Non-linear interference cancellation for wireless transceivers
Non-linear interference cancellation techniques are provided for wireless transceivers. Non-linear reduction of interference of a transmit signal on a received signal in a transceiver device, comprises applying the transmit signal to a first non-linear system; applying the received signal to a second non-linear system; and subtracting an output of the first non-linear system output from an output of second non-linear system output to produce an interference mitigated received signal. The first non-linear system and/or the second non-linear system can be implemented using one or more of a Volterra series and a Generalized Memory Polynomial Model. System parameters of the first non-linear system and/or the second non-linear system are adapted to reduce a power of the interference mitigated received signal.
1. A method for non-linear reduction of interference of a transmit signal and a received signal in a transceiver device, comprising:
applying said transmit signal to a first non-linear system wherein the first non-linear system comprises a non-linear filter operating on the transmit signal and wherein the first non-linear system is configured to model a non-linearity of a transmit (TX) chain of the transceiver device using a first memory model;
applying said received signal to a second non-linear system wherein the second non-linear system comprises a non-linear post distortion filter operating on the received signal and the second non-linear system is configured to model an inverse of a non-linearity in a receive (RX) chain using a second memory model;
adapting first parameters of the first non-linear system using tap adaptation circuitry;
adapting second parameters of the second non-linear system using the tap adaptation circuitry; and
subtracting an output of said first non-linear system from an output of said second nonlinear system to produce an interference mitigated received signal;
wherein the first parameters and the second parameters are adapted to provide a least squares algorithm generated value for the interference mitigated received signal, and wherein the second parameters comprise an arbitrary linear gain value to prevent the interference mitigated received signal from going to zero.
2. The method of claim 1 , wherein one or more of said first non-linear system and said second non-linear system is a non-linear system with memory.
3. The method of claim 1 , wherein one or more of said first non-linear system and said second non-linear system is implemented using one or more of a Volterra series and a Generalized Memory Polynomial Model.
4. The method of claim 1 , wherein one or more of said first non-linear system and said second non-linear system is implemented using a Volterra series with reduced number of terms by pruning an original of said Volterra series.
5. The method of claim 1 , wherein system parameters of one or more of said first non-linear system and said second non-linear system are adapted to reduce a power of said interference mitigated received signal.
6. The method of claim 5 , wherein a non-zero linear gain in the non-linear post-distortion filter is adjusted to deliver a target non-zero signal power; and
wherein a non-linear part of the non-linear post-distortion filter is adapted to reduce the power of said interference mitigated received signal.
7. The method of claim 5 , wherein the system parameters are obtained using one or more the least squares algorithm, recursive least squares (RLS) and least mean square (LMS).
8. The method of claim 1 wherein the first memory model comprises a first Generalized Memory Polynomial (GMP) Model, and
wherein the second memory model comprises a Volterra Series Model.
9. The method of claim 1 wherein the inverse of the non-linearity in the receive (RX) chain is modeled as a function ƒ′ with for the received signal RX″ as:
ƒ′( RX ″)= a*RX″+ƒ′ NL ( RX ″)
where a is the arbitrary linear gain value to prevent the interference mitigated received signal from going to zero, and wherein ƒ′NL is a non-linear portion of the function ƒ′.
10. A system for non-linear reduction of interference of a transmit signal and a received signal in a transceiver device, comprising:
a memory; and
at least one hardware device, coupled to the memory, operative to:
apply said transmit signal to a first non-linear system wherein the first non-linear system comprises a non-linear filter operating on the transmit signal and wherein the first non-linear system is configured to model a non-linearity of a transmit (TX) chain of the transceiver device using a first memory model;
apply said received signal to a second non-linear system wherein the second non-linear system comprises a non-linear post distortion filter operating on the received signal and the second non-linear system is configured to model an inverse of a non-linearity in a receive (RX) chain using a second memory model;
adapting first parameters of the first non-linear system using tap adaptation circuitry;
adapting second parameters of the second non-linear system using the tap adaptation circuitry;
subtract an output of said first non-linear system from an output of said second non-linear system to produce an interference mitigated received signal;
wherein the first parameters and the second parameters are adapted to provide a least squares algorithm generated value for the interference mitigated received signal, and wherein the second parameters comprise an arbitrary linear gain value to prevent the interference mitigated received signal from going to zero.
11. The system of claim 10 , wherein one or more of said first non-linear system and said second non-linear system is implemented using one or more of a Volterra series and a Generalized Memory Polynomial Model.
12. The system of claim 10 , wherein one or more of said first non-linear system and said second non-linear system is implemented using a Volterra series with reduced number of terms by pruning an original of said Volterra series.
13. The system of claim 10 , wherein system parameters of one or more of said first non-linear system and said second non-linear system are adapted to reduce a power of said interference mitigated received signal.
14. The system of claim 13 , wherein a non-zero linear gain in the non-linear post-distortion filter is adjusted to deliver a target non-zero signal power; and
wherein a non-linear part of the non-linear post-distortion filter is adapted to reduce the power of said interference mitigated received signal.
15. The system of claim 13 , wherein the system parameters are obtained using one or more of the least squares algorithm, recursive least squares (RLS) and least mean square (LMS).
16. A system for non-linear reduction of interference of a transmit signal and a received signal in a transceiver device, comprising:
first circuitry to apply said transmit signal to a first non-linear system wherein the first nonlinear system comprises a non-linear filter operating on the transmit signal and wherein the first non-linear system is configured to model a non-linearity of a transmit (TX) chain of the transceiver device using a first memory model;
second circuitry to apply said received signal to a second non-linear system wherein the second non-linear system comprises a non-linear post distortion filter operating on the received signal and the second non-linear system is configured to model an inverse of a non-linearity in a receive (RX) chain using a second memory model;
fourth circuitry comprising tap adaptation circuitry to adapt first parameters of the first non-linear system and second parameters of the second non-linear system; and
third circuitry to subtract an output of said first non-linear system from an output of said second non-linear system to produce an interference mitigated received signal;
wherein the first parameters and the second parameters are adapted to provide a least squares algorithm generated value for the interference mitigated received signal, and wherein the second parameters comprise an arbitrary linear gain value to prevent the interference mitigated received signal from going to zero.
17. The system of claim 16 , wherein one or more of said first non-linear system and said second non-linear system is a non-linear system with memory.
18. The system of claim 16 , wherein one or more of said first non-linear system and said second non-linear system is implemented using one or more of a Volterra series and a Generalized Memory Polynomial Model.
19. The system of claim 16 , wherein one or more of said first non-linear system and said second non-linear system is implemented using a Volterra series with reduced number of terms by pruning an original of said Volterra series.
20. The system of claim 16 , wherein system parameters of one or more of said first non-linear system and said second non-linear system are adapted to reduce a power of said interference mitigated received signal.