Systems and methods for multi-rate digital self-interference cancellation
A system for multi-rate digital self-interference cancellation including a signal component generation system coupled to a digital transmit signal of a communication system that generates a set of signal components from the digital transmit signal; a multi-rate adaptive filter that transforms the set of signal components into a digital self-interference cancellation signal, according to a transform configuration, to form an interference-reduced receive signal; and a transform adaptor that dynamically sets the transform configuration in response to changes in the interference-reduced receive signal.
1. A system for multi-rate digital self-interference cancellation comprising:
a signal component generation system coupled to a digital transmit signal of a communication system that generates a set of signal components from the digital transmit signal; wherein the signal component generation system comprises a set of transform paths; wherein each transform path comprises a component generator and an anti-aliasing filter; wherein a majority of the set of transform paths further comprise an upsampler, a downsampler, and a signal multiplier; wherein signal multipliers couple transform paths to at least one other transform path;
a multi-rate adaptive filter that transforms the set of signal components into a digital self-interference cancellation signal according to a transform configuration, wherein the digital self-interference cancellation signal is combined with a receive signal of the communication system to form an interference-reduced receive signal; and
a transform adaptor that dynamically sets the transform configuration in response to changes in the interference-reduced receive signal.
2. The system of claim 1 , wherein each transform path further comprises a frequency shifter.
3. The system of claim 1 , wherein the set of transform paths comprises a first transform path and a second transform path; the first transform path having a component generator of order one, and the second transform path having a component generator of order three.
4. The system of claim 3 , wherein the first transform path comprises a downsampler that downsamples by a first factor; wherein the second transform path comprises a downsampler that downsamples by a second factor.
5. The system of claim 4 , wherein the first factor and the second factor are equal.
6. The system of claim 4 , wherein the second transform path further comprises an upsampler that upsamples by a third factor.
7. The system of claim 3 , wherein the multi-rate adaptive filter comprises a first filter and a second filter; wherein the self-interference cancellation signal is generated from a combination of outputs of the first filter and the second filter; wherein the first filter transforms only first order signal components; wherein the second filter transforms only non-first order signal components.
8. The system of claim 1 , further comprising a blocker filter that removes undesired components of the self-interference cancellation signal.
9. The system of claim 8 , further comprising a filter inverter coupled to the transform adaptor that reduces the effect of the blocker filter on the interference-reduced receive signal as sampled by the transform adaptor.
10. The system of claim 8 , further comprising a filter inverter coupled to the transform adaptor that reduces the effect of receiver components on the interference-reduced receive signal as sampled by the transform adaptor.
11. The system of claim 1 , further comprising a gain/phase compensator that modifies gain and phase of the digital self-interference cancellation signal to reduce gain/phase error relative to the receive signal.
12. The system of claim 1 , further comprising a gain/phase compensator that modifies gain and phase of the receive signal to reduce gain/phase error relative to the digital self-interference cancellation signal.
13. The system of claim 1 , wherein size of the set of signal components is determined by the transform configuration.
14. The system of claim 1 , wherein the transform adaptor dynamically sets the transform configuration in response to changes in a ratio of a frequency-domain-transformed interference-reduced receive signal to a frequency-domain-transformed digital transmit signal.
15. A method for multi-rate digital self-interference cancellation comprising:
receiving a digital transmit signal of a communication system;
generating a set of signal components from the digital transmit signal;
wherein generating the set of signal components comprises:
generating a first signal component by upsampling the digital transmit signal;
performing signal component generation, according to a self-interference model, on the upsampled digital transmit signal;
downsampling the generated signal component; and
performing anti-aliasing filtering on the downsampled signal component;
transforming the set of signal components into a digital self-interference cancellation signal according to a transform configuration;
combining the digital self-interference cancellation signal with a receive signal of the communication system to form an interference-reduced receive signal; and
dynamically adapting the transform configuration in response to changes in the interference-reduced receive signal.
16. The method of claim 15 , wherein generating the set of signal components comprises generating a second signal component by downsampling the digital transmit signal; and performing anti-aliasing filtering on the downsampled signal.
17. The method of claim 16 , wherein dynamically adapting the transform configuration comprises dynamically adapting the transform configuration in response to changes in a ratio of receive and transmit signals.
18. The method of claim 16 , wherein dynamically adapting the transform configuration comprises dynamically adapting the transform configuration in response to changes in a frequency-domain-converted ratio of receive and transmit signals.
19. The method of claim 16 , wherein dynamically adapting the transform configuration comprises dynamically adapting the transform configuration in response to changes in a time-averaged ratio of receive and transmit signals; wherein the time-averaged ratio is averaged over a first number of samples.
20. The method of claim 19 , wherein dynamically adapting the transform configuration further comprises dynamically changing the first number of samples.
21. The method of claim 20 , wherein dynamically changing the first number of samples comprises increasing the first number of samples in response to a decrease in the time-averaged ratio of receive and transmit signals.
22. The method of claim 16 , wherein dynamically adapting the transform configuration comprises dynamically adapting the transform configuration in response to changes in a ratio of a first product and a second product; wherein the first product is a product of a receive signal and a conjugate of a transmit signal; wherein the second product is a product of the transmit signal and the conjugate of the transmit signal.