Signal processing device, signal processing method, and computer program

Abstract

This provides MIMO signal estimation and filter coefficient optimization. [Means] The system comprises D multi-input single-output (MISO) filters and D interference rejection filters. The multiple received signal sequences are the first D received signal sequences. Each of the ith (i is an integer between 1 and D) MISO filters in the D MISO filters receives the ith D received signal sequences as input and estimates the ith single transmitted signal sequence in the D transmitted signal sequences. Each of the ith interference rejection filters in the D interference rejection filters receives a signal obtained by transforming the ith single estimated transmitted signal sequence, which is the estimated result of the ith single transmitted signal sequence, through phase correction and noise correction processing, along with the ith D received signal sequences as input. The filter removes interference signals contained in the ith D received signal sequences and outputs the i+1th D received signal sequences, estimating D transmitted signal sequences including the ith single transmitted signal sequence.

Description

[Technical Field]

[0001] This disclosure relates to a signal processing device, a signal processing method, and a computer program capable of estimating a plurality of corresponding transmission signal sequences from a plurality of spatially multiplexed reception signal sequences. [Background technology]

[0002] The demand for information transmission systems using optical fiber or wireless transmission technologies as communication infrastructure is increasing. Along with this increased demand for information transmission systems, there is a need for higher transmission capacity. In this context, transmission technology using multi-core optical fibers with multiple cores is attracting attention in optical fiber transmission. Multi-core fiber (MCF) technology increases communication capacity by increasing core density while allowing crosstalk (XT) between cores. The introduction of MCF technology into long-distance transmission systems such as optical submarine cables is anticipated.

[0003] In coupled MCF transmission, MIMO equalization is essential to compensate for XT between cores and to estimate multiple transmitted signals corresponding to multiple received signal sequences. One example of MIMO equalization is signal estimation using a linear equalizer. In this case, the filter coefficients (tap coefficients) of each linear equalizer are optimized to minimize the error between the estimated results of multiple transmitted signals from the signal estimation process and the multiple transmitted signals that were actually transmitted. For example, one example of signal estimation is MMSE (Minimum Mean Square Error) estimation, which estimates multiple transmitted signals using a linear equalizer whose filter coefficients (tap coefficients) are optimized to minimize the least squares error between the estimated results of multiple transmitted signals from the signal estimation process and the multiple transmitted signals that were actually transmitted.

[0004] While MMSE processing has the advantage of reducing computational costs through the LMS (Least Mean Square) algorithm, it has the technical challenge of having room for improvement in the estimation accuracy of multiple transmitted signals. As an example of a technology that can improve the estimation accuracy of such transmitted signals, Patent Document 1 discloses a successive interference rejection technology that assumes the sequential estimation of multiple transmitted signals one by one, generates a replica of the interference signal from one estimated transmitted signal, and subtracts the replica of the interference signal from the received signal to improve the estimation accuracy of the transmitted signal estimated in the next stage. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-11577 [Overview of the project] [Problems that the invention aims to solve]

[0006] While MMSE estimation processing offers advantages in terms of computational cost, it has technical challenges, such as the fact that its estimation accuracy for multiple transmitted signals is not optimal and there is room for improvement. On the other hand, while the aforementioned successive interference rejection technique enables improvement in the estimation accuracy of transmitted signals, it has problems with error propagation. In addition to determining the order of successive processing, calculating filter coefficients for estimating transmitted signals, and calculating filter coefficients for interference signal rejection, if there is an error in the transmitted signal estimated in the previous stage, the accuracy of the interference signal rejection processing performed as a result deteriorates, negatively affecting the estimation of subsequent transmitted signals. This disclosure aims to provide MIMO signal estimation and filter coefficient optimization that can solve these technical problems. [Means for solving the problem]

[0007] One embodiment of a signal processing device is a signal processing device that estimates a plurality of transmission signal sequences corresponding to each of a plurality of spatially multiplexed reception signal sequences that interfere with each other, comprising: D multi-input single-output (MISO) filters, each receiving D (D is a positive integer) data sequences equal to the number of the plurality of reception signal sequences as input and outputting a single data sequence; and D interference rejection filters, each receiving a single data sequence and D data sequences as input and removing interference signals from the D input data sequences by the input single data sequence, wherein the plurality of reception signal sequences are a first D number of reception signal sequences, and the D number of M Each of the i-th (where i is an integer between 1 and D) MISO filters included in the ISO filter receives the i-th D received signal sequences as input and estimates the i-th single transmitted signal sequence included in the D transmitted signal sequences. Each of the i-th interference rejection filters included in the D interference rejection filters receives the signal obtained by transforming the i-th single estimated transmitted signal sequence, which is the estimated result of the i-th single transmitted signal sequence, through phase correction and noise correction processing, along with the i-th D received signal sequences as input, removes interference signals included in the i-th D received signal sequences, outputs the i+1-th D received signal sequences, and estimates the D transmitted signal sequences including the i-th single transmitted signal sequence.

[0008] One aspect of the signal processing method comprises D multi-input single-output (MISO) filters, each receiving D (where D is a positive integer) data sequences equal to the number of received signal sequences as input, and outputting a single data sequence; and D interference rejection filters, each receiving a single data sequence and D data sequences as input, and removing interference signals from the D input data sequences by the input single data sequence; and estimating a plurality of transmitted signal sequences corresponding to each of the plurality of received signal sequences from a plurality of spatially multiplexed received signal sequences that interfere with each other, and the plurality of received signal sequences are executed by the signal processing device which is a first D received signal sequence, and the D MISO filters Each of the ith (where i is an integer between 1 and D) MISO filters included in the system takes the ith D received signal sequences as input and estimates the ith single transmitted signal sequence that includes the D transmitted signal sequences. Each of the ith interference rejection filters included in the D interference rejection filters takes the ith single estimated transmitted signal sequence, which is the estimation result of the ith single transmitted signal sequence, as input along with the ith D received signal sequences, removes interference signals contained in the ith D received signal sequences, and outputs the i+1th D received signal sequences. The system estimates the D transmitted signal sequences that include the ith single transmitted signal sequence.

[0009] One aspect of a computer program comprises D multi-input single-output (MISO) filters, each receiving D (where D is a positive integer) data sequences as the number of received signal sequences as inputs, and outputting a single data sequence; and D interference rejection filters, each receiving a single data sequence and D data sequences as inputs, and removing interference signals from the D input data sequences by the input single data sequence. The program estimates a plurality of transmitted signal sequences corresponding to each of the plurality of received signal sequences from a plurality of spatially multiplexed received signal sequences that interfere with each other, and the plurality of received signal sequences are sent to a signal processing device which is a first D received signal sequence, and the D MISO filters Each of the ith (where i is an integer between 1 and D) MISO filters included in the system takes the ith D received signal sequences as input and estimates the ith single transmitted signal sequence that includes the D transmitted signal sequences. Each of the ith interference rejection filters included in the D interference rejection filters takes the ith single estimated transmitted signal sequence, which is the estimation result of the ith single transmitted signal sequence, as input, along with the ith D received signal sequences, removes interference signals contained in the ith D received signal sequences, and outputs the i+1th D received signal sequences. The system estimates the D transmitted signal sequences that include the ith single transmitted signal sequence. [Effects of the Invention]

[0010] According to the respective embodiments of the signal processing device, signal processing method, and computer program described above, the accuracy of signal estimation can be improved. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a block diagram showing the configuration of the transmission system in this embodiment. [Figure 2] Figure 2 is a block diagram showing the configuration of the signal processing device in this embodiment. [Figure 3] Figure 3 is a block diagram showing the configuration of a multi-input single-output (MISO) filter. [Figure 4]Figure 4 is a block diagram showing the configuration of the interference rejection filter. [Figure 5] Figure 5 is a block diagram showing the configuration of the noise correction device. [Figure 6] Figure 6 is a block diagram showing the configuration of the filter coefficient updating device. [Figure 7] Figure 7 is a block diagram showing the configuration of the MISO filter coefficient update device. [Figure 8] Figure 8 is a block diagram showing the configuration of the interference rejection filter coefficient update device. [Figure 9] Figure 9 is a block diagram showing the configuration of the signal processing device in this embodiment. [Modes for carrying out the invention]

[0012] Embodiments of a signal processing device, a signal processing method, and a computer program will be described below with reference to the drawings. However, this disclosure is not limited to the embodiments described below. [1: First Embodiment]

[0013] A first embodiment of a signal processing device, a signal processing method, and a computer program will be described. [1-1: Configuration of the SYS transmission system]

[0014] First, the overall configuration of the transmission system SYS in this embodiment will be described with reference to Figure 1. Figure 1 is a block diagram showing the configuration of the transmission system SYS in this embodiment.

[0015] As shown in Figure 1, the transmission system SYS comprises a transmitter 1 and a receiver 2. Transmitter 1 transmits multiple spatially multiplexed transmission signals x to receiver 2 via a transmission line 3. Receiver 2 receives the multiple transmission signals x transmitted from transmitter 1 as multiple reception signals y via the transmission line 3. Each transmission signal x may contain multiple signal components and may therefore be referred to as a transmission signal sequence. Similarly, each reception signal y may contain multiple signal components and may therefore be referred to as a reception signal sequence.

[0016] To receive a received signal sequence y, the receiving device 2 comprises a signal processing device 10 and a storage device 4. The signal processing device 10 may include at least one of a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), and an FPGA (Field Programmable Gate Array). The signal processing device 10 may read computer programs. For example, the signal processing device 10 may read computer programs stored in the storage device 4. For example, the signal processing device 10 may read computer programs stored on a computer-readable recording medium using a recording medium reader (not shown). The signal processing device 10 may obtain (i.e., download or read) computer programs from a device (not shown) located outside the receiving device 2 via a communication device (not shown). The signal processing device 10 executes the read computer program. As a result, a logical functional block for performing the operation that the receiving device 2 should perform is realized within the signal processing device 10. Specifically, a logical functional block for performing the receiving operation of receiving the received signal sequence y is realized within the signal processing device 10. In other words, the signal processing device 10 can function as a controller for realizing logical functional blocks necessary for the receiving device 2 to perform the operations it should perform.

[0017] The storage device 4 is capable of storing desired data. For example, the storage device 4 may temporarily store a computer program executed by the signal processing device 10. The storage device 4 may temporarily store data that the signal processing device 10 uses temporarily while the signal processing device 10 is executing a computer program. The storage device 4 may store data that the receiving device 2 stores long-term. The storage device 4 may include at least one of the following: RAM (Random Access Memory), ROM (Read Only Memory), hard disk drive, magneto-optical disk drive, SSD (Solid State Drive), and disk array device.

[0018] To transmit a transmission signal sequence, the transmitting device 1 may include a signal processing device and a storage device. The signal processing device in the transmitting device 1 may function in the same way as the signal processing device 10 described above. The storage device in the transmitting device 1 may function in the same way as the storage device 4 described above.

[0019] The transmission system SYS according to this embodiment performs multi-core optical fiber transmission and communication using multiple antennas.

[0020] The receiving device 2 performs a signal estimation process, which estimates the transmitted signal sequence from the received signal sequence y, as at least part of its receiving operation.

[0021] In the following explanation, the multiplexing of the MIMO transmit signal sequence is denoted as D, and the multiplexing of the MIMO receive signal sequence is denoted as D (where D is an integer greater than or equal to 2). t and the multiplexing number D of the MIMO received signal sequence r Similar processing is possible even when the values ​​are different, but the description becomes complicated, so the number of multiplexers D of the MIMO transmission signal sequence is used. t and the multiplexing number D of the MIMO received signal sequence r If and are the same (D=D t =D r Let's explain the case of ).

[0022] Each of the D transmission signal sequences is a sequence consisting of pre-set quadrature amplitude modulation (QAM) signal points with a multi-value number, and each is represented by a complex number. Hereinafter, the i-th transmission signal sequence with length N is simply denoted as x (i) (where i is an integer between 1 and D, and N is an integer of 1 or more), and the received signal sequence with length N is simply denoted as y (i) . Note that the length N can be any positive integer, but for the sake of avoiding complexity, hereinafter, without loss of generality, N = 1 will be described for explanation.

[0023] Each of the D transmission signal sequences constituting the MIMO transmission signal sequence is denoted as x (1) , x (2) , … x (D) , and each of the D received signal sequences constituting the MIMO received signal sequence is denoted as y (1) , y (2) , … y (D) . As described above, each of the transmission signal sequences is a complex number consisting of QAM signal points, and each received signal forming the received signal sequence corresponding to the transmission signal sequence is also a complex number.

[0024] Based on the premise that the D received signal sequences y (1) , y (2) , … y (D) are determined by the convolution of the D transmission signal sequences x (1) , x (2) , … x (D) with the D×D impulse responses in the MIMO transmission path and the addition of white noise components, signal estimation processing may be performed. [2-1: Configuration of Receiver 2 (Signal Processing Device 10)]

[0025] Referring to FIG. 2, the configuration of the receiver 2 that performs signal sequence estimation processing (particularly, the configuration of the signal processing device 10) will be described. FIG. 2 is a block diagram showing the logical functional blocks realized in the signal processing device 10 for performing signal estimation processing. The signal processing device according to the present embodiment includes D received signal sequences y (1) , y (2) , … y (D)From this, D transmit signal sequences x correspond to D received signal sequences. (1) ,x (2) ,…x (D) Each of these is estimated. For this reason, the signal processing device according to this embodiment may be referred to as a MIMO signal sequence estimation device.

[0026] As shown in Figure 2, the MIMO signal sequence estimation device 10 comprises D multi-input single-output (MISO) filter devices 101, D interference rejection filter devices 102, D phase correction units 103, and D noise correction devices 104. The D MISO filter devices 101 and D interference rejection filter devices 102 may be connected alternately via the phase correction units 103 and noise correction devices 104. The phase correction unit 103 may also be a phase-locked loop (PLL).

[0027] Figure 3 shows an example configuration of the MISO filter device 101. As shown in Figure 3, the MISO filter device 101 has D filters 201 and an adder 202. In the following description, to avoid complexity and without loss of generality, each filter 201 will be described as a finite impulse response (FIR) filter of length 1.

[0028] Figure 4 shows an example of the configuration of the interference rejection filter device 102. As shown in Figure 4, the interference rejection filter device 102 has D filters 301 and D subtractors 302. In the following description, to avoid complexity, as with the MISO filter, each filter 301 will be described as an FIR filter of length 1.

[0029] Figure 5 shows an example of the configuration of the noise correction device 104. As shown in Figure 5, the noise correction device 104 includes a conversion unit 401. As described above, the noise correction device 104 receives a signal expressed as a complex number, decomposes it into real and imaginary parts, converts it using the conversion unit 401, and then recombines it back into a complex number for output. [2-2: Flow of MIMO signal sequence estimation process]

[0030] Referring to Figure 2, the operation of the MIMO signal sequence estimation process in this embodiment will be described. The MIMO signal sequence estimation device 10 processes D transmitted signal sequences x (1) ,x (2) ,…x (D) We estimate each one in a predetermined order. The order setting will be explained later, but for simplicity, we will use x below. (1) ,x (2) ,…x (D) We will explain this assuming that the estimation is performed in the following order.

[0031] First, there are D received signal sequences y (1) ,y (2) ,…y (D) (Simply denoted as y1 in Figure 2) is input to the first MISO filter device 101. The coefficients of the D filters in the first MISO filter device 101 are each w1 (1) ,w2 (1) ,…,w D (1) The first MISO filter device 101 performs the calculation shown in the following equation 1, and the resulting signal s (1) Outputs. [Formula 1] TIFF2026093692000002.tif14150

[0032] Output signals s of the first MISO filter device 101 (1) This is input to the phase correction unit 103. Output signal s of the first MISO filter device 101 (1) The phase noise component is corrected by the phase rotation processing performed by the phase correction unit 103, thereby correcting the first transmission signal x (1) This is the estimated result. Note that the output signal of the phase correction unit 103 contains noise components and is not necessarily the QAM signal point. Therefore, to be precise, the estimated transmission signal is the QAM signal point that is closest in distance to the output signal of the phase correction unit 103.

[0033] The output signal from the phase correction unit 103 is input to the noise correction device 104. The noise correction device converts the input signal into a QAM signal point or a signal close to a QAM signal point and outputs it. If there is a QAM signal point very close to the input signal (i.e., the output signal from the phase correction unit 103), the noise correction device removes the noise component and outputs that very close QAM signal point. However, if there is no QAM signal point very close to the input signal, the noise correction device does not completely remove the noise component and outputs a signal point that is a certain distance away from the QAM signal point closest to the input signal. This is a measure to reduce the impact of errors in determining the transmission signal point and is a countermeasure against error propagation, which was a problem with successive interference rejection methods.

[0034] The signal output from the noise correction device 104 undergoes a phase rotation process in the opposite direction to the phase rotation process performed by the phase correction unit 103, and is then input to the first interference rejection filter device 102. This is denoted as TIFF2026093692000003.tif6150. In addition to this signal, there are D received signal sequences y (1) ,y (2) ,…y (D) This is input to the first interference rejection filter device 102. The first interference rejection filter device 102 performs the calculation shown in the following equation 2, and the resulting y2 (1) ,y2 (2) ,…y2 (D) Let these be the D output signals. [Formula 2] TIFF2026093692000004.tif6150 TIFF2026093692000005.tif6150 TIFF2026093692000006.tif6150 TIFF2026093692000007.tif6150

[0035] Furthermore, in formula 2, h1 (1) ,h1 (2) ...,h1 (D) This is the coefficient of the D SIMO filters in the first interference rejection filter device 102, and corresponds to the impulse response of the transmission line. Output signal y2 of the first interference rejection filter device 102 shown in Equation 2 above (1) ,y2 (2) ,…y2 (D) The received signal y (1) ,y (2) ,…y (D) From the first transmission signal x (1) This is the signal from which interference signals caused by [the aforementioned factor] have been removed, and will be referred to as the second received signal sequence below.

[0036] Similarly, for each integer i from 2 to D-1, the i-th MISO filter device 101 receives the i-th signal sequence y i (1) ,y i (2) ,…y i (D) The input is given, and the signal s obtained by performing the operation shown in the following equation 3 is obtained. (i) Outputs. [Formula 3] TIFF2026093692000008.tif14150

[0037] Furthermore, in formula 3, w1 (i) ,w2 (i) ,…,w D (i) is the coefficient of the i-th MISO filter device 101. The output signal s of the first MISO filter device 101 (1) Similar to the processing for the i-th MISO filter device 101 output signal s (i) This is input to the phase correction unit 103, and after the phase noise component is corrected by the phase correction unit 103, the i-th transmission signal x (i) This is the estimated result. Similarly, the output signal of the phase correction unit 103 is input to the noise correction device 104 to correct the noise components, and then input to the i-th interference rejection filter. This input signal This is denoted as TIFF2026093692000009.tif6150. In addition to this signal, there is also the i-th received signal sequence y. i (1) ,y i (2) ,…y i (D)is input to the i-th interference cancellation filter device 102. The i-th interference cancellation filter device 102 performs the operation shown in the following Equation 4 and outputs D signals y i+1 (1) , y i+1 (2) , … y i+1 (D) . [Equation 4] TIFF2026093692000010.tif6150 TIFF2026093692000011.tif6150 TIFF2026093692000012.tif6150 TIFF2026093692000013.tif6150

[0038] In addition, in Equation 4, h i (1) , h i (2) , …, h i (D) are the coefficients of the D SIMO filters in the i-th interference cancellation filter device 102 and correspond to the impulse response of the transmission path. The output signals y i+1 (1) , y i+1 (2) , … y i+1 (D) become the (i + 1)-th received signal sequence.

[0039] Finally, the D-th MISO filter device 101 receives the D-th received signal sequence y D (1) , y D (2) , … y D (D) and outputs an output signal s (D) obtained through the operation shown in the following Equation 5. [Equation 5] TIFF2026093692000014.tif13150

[0040] In addition, in Equation 5, w1 (D) , w2 (D) , …, wD (D) is the coefficient of the D MISO filter device 101. The output signal s of the D MISO filter device 101 (D) This is input to the phase correction unit 103, and after correction of the phase noise component by the phase correction unit 103, the D transmission signal x (D) This is the estimated result.

[0041] As shown above, through D MISO filtering and D-1 interference rejection filtering, D transmitted signals x (1) ,x (2) ,…,x (D) These are estimated one by one in order.

[0042] In addition to the above processing, the D interference rejection filter device 102 applies noise correction processing and a phase rotation processing in the opposite direction to the phase rotation processing performed by the phase correction unit 103 to the D estimated transmission signal. TIFF2026093692000015.tif6150 and the D received signal sequence y D (1) ,y D (2) ,…y D (D) Therefore, the following equation 6 gives the D signals Δy (1) ,Δy (2) ,…Δy (D) Calculate and output the result. [Formula 6] TIFF2026093692000016.tif6150 TIFF2026093692000017.tif6150 TIFF2026093692000018.tif6150 TIFF2026093692000019.tif6150

[0043] D signals Δy according to the above formula 6 (1) ,Δy (2) ,…Δy (D) This is used in the filter coefficient update processing device (Figure 8), which will be described later, for calculating and updating the filter tap coefficients. [2-3: Configuration of a Multi-Input Single-Output (MISO) Filter Processing Unit]

[0044] As explained in [Flow of MIMO Signal Sequence Estimation Processing], the MISO filter device 101 is a device that performs the processing of Equations 1, 3, and 5, and one example of its configuration is shown in Figure 3. As mentioned above, the MISO filter device 101 has D filters 201 and one adder 202. Each of the D filters 201 performs multiplication of the input signal y and the filter coefficient w and outputs the multiplication result. The adder 202 performs the process of adding all the output signals of the D filters 201. It is clear that the processing of Equations 1, 3, and 5 can be realized with D filters 201 and one adder 202. [2-4: Configuration of the interference removal filter processing device]

[0045] As explained in [MIMO Signal Sequence Estimation Processing Flow], the interference rejection filter device 102 is a device that performs the processing of equations 2, 4, and 6, and one example of its configuration is shown in Figure 4. As mentioned above, the interference rejection filter device 102 has D filters 301 and D subtractors 302. Each of the D filters 301 processes the input signal The output is generated by multiplying TIFF2026093692000020.tif6150 by the filter coefficient h. The subtractor 302 also outputs the input signal. This calculates the difference between an input signal y (different from TIFF2026093692000021.tif6150) and the filter output. It is clear that the processing of equations 2, 4, and 6 can be realized with D filters 301 and D subtractors 302. [2-5: Configuration of Noise Correction Processing Device]

[0046] As explained in [MIMO Signal Sequence Estimation Processing Flow], the noise correction device 104 is a device that converts the input signal into a signal at or near the QAM signal point and outputs it, and one example of its configuration is shown in Figure 5. The noise correction device 104 shown in Figure 5 receives a signal expressed in complex numbers as input and decomposes the signal into a real part (common-mode component) and an imaginary part (orthogonal component). The noise correction device converts the real part (common-mode component) and the imaginary part (orthogonal component) using a conversion unit 401 and recombines them into a complex number for output. The conversion unit 401 outputs a function value f(a) shown in the following equation 7 for the input real number a. [Equation 7] TIFF2026093692000022.tif14150

[0047] In equation 7, ReLU(x) is a function that outputs 0 when x is negative, and outputs the value as is when x is 0 or positive, and is called a Rectified Linear Function Unit (ReLU). The I / Q components of the QAM signal point are {±1, ±3, ..., ±(2Q+1)}, respectively (q is a non-negative integer). In equation 7, γ is a parameter that takes a value between 0.0 and 1.0, and is set to an appropriate value beforehand. As shown above, the function in equation 7 is a nonlinear function and is characterized by being composed of a combination of Rectified Linear Function Units (ReLU).

[0048] The configuration shown in Figure 5, which includes a conversion unit 401 that executes equation 7, removes noise components and outputs the closest QAM signal point when there is a QAM signal point very close to the input signal. On the other hand, when there is no QAM signal point very close to the input signal, the noise components are not completely removed, and a signal point that is a certain distance away from the closest QAM signal point is output. The extremely close QAM signal point and the signal point that is a certain distance away from the QAM signal point can be adjusted by setting the parameter γ. [3: How to update filter coefficients]

[0049] Next, embodiments of the method for updating the filter coefficients in the multi-input single-output (MISO) filter device 101 (Figure 3) and the interference rejection filter device 102 (Figure 4) used in the MIMO signal sequence estimation device according to this embodiment will be described with reference to the drawings. However, this disclosure is not limited to the embodiments described below.

[0050] Figure 7 is a block diagram showing one example configuration of a MISO filter coefficient update device 600. The MISO filter coefficient update device 600 comprises D filter coefficient update devices, the same number as the MISO filter devices 101 provided in the MIMO signal sequence estimation device 10 (Figure 2).

[0051] Figure 6 is a block diagram showing an example configuration of the filter coefficient update device 500, which has D filter coefficient storage units 504, D adders 503, D constant multipliers 502, and D multipliers 501.

[0052] The MISO filter coefficient update device 600 shown in Figure 7 updates the received signal sequences y1, y2, ..., D When this is input, the error e contained in each output signal of the D MISO filter devices 101 in the MIMO signal sequence estimation device 10 is also included. (1) ,e (2) ,…,e (D) The following is input. Note that the error signal e (1) ,e (2) ,…,e (D) The signal calculated during phase correction in the phase correction unit (PLL) 103 may also be used.

[0053] In the MISO filter coefficient update device 600 shown in Figure 7, among the D filter coefficient update devices, the i-th filter coefficient update device (where i is an integer between 1 and D) is the one that updates the i-th error signal e (i) And the i-th received signal y is the input signal to the i-th MISO filter device. i =( y i (1) ,yi (2) ,…,y i (D) The complex conjugate signal y of ) i * =( y i (1)* ,y i (2)* ,…,y i (D)* ) From this, the D filter coefficients w1 in the i-th MISO filter device (i) ,w2 (i) ,…,w D (i) Update it according to the following formula 8. [Formula 8] TIFF2026093692000023.tif6150 TIFF2026093692000024.tif6150 TIFF2026093692000025.tif6150 TIFF2026093692000026.tif6150

[0054] In equation 8, μ is a real-valued parameter that has been adjusted and set in advance. The filter coefficient update device in Figure 6 stores the filter coefficients w1 in the D filter coefficient storage units 504. (i) ,w2 (i) ,…,w D (i) The system reads the data, updates it according to the procedure in equation 8, and then performs a series of operations to write it to the filter coefficient storage unit 504.

[0055] As shown above, updating the filter coefficients in the i-th MISO filter device is performed by updating the error signal e included in the output signal of the i-th MISO filter device. (i) And the input signal y to the i-th MISO filter device i (1) ,y i (2) ,…,y i (D) The complex conjugate of is obtained by the process described in equation 8 above.

[0056] Next, the interference rejection filter coefficient update device 700 shown in Figure 8 will be described. The interference rejection filter coefficient update device 700 shown in Figure 8 consists of D filter coefficient update devices, and the estimated signal x estimated by the MIMO signal sequence estimation device 10 (1) ,x (2) ,… (D) And the output signal output Δy of the D interference rejection filter. (1) ,Δy (2) ,…Δy (D) The following is entered.

[0057] The i-th filter coefficient update device in the interference rejection filter coefficient update device 700 shown in Figure 8 is the SIMO filter coefficient h in the i-th interference rejection filter. i (1) ,h i (2) ,…,h i (D) Update it according to the following formula 9. [Formula 9] TIFF2026093692000027.tif6150 TIFF2026093692000028.tif6150 TIFF2026093692000029.tif6150 TIFF2026093692000030.tif6150

[0058] In equation 9, μ is a real-valued parameter that has been adjusted and set in advance. Although the same symbol as in equation 8 is used, it does not need to be the same value. As shown above, updating the interference rejection filter coefficients can be done using the same procedure as updating the MISO filter coefficients. [4-1: Configuration and Operation of the Estimated Order Calculation Device]

[0059] The MIMO signal sequence estimation device 10 shown in Figure 2 estimates D transmission signals one by one in sequence, and there are a total of D factorial (D!) ways to choose the estimation order. The signal processing device 80 shown in Figure 9 is a device that selects the estimation order of transmission signals, and its configuration and operation flow are described below.

[0060] Figure 9 is a block diagram showing the configuration of the signal processing device 80. The signal processing device 80 includes a simplified MIMO signal estimation device 800 and an estimation sequence calculation device 801, which are based on the MIMO signal sequence estimation device 10 shown in Figure 2, but with the interference rejection filter device 102 and noise correction device 104 omitted. This simplified MIMO signal sequence estimation device 800 does not need to be provided separately and may be shared with the MIMO signal sequence estimation device 10 shown in Figure 2.

[0061] The simplified MIMO signal sequence estimation device 800 comprises D MISO filter devices 101 and D phase correction units 103. The input signals to the second through D MISO filters may be the same received signal sequence as the input signal to the first MISO filter.

[0062] Thus, the simplified MIMO signal sequence estimation device 800 omits the processing of the interference rejection filter device 102 and the noise correction device 104, eliminating the need to specify an order, and enabling simultaneous estimation of D transmitted signals through parallel processing. However, compared to the configuration shown in Figure 2, the accuracy of the transmitted signal estimation of the simplified MIMO signal sequence estimation device 800 is reduced.

[0063] The estimation sequence calculation device 801 shown in Figure 9 comprises D noise level calculation units 802 and a comparison unit 803. Each of the D noise level calculation units 802 receives the output signals from the corresponding D phase correction units 103 in the simplified MIMO signal sequence estimation device 800. As mentioned above, the output signals from the phase correction units 103 contain noise components and are not necessarily QAM signal points. More precisely, the QAM signal point closest to the output signal of the phase correction unit 103 becomes the estimated result of the transmitted signal. That is, the difference between the output signal of the phase correction unit 103 and the closest QAM signal point is the amount of noise component. The noise level calculation unit 802 shown in Figure 9 is a device that calculates and outputs this amount of noise component.

[0064] The comparison unit 803 shown in Figure 9 receives the noise levels output by the D noise level calculation units 802, compares each noise level, sorts them in ascending order, and outputs the resulting order. The order output by the comparison unit 803 is the order in which the MIMO signal sequence estimation device shown in Figure 2 estimates the D transmitted signals one by one.

[0065] In the initial stages of data transmission, the transmitted signal may be estimated using the simplified MIMO signal sequence estimation device 800 shown in Figure 9. Based on the results, the estimation order may be determined by the estimation order calculation device 801. After that, the configuration of the simplified MIMO signal sequence estimation device 800 may be switched to the configuration of the MIMO signal sequence estimation device 10 shown in Figure 2, which includes the processing of an interference rejection filter device 102 and a noise correction device 104. From the time of the switch onward, the transmitted signal may be estimated using the MIMO signal sequence estimation device 10 shown in Figure 2. [4-2: Effects of MIMO signal sequence estimation processing]

[0066] According to this disclosure, in a successive interference rejection technique for MIMO signal sequence estimation, the computational cost required for determining the order of successive processing, calculating filter coefficients for estimating the transmitted signal, and calculating filter coefficients for interference signal rejection can be reduced. Furthermore, even if there is an error in the transmitted signal estimated in the preceding stage, the noise correction processing of this disclosure reduces the degradation of the accuracy of the interference signal rejection processing and reduces error propagation, thereby enabling highly accurate signal estimation. [5: Addendum] The following additional information is disclosed regarding the embodiments described above. [Note 1] A signal processing device for estimating a plurality of transmitted signal sequences corresponding to each of a plurality of spatially multiplexed received signal sequences that interfere with each other, Each of the D multi-input single-output (MISO) filters receives D (where D is a positive integer) data sequences as input, and outputs a single data sequence. Each comprises a single data sequence and D data sequences as inputs, and D interference rejection filters that remove interference signals from the D input data sequences using the input single data sequence. The aforementioned plurality of received signal sequences are the first D received signal sequences, Each of the i-th (where i is an integer between 1 and D) MISO filters in the aforementioned D MISO filters is input to the i-th D received signal sequences and estimates the i-th single transmitted signal sequence that comprises the D transmitted signal sequences. Each of the i-th interference rejection filters included in the D interference rejection filters receives a signal obtained by transforming the i-th single estimated transmitted signal sequence, which is the estimation result of the i-th single transmitted signal sequence, through phase correction and noise correction processing, and the i-th D received signal sequences as inputs, removes interference signals contained in the i-th D received signal sequences, and outputs the i+1-th D received signal sequences. Estimate the D transmission signal sequences, including the single transmission signal sequence i mentioned above. Signal processing device. [Note 2] Each of the D MISO filters is: D finite impulse response filters, The system includes an adder that adds up each of the output signals output by each of the D finite impulse response filters. The signal processing device according to Appendix 1, characterized in that... [Note 3] Each of the D interference rejection filters is: The single data series and the D data series are input. A single-input multiple-output (SIMO) filter comprising D finite impulse response filters, each of which is input to the single data sequence, and which outputs D output signals, It includes a subtractor that subtracts the corresponding output signal from the D output signals from each of the D data sequences. The signal processing device according to Appendix 1, characterized in that... [Note 4] The noise correction process is a process that converts the input signal into a quadrature amplitude modulation (QAM) signal point used for modulation of the transmitted signal sequence or a signal point near the QAM signal point and outputs it, The input signal is decomposed into a common-mode component and an orthogonal component. A nonlinear transformation, including the synthesis of normalized linear function units (ReLU), is applied to each of the aforementioned in-phase components and the aforementioned orthogonal components. This process outputs a signal obtained by combining the in-phase component, which has undergone the aforementioned nonlinear transformation, and the orthogonal component, which has undergone the aforementioned nonlinear transformation. The signal processing device according to Appendix 1, characterized in that... [Note 5] The system includes a filter coefficient updating device that updates the filter coefficients of the D finite impulse response filters, The i-th filter coefficient update device, included in the D filter coefficient update devices, performs a sum-of-products operation using the i-th D received signal sequences and the error signal relating to the output of the i-th MISO filter, and updates the filter coefficients of the i-th MISO filter. The signal processing device described in Appendix 2, characterized in that it is a signal processing device. [Note 6] The system includes a filter coefficient updating device that updates the filter coefficients of the D finite impulse response filters, The i-th filter coefficient updating device, included in the D filter coefficient updating devices, is characterized by performing a sum-of-products operation using the i-th estimated transmission signal sequence and the output signal of the D-th interference rejection filter included in the D interference rejection filters, and updating the filter coefficients of the SIMO filter of the i-th interference rejection filter. The signal processing device as described in Appendix 3. [Note 7] Each of the D filter coefficient updating devices is: It has D filter coefficient storage units, D adders, D constant multipliers, and D multipliers. Each of the D data series is multiplied by a single data series, and each of the results of the predetermined constant multiplication process is added to each of the corresponding D filter coefficients stored in the filter coefficient storage units to update the filter coefficients. The signal processing apparatus according to Appendix 5 or 6, characterized in that... [Note 8] The D MISO filters receive the first D received signal sequences as input and estimate the D transmitted signal sequences. A noise amount calculation means calculates the amount of noise contained in each of the D estimated transmission signal sequences obtained by applying phase correction processing to each of the D output signals output by the D MISO filters, The system includes a comparison means for rearranging the D estimated transmission signals in order of decreasing noise levels, The estimation process using the i-th MISO filter and the output of the i+1 D-th received signal sequences using the i-th interference rejection filter are performed to estimate the single transmitted signal sequence in order of increasing noise level. The signal processing device according to Appendix 1, characterized in that... [Note 9] Each of the D multi-input single-output (MISO) filters takes D data sequences (D being a positive integer) as input, and outputs a single data sequence. Each comprises a single data sequence and D data sequences as inputs, and D interference rejection filters that remove interference signals from the D input data sequences using the input single data sequence. From a plurality of spatially multiplexed received signal sequences that interfere with each other, a plurality of transmitted signal sequences corresponding to each of the plurality of received signal sequences are estimated, and the plurality of received signal sequences are executed by a signal processing device which is a first of D received signal sequences. Each of the i-th (where i is an integer between 1 and D) MISO filters in the aforementioned D MISO filters takes the i-th D received signal sequences as input and estimates the i-th single transmitted signal sequence that comprises the D transmitted signal sequences. Each of the i-th interference rejection filters included in the D interference rejection filters receives a signal obtained by transforming the i-th single estimated transmitted signal sequence, which is the estimated result of the i-th single transmitted signal sequence, through phase correction and noise correction processing, and the i-th D received signal sequences as inputs, removes interference signals contained in the i-th D received signal sequences, and outputs the i+1-th D received signal sequences. Includes, Estimate the D transmission signal sequences, including the single transmission signal sequence i mentioned above. Signal processing method. [Note 10] Each of the D multi-input single-output (MISO) filters takes D data sequences (D being a positive integer) as input, and outputs a single data sequence. Each comprises a single data sequence and D data sequences as inputs, and D interference rejection filters that remove interference signals from the D input data sequences using the input single data sequence. From a plurality of spatially multiplexed received signal sequences that interfere with each other, a plurality of transmitted signal sequences corresponding to each of the plurality of received signal sequences are estimated, and the plurality of received signal sequences are sent to a signal processing device which is a first of D received signal sequences. Each of the i-th (where i is an integer between 1 and D) MISO filters in the aforementioned D MISO filters takes the i-th D received signal sequences as input and estimates the i-th single transmitted signal sequence that comprises the D transmitted signal sequences. Each of the i-th interference rejection filters included in the D interference rejection filters receives a signal obtained by transforming the i-th single estimated transmitted signal sequence, which is the estimated result of the i-th single transmitted signal sequence, through phase correction and noise correction processing, and the i-th D received signal sequences as inputs, removes interference signals contained in the i-th D received signal sequences, and outputs the i+1-th D received signal sequences. Includes, Estimate the D transmission signal sequences, including the single transmission signal sequence i mentioned above. A computer program that executes a signal processing method.

[0067] This disclosure may be modified as appropriate, insofar as it does not contradict the gist or idea of ​​the invention as can be inferred from the claims and the specification as a whole, and signal processing devices, signal processing methods, and computer programs with such modifications are also included in the technical concept of the present invention. [Explanation of symbols]

[0068] 2. Receiving device 10,80 Signal Processing Equipment 101 MIMO filter device 102 Interference Removal Filter Device 103 Phase correction section 104 Noise Correction Device 201 Filter 202 Adder 301 Filter 302 Subtractor 401 Conversion Unit 500, 600, 700 Filter Coefficient Update Device 501 Multiplier 502 Constant Multiplier 503 Adder 504 Filter coefficient storage unit 601 Filter coefficient update section 701 Filter coefficient update section 800 Signal sequence estimation device 801 Estimated order calculation device 802 Noise level calculation unit 803 Comparison Section

Claims

1. A signal processing device for estimating a plurality of transmitted signal sequences corresponding to each of a plurality of spatially multiplexed received signal sequences that interfere with each other, Each of the D multi-input single-output (MISO) filters receives D data sequences (D being a positive integer), the same number as the number of received signal sequences, and outputs a single data sequence. Each unit comprises a single data sequence and D data sequences as inputs, and D interference rejection filters that remove interference signals from the D input data sequences using the input single data sequence. The aforementioned plurality of received signal sequences are the first D received signal sequences, Each of the i-th (where i is an integer between 1 and D) MISO filters in the D MISO filters receives the i-th D received signal sequences as input and estimates the i-th single transmitted signal sequence that comprises the D transmitted signal sequences. Each of the i-th interference rejection filters included in the D interference rejection filters receives a signal obtained by transforming the i-th single estimated transmitted signal sequence, which is the estimation result of the i-th single transmitted signal sequence, through phase correction and noise correction processing, and the i-th D received signal sequences as inputs, removes interference signals contained in the i-th D received signal sequences, and outputs the i+1-th D received signal sequence. Estimate the D transmission signal sequences, including the single transmission signal sequence i mentioned above. Signal processing device.

2. Each of the D MISO filters is D finite impulse response filters, The system includes an adder that adds up each of the output signals output by each of the D finite impulse response filters. The signal processing apparatus according to claim 1, characterized in that

3. Each of the D interference rejection filters is: The single data series and the D data series are input. A single-input, multiple-output (SIMO) filter comprising D finite impulse response filters, each of which is input to the single data sequence, and which outputs D output signals, It includes a subtractor that subtracts the corresponding output signal from the D output signals from each of the D data sequences. The signal processing apparatus according to claim 1, characterized in that

4. The noise correction process is a process that converts the input signal into a quadrature amplitude modulation (QAM) signal point used for modulation of the transmitted signal sequence or a signal point near the QAM signal point and outputs it, The input signal is decomposed into a common-mode component and an orthogonal component. A nonlinear transformation including the synthesis of normalized linear function units (ReLUs) is applied to each of the aforementioned in-phase components and the aforementioned orthogonal components. This process outputs a signal obtained by combining the in-phase component, which has undergone the aforementioned nonlinear transformation, and the orthogonal component, which has undergone the aforementioned nonlinear transformation. The signal processing apparatus according to claim 1, characterized in that

5. The system includes a filter coefficient updating device that updates the filter coefficients of the D finite impulse response filters, The i-th filter coefficient updating device, included in the D filter coefficient updating devices, performs a sum-of-products operation using the i-th D received signal sequences and the error signal relating to the output of the i-th MISO filter, and updates the filter coefficients of the i-th MISO filter. The signal processing apparatus according to claim 2, characterized in that

6. The system includes a filter coefficient updating device that updates the filter coefficients of the D finite impulse response filters, The i-th filter coefficient updating device, included in the D filter coefficient updating devices, is characterized by performing a sum-of-products operation using the i-th estimated transmission signal sequence and the output signal of the D-th interference rejection filter included in the D interference rejection filters, and updating the filter coefficients of the SIMO filter of the i-th interference rejection filter. The signal processing apparatus according to claim 3.

7. Each of the D filter coefficient updating devices is: It has D filter coefficient storage units, D adders, D constant multipliers, and D multipliers. Each of the D data series is multiplied by a single data series, and the result of each of the results after applying a predetermined constant multiplication process is added to each of the corresponding D filter coefficients stored in the filter coefficient storage units to update the filter coefficients. The signal processing apparatus according to claim 5 or 6, characterized in that

8. The D MISO filters receive the first D received signal sequences and estimate the D transmitted signal sequences. A noise amount calculation means calculates the amount of noise contained in each of the D estimated transmission signal sequences obtained by applying phase correction processing to each of the D output signals output by the D MISO filters, The system includes a comparison means for rearranging the D estimated transmission signals in order of increasing noise levels, To estimate the single transmitted signal sequence in order of increasing noise level, the estimation process using the i MISO filter and the output of the i+1 D received signal sequences using the i interference rejection filter are performed. The signal processing apparatus according to claim 1, characterized in that

9. Each of the D multi-input single-output (MISO) filters takes D data sequences (D being a positive integer) as input, and outputs a single data sequence. Each unit comprises a single data sequence and D data sequences as inputs, and D interference rejection filters that remove interference signals from the D input data sequences using the input single data sequence. From a plurality of spatially multiplexed received signal sequences that interfere with each other, a plurality of transmitted signal sequences corresponding to each of the plurality of received signal sequences are estimated, and the plurality of received signal sequences are executed by a signal processing device which is a first of D received signal sequences. Each of the i-th (where i is an integer between 1 and D) MISO filters in the aforementioned D MISO filters receives the i-th D received signal sequences as input and estimates the i-th single transmitted signal sequence contained within the D transmitted signal sequences. Each of the i-th interference rejection filters included in the D interference rejection filters receives a signal obtained by transforming the i-th single estimated transmitted signal sequence, which is the estimation result of the i-th single transmitted signal sequence, through phase correction and noise correction processing, and the i-th D received signal sequences as inputs, removes interference signals contained in the i-th D received signal sequences, and outputs the i+1-th D received signal sequences. Includes, Estimate the D transmission signal sequences, including the single transmission signal sequence i mentioned above. Signal processing method.

10. Each of the D multi-input single-output (MISO) filters takes D data sequences (D being a positive integer) as input, and outputs a single data sequence. Each unit comprises a single data sequence and D data sequences as inputs, and D interference rejection filters that remove interference signals from the D input data sequences using the input single data sequence. From a plurality of spatially multiplexed received signal sequences that interfere with each other, a plurality of transmitted signal sequences corresponding to each of the plurality of received signal sequences are estimated, and the plurality of received signal sequences are sent to a signal processing device which is a first of D received signal sequences. Each of the i-th (where i is an integer between 1 and D) MISO filters in the aforementioned D MISO filters receives the i-th D received signal sequences as input and estimates the i-th single transmitted signal sequence contained within the D transmitted signal sequences. Each of the i-th interference rejection filters included in the D interference rejection filters receives a signal obtained by transforming the i-th single estimated transmitted signal sequence, which is the estimation result of the i-th single transmitted signal sequence, through phase correction and noise correction processing, and the i-th D received signal sequences as inputs, removes interference signals contained in the i-th D received signal sequences, and outputs the i+1-th D received signal sequences. Includes, Estimate the D transmission signal sequences, including the single transmission signal sequence i mentioned above. A computer program that executes a signal processing method.

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