Adaptive interference canceller for multiple reference inputs
An interference canceller and a method for canceling interference are disclosed. The interference canceller includes: a subtractor to receive a primary signal including a desired signal and multiple interferers and to generate an output signal including the desired signal; a plurality of Finite Impulse Response (FIR) filters, wherein each FIR filter receives a reference signal from a plurality of reference signals and outputs a filtered reference signal; and a plurality of loop filters, wherein each loop filter outputs coefficients. In the interference canceller, each of the reference signals includes signals from a subset of the multiple interferers, each loop filter corresponds to one of the FIR filters and receives the corresponding reference signal, each loop filter receives the output signal, the output coefficients of each loop filter are based on the output signal and the corresponding reference signal, the output coefficients adaptively adjust the filtered reference signal of the corresponding FIR filter, and the subtractor subtracts each of the filtered reference signals from the primary signal to generate the output signal.
1. An interference canceller comprising:
a subtractor to receive a primary signal comprising a desired signal and multiple interferers and to generate an output signal comprising the desired signal;
a plurality of Finite Impulse Response (FIR) filters, wherein each FIR filter receives a reference signal from a plurality of reference signals and outputs a filtered reference signal; and
a plurality of loop filters, wherein each loop filter outputs coefficients,
wherein
each of the reference signals comprises signals from a subset of the multiple interferers,
each loop filter corresponds to one of the FIR filters and receives the corresponding reference signal,
each loop filter receives the output signal,
the output coefficients of each loop filter are based on the output signal and the corresponding reference signal,
the output coefficients adaptively adjust the filtered reference signal of the corresponding FIR filter, and
the subtractor subtracts each of the filtered reference signals from the primary signal to generate the output signal.
2. The interference canceller of claim 1 , wherein each of the FIR filters and the corresponding output coefficients adjust for a path delay difference between the reference signals.
3. The interference canceller of claim 1 , wherein each loop filter comprises a coefficient updater to adaptively adjust the coefficients based on the output signal and the corresponding reference signal.
4. The interference canceller of claim 1 , wherein each loop filter comprises a coefficient updater to adaptively adjust the coefficients using a Least Mean Squared (LMS) process.
5. The interference canceller of claim 1 , wherein each loop filter comprises a coefficient updater to adaptively adjust the coefficients using a Recursive Least Squares (RLS) process.
6. The interference canceller of claim 1 , wherein a count of the multiple interferers is less than a count of the plurality of FIR filters.
7. The interference canceller of claim 1 , wherein at least one of the reference signals is generated by an omnidirectional antenna.
8. The interference canceller of claim 1 , wherein at least one of the reference signals is generated by a directional antenna.
9. The interference canceller of claim 1 , wherein at least one of the multiple interferers comprises a frequency range overlapping with a frequency range of the desired signal.
10. A method for canceling interference, the method comprising:
receiving a primary signal comprising a desired signal and multiple interferers;
receiving a plurality of reference signals;
filtering each of the plurality of reference signals with a corresponding Finite Impulse Response (FIR) filter, wherein each FIR filter outputs a filtered reference signal;
subtracting each of the filtered reference signals from the primary signal to generate an output signal comprising the desired signal; and
generating output coefficients for each FIR filter using a corresponding loop filter, wherein
each of the reference signals comprises signals from a subset of the multiple interferers,
the output coefficients generated by each loop filter are based on the output signal and the corresponding reference signal, and
the output coefficients adaptively adjust the filtered reference signal of the corresponding FIR filter.
11. The method of claim 10 , wherein each of the FIR filters and the corresponding output coefficients adjust for a path delay difference between the reference signals.
12. The method of claim 10 , wherein each loop filter adaptively adjusts the coefficients based on the output signal and the corresponding reference signal.
13. The method of claim 10 , wherein each loop filter comprises a coefficient updater to adaptively adjust the coefficients using a Least Mean Squared (LMS) process.
14. The method of claim 10 , wherein each loop filter comprises a coefficient updater to adaptively adjust the coefficients using a Recursive Least Squares (RLS) process.
15. The method of claim 10 , wherein a count of the multiple interferers is less than a count of the FIR filters.
16. The method of claim 10 , wherein at least one of the reference signals is generated by an omnidirectional antenna.
17. The method of claim 10 , wherein at least one of the reference signals is generated by a directional antenna.
18. The method of claim 10 , wherein at least one of the multiple interferers comprises a frequency range overlapping with a frequency range of the desired signal.