in step S3, the threshold values λAn and λBn are read from the threshold value table of the threshold value table memory 26 in step S4, and the process returns to step S2.

In step S5, it is determined whether or not the eigenvalue λ _i in the current frame is greater than the threshold value λBn. If YES, the process proceeds to step S6. If NO, the process proceeds to step S2. Further, in step S6, 1 is added to the multi-value level n, and then the process proceeds to step S4. Note that the modulation scheme selection process of FIG. 5 is executed for each frame, whereby the multilevel halftoning level n for each channel is determined for each frame, and the modulation scheme used for each channel is selected.

FIG. 6A is a graph showing an example of the temporal change of the eigenvalue λ _i , and FIG. 6B is a diagram in which the modulation scheme selection process of FIG. 5 is performed on the eigenvalue λ _i of FIG. It is a graph which shows the time change of the multi-value quantization level n at the time.

In FIG. 6B, since the eigenvalue λ _i is larger than the threshold value λA1 and smaller than the threshold value λB1 in the period from the timing t0 to the timing t1, the multilevel level n is set to “1”, and the channel QPSK is used in i. Since the eigenvalue λ _i exceeds the threshold value λB1 at the timing t1, the multilevel level n is set to “2”, and 16QAM is used in the channel i. Further, since the eigenvalue λ _i falls below the threshold value λA2 at the timing t2, the multilevel level n is set to “1”, and QPSK is used in the channel i. Furthermore, since eigenvalue λ _i exceeds threshold value λB1 at timing t3, multilevel level n is set to “2”, and 16QAM is used in channel i. Furthermore, since eigenvalue λ _i exceeds threshold value λB2 at timing t4, multi-value level n is set to “3”, and 64QAM is used in channel i. Further, at the timing t5, the eigenvalue λ _i is lower than λA3, so the multi-value level n is set to “2”, and 16QAM is used in the channel i.

  As described above in detail, according to the radio receiving apparatus 200 according to the present embodiment, the magnitudes | λB1-λA2 | and | λB2-λA3 | of the differences between the threshold values are set to positive constants D, respectively. Since the modulation scheme used in each channel is selected with reference to the threshold value table (see equation (11) and FIGS. 3 and 4), the magnitude of the difference between the threshold values | λB1−λA2 | and | Compared to a case where a threshold value table in which λB2-λA3 | is set to “0” is referred to, the number of modulation scheme switching processes in the wireless transmission device 200 is reduced. Accordingly, the frequency of occurrence of communication discontinuity is reduced, and wireless communication with a large transmission capacity and high transmission quality can be performed.

Incidentally, the modulation scheme selection processing of FIG. 5, after the eigenvalues lambda _i is compared with the threshold value λAn In step S2, have been compared the eigenvalues lambda _i and threshold λBn In step S3, the present invention is not limited thereto The eigenvalue λ _i may be compared with the threshold value λAn after the eigenvalue λ _i is compared with the threshold value λBn. Further, in the modulation scheme selection process of FIG. 5, when the multi-value level n is the lowest value “1”, the determination result in step S2 may be always NO. Furthermore, in the modulation scheme selection process of FIG. 5, when the multi-level level n is the highest value “3”, the determination result in step S5 may be always NO.

Modification of the first embodiment.
FIG. 7 shows the standardization of the wireless reception device 200 normalized by the wavelength of the wireless reception signal when the wireless transmission device 100 of FIG. 1 is installed in a base station and the wireless transmission device 200 is mounted on a mobile body. it is a graph showing the instantaneous value of the eigenvalues level of each eigenvalue lambda _i with respect to the travel distance. As shown in FIG. 7, the lower the eigenvalue λ _i has a lower eigenvalue level, the greater the fluctuation range of the eigenvalue λ _i . As compared with the first embodiment, the modified example of the first embodiment uses threshold values λA2, λB1, λA3, and λB2 in the threshold value table stored in advance in the threshold value table memory 26 of FIG. Is set to satisfy Expression (10) and satisfy (λB1-λA2)> (λB2-λA3).

  FIG. 8 shows the relationship between the threshold value λAn and λBn of the threshold value table stored in the threshold value table memory 26 of FIG. 1 and the multi-value level n according to a modification of the first embodiment. It is a graph. As shown in FIG. 8, a threshold value λB2 for switching the modulation method from a modulation method having a multi-value level “2” to a modulation method having a multi-value level “3”, and a multi-value level “3” Is set to a constant Da (0 <Da <D), and the magnitude Δλ3 of the difference from the threshold value λA3 for switching the modulation method from the modulation method having the multivalue level “2” to the modulation method having the multivalue level “2” is set. A threshold value λB1 for switching the modulation scheme from a modulation scheme having a digitization level “1” to a modulation scheme having a multilevel quantization level “2”, and a modulation scheme having a multilevel binarization level “2”. A constant Δλ2 is set to a difference magnitude Δλ2 from a threshold value λA2 for switching the modulation method to a modulation method having “1”.

9 (a) is a graph showing an example of time change of the eigenvalue lambda _i, FIG. 9 (b), the threshold λAn and λBn 8 relative eigenvalues lambda _i shown in FIG. 9 (a) 6 is a graph showing the time change of the multi-value level n when the modulation scheme selection process of FIG. 5 is executed.

In FIG. 9B, since the eigenvalue λ _i is larger than the threshold value λA1 and smaller than the threshold value λB1 in the period from the timing t6 to the timing t7, the multi-value level n is set to “1”. QPSK is used in i. Since the eigenvalue λ _i exceeds the threshold value λB1 at the timing t7, the multilevel level n is set to “2”, and 16QAM is used in the channel i. Furthermore, since the eigenvalue λ _i exceeds the threshold value λB2 at timing t8, the multilevel level n is set to “3”, and 64QAM is used in the channel i. At timing t9, the eigenvalue λ _i falls below the threshold value λA3, so that the multilevel level n is set to “2”, and 16QAM is used in the channel i.

As described above in detail, according to the modification of the first embodiment, the thresholds λA2, λB1, λA3, and λB2 satisfy the equation (10) based on the actually measured values of the eigenvalues λ _i and ( λB1-λA2)> (since λB2-λA3) was set so as to satisfy the eigenvalues fluctuation range of lambda _i even when the changes according to the level of the eigenvalues lambda _i, in the wireless transmission device 200, the QPSK and 16QAM As compared with the first embodiment, the frequency of communication discontinuity due to the switching of the modulation scheme is less than the number of times of switching between 16QAM and 64QAM. Wireless communication with a reduced transmission capacity and a high transmission quality can be performed.

  Note that the characteristic configuration of the modification of the first embodiment can be applied to second and third embodiments described later.

Second embodiment.
As shown in FIG. 7, in a MIMO communication system, as the eigenvalue lambda _i having a low eigenvalue levels, large fluctuation range of eigenvalues lambda _i. In the second embodiment, compared to the first embodiment, the controller 20 of the wireless reception device 200 stores the first threshold value table and the second threshold value table in the threshold value table memory 26 in advance. stored, to calculate the eigenvalue lambda _i based on the received wireless reception signal, detects a fluctuation width Ramudapp _i within a predetermined time period of the calculated eigenvalues lambda _i, the detected eigenvalues lambda _i width variations Ramudapp _i Based on, one of the first and second threshold tables is selected and referred to, and is used in each channel i based on the modulation scheme used in each channel i and the calculated eigenvalue λ _i. One of the modulation schemes is selected from QPSK, 16QAM, and 64QAM. Here, the magnitude of the difference between the threshold λB1 and the threshold λA2 and the magnitude of the difference between the threshold λB2 and the threshold λA3 are different from each other between the first and second threshold tables. Is set.

  FIG. 10A shows the threshold values λAn and λBn of the first threshold value table stored in the threshold value table memory 26 of FIG. 1 and the multi-value levels according to the modification of the second embodiment. FIG. 10B is a graph of the second threshold value table stored in the threshold value table memory 26 of FIG. 1 according to a modification of the second embodiment. It is a graph which shows the relationship between threshold value (lambda) An and (lambda) Bn, and the multi-value level n.

  As shown in FIG. 10A, the threshold values λAn and λBn of the first threshold value table are respectively stored in the threshold value table memory 26 of FIG. 1 according to the first embodiment. It has the same value as the threshold values λAn and λBn of the value table (see FIGS. 3 and 4). Here, in the first threshold value table, the value of the threshold λB1 is λB1a, and the value of the threshold λB2 is λB2a. Further, as shown in FIG. 10B, in the second threshold value table, only threshold values λB1 and λB2 have values different from threshold values λB1 and λB2 in the first threshold value table, respectively. Here, in the second threshold value table, when the threshold value λB1 is λB1b and the threshold value λB2 is λB2b, the threshold values λAn and λBn in the second threshold value table (10) and the following expression are satisfied.

[Equation 6]
λB1b> λB1a (12)

[Equation 7]
λB2b> λB2a (13)

  In this embodiment, in the second threshold value table, Δλ2 = | λB1b−λA2 | = Db> D and Δλ3 = | λB2b−λA3 | = Db.

  FIG. 11 is a flowchart showing a modulation scheme selection process executed by the controller 20 of FIG. 1 according to the second embodiment. Note that the modulation scheme selection processing in FIG. 5 is executed for each channel.

In FIG. 11, first, in step S10, the multi-value level n is set to the initial value “3”, and the threshold value table to be referred to is the first threshold value table in the threshold value table memory 26 (FIG. 10 ( Refer to a), and read the threshold values λA3 and λB3 from the threshold value table. Further, in step S11, the eigenvalue λ _i within the predetermined period Δt (Δt> 0) is stored. Next, in step S12, it is determined whether or not the eigenvalue λ _i in the latest frame is smaller than the threshold value λAn. If YES, the process proceeds to step S13, and if NO, the process proceeds to step S15. Further, after subtracting 1 from the multi-value level n in step S13, the threshold values λAn and λBn are read from the threshold value table in step S14, and the process returns to step S11.

In step S15, based on the eigenvalue λ _i within the predetermined period Δt stored in step S11, the fluctuation range λpp _i that is the peak-to-peak value of the eigenvalue λ _i within the predetermined period Δt is detected. Further, in step S16, it is determined whether or not the fluctuation range λpp _i is larger than the threshold value λppc. If YES, the process proceeds to step S18, and if NO, the process proceeds to step S17. In step S17, the threshold value table to be referred to is set in the first threshold value table, and the process proceeds to step S19. In step S18, the threshold value table to be referred to is set in the second threshold value table. Proceed to step S19. Further, in step S19, the threshold values λAn and λBn are read from the threshold value table, and the process proceeds to step S20. In step S20, the eigenvalue λ _i within the predetermined period Δt is stored. Next, in step S21, it is determined whether or not the eigenvalue λ _i in the latest frame is larger than the threshold value λBn. If YES, the process proceeds to step S22. If NO, the process proceeds to step S24. Further, after adding 1 to the multi-value level n in step S22, the threshold values λAn and λBn are read from the threshold value table in step S23, and the process returns to step S11.

In step S24, based on the eigenvalue λ _i in the predetermined period Δt stored in step S20, the fluctuation range λpp _i that is the peak-to-peak value of the eigenvalue λ _i in the predetermined period Δt is detected. Further, in step S25, it is determined whether or not the fluctuation range λpp _i is larger than the threshold value λppc. If YES, the process proceeds to step S27, and if NO, the process proceeds to step S26. In step S26, the threshold value table to be referred to is set in the first threshold value table, and the process proceeds to step S28. In step S27, the threshold value table to be referred to is set in the second threshold value table. Proceed to step S28. In step S28, the threshold values λAn and λBn are read from the threshold value table, and the process returns to step S11.

According to the modulation method selection processing of FIG. 11, the multi-value level n in each channel is determined every predetermined period Δt, and the modulation method used in each channel is selected. In step S11 of FIG. 11, for example, eigenvalues λ _i for 10 frames are stored, and in step S20, eigenvalues λ _i for the next 10 frames are stored. Further, the processes in steps S15 to S19 in FIG. 11 and the processes in steps S24 to S28 are the same. Further, in the modulation scheme selection process of FIG. 5, when the multi-level level n is the lowest value “1”, the determination result in step S12 may be always NO. Further, in the modulation scheme selection process of FIG. 5, when the multi-level level n is the highest value “3”, the determination result in step S21 may be always NO.

FIG. 12A is a graph showing an example of the temporal change of the eigenvalue λ _i , and FIG. 12B is a graph showing the modulation scheme selection process of FIG. 11 performed on the eigenvalue λ _i of FIG. It is a graph which shows the time change of the multi-value quantization level n at the time.

In FIG. 12A, the controller 20 has a fluctuation range λpp that is a peak-to-peak value of the eigenvalue λ _i within the time period Δt every predetermined time period Δt (for example, a certain time period). _i is detected. In FIG. 12A, for convenience of illustration, only the first time period Δt and the fluctuation range λpp _i of the eigenvalue λ _i within the time period are shown. In FIG. 12B, in the period from the timing t10 to the timing t13, the fluctuation range λpp _i of the eigenvalue λ _i within the predetermined time period Δt is equal to or smaller than the threshold λppc, and the first threshold table is referred to. On the other hand, in the period after timing t13, the variation width λpp _i of the eigenvalue λ _i within the predetermined time period Δt is larger than the threshold value λppc, and the second threshold value table is referred to. The controller 20 may detect the fluctuation range λpp _i of the eigenvalue λ _i within the time period Δt for every predetermined time period Δt / 2, for example, every predetermined time period Δt / 2.

12 (a) and 12 (b), the eigenvalue λ _i is larger than the threshold value λA2 and smaller than the threshold value λB2 (= λB2a) in the period from the timing t10 to the timing t11. n is set to “2”, and 16QAM is used in channel i. Further, since the eigenvalue λ _i falls below the threshold value λA2 at timing t11, the multilevel level n is set to “1”, and QPSK is used in the channel i. Further, at the timing t12, the eigenvalue λ _i exceeds the threshold value λB1 (= λB1a), the multilevel level n is set to “2”, and 16QAM is used in the channel i.

Furthermore, since the eigenvalue λ _i falls below the threshold value λA2 at timing t13, the multi-value level n is set to “1”, and QPSK is used in the channel i. Furthermore, since eigenvalue λ _i exceeds threshold value λB1 (= λB1b) at timing t14, multilevel level n is set to “2”, and 16QAM is used in channel i.

As described above in detail, according to the second embodiment, the controller 20 of the wireless reception device 200 stores the first threshold value table in the threshold value table memory 26 and the threshold value at each multi-value level n. The measured value of the eigenvalue λ _i so that the magnitude Δλn (n = 2, 3) of the difference between the value λBn (n−1) and the threshold value λAn is larger than the value in the first threshold value table. Is stored in advance, and when the fluctuation width λpp _i of the eigenvalue λ _i within a predetermined period is equal to or smaller than the predetermined value λppc, the first threshold table is referred to When the fluctuation width λpp _i is larger than the predetermined value λppc, the first threshold value table is referred to, and the modulation scheme used in each channel i is selected one by one from QPSK, 16QAM and 64QAM. Therefore, when the fluctuation width Ramudapp _i eigenvalue lambda _i is larger, the number of switching processes of the modulation scheme is not increased in the wireless transmission apparatus 200, as a result, in comparison with the first embodiment, the eigenvalues lambda _{Even when} the fluctuation range λpp _{i of i} changes with time, the frequency of communication discontinuity due to switching of the modulation method does not increase, and wireless communication with a large transmission capacity and high transmission quality can be performed.

Third embodiment.
As shown in FIG. 7, in a fading environment, as the eigenvalue lambda _i having a low eigenvalue levels, a large fluctuation width of the eigenvalues lambda _i. In the third embodiment, compared to the second embodiment, the controller 20 of the wireless reception device 200 detects the average value Avei within a predetermined period of the calculated eigenvalue λ _i and detects the detected eigenvalue λ. One of the first and second threshold value tables is selected and referred to based on the average value Avei of _i . In the third embodiment, the first and second threshold tables are respectively the first and second threshold tables in the second embodiment (see FIGS. 10A and 10B). ).

FIG. 13 is a flowchart showing a modulation scheme selection process executed by the controller 20 of FIG. 1 according to the third embodiment. The modulation method selection process in FIG. 13 is obtained by replacing steps S15, S16, S24, and S25 of the modulation method selection process in FIG. 11 with steps S15a, S16a, S24a, and S25a, respectively. In step S15a, based on the eigenvalue λ _i within the predetermined period Δt stored in step S11, the average value Ave _i of the eigenvalue λ _i within the predetermined period Δt is detected. Further, in step S16a, it is determined whether or not the average value Ave _i is larger than the threshold value Avec. If YES, the process proceeds to step S18. If NO, the process proceeds to step S17. In step S24a, based on the eigenvalue λ _i within the predetermined period Δt stored in step S20, an average value Ave _i of the eigenvalue λ _i within the predetermined period Δt is detected. Further, in step S25a, it is determined whether or not the average value Ave _i is larger than the threshold value Avec. If YES, the process proceeds to step S27. If NO, the process proceeds to step S26.

  By the modulation method selection processing of FIG. 13, the multilevel level n in each channel is determined every predetermined period Δt, and the modulation method used in each channel is selected. Further, the processing in steps S15a to S19 in FIG. 13 is the same as the processing in steps S24a to S28.

14 (a) is a graph showing an example of time change of the eigenvalue lambda _i, FIG. 14 (b), and performs modulation scheme selection process of FIG. 13 with respect to the eigenvalue lambda _i shown in FIG. 14 (a) It is a graph which shows the time change of the multi-value quantization level n at the time.

In FIG. 14A, the controller 20 detects the average value Ave _i of the eigenvalues λ _i every predetermined time period Δt. In FIG. 14A, only the first time period Δt is shown for convenience of illustration. In FIG. 14B, in the period from timing t15 to timing t16, the average value Ave _i of the eigenvalue λ _i within the predetermined time period Δt is larger than the threshold value Avec, and the second threshold value table is referred to. On the other hand, in the period after the timing t16, the average value Ave _i of the eigenvalues λ _i within the predetermined time period Δt is equal to or less than the threshold value Avec, and the first threshold value table is referred to. Note that the controller 20 may detect the average value Ave _i of the eigenvalues λ _i within the time period Δt for every predetermined time period Δt / 2, for example, greater than 0 and shorter than the time period Δt.

14A and 14B, the eigenvalue λ _i is larger than the threshold value λA2 and smaller than the threshold value λB2 (= λB2a) in the period from the timing t15 to the timing t16. n is set to “2”, and 16QAM is used in channel i. Further, since the eigenvalue λ _i falls below the threshold value λA2 at timing t16, the multi-value level n is set to “1”, and QPSK is used in the channel i. Further, at the timing t17, the eigenvalue λ _i exceeds the threshold value λB1 (= λB1b), the multilevel level n is set to “2”, and 16QAM is used in the channel i.

As described above in detail, according to the third embodiment, the controller 20 of the wireless reception device 200 stores the first threshold value table in the threshold value table memory 26 and the threshold value at each multi-value level n. A second threshold value table set in advance so that the difference Δλn between the value λBn (n−1) and the threshold value λAn is larger than the value in the first threshold value table; When the average value Ave _i of the eigenvalues λ _i within the period is equal to or smaller than the predetermined value Avec, the first threshold value table is referred to, and when the average value Ave _i is larger than the predetermined value Avec, the second threshold value table is referred to. , The modulation scheme used in each channel i was selected from QPSK, 16QAM and 64QAM. Therefore, when the eigenvalue λ _i increases momentarily, the modulation method is not switched, and wireless communication with a larger transmission capacity and higher transmission quality can be performed as compared with the first embodiment. Further, when the average value Ave _i eigenvalue lambda _i is larger, the number of switching processes of the modulation scheme is not increased in the wireless transmission apparatus 200, as a result, changes the average value Ave _i eigenvalue lambda _i is the time Sometimes, the frequency of communication discontinuity caused by the switching of the modulation method does not substantially change, and wireless communication with a large transmission capacity and high transmission quality can be performed as compared with the first embodiment. .

  In each of the above embodiments, the wireless transmission circuits 12a to 12d use QPSK, 16QAM, or 64QAM, but the present invention is not limited to this, and other modulation schemes such as BPSK or 8-phase PSK may be used. Alternatively, four or more modulation schemes having different transmission capacities may be used.

In each of the above embodiments, the eigenvalue λ _i in the eigentransmission mode scheme in the MIMO communication system is used as an evaluation value for switching between modulation schemes having different multilevel levels n. Not limited to this, the received power intensity of each wireless reception signal in the wireless reception device 200 may be used.

  Further, in each of the above embodiments, the wireless transmission device 100 and the wireless reception device 200 perform wireless communication using the specific transmission mode method in the MIMO communication system, but the present invention is not limited to this. The wireless transmission device 100 generates one wireless signal and transmits it to the wireless reception device 200. The wireless reception device 200 receives the wireless signal using a plurality of antenna elements, and receives the received wireless reception signal. Thus, the adaptive control process may be executed. In this case, the wireless reception device 200 may use the minimum value or the average value of the received power intensity of each wireless reception signal as an evaluation value for switching between modulation schemes having different multilevel levels n. As a result, compared to the prior art, the frequency of communication discontinuity associated with switching of the modulation method is reduced, and wireless communication with a large transmission capacity and high transmission quality can be performed.

  Further, in each of the above embodiments, a multilevel level n, that is, a plurality of modulation schemes having different modulation multilevel numbers are used as radio parameters. However, the present invention is not limited to this, and the radio parameters are modulated. It may include at least one of a plurality of modulation schemes having different multi-value numbers and a plurality of error correction coding schemes having different error correction coding rates.

  In the second and third embodiments, the difference between the threshold λA2 and the threshold λB1 and the difference between the threshold λA3 and the threshold λB2 are the first and second values. The threshold value tables are set to be different from each other. However, the present invention is not limited to this, and the difference between the threshold value λA2 and the threshold value λB1 and the difference between the threshold value λA3 and the threshold value λB2 One of the sizes may be set to be different between the first and second threshold value tables.

In the second and third embodiments, the controller 20 calculates the eigenvalue λ _i based on the received radio reception signal, and detects the fluctuation range or average value of the calculated eigenvalue λ _i. The invention is not limited to this, and a value indicating a temporal change in the calculated eigenvalue λ _i may be detected.

Furthermore, in the second and third embodiments, two threshold tables are stored in the threshold table memory. However, the present invention is not limited to this, and three or more threshold tables are stored. May be. In this case, at least one of the difference between the threshold λA2 and the threshold λB1 and the difference between the threshold λA3 and the threshold λB2 is at least two of the plurality of threshold tables. The threshold values are set to be different from each other. Furthermore, the controller 20 calculates the eigenvalues lambda _i based on the received wireless reception signal, detects the time variation of the calculated eigenvalues lambda _i, a plurality of teeth on the basis of the time variation of the detected eigenvalues lambda _i One threshold table in the threshold table is selected and referred to, and one radio parameter is selected from the plurality of radio parameters based on the selected radio parameter and the calculated eigenvalue λ _i. .

  As described above in detail, according to the wireless reception device of the first invention, when the wireless parameter includes the first, second, and third wireless parameters, the second wireless parameter is changed to the first wireless parameter. A first threshold value of an evaluation value related to the radio reception signal when switching, a second threshold value of an evaluation value related to the radio reception signal when switching from the first radio parameter to the second radio parameter, and a third The third threshold value of the evaluation value related to the radio reception signal when switching from the radio parameter to the second radio parameter, and the evaluation value related to the radio reception signal when switching from the second radio parameter to the third radio parameter The fourth threshold value is set to be different from each other, the magnitude of the difference between the first threshold value and the second threshold value, and the third threshold value and the fourth threshold value; of And size to store a threshold value table set to be different from each other in. Further, an evaluation value related to the wireless reception signal is calculated based on the received wireless reception signal, and a wireless communication is performed based on the selected wireless parameter and the calculated evaluation value regarding the wireless reception signal by referring to the threshold value table. One radio parameter is selected from the parameters, and the radio transmission apparatus is controlled to generate a radio signal using the selected radio parameter. Therefore, compared with the prior art, the frequency of communication discontinuity due to switching of wireless parameters is reduced, and wireless communication with a large transmission capacity and high transmission quality can be performed.

  Further, according to the radio receiving apparatus according to the second invention, when the radio parameter includes the first, second and third radio parameters, the MIMO communication for switching from the second radio parameter to the first radio parameter A first threshold of eigenvalues in the eigentransmission mode system in the system, a second threshold of eigenvalues when switching from the first radio parameter to the second radio parameter, and a second from the third radio parameter A plurality of eigenvalue third threshold values for switching to the radio parameter and a fourth eigenvalue threshold value for switching from the second radio parameter to the third radio parameter are different from each other. The threshold table is stored. Here, at least one of the magnitude of the difference between the first threshold and the second threshold and the magnitude of the difference between the third threshold and the fourth threshold is a plurality of The threshold value tables are set to be different from each other between at least two of the threshold value tables. Further, an eigenvalue is calculated based on the received radio reception signal, a time change of the calculated eigenvalue is detected, and a threshold of one of a plurality of threshold tables is detected based on the time change of the detected eigenvalue. A value table is selected and referred to, one radio parameter is selected from a plurality of radio parameters based on the selected radio parameter and the calculated eigenvalue, and a radio signal is used using the selected radio parameter. The wireless transmission device is controlled to generate Therefore, compared to the prior art, even when the eigenvalue changes with time, the frequency of communication discontinuity due to switching of the modulation method does not increase, and wireless communication with high transmission capacity and high transmission quality is performed. Can do.

1 is a block diagram illustrating a configuration of a wireless transmission system including a wireless transmission device 100 and a wireless reception device 200 according to a first embodiment. It is a sequence diagram which shows operation | movement of the wireless transmission system of FIG. It is a figure which shows an example of the threshold value table memorize | stored in the threshold value table memory 26 of FIG. 6 is a graph showing a relationship between threshold values λAn and λBn of a threshold value table stored in the threshold value table memory 26 of FIG. 1 and a multi-value level n according to the first embodiment. It is a flowchart which shows the modulation system selection process performed by the controller 20 of FIG. 1 based on 1st Embodiment. (A) is a graph showing an example of a time change of the eigenvalue λ _i , and (b) is a multi-value when the modulation scheme selection process of FIG. 5 is executed on the eigenvalue λ _i of FIG. It is a graph which shows the time change of the conversion level n. When the wireless transmission device 100 of FIG. 1 is installed in a base station and the wireless transmission device 200 is mounted on a mobile body, each standardized travel distance of the wireless reception device 200 normalized by the wavelength of the wireless reception signal is shown. It is a graph which shows the instantaneous value of the eigenvalue level of eigenvalue (lambda) _i (i = 1,2,3,4). 7 is a graph showing a relationship between threshold values λAn and λBn of a threshold value table stored in the threshold value table memory 26 of FIG. 1 and a multi-value level n according to a modification of the first embodiment. (A) is a graph showing an example of the temporal change of the eigenvalue λ _i , and (b) shows the eigenvalue λ _i of FIG. 9A using threshold values λAn and λBn shown in FIG. 6 is a graph showing a time change of the multi-value level n when the modulation method selection process of FIG. 5 is executed. (A) shows the threshold values λAn and λBn of the first threshold value table stored in the threshold value table memory 26 of FIG. 1 and the multi-value level n according to the modification of the second embodiment. (B) shows a threshold value λAn of the second threshold value table stored in the threshold value table memory 26 of FIG. 1 according to a modification of the second embodiment, and It is a graph which shows the relationship between (lambda) Bn and the multi-value-ized level n. It is a flowchart which shows the modulation system selection process performed by the controller 20 of FIG. 1 based on 2nd Embodiment. (A) is a graph showing an example of a time change of the eigenvalue λ _i , and (b) is a multi-value when the modulation scheme selection process of FIG. 11 is executed on the eigenvalue λ _i of FIG. It is a graph which shows the time change of the conversion level n. It is a flowchart which shows the modulation system selection process performed by the controller 20 of FIG. 1 based on 3rd Embodiment. (A) is a graph showing an example of a temporal change of the eigenvalue λ _i , and (b) is a multi-value when the modulation scheme selection process of FIG. 13 is executed on the eigenvalue λ _i of FIG. It is a graph which shows the time change of the conversion level n.

Explanation of symbols

10 ... Controller,
11 ... MIMO encoding circuit,
12a to 12d: wireless transmission circuit,
13: Wireless receiver circuit,
14a-14d, 15 ... antenna,
20 ... Controller,
21a to 21d, 22 ... antennas 23a to 23d ... wireless receiving circuits,
24 ... wireless transmission circuit,
25 ... MIMO decoding circuit,
26: Threshold table memory,
100: wireless transmission device,
200: Wireless receiver.

Claims (6)

Receiving means for receiving at least one wireless signal from the wireless transmission device by a plurality of antennas;
Radio reception comprising: control means for selecting a predetermined radio parameter based on the received radio reception signal and controlling the radio transmission apparatus so as to generate the radio signal using the selected radio parameter In the device
The radio parameter includes at least one of a plurality of different modulation schemes and a plurality of different error correction coding schemes,
A first threshold value of an evaluation value related to the radio reception signal when switching from the second radio parameter to the first radio parameter when the radio parameter includes first, second and third radio parameters; , A second threshold value of the evaluation value related to the radio reception signal when switching from the first radio parameter to the second radio parameter, and the above when switching from the third radio parameter to the second radio parameter The third threshold value of the evaluation value related to the radio reception signal is different from the fourth threshold value of the evaluation value related to the radio reception signal when switching from the second radio parameter to the third radio parameter. A threshold value table that indicates the relationship of the first to fourth threshold values with respect to the first to third wireless parameters. Equipped with a stage,
The magnitude of the difference between the first threshold and the second threshold is set different from the magnitude of the difference between the third threshold and the fourth threshold. ,
The control means calculates an evaluation value related to the radio reception signal based on the received radio reception signal, refers to the threshold value table, and selects the selected radio parameter and the calculated radio reception signal. A wireless reception device that selects one of the wireless parameters based on the evaluation value for the wireless parameter.   The radio reception apparatus according to claim 1, wherein the evaluation value is a reception power intensity of the radio reception signal. The reception means receives a plurality of radio signals from the radio transmission device with a plurality of antennas,
The radio reception apparatus according to claim 1, wherein the evaluation value is an eigenvalue in an eigentransmission mode system in a MIMO (Multi-Input Multi-Output) communication system. Receiving means for receiving a plurality of radio signals from a radio transmitting apparatus by a plurality of antennas;
Radio reception comprising: control means for selecting a predetermined radio parameter based on the received radio reception signal and controlling the radio transmission apparatus to generate the radio signal using the selected radio parameter In the device
The radio parameter includes at least one of a plurality of different modulation schemes and a plurality of different error correction coding schemes,
A first threshold value of an evaluation value related to the radio reception signal when switching from the second radio parameter to the first radio parameter when the radio parameter includes first, second and third radio parameters; , A second threshold value of the evaluation value related to the radio reception signal when switching from the first radio parameter to the second radio parameter, and the above when switching from the third radio parameter to the second radio parameter The third threshold value of the evaluation value related to the radio reception signal is different from the fourth threshold value of the evaluation value related to the radio reception signal when switching from the second radio parameter to the third radio parameter. And stores a plurality of threshold value tables indicating the relationship of the first to fourth threshold values with respect to the first to third wireless parameters. Comprising a storage unit,
The evaluation value is an eigenvalue in an eigentransmission mode scheme in a MIMO (Multi-Input Multi-Output) communication system,
At least one of the magnitude of the difference between the first threshold and the second threshold and the magnitude of the difference between the third threshold and the fourth threshold is the plurality of Of at least two of the threshold tables are different from each other,
The control means calculates the eigenvalue based on the received radio reception signal, detects a time change of the calculated eigenvalue, and determines the plurality of threshold values based on the time change of the detected eigenvalue. Selecting and referring to one threshold table of the tables, and selecting one of the radio parameters based on the selected radio parameter and the calculated eigenvalue; A wireless receiver.   The radio reception apparatus according to claim 4, wherein the time variation of the eigenvalue is a fluctuation range of the eigenvalue within a predetermined period.   5. The radio reception apparatus according to claim 4, wherein the time variation of the eigenvalue is an average value of the eigenvalue within a predetermined period.

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