Systems and methods for efficiently-transformed digital self-interference cancellation
An efficiently-transformed digital self-interference canceller, preferably including an FD transformer, a TD transformer, a channel estimator, a composer, and a controller. The canceller can optionally include a channel memory, a predictor, and/or an extender. A method for digital self-interference cancelation, preferably including receiving inputs, transforming the inputs, generating outputs based on the transformed inputs, transforming the outputs, and/or generating a cancellation signal based on the outputs.
1. A method for digital self-interference cancellation, the method comprising:
receiving a digital transmit signal and a digital residue signal of a communication system;
based on the digital transmit signal and the digital residue signal, generating a self-interference channel estimate in a frequency domain;
transforming the self-interference channel estimate from the frequency domain to a time domain, comprising:
in the frequency domain, generating a low-dimension channel estimate, comprising downsampling the self-interference channel estimate;
transforming the low-dimension channel estimate from the frequency domain to the time domain; and
in the time domain, generating a compensated channel estimate based on the low-dimension channel estimate;
in the time domain, generating a digital self-interference cancellation signal based on the digital transmit signal and the compensated channel estimate; and
generating the digital residue signal, comprising combining the digital self-interference cancellation signal with a receive signal of the communication system.
2. The method of claim 1 , wherein the digital transmit signal and the digital residue signal are received as time domain signals, the method further comprising transforming the digital transmit signal and the digital residue signal from the time domain to the frequency domain.
3. The method of claim 2 , wherein transforming the digital transmit signal from the time domain to the frequency domain comprises:
in the time domain, generating a compensated transmit signal based on the digital transmit signal;
transforming the compensated transmit signal into a low-dimension frequency-domain transmit signal; and
in the frequency domain, upsampling the low-dimension frequency-domain transmit signal to generate an upsampled transmit signal;
wherein generating the self-interference channel estimate is performed using the upsampled transmit signal.
4. The method of claim 1 , wherein:
downsampling the self-interference channel estimate is associated with a window function, thereby distorting the low-dimension channel estimate; and
generating the compensated channel estimate comprises compensating for distortion of the low-dimension channel estimate.
5. The method of claim 4 , wherein the window function is associated with a discrete prolate spheroidal function.
6. The method of claim 4 , wherein compensating for distortion of the low-dimension channel estimate comprises dividing the low-dimension channel estimate by the window function.
7. The method of claim 4 , wherein downsampling the self-interference channel estimate is performed by a finite impulse response filter.
8. The method of claim 1 , wherein downsampling the self-interference channel estimate is performed by a finite impulse response filter.
9. The method of claim 1 , wherein:
transforming the low-dimension channel estimate from the frequency domain to the time domain comprises:
performing a first transformation stage defining a first radix; and
performing a second transformation stage defining a second radix;
downsampling the self-interference channel estimate comprises downsampling the self-interference channel estimate by a downsampling factor, wherein a square root of the downsampling factor is greater than or equal to the first radix and is greater than or equal to the second radix.
10. The method of claim 9 , wherein the first radix is equal to the second radix.
11. The method of claim 9 , wherein at least one of the first radix or the second radix is greater than 3.
12. The method of claim 11 , wherein transforming the low-dimension channel estimate from the frequency domain to the time domain further comprises performing a third transformation stage defining a third radix.
13. The method of claim 1 , further comprising:
receiving a prior channel estimate from a channel memory;
before transforming the self-interference channel estimate from the frequency domain to the time domain, in the frequency domain, modifying the self-interference channel estimate based on the prior channel estimate; and
at the channel memory, storing information associated with the self-interference channel estimate.
14. The method of claim 13 , further comprising generating the information associated with the self-interference channel estimate by transforming the compensated channel estimate from the time domain to the frequency domain.
15. The method of claim 1 , further comprising:
transforming the compensated channel estimate from the time domain to the frequency domain, comprising:
transforming the compensated channel estimate into a low-dimension frequency-domain self-interference channel estimate; and
generating an upsampled channel estimate, comprising, in the frequency domain, upsampling the low-dimension frequency-domain self-interference channel estimate; and
at a channel memory, storing the upsampled channel estimate.
16. The method of claim 15 , further comprising:
receiving a prior channel estimate from the channel memory; and
before transforming the self-interference channel estimate from the frequency domain to the time domain, modifying the self-interference channel estimate, in the frequency domain, based on the prior channel estimate.
17. The method of claim 15 , wherein:
upsampling the low-dimension frequency-domain self-interference channel estimate distorts the upsampled channel estimate based on a first window function; and
transforming the compensated channel estimate from the time domain to the frequency domain further comprises, before transforming the compensated channel estimate into the low-dimension frequency-domain self-interference channel estimate, in the time domain, pre-compensating the compensated channel estimate based on the first window function.
18. The method of claim 17 , wherein:
downsampling the self-interference channel estimate is associated with a second window function, thereby distorting the low-dimension channel estimate; and
generating the compensated channel estimate comprises compensating for distortion of the low-dimension channel estimate.
19. The method of claim 18 , wherein the first window function is substantially equal to the second window function.
20. The method of claim 18 , wherein at least one of the first window function or the second window function is associated with a discrete prolate spheroidal function.
21. The method of claim 17 , wherein the first window function is associated with a discrete prolate spheroidal function.
22. The method of claim 17 , wherein pre-compensating the compensated channel estimate based on the first window function comprises dividing the compensated channel estimate by the first window function.