JP2018011219A - Reception device, transmission device, communication system and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reception device capable of securing a maximum communication capacity corresponding to a state of a radio transmission path while enabling a stable communication to be performed, a transmission device, a communication system and a communication method.SOLUTION: A reception device 200 comprises: a reception part for receiving a modulation signal transmitted from a transmission device 100; a demodulation part for calculating a parameter indicating a present state of a radio transmission path with the transmission device from the modulation signal received by the reception part, and demodulating the modulation signal; and a control part 300 for selecting a communication system, a modulation system and a signal bandwidth to be used for transmitting/receiving the modulation signal based on the parameter, setting the selected communication system, modulation system and signal bandwidth to be used for transmission/reception to the demodulation part as the systems and thee signal bandwidth to be used for demodulation, and transmitting a control signal indicating the selected communication system, modulation system and signal bandwidth to the transmission device.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reception device, a transmission device, a communication system, and a communication method that support a plurality of communication methods.

  As communication traffic increases in recent years, communication systems are required to have a larger communication capacity. For example, in Patent Document 1, a polarization multiplexing transmission method using an XPIC (Cross Polarization Interference Cancellation) method and a spatial multiplexing using a MIMO (Multiple-Input Multiple-Output) method. A communication method combined with a transmission method has been proposed.

  In the communication system described in Patent Document 1, since the multiplicity of signals can be increased, the communication capacity can be increased. However, when a communication device that supports the above two communication methods is actually operated, the stability of the communication by the polarization multiplexing transmission method and the spatial multiplexing transmission method changes depending on the state of the wireless transmission path, thereby realizing stable communication. Difficult to do.

  On the other hand, Patent Document 2 describes that the communication method is adaptively switched according to the state of the wireless transmission path.

Re-specialized WO2009 / 069798 JP2013-251915A

  Patent Document 2 described above does not disclose anything about a specific switching method of a communication method for realizing stable communication that does not cause communication interruption. Therefore, when actually operating a communication device that supports a plurality of communication methods, it is difficult to achieve stable communication even with reference to the technique described in Patent Document 2.

  The present invention has been made in order to solve the problems of the background art as described above, and enables a stable communication and a maximum amount of communication capacity according to the state of the wireless transmission path. An object is to provide an apparatus, a communication system, and a communication method.

In order to achieve the above object, a receiving device of the present invention includes a receiving unit that receives a modulated signal transmitted from a transmitting device;
While calculating a parameter indicating the current state of the wireless transmission path between the transmitter and the modulated signal received by the receiver, a demodulator that demodulates the modulated signal;
The communication method, modulation method and signal bandwidth used for transmission / reception of the modulated signal are selected based on the parameters, and the demodulation is performed assuming that the selected communication method, modulation method and signal bandwidth used for transmission / reception are used for the demodulation. A control unit configured to transmit a control signal indicating the selected communication method, modulation method, and signal bandwidth to the transmission device,
Have

The transmission device of the present invention includes a modulation unit that outputs a modulated signal modulated using a set modulation method,
A transmitter for transmitting the modulated signal;
A communication method, a modulation method, and a signal bandwidth used for transmission / reception of the modulated signal, selected by a receiving device that receives the modulated signal based on a parameter indicating a current state of a wireless transmission path with the receiving device. A setting unit that receives a control signal indicating the communication method used to generate a modulation signal according to the control signal, a modulation method, and a signal bandwidth in the modulation unit;
Have

  The communication system of the present invention includes the receiving device and the transmitting device.

In the communication method of the present invention, the receiving device
A parameter indicating the current state of the wireless transmission path between the transmitter and the modulation signal transmitted from the transmitter is calculated, and a communication scheme, a modulation scheme, and a signal band used for transmitting and receiving the modulated signal based on the parameter A width is selected, and the selected communication method, modulation method, and signal bandwidth are set in a demodulator that performs demodulation, and a control signal indicating the selected communication method, modulation method, and signal bandwidth is sent to the transmission device. Send
The transmitter is
This is a method for setting a communication method, a modulation method, and a signal bandwidth used for generating a modulated signal in a modulation unit according to a communication method, a modulation method, and a signal bandwidth indicated by the control signal received from the receiving device.

  ADVANTAGE OF THE INVENTION According to this invention, the maximum communication capacity according to the state of a wireless transmission path is securable, enabling the stable communication.

It is a block diagram which shows the example of 1 structure of the communication system of this invention. It is a block diagram which shows the example of 1 structure of the transmitter shown in FIG. FIG. 3 is a block diagram illustrating a configuration example of an analog modulation unit illustrated in FIG. 2. FIG. 2 is a block diagram illustrating a configuration example of a receiving device illustrated in FIG. 1. FIG. 5 is a block diagram illustrating a configuration example of an analog demodulator illustrated in FIG. 4. FIG. 3 is a block diagram illustrating a configuration example of a digital modulation unit illustrated in FIG. 2. FIG. 5 is a block diagram illustrating a configuration example of a digital demodulator illustrated in FIG. 4. FIG. 8 is a block diagram illustrating a configuration example of an amplitude phase adjustment circuit illustrated in FIG. 7. FIG. 8 is a block diagram illustrating a configuration example of a transversal filter included in the interference compensation circuit illustrated in FIG. 7 as a cross polarization interference compensator. It is a flowchart which shows operation | movement of 1st Example of the communication system of this invention. It is a block diagram which shows the structural example of 1st Example of a digital modulation part. It is a block diagram which shows the structural example of 1st Example of a digital demodulation part. It is a block diagram which shows the other structural example of 1st Example of a digital modulation part. It is a block diagram which shows the other structural example of 1st Example of a digital demodulation part. It is a flowchart which shows operation | movement of 2nd Example of the communication system of this invention. It is a block diagram which shows the structural example of 2nd Example of a digital modulation part. It is a block diagram which shows the structural example of 2nd Example of a digital demodulation part. It is a block diagram which shows the other structural example of 2nd Example of a digital modulation part. It is a block diagram which shows the other structural example of 1st Example of a digital demodulation part. It is a flowchart which shows operation | movement of 3rd Example of the communication system of this invention. It is a block diagram which shows the structural example of 3rd Example of a digital modulation part. It is a block diagram which shows the structural example of 3rd Example of a digital demodulation part. It is a block diagram which shows the other structural example of 3rd Example of a digital modulation part. It is a block diagram which shows the other structural example of 3rd Example of a digital demodulation part. It is a block diagram which shows the further another structural example of 3rd Example of a digital modulation part. It is a block diagram which shows the further another structural example of 3rd Example of a digital demodulation part.

Next, the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration example of a communication system according to the present invention.
As shown in FIG. 1, the communication system 1 of the present invention includes a transmission device 100 and a reception device 200 that are communication devices capable of supporting a plurality of communication methods.

The transmission apparatus 100 transmits one or a plurality of modulated signals modulated by the modulation scheme used in the selected communication scheme among the plurality of compatible communication schemes to the reception apparatus 200. When receiving the control signal from the receiving device 200, the transmission device 100 selects a communication method and a modulation method according to the control signal. The control signal is a signal that specifies a communication method and a modulation method used in the transmission device 100 and the reception device 200, and the transmission device 100 selects a modulation method to be used according to the control signal. Communication systems that can be supported by the transmission apparatus 100 and the reception apparatus 200 include a MIMO system, an STBC (Space Time Block Code) system, a PD (Polarized Wave Diversity) system, and an XPIC system. . The transmission device 100 and the reception device 200 may transmit and receive information using only one communication method, or may transmit and receive information by combining the following two communication methods.
MIMO system and PD system MIMO system and XPIC system STBC system and XPIC system STBC system and PD system Further, in the transmission apparatus 100 and the reception apparatus 200 of the present invention, well-known AMR (Adaptive Modulation Radio) and signals described later in each communication system Bandwidth switching control is also executed.

  The receiving apparatus 200 receives a transmission signal that is a modulated signal transmitted from the transmitting apparatus 100, and demodulates the received signal that is the received modulated signal. In addition, the receiving apparatus 200 controls to select a communication method, a modulation method, and a signal bandwidth based on a parameter calculated by the receiving apparatus 200 and indicating a state of a wireless transmission path between the transmitting apparatus 100 and the receiving apparatus 200. Part 300. The control unit 300 transmits a control signal indicating the selected communication method, modulation method, and signal bandwidth to the transmission device 100.

FIG. 2 is a block diagram illustrating a configuration example of the transmission apparatus illustrated in FIG.
As illustrated in FIG. 2, the transmission device 100 includes transmission antennas 101 and 102, a digital modulation unit (Di-MOD) 103, analog modulation units (An-MOD) 106 to 109, local oscillators 105 and 110, And a transmission circuit (RF) 111-114.

  The transmission antennas 101 and 102 are dual-polarization antennas that can transmit modulated signals having different polarizations. In the present embodiment, a modulated signal is transmitted and received using V (Vertical) polarization and H (Horizontal) polarization. The transmission antennas 101 and 102 are installed at an interval dT suitable for the MIMO scheme, for example.

  In the digital modulation unit 103, a modulation method used in the selected communication method among a plurality of communication methods that can be supported by the transmission apparatus 100 is set. The digital modulation unit 103 outputs a plurality of modulated signals to the analog modulation units 106 to 109, respectively. In the present embodiment, a maximum of four signals S1 to S4 are input to the digital modulation unit 103, and the digital modulation unit 103 modulates the input signal and converts the D / A (Digital to Analog) converted IQ signal. Output a maximum of four. Here, I is an abbreviation for “in-phase”, and Q is an abbreviation for “Quadrature”.

  The setting unit 104 sets the modulation scheme specified by the control signal received from the receiving device 200 to the digital modulation unit 103 and the analog modulation units 106 to 109. In FIG. 2, the setting unit 104 is connected only to the digital modulation unit 103 for simplification, but the actual setting unit 104 is connected to the digital modulation unit 103 and the analog modulation units 106 to 109, respectively.

  The local oscillator 105 generates an oscillation signal for converting the IQ signal into an IF (Intermediate Frequency) signal, and supplies the oscillation signal to the analog modulation units 106 to 109, respectively. In FIG. 2, the local oscillator 105 is connected only to the analog modulators 107 and 108 for simplification, but the actual local oscillator 105 is connected to the analog modulators 106 to 109, respectively.

FIG. 3 is a block diagram illustrating a configuration example of the analog modulation unit illustrated in FIG.
As illustrated in FIG. 3, the analog modulation units 106 to 109 include LPFs (Low-Pass Filters) 125-1 to 125-N (N is an integer equal to or greater than 1) and a Q-MOD 126.
The analog modulation units 106 to 109 remove aliasing noise generated by the D / A conversion of the digital modulation unit 103 by the LPFs 125-1 to 125-N. The analog modulation units 106 to 109 convert the IQ signals that have passed through the LPFs 125-1 to 125-N by the Q-MOD 126 using the oscillation signal of the local oscillator 105 into IF signals. The analog modulators 106 to 109 include LPFs 125-1 to 125-N that pass signals of different frequencies or lower, respectively, and the setting received from the setting unit 104 when the signal bandwidth of the input IQ signal is changed. In this configuration, an LPF having characteristics suitable for the changed signal bandwidth can be selected based on the signal.

  The transmission circuits 111 to 114 are circuits for transmitting the IF signals output from the analog modulation circuits 106 to 109. The transmission circuits 111 to 114 convert the input IF signal into an RF (Radio Frequency) signal using the oscillation signal of the local oscillator 110, amplify the RF signal, and receive the signal via the transmission antenna 101 or 102. 200.

FIG. 4 is a block diagram illustrating a configuration example of the receiving apparatus illustrated in FIG.
As illustrated in FIG. 4, the reception device 200 includes reception antennas 201 and 202, local oscillators 203 and 208, reception circuits (RF) 204 to 207, analog demodulation units (An-DEM) 209 to 212, digital A demodulator (Di-DEM) 213 and a controller 300 are included.

The receiving antennas 201 and 202 are installed at an interval dR suitable for a MIMO system, for example. The interval dR may be the same as the installation interval dT of the transmission antennas 101 and 102 provided in the transmission device 100, for example.
The local oscillator 203 generates an oscillation signal for converting the RF signal into an IF signal, and supplies the oscillation signal to the reception circuits 204 to 207, respectively.

  The reception circuits 204 to 207 receive RF signals that are a plurality of transmission signals transmitted from the transmission device 100. Specifically, the receiving circuits 204 to 207 receive the RF signal via the receiving antenna 201 or 202, convert the RF signal into an IF signal using the oscillation signal of the local oscillator 203, and the converted IF signal. Are output to the analog demodulation units 209 to 212.

Analog demodulation sections 209 to 212 convert each IF signal received from receiving circuits 204 to 207 into an IQ signal and output the IQ signal.
FIG. 5 is a block diagram showing a configuration example of the analog demodulator shown in FIG.
As illustrated in FIG. 5, the analog demodulation units 209 to 212 include a Q-DEM 232 and LPFs 233-1 to 233 -N (N is an integer equal to or greater than 1).

The Q-DEM 232 converts the input IF signal into an IQ signal using the oscillation signal generated by the local oscillator 208 and outputs the IQ signal. The LPFs 233-1 to 233 -N output IQ signals from which aliasing noise has been removed in order to suppress signal degradation due to aliasing noise that occurs in A / D (Analog to Digital) conversion.
The analog demodulation units 209 to 212 include LPFs 233-1 to 233 -N that allow signals of different frequencies or less to pass in order to cope with the case where the signal bandwidth of the IF signal is changed, and the signal bandwidth of the IF signal Is changed, an LPF having characteristics suitable for the signal bandwidth can be selected.

  The digital demodulation unit 213 converts each IQ signal output from the analog demodulation units 209 to 212 into a digital signal and demodulates it. From the digital demodulator 213, a maximum of four signals S1_OUT to S4_OUT are output according to the communication method used in the receiving apparatus 200.

  The control unit 300 reads a parameter indicating the state of the wireless transmission path between the transmission device 100 and the reception device 200 from the digital demodulation unit 213, and selects a communication method and a modulation method used by the transmission device 100 and the reception device 200. The parameter acquisition method and the communication method and modulation method selection method will be described later.

Next, the configuration of digital modulation section 103 provided in transmitting apparatus 100 shown in FIG. 2 will be described.
FIG. 6 is a block diagram illustrating a configuration example of the digital modulation unit illustrated in FIG.
As shown in FIG. 6, the digital modulation unit 103 includes space-time block code (STBC) circuits 115 and 116, modulation (MOD) circuits 117 to 120, and transmission side bandwidth control circuits 121 to 124.

When the transmitting apparatus 100 uses the STBC method, the space-time block coding circuits 115 and 116 separate an input signal into two encoded signals and output the separated signals.
The modulation circuits 117 to 120 modulate the signals output from the space-time block code circuits 115 and 116 into a multi-level modulation signal such as selected QAM (Quadrature Amplitude Modulation). Also, the modulation circuits 117 to 120 add pilot signals, which are known to the receiving apparatus 200, including information on the communication scheme and modulation scheme currently used by the transmitting apparatus 100, to the multilevel modulation signal at regular intervals.

  The transmission-side bandwidth control circuits 121 to 124 convert the multi-level modulation signals output from the modulation circuits 117 to 120 into analog signals having a modulation speed corresponding to the signal bandwidth specified by the control unit 300 and output the analog signals. The signal bandwidth of the transmission signal can be adjusted by changing the modulation speed.

  The setting unit 104 included in the transmission device 100 illustrated in FIG. 2 changes the connection relationship of each component included in the digital modulation unit 103 illustrated in FIG. 6 based on the communication scheme and modulation scheme indicated by the control signal. By switching the connection with the analog modulation circuits 106 to 109, the modulation method used in the transmission apparatus 100 is set.

Next, the configuration of the digital demodulator 213 provided in the receiving apparatus 200 illustrated in FIG. 4 will be described.
FIG. 7 is a block diagram showing an example of the configuration of the digital demodulator shown in FIG. FIG. 8 is a block diagram showing an example of the configuration of the amplitude / phase adjustment circuit shown in FIG.
As shown in FIG. 7, the digital demodulation unit 213 includes amplitude phase adjustment (APC) circuits 214 to 215, reception side bandwidth control circuits 216 to 219, MIMO demodulation circuits 220 to 221, and an interference compensation circuit (DEM XPIC). ) 222-225, demodulation circuits (DEM) 226-229, and space-time decoding circuits (STBC-De) 230-231.

The APC circuits 214 to 215 receive V-polarized or H-polarized received signals (modulated signals) received by the same receiving antenna. The APC circuits 214 to 215 adjust the amplitude and phase of the input V-polarized or H-polarized modulation signal, and multiply and output the adjusted signal.
As shown in FIG. 8, the APC circuits 218 and 219 include amplitude / phase adjustment circuits 234 and 235 and a multiplier 236. The amplitude and phase adjustment circuits 234 and 235 adjust the amplitude and phase of the input modulation signal (V polarization or H polarization) so as to be within a predetermined range, and output the result. The multiplier 236 multiplies the modulation signals output from the amplitude / phase adjustment circuits 234 and 235 and outputs the result.

  The reception side bandwidth control circuits 216 to 219 convert the input analog modulation signal into a digital signal at a modulation speed corresponding to the set signal bandwidth and outputs the digital signal. Further, the receiving side bandwidth control circuits 216 to 219 extract pilot signals from the digital signals after bandwidth conversion, and perform correlation calculation with the pilot signals applied to the signals to be demodulated to thereby calculate the channel matrix H. Each element is obtained, and phase information is obtained from each element of the channel matrix H. Each element of the channel matrix H obtained by this correlation calculation is used as a coefficient when demodulated by the MIMO demodulation circuits 220-221.

  A plurality of (here, two) digital signals multiplexed by spatial multiplexing and phase information from the reception side bandwidth control circuits 216 to 219 are input to the MIMO demodulation circuits 220 to 221. The signals multiplexed by spatial multiplexing are the same polarization signals received by different receiving antennas. The MIMO demodulators 220 to 221 separate the input multiplexed signals based on the phase information from the reception side bandwidth control circuits 216 to 219 and output the separated signals.

  The interference compensation circuits 222 to 225 include a cross-polarization interference compensator (XPIC) that compensates for cross-polarization interference, and outputs a signal in which the cross-polarization interference is compensated by the cross-polarization interference compensator.

  The demodulation circuits 226 to 229 demodulate and output the input modulation signals based on the currently selected modulation method (multilevel modulation method). Further, the demodulation circuits 226 to 229 calculate an estimated CNR (Carrier to Noise Ratio) from the error amount with respect to the correct signal point in the received multilevel modulation signal.

When using the STBC method, the space-time decoding circuits 230 to 231 decode an input signal and output two separated data signals.
The digital demodulator 213 switches the connection relationship of each component shown in FIG. 7 according to the modulation scheme used in the transmission apparatus 100, thereby changing the demodulation scheme corresponding to the communication scheme and modulation scheme set in the transmission apparatus 100. Realize.

In the configuration described above, in the present invention, the control unit 300 adaptively switches the communication method, multilevel modulation method, and signal bandwidth used in the transmission device 100 and the reception device 200. There are the following four types of switching control of the communication method, multi-level modulation method and signal bandwidth by the control unit 300.
First switching control: switching control between MIMO method and STBC method,
Second switching control: AMR switching control as AMR,
Third switching control: XPIC mode and PD mode switching control,
Fourth switching control: signal bandwidth switching control.

Next, communication system, multilevel modulation system and signal bandwidth switching control by the control unit 300 will be described.
First, the switching control between the MIMO method and the STBC method, which is the first switching control, will be described.
In the first switching control, the control unit 300 uses the estimated CNR calculated by the digital demodulation unit 213 and the eigenvalue of the channel matrix (communication channel matrix) calculated from the pilot signals received by the MIMO demodulation circuits 220 and 221. The MIMO method or STBC method is selected using the parameters.

ここで、ｈ_ij（ｈ₁₁〜ｈ₂₂）成分から成る行列Ｈはチャネル行列（通信路行列）であり、Ｘ₁及びＸ₂は送信信号であり、ｎ₁及びｎ₂は雑音である。また、ｈ_ijは、送信アンテナ１０ｊから受信アンテナ２０ｉまでの複素伝達関数に対応する。ＭＩＭＯ復調回路２２０及び２２１は、チャネル行列Ｈの固有値分解を行うことでチャネル行列Ｈの固有値を求める。 The eigenvalue is obtained as follows. For example, in the case of a 2 × 2 MIMO system (a MIMO system having two transmission antennas and two reception antennas), the received signals Y ₁ and Y ₂ can be calculated by the following equation (1).

Here, a matrix H composed of h _ij (h _{11 to} h ₂₂ ) components is a channel matrix (communication channel matrix), X ₁ and X ₂ are transmission signals, and n ₁ and n ₂ are noises. H _ij corresponds to a complex transfer function from the transmitting antenna 10j to the receiving antenna 20i. The MIMO demodulation circuits 220 and 221 obtain eigenvalues of the channel matrix H by performing eigenvalue decomposition of the channel matrix H.

また、同一条件下でＳＴＢＣ方式を用いた場合のチャネル容量は、最大の固有値λ₁用いて以下の式（３）で算出できる。

First, in general, assuming that a plurality of transmission paths according to the MIMO scheme are equivalent parallel transmission paths, assuming that the channel response is 1 and the SN ratio is γ, the channel capacity C per 1 second per second is as follows: (2). In Equation (2), λ _k is an eigenvalue, and k is 2 in the case of the 2 × 2 MIMO scheme.

Further, the channel capacity when the STBC method is used under the same conditions can be calculated by the following equation (3) using the maximum eigenvalue λ ₁ .

In the above formula (2) and (3), by replacing the SN ratio γ to estimate CNR, the channel capacity C _STBC channel capacity C _MIMO and STBC scheme MIMO system can be estimated, respectively. Note that the earlier application (Japanese Patent Application No. 2014-225200) by the present applicant also shows that the communication capacity of the MIMO system and the STBC system can be estimated from the SN ratio of the transmission path and the eigenvalue of the channel matrix H.
The controller 300 calculates the channel capacities C _MIMO and C _STBC from the eigenvalue λ and the estimated CNR read as parameters, respectively, and switches to a communication method with a large channel capacity, so that the communication capacity is maximized in the current wireless transmission path state. A communication method (MIMO method or STBC method) can be selected.

Next, modulation control switching by AMR, which is the second switching control, will be described.
In AMR, using the estimated CNR obtained by the digital demodulator 213 as a parameter, the controller 300 selects a modulation scheme (multi-level modulation scheme) with reference to a previously held table.
Table 1 is a table showing the CNR threshold values held by the control unit 300.

Table 1 holds a preset upper limit value (CN upper limit value) and lower limit value (CN lower limit value) of the CNR threshold, which can be used for each modulation scheme. However, among the usable modulation schemes, the CN upper limit value of the modulation scheme having the largest multilevel number and the CN lower limit value of the modulation scheme having the smallest multilevel number are not set.
The control unit 300 reads the estimated CNR obtained by the digital demodulation unit 213, compares the estimated CNR with each CNR threshold shown in Table 1, and determines a multi-level modulation scheme in which the estimated CNR is within the range from the CN upper limit value to the CN lower limit value. select. Therefore, it is possible to select a multi-level modulation method that allows stable communication in the current wireless transmission path state and that maximizes the multi-level number.

Next, the switching control between the XPIC method and the PD method, which is the third switching control, will be described.
In the third switching control, the XPIC method or the PD method is selected using the tap coefficient of the filter used as the cross polarization interference compensator included in the interference compensation circuits 222 to 225 shown in FIG. 7 as a parameter.

FIG. 9 is a block diagram illustrating a configuration example of a transversal filter used by the interference compensation circuit illustrated in FIG. 7 as a cross polarization interference compensator.
As shown in FIG. 9, the transversal filter includes delay elements 401-(-n) to 401- (n), correlators 402-(-n) to 402- (n), and an integrator 403-(- n) to 403- (n), and a control circuit 404. Here, n is an integer of 1 or more.

Signals input to the transversal filter are sequentially delayed by delay elements 401-(− n) to 401- (n). Correlators 402-(− n) to 402- (n) are correlation strengths between signals delayed by the respective delay elements 401-(− n) to 401- (n) and error signals obtained from these signals. Is calculated and output. Integrator 403 - (- n) ~403- ( n) , each correlator 402 - (- n) ~402- tap coefficients by integrating the correlation strength output from the _(n) C _-n ~C n Ask for. The control circuit 404 generates an error signal based on the sum of the output signals of the integrators 403-(− n) to 403- (n).

The controller 300 calculates the integral value of the tap coefficient using the following equation (4).

  The integral value Y of the tap coefficient calculated by the equation (4) can be regarded as the magnitude of the inter-polarization interference when communicating by the XPIC method. The control unit 300 has a threshold value set in advance with respect to the integral value Y, and switches to the PD method when the polarization plane shift is large and the amount of interference increases and the above Y exceeds the threshold value. On the other hand, the control unit 300 switches to the XPIC method when the deviation of the polarization plane is small and the amount of interference is small so that Y becomes less than or equal to the threshold value. Therefore, it is possible to select a communication method (XPIC method or PD method) that maximizes the communication capacity in the current wireless transmission path state.

Next, signal bandwidth switching control (bandwidth control), which is the fourth switching control, will be described.
In the bandwidth control, the signal bandwidth of the transmission / reception signal is switched using the estimated CNR calculated by the digital demodulation unit 213 and information indicating the current communication scheme and modulation scheme as parameters.
In general, when the signal bandwidth of a transmission / reception signal is halved, the channel capacity is halved, but the influence of noise is also halved. Therefore, communication disconnection can be suppressed even if the state of the wireless transmission path deteriorates. Therefore, for example, in the case of a transmission path in which a communication error occurs even when the STBC method or PD method is selected and the BPSK modulation with the smallest multi-value is selected, communication interruption is suppressed by narrowing the signal bandwidth. To do.

Table 2 is a table indicating the preset estimated CNR threshold value held by the control unit 300. Table 2 holds an upper limit value (CNR upper limit threshold value) and a lower limit value (CNR lower limit threshold value) that can be used for each signal bandwidth set in advance. However, among the settable signal bandwidths, the maximum bandwidth CNR upper limit threshold and the minimum bandwidth CNR lower limit threshold are not set. Table 2 shows an example in which three types of signal bandwidths (BW1 to BW3) can be selected. However, the number of signal bandwidths that can be set is two or more.

The control unit 300 compares the estimated CNR read from the digital demodulation unit 213 with each threshold shown in Table 2, and when the estimated CNR falls below the CNR lower limit threshold of the current signal bandwidth, the transmission side bandwidth The signal bandwidth is narrowed by transmitting control signals to the control circuits 121 to 124 and the reception side bandwidth control circuits 216 to 219.
In addition, the control unit 300 compares the estimated CNR read from the digital demodulation unit 213 with each threshold shown in Table 2, and when the estimated CNR is higher than the CNR upper limit threshold of the current signal bandwidth, The signal bandwidth is widened by transmitting control signals to the bandwidth control circuits 121 to 124 and the reception side bandwidth control circuits 216 to 219. By controlling the signal bandwidth of the transmission / reception signal in this way, communication disconnection is suppressed and stable communication is possible even when the state of the wireless transmission path is deteriorated.

  Further, the control unit 300 holds a threshold A that is used only when the signal bandwidth set when the PD method is selected is the narrowest bandwidth among selectable signal bandwidths. The control unit 300 compares the estimated CNR read from the digital demodulating unit 213 with the threshold A, and when the estimated CNR is equal to or less than the threshold A, the control unit 300 proceeds to switching control of the MIMO scheme or the STBC scheme. Further, when the estimated CNR is larger than the threshold A, the control unit 300 executes again the switching control of the XPIC method or the PD method.

  As described above, the control unit 300 performs comprehensive control by combining the first to fourth switching controls, so that communication interruption is suppressed while ensuring the maximum communication capacity according to the state of the wireless transmission path. Stable communication is possible.

(First embodiment)
Next, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 10 is a flowchart showing the operation of the first embodiment of the communication system of the present invention.
FIG. 11 is a block diagram illustrating a configuration example of the first embodiment of the digital modulation unit, and FIG. 12 is a block diagram illustrating a configuration example of the first embodiment of the digital demodulation unit. FIG. 13 is a block diagram showing another configuration example of the first embodiment of the digital modulation unit, and FIG. 14 is a block diagram showing another configuration example of the first example of the digital demodulation unit.
The communication system according to the first embodiment is an example in which the first switching control and the second switching control are combined and controlled. In the first embodiment and the second and third embodiments to be described later, a circuit or an antenna that is not used may be generated by switching the communication method or the modulation method. Those unused circuits and antennas may be used as a spare circuit for hot standby.

  As illustrated in FIG. 10, when the operation starts, the transmission device 100 and the reception device 200 perform communication using a preset MIMO scheme or STBC scheme and a preset multi-level modulation scheme (step S101). ). Transmitting apparatus 100 and receiving apparatus 200 may arbitrarily select a MIMO scheme or an STBC scheme at the start of operation, or may use any multilevel modulation scheme.

  When the transmission device 100 and the reception device 200 start operation, the control unit 300 includes the estimated CNR calculated by the digital demodulation unit 213, the eigenvalue calculated by the MIMO demodulation circuits 220 to 221 and the communication method currently used. Are read out (step S102).

Next, the control unit 300 uses the estimated CNR calculated by the digital demodulation unit 213 and the eigenvalues calculated by the MIMO demodulation circuits 220 to 221 to use the MIMO channel capacity C _MIMO and the STBC channel capacity C. _STBC is calculated, and a communication method (MIMO or STBC) having a large channel capacity is selected (decision 1: step S103). The control unit 300 transmits a control signal indicating the selected communication method to the digital modulation unit 103 and the digital demodulation unit 213. In addition, when the change of the communication method is unnecessary, the control unit 300 may not transmit the control signal indicating the selected communication method to the digital modulation unit 103 and the digital demodulation unit 213. In that case, the control part 300 should just transfer to the process of step S106 mentioned later after the process of step S103 is complete | finished.

  When the control signal transmitted from the control unit 300 indicates the STBC system, the digital modulation unit 103 is switched to the configuration shown in FIG. 11, and the digital demodulation unit 213 is switched to the configuration shown in FIG. As a result, the communication method used in the transmission device 100 and the reception device 200 is switched to the STBC method (step S104). Note that, when it is not necessary to change the communication method, the control unit 300 may not transmit a control signal indicating the communication method selected in step S103 to the digital modulation unit 103 and the digital demodulation unit 213. In that case, the control part 300 should just transfer to the process of step S106 mentioned later after the process of step S103 is complete | finished.

  On the other hand, when the control signal transmitted from the control unit 300 indicates the MIMO scheme, the digital modulation unit 103 is switched to the configuration shown in FIG. 13, and the digital demodulation unit 213 is switched to the configuration shown in FIG. As a result, the communication method used in the transmission device 100 and the reception device 200 is switched to the MIMO method (step S105).

When the communication method is switched to the MIMO method or the STBC method, the control unit 300 reads the estimated CNR calculated by the digital demodulation unit 213 and information indicating the currently used multi-level modulation method (step S106).
The control unit 300 determines whether or not to change the multi-level modulation scheme from the estimated CNR calculated by the digital demodulator 213 and the currently used multi-level modulation scheme using Table 1 above (determination 2: Step S107). When changing the multi-level modulation method, the control unit 300 transmits a control signal indicating the selected multi-level modulation method to the digital modulation unit 103 and the digital demodulation unit 213.

  The digital modulation unit 103 and the digital demodulation unit 213 switch the multi-level modulation method according to the control signal transmitted from the control unit 300 (step S108), return to the process of step S102, and repeat the processes of steps S102 to S108. Note that, when it is not necessary to change the multilevel modulation method, the control unit 300 may not transmit the control signal indicating the multilevel modulation method selected in step S107 to the digital modulation unit 103 and the digital demodulation unit 213. In that case, the control part 300 should just return to the process of step S102 after the process of step S107 is complete | finished.

  Through the above processing, the communication method used in the transmission device 100 and the reception device 200 can be switched to the MIMO method or the STBC method in accordance with the change in the state of the wireless transmission path, and multilevel modulation method switching control by AMR is possible. It becomes possible.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 15 is a flowchart showing the operation of the second embodiment of the communication system of the present invention.
FIG. 16 is a block diagram showing a configuration example of the second embodiment of the digital modulation section, and FIG. 17 is a block diagram showing a configuration example of the second embodiment of the digital demodulation section. FIG. 18 is a block diagram showing another configuration example of the second embodiment of the digital modulation section, and FIG. 19 is a block diagram showing another configuration example of the first embodiment of the digital demodulation section.
The second embodiment is an example in which the second switching control, the third switching control, and the fourth switching control are combined and controlled.

  As shown in FIG. 15, when the transmission apparatus 100 and the reception apparatus 200 start operation, the transmission apparatus 100 and the reception apparatus 200 perform communication using a preset XPIC scheme or PD scheme, and a preset multilevel modulation scheme and signal bandwidth. (Step S201). The transmission device 100 and the reception device 200 may arbitrarily select the XPIC method or the PD method at the start of operation, and may use any multilevel modulation method and signal bandwidth.

  When the transmission device 100 and the reception device 200 start operation, the control unit 300 reads the estimated CNR calculated by the digital demodulation unit 213 and information indicating the currently used multi-level modulation scheme (step S202). .

Next, the control unit 300 determines whether or not to change the multilevel modulation scheme using Table 1 from the estimated CNR calculated by the digital demodulation unit 213 and the currently used multilevel modulation scheme (determination). 2: Step S203).
When changing the multi-level modulation method, the control unit 300 transmits a control signal indicating the selected multi-level modulation method to the digital modulation unit 103 and the digital demodulation unit 213.
The digital modulation unit 103 and the digital demodulation unit 213 switch the multi-level modulation method according to the control signal transmitted from the control unit 300 (step S204). Note that, when it is not necessary to change the multilevel modulation method, the control unit 300 may not transmit a control signal indicating the selected multilevel modulation method to the digital modulation unit 103 and the digital demodulation unit 213. In that case, the control part 300 should just transfer to the process of step S205 mentioned later after completion | finish of the process of step S203.

  Next, the control unit 300 reads out the integral value of the tap coefficient of the cross polarization interference compensator provided in the interference compensation circuits 222 to 225 and information indicating the currently used communication method (step S205).

  The control unit 300 compares the integrated value of the tap coefficient of the cross polarization interference compensator with a preset threshold value, and determines whether or not it is necessary to change to the XPIC method or the PD method (determination 3: step S206). When changing the communication method, the control unit 300 transmits a control signal indicating the selected communication method to the digital modulation unit 103 and the digital demodulation unit 213.

  When the control signal transmitted from the control unit 300 indicates the PD method, the digital modulation unit 103 is switched to the configuration shown in FIG. 16, and the digital demodulation unit 213 is switched to the configuration shown in FIG. As a result, the communication method used in the transmission device 100 and the reception device 200 is switched to the PD method (step S207).

  When the control signal transmitted from the control unit 300 indicates the XPIC method, the digital modulation unit 103 is switched to the configuration shown in FIG. 18, and the digital demodulation unit 213 is switched to the configuration shown in FIG. As a result, the communication method used by the transmission device 100 and the reception device 200 is switched to the XPIC method (step S208). After switching to the XPIC method, the control unit 300 returns to the process of step S202 and repeats the process from step S202. In addition, when the change of the communication method is unnecessary, the control unit 300 may not transmit the control signal indicating the selected communication method to the digital modulation unit 103 and the digital demodulation unit 213. In that case, the control unit 300 may return to step S202 after the process of step S206 is completed, or may proceed to a process of step S209 described later.

When the communication method used in the transmission device 100 and the reception device 200 is switched to the PD method, the control unit 300 reads the estimated CNR calculated by the digital demodulation unit 213 and information indicating the currently used signal bandwidth ( Step S209).
Subsequently, the control unit 300 compares the estimated CNR with each threshold value shown in Table 2 above, and determines whether or not the signal bandwidth needs to be changed (determination 4: step S210). When changing the signal bandwidth, the control unit 300 transmits a control signal indicating the changed signal bandwidth to the digital modulation unit 103 and the digital demodulation unit 213.

  When the control unit 300 instructs the digital modulation unit 103 and the digital demodulation unit 213 to change the signal bandwidth, the digital modulation unit 103 and the digital demodulation unit 213 change the signal bandwidth according to the instruction, and return to the process of step S202 to return to step S202. Repeat the process from. Note that when the change in the signal bandwidth is unnecessary, the control unit 300 may not transmit the control signal indicating the changed signal bandwidth to the digital modulation unit 103 and the digital demodulation unit 213. In that case, the control part 300 should just return to the process of step S202 after the process of step S210 is complete | finished.

Through the above processing, the communication method used in the transmission device 100 and the reception device 200 can be switched to the XPIC method or the PD method according to the change in the state of the wireless transmission path, and the multi-level modulation method switching control by AMR can be performed. Signal bandwidth switching control becomes possible.
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to the drawings.
FIG. 20 is a flowchart showing the operation of the third embodiment of the communication system of the present invention.
FIG. 21 is a block diagram showing a configuration example of the third embodiment of the digital modulation section, and FIG. 22 is a block diagram showing a configuration example of the third embodiment of the digital demodulation section. FIG. 23 is a block diagram showing another configuration example of the third embodiment of the digital modulation section, and FIG. 24 is a block diagram showing another configuration example of the third embodiment of the digital demodulation section, FIG. 25 is a block diagram showing still another configuration example of the third embodiment of the digital modulation section, and FIG. 26 is a block diagram showing still another configuration example of the third embodiment of the digital demodulation section.
The third embodiment is a control example in which the first switching control, the second switching control, the third switching control, and the fourth switching control are combined.

  As shown in FIG. 20, when the transmission apparatus 100 and the reception apparatus 200 start operation, the MIMO scheme or STBC scheme set in advance, the XPIC scheme or PD scheme set in advance, and the multi-level modulation scheme set in advance Communication is executed using the signal bandwidth (step S301). The transmitting apparatus 100 and the receiving apparatus 200 may arbitrarily select a MIMO scheme or STBC scheme, an XPIC scheme or a PD scheme at the start of operation, and may use any multilevel modulation scheme and signal bandwidth.

  When the transmission device 100 and the reception device 200 start operation, the control unit 300 includes the estimated CNR calculated by the digital demodulation unit 213, the eigenvalue calculated by the MIMO demodulation circuits 220 to 221 and the communication method currently used. Are read out (step S302).

Next, the control unit 300 uses the estimated CNR calculated by the digital demodulation unit 213 and the eigenvalues calculated by the MIMO demodulation circuits 220 to 221 to use the MIMO channel capacity C _MIMO and the STBC channel capacity C. _STBC is calculated, and a communication method (MIMO or STBC) having a large channel capacity is selected (decision 1: step S303). The control unit 300 transmits a control signal indicating the selected communication method to the digital modulation unit 103 and the digital demodulation unit 213. In addition, when the change of the communication method is unnecessary, the control unit 300 may not transmit the control signal indicating the selected communication method to the digital modulation unit 103 and the digital demodulation unit 213. In that case, the control part 300 should just transfer to the process of step S306 mentioned later after the process of step S303 is complete | finished.

When the control signal transmitted from the control unit 300 indicates the STBC method, the digital modulation unit 103 of the transmission device 100 and the digital demodulation unit 213 of the reception device 200 are each switched to the STBC method configuration (step S304).
On the other hand, when the control signal transmitted from the control unit 300 indicates the MIMO scheme, the digital modulation unit 103 of the transmission device 100 and the digital demodulation unit 213 of the reception device 200 are each switched to the configuration of the MIMO scheme (step S305).

When the communication method is switched to the MIMO method or the STBC method, the control unit 300 reads the estimated CNR calculated by the digital demodulation unit 213 and information indicating the currently used multi-level modulation method (step S306).
The control unit 300 determines whether or not to change the multi-level modulation scheme from the estimated CNR calculated by the digital demodulator 213 and the currently used multi-level modulation scheme using Table 1 above (determination 2: Step S307). When changing the multi-level modulation method, the control unit 300 transmits a control signal indicating the selected multi-level modulation method to the digital modulation unit 103 and the digital demodulation unit 213.

  The digital modulation unit 103 and the digital demodulation unit 213 switch the multi-level modulation method according to the control signal transmitted from the control unit 300 (step S308). If there is no need to change the multi-level modulation method, the control unit 300 A control signal indicating the selected multi-level modulation method may not be transmitted to the digital modulation unit 103 and the digital demodulation unit 213. In that case, the control part 300 should just transfer to the process of step S309 mentioned later after completion | finish of the process of step S307.

After switching the multi-level modulation method, the control unit 300 reads the integrated value of the tap coefficient of the cross polarization interference compensator included in the interference compensation circuits 222 to 225 and information indicating the currently used communication method ( Step S309).
The controller 300 compares the integrated value of the tap coefficient of the cross polarization interference compensator with a preset threshold value, and determines whether or not it is necessary to change to the XPIC method or the PD method (determination 3: step S310). When changing the communication method, the control unit 300 transmits a control signal indicating the selected communication method to the digital modulation unit 103 and the digital demodulation unit 213.

When the control signal transmitted from the control unit 300 indicates the PD method, the digital modulation unit 103 of the transmission device 100 and the digital demodulation unit 213 of the reception device 200 are each switched to the configuration of the PD method (step S311).
When the control signal transmitted from the control unit 300 indicates the XPIC method, the digital modulation unit 103 of the transmission device 100 and the digital demodulation unit 213 of the reception device 200 are each switched to the configuration of the XPIC method (step S312).

When the communication method used in the transmission device 100 and the reception device 200 is switched to the XPIC method or the PD method, the control unit 300 includes the estimated CNR calculated by the digital demodulation unit 213 and information indicating the signal bandwidth currently used. Is read (step S313).
Subsequently, the control unit 300 compares the estimated CNR with each threshold value shown in Table 2 above, and determines whether or not the signal bandwidth needs to be changed (determination 4: step S314). When changing the signal bandwidth, the control unit 300 transmits a control signal indicating the changed signal bandwidth to the digital modulation unit 103 and the digital demodulation unit 213.

  When the control unit 300 instructs the digital modulation unit 103 and the digital demodulation unit 213 to change the signal bandwidth, the digital modulation unit 103 and the digital demodulation unit 213 change the signal bandwidth in accordance with the instruction (step S315).

When the PD method is selected, the control unit 300 reads again the estimated CNR calculated by the digital demodulation unit 213 and information indicating the currently used signal bandwidth (step S316).
Subsequently, the control unit 300 determines whether the currently used signal bandwidth is the narrowest selectable signal bandwidth, and the currently used signal bandwidth is selectable. In the case of the narrowest, the estimated CNR calculated by the digital demodulator 213 is compared with the threshold value A held in advance (determination 5: step S317). When the estimated CNR is greater than or equal to the threshold A, the control unit 300 returns to the process of step S309 and repeats the process from step S309. When the estimated CNR is greater than the threshold A, the control unit 300 returns to the process of step S302. The processing from step S302 is repeated.

  Here, when using the MIMO method and the XPIC method, the digital modulation unit 103 is changed to the configuration shown in FIG. 21, and the digital demodulation unit 213 is changed to the configuration shown in FIG.

  Further, when the MIMO method and the PD method are used, the digital modulation unit 103 is changed to the configuration shown in FIG. 23, and the digital demodulation unit 213 is changed to the configuration shown in FIG.

  When the STBC method and the XPIC method are used, the digital modulation unit 103 is changed to the configuration shown in FIG. 25, and the digital demodulation unit 213 is changed to the configuration shown in FIG.

  Further, when the STBC method and the PD method are used, the digital modulation unit 103 is changed to the configuration shown in FIG. 27, and the digital demodulation unit 213 is changed to the configuration shown in FIG.

  By repeating the above processing, the communication method used in the transmission device 100 and the reception device 200 can be switched to the MIMO or STBC method according to the change in the state of the wireless transmission path, and can be switched to the XPIC method or the PD method. At the same time, multi-level modulation switching control and signal bandwidth switching control by AMR become possible.

DESCRIPTION OF SYMBOLS 100 Transmitting apparatus 101-102 Transmitting antenna 103 Digital modulation part 104 Setting part 105,110,203,208 Local oscillator 106-109 Analog modulation circuit 111-114 Transmission circuit 115-116 Space-time block code circuit 117-120 Modulation circuit 121- 124 Transmission side bandwidth control circuit 125-1 to 125-N, 233-1 to LPF233-N LPF
126 Q-MOD
200 receiving apparatus 201-202 receiving antenna 204-207 receiving circuit 209-212 analog demodulating unit 213 digital demodulating unit 214-215 APC circuit 216-219 receiving side bandwidth control circuit 220-221 MIMO demodulating circuit 222-225 interference compensation circuit 226 ~ 229 Demodulation circuit 230 ~ 231 Space-time decoding circuit 232 Q-DEM
234 to 235 Amplitude phase adjustment circuit 236 Multipliers 401-(− n) to 401- (n) Delay elements 402-(− n) to 402- (n) Correlators 403-(− n) to 403- (n) Integrator 404 Control circuit

Claims (10)

A receiver that receives the modulated signal transmitted from the transmitter;
While calculating a parameter indicating the current state of the wireless transmission path between the transmitter and the modulated signal received by the receiver, a demodulator that demodulates the modulated signal;
The communication method, modulation method and signal bandwidth used for transmission / reception of the modulated signal are selected based on the parameters, and the demodulation is performed assuming that the selected communication method, modulation method and signal bandwidth used for transmission / reception are used for the demodulation. A control unit configured to transmit a control signal indicating the selected communication method, modulation method, and signal bandwidth to the transmission device,
A receiving apparatus.   As the communication method, a MIMO (Multiple-Input Multiple-Output) method, an STBC (Space Time Block Code) method, an XPIC (Cross Polarization Interference Cancellation) method, and The receiving apparatus according to claim 1, comprising at least one of a PD (Polarized Wave Diversity) system. The controller is
Depending on the current state of the wireless transmission path, at least one of switching between the MIMO system and the STBC system, switching between the XPIC system and the PD system, and switching the modulation system and switching the signal bandwidth are performed. The receiving device according to claim 2 which performs. The controller is
4. The CNR (Carrier to Noise Ratio) of the wireless transmission path calculated by the demodulator and the eigenvalue of a communication path matrix indicating the wireless transmission path are used as the parameters used for switching between the MIMO scheme and the STBC. The receiving device described. The controller is
The receiving apparatus according to claim 3, wherein a tap coefficient of a filter serving as a cross polarization interference compensator for realizing the XPIC method is used as the parameter used for switching between the XPIC method and the PD method. The controller is
The receiving apparatus according to claim 3, wherein a CNR (Carrier to Noise Ratio) of the wireless transmission path calculated by the demodulator is used as the parameter used for the switching determination of the modulation scheme and the switching of the signal bandwidth. A modulation unit that outputs a modulated signal modulated using the set modulation method;
A transmitter for transmitting the modulated signal;
A communication method, a modulation method, and a signal bandwidth used for transmission / reception of the modulated signal, selected by a receiving device that receives the modulated signal based on a parameter indicating a current state of a wireless transmission path with the receiving device. A setting unit that receives a control signal indicating the communication method used to generate a modulation signal according to the control signal, a modulation method, and a signal bandwidth in the modulation unit;
A transmission device.   As the communication method, a MIMO (Multiple-Input Multiple-Output) method, an STBC (Space Time Block Code) method, an XPIC (Cross Polarization Interference Cancellation) method, and 8. The transmission apparatus according to claim 7, comprising at least one of a PD (Polarized Wave Diversity) system. The receiving device according to any one of claims 1 to 6,
A transmission device according to claim 7 or 8,
A communication system. The receiving device
A parameter indicating the current state of the wireless transmission path between the transmitter and the modulation signal transmitted from the transmitter is calculated, and a communication scheme, a modulation scheme, and a signal band used for transmitting and receiving the modulated signal based on the parameter A width is selected, and the selected communication method, modulation method, and signal bandwidth are set in a demodulator that performs demodulation, and a control signal indicating the selected communication method, modulation method, and signal bandwidth is sent to the transmission device. Send
The transmitter is
A communication method for setting a modulation method, a modulation method, and a signal bandwidth used for generating a modulation signal in accordance with a communication method, a modulation method, and a signal bandwidth indicated by the control signal received from the receiving device.

Images