Method and system for signal dynamic range improvement for frequency-division duplex communication systems

1. A method for canceling intermodulation noise in a radio receive path, the method comprising:

filtering an out-of-band signal in the radio receive path by providing a bandpass load of a low-noise amplifier (LNA) output and a bandpass mixer, wherein the bandpass load includes an RC network coupled with differential transconductance inputs of the bandpass mixer;

forwarding an RF transmit signal from a source between a power amplifier output and an antenna in a radio transmit path to a down-converting mixer;

in the down-converting mixer, down-converting the forwarded RF transmit signal;

forwarding the down-converted transmit signal to the radio receive path;

forwarding an intermodulation signal from a neighboring active antenna system antenna element to the radio receive path; and

actively canceling at least a portion of the intermodulation noise included in a receive path signal using the down-converted transmit signal and the forwarded active antenna system intermodulation signal to create an intermodulation-reduced receive path signal.

2. The method of claim 1 , further comprising digitizing the down-converted transmit signal, and wherein cancelation is performed in the digital domain.

3. The method of claim 2 , further comprising forwarding the digitized down-converted transmit signal to a digital pre-distortion system.

4. The method of claim 1 , wherein down-converting is performed by a band-stop or bandpass mixer.

5. The method of claim 1 , further comprising processing the down-converted transmit signal to cancel at least an additional portion of the intermodulation noise included in the receive path signal.

6. The method of claim 5 , wherein the processing includes frequency decomposition.

7. The method of claim 5 , wherein the processing includes:

forwarding the digitized down-converted transmit signal to a digital pre-distortion system; and

modifying an LMS digital pre-distortion optimization cost function using the digitized down-converted transmit signal.

8. The method of claim 5 , wherein the processing includes gain estimation.

9. The method of claim 5 , wherein the processing includes nested optimization loops.

10. The method of claim 5 , further comprising:

demodulating the intermodulation-reduced receive path signal;

detecting data errors in the demodulated receive path signal;

correcting the data errors to generate a data-error-corrected signal;

re-modulating the data-error-corrected signal;

comparing the re-modulated signal with the intermodulation-reduced receive path signal to measure a receive path signal error;

estimating distortion in the receive path signal based on the receive path signal error; and

canceling at least a third portion of the intermodulation noise in the receive path signal using the estimated distortion.

11. The method of claim 10 , further comprising up-converting the re-modulated signal prior to comparing it with the intermodulation-reduced receive path signal.

12. An intermodulation cancelation radio system, comprising:

a low-noise amplifier with an output coupled with a bandpass load, wherein the bandpass load includes an RC network;

a receive path bandpass mixer with differential transconductance inputs, the differential transconductance inputs being coupled with the bandpass load, and wherein the bandpass load is configured to filter an out-of-band signal in the radio receive path;

a transmit path down-converting mixer including:

a first mixer input coupled with an RF signal transmit path and a second mixer input coupled with a local oscillator; and

a receive path cancelation module including:

a first cancelation module input coupled with a cancelation signal based on an output of the transmit path down-converting mixer;

a second cancelation module input coupled with a receive path down-converting mixer output; and

a third cancelation module input configured for receiving an active antenna system intermodulation signal;

wherein the cancelation module includes a receive path signal output coupled to a baseband receive module.

13. The radio system of claim 12 , wherein the transmit path down-converting mixer and the cancelation module operate in the digital domain.

14. The radio system of claim 13 , comprising:

a digital pre-distortion module included in a baseband transmit module and coupled with the output of the transmit path down-converting mixer.

15. The radio system of claim 12 , further comprising:

a re-modulator including:

an input coupled with a demodulated and error-corrected signal output from the baseband receive module and

an output coupled with a third cancelation module input;

wherein the cancelation module includes a fourth cancelation module input coupled with a baseband or intermediate frequency transmit signal output of the transmit path.

16. The radio system of claim 12 , wherein the transmit path down-converting mixer includes a band-stop or bandpass mixer.