Signal estimation device, signal estimation method, and computer program

Claims

1. A signal estimation device that estimates multiple transmission signals corresponding to each of the multiple received signals from a plurality of spatially multiplexed received signals, The signal estimation device comprises a signal estimation unit that includes two frequency domain equalizers and one nonlinear converter that performs a nonlinear transformation. The signal estimation device performs R (where R is a predetermined positive integer) signal estimation operations using the signal estimation unit. The signal estimation device generates, in the r-th signal estimation operation (where r is a positive integer less than or equal to R) in the R signal estimation operations, a plurality of estimated signals which are the r-th provisional estimation results of the plurality of transmitted signals, and the auxiliary signals used in the r+1 signal estimation operation, from the plurality of received signals and the auxiliary signals generated in the r-1 signal estimation operation. The signal estimation device uses the plurality of estimated signals generated in the R-th signal estimation operation as the estimation result of the plurality of transmitted signals. Signal estimation device.

2. Each of the two frequency-domain equalizers comprises a discrete Fourier transform device, a multiplier, and an inverse discrete Fourier transform device. The signal estimation device according to claim 1.

3. The signal estimation unit, As the auxiliary signals, a first auxiliary signal and a second auxiliary signal are generated. From the plurality of received signals and the first auxiliary signal generated in the r-1th signal estimation operation, the plurality of estimated signals in the rth signal estimation operation are generated. Using the nonlinear converter, the first auxiliary signal and the second auxiliary signal are updated from the plurality of estimated signals generated in the r-th signal estimation operation and the second auxiliary signal generated in the (r-1)th signal estimation operation to generate the first auxiliary signal and the second auxiliary signal to be used in the (r+1)th signal estimation operation. The signal estimation device according to claim 1.

4. The first frequency-domain equalizer, one of the two frequency-domain equalizers provided in the signal estimation unit, performs a first equalization process using the first filter coefficients updated by the first filter coefficient update device. The first filter coefficient updating device is Using a frequency domain equalizer, replicas of the multiple received signals are generated from the input signals relating to the multiple transmitted signals. From the difference between the replica and the plurality of received signals, and from the input signal, update information for the first filter coefficient is generated. The update information for the first filter coefficient is subtracted from the first filter coefficient to update the first filter coefficient. The input signal is a signal relating to the plurality of transmission signals or the estimation result of the plurality of transmission signals. The signal estimation device according to claim 1.

5. The second frequency-domain equalizer, one of the two frequency-domain equalizers provided in the signal estimation unit, performs a second equalization process using the second filter coefficients updated by the second filter coefficient update device. The second filter coefficient updating device comprises an error propagation unit and a coefficient updating unit, The error propagation unit is, The update information generation operation, which includes generating an error signal which is the difference between the estimation results of the plurality of transmission signals by the signal estimation device and the input signal, generating update information for the second filter coefficient using the auxiliary signal and the first filter coefficient, and updating the error signal, is performed R times. In the r-th update information generation operation in the R update information generation operations, In the r-1th update information generation operation, the r-th update information for the second filter coefficient is generated from the updated error signal and the auxiliary signal. From the error signal updated in the r-1th update information generation operation, the auxiliary signal, and the first filter coefficient, the error signal used in the r+1th update information generation operation is updated by nonlinear processing. The coefficient update unit updates the second filter coefficient by subtracting from the second filter coefficient an amount based on each of the R update information pieces of the second filter coefficient generated by the R update information generation operations. The signal estimation device according to claim 4.

6. The first discrete Fourier transform device provided in the first frequency domain equalizer performs a discrete Fourier transform on the first auxiliary signal, The first multiplier in the first frequency domain equalizer performs a first multiplication process using the first filter coefficients and the processing result of the first discrete Fourier transform device. The first inverse discrete Fourier transform device provided in the first frequency domain equalizer performs an inverse discrete Fourier transform on the result of the first multiplication process, The second discrete Fourier transform device in the second frequency domain equalizer performs a discrete Fourier transform on the difference between the output of the first frequency domain equalizer and the plurality of received signals. The second multiplier in the second frequency domain equalizer performs a second multiplication process using the second filter coefficients and the processing result of the second discrete Fourier transform device. The second inverse discrete Fourier transform device in the second frequency domain equalizer performs an inverse discrete Fourier transform on the result of the second multiplication process. The signal estimation device according to claim 5.

7. A signal estimation method for estimating multiple transmission signals corresponding to each of the multiple received signals from a plurality of spatially multiplexed received signals, The aforementioned signal estimation method is: The above-mentioned multiple received signals are input, Initializing auxiliary signals, The process involves generating estimation results for the multiple transmitted signals by performing two frequency-domain equalization processes that convert each of the multiple received signals and the auxiliary signal into the frequency domain and perform equalization, and updating the auxiliary signal by performing a nonlinear process using the auxiliary signal and the estimation results, and repeating this process a predetermined number of times. The last estimation result in the predetermined number of repetitions is taken as the estimation result of the plurality of transmission signals. A computer-based signal estimation method, including [a specific method].

8. Of the two frequency domain equalization processes, the first frequency domain equalization process performs a first equalization process using the first filter coefficients updated by the first filter coefficient update method. The first filter coefficient update method is: Inputting the input signals for the plurality of transmission signals and the plurality of reception signals, The process involves generating replicas of the multiple received signals by frequency domain equalization using the aforementioned input signals, The difference between the replica and the plurality of received signals, and the input signal are used to generate update information for the first filter coefficient, The first filter coefficient is updated by subtracting the update information of the first filter coefficient from the first filter coefficient. Includes, The input signal is a signal relating to the plurality of transmission signals or the estimation result of the plurality of transmission signals. The signal estimation method according to claim 7.

9. Of the two frequency domain equalization processes mentioned above, the second frequency domain equalization process performs a second equalization process using the second filter coefficients updated by the second filter coefficient update method. The second filter coefficient update method is: The estimation error information of the signal estimation method, the auxiliary signal updated by the signal estimation method, and the first filter coefficient are input. The process involves generating update information for the second filter coefficient from the estimated error information and the auxiliary signal, and updating the estimated error information by nonlinear processing using the estimated error information, the auxiliary signal, and the first filter coefficient, and repeating this process a predetermined number of times. The second filter coefficient is updated by subtracting from the second filter coefficient an amount based on the update information of the second filter coefficient generated by the predetermined number of repetitions. The signal estimation method according to claim 8, including the method described in claim 8.

10. A computer program that causes a computer to execute a signal estimation method for estimating multiple transmission signals corresponding to multiple received signals from multiple spatially multiplexed received signals, The aforementioned signal estimation method is: The above-mentioned multiple received signals are input, Initializing auxiliary signals, The process involves generating estimation results for the multiple transmitted signals by performing two frequency-domain equalization processes that convert each of the multiple received signals and the auxiliary signal into the frequency domain and perform equalization, and updating the auxiliary signal by performing a nonlinear process using the auxiliary signal and the estimation results, and repeating this process a predetermined number of times. The last estimation result in the predetermined number of repetitions is taken as the estimation result of the plurality of transmission signals. Includes.