Modem control using cross-polarization interference estimation

A wireless communication system, comprising:

• a transmitter, which is operative to transmit first and second signals over the air;
• and
• a receiver, which comprises:
• an input circuit, which is coupled to at least one antenna so as to receive, process and digitize the first and second signals, thus generating first and second streams of input samples;
• and
• an interference cancellation circuit, comprising:
• first and second adaptive filters, which are respectively coupled to filter the first and second streams of input samples using respective first and second coefficients to generate respective first and second filter outputs;
• a phase rotator, which is adapted to apply a variable phase shift between the first and second signals, the phase rotator having at least one configuration parameter;
• and
• a control module, which is operative to compute the variable phase shift and to provide the variable phase shift to the phase rotator so as to compensate for a phase deviation between the first and second signals, to estimate interference in the first signal due to the second signal, and to set the at least one configuration parameter of the phase rotator responsively to the estimated interference.

An interference cancellation circuit for processing first and second streams of input samples representing respective first and second signals, the circuit comprising:

• first and second adaptive filters, which are respectively coupled to filter the first and second streams of input samples using respective first and second coefficients to generate respective first and second filter outputs;
• a phase rotator, which is adapted to apply a variable phase shift between the first and second signals, the phase rotator having at least one configuration parameter;
• and
• a control module, which is operative to compute the variable phase shift and to provide the variable phase shift to the phase rotator so as to compensate for a phase deviation between the first and second signals, to estimate interference in the first signal due to the second signal, and to set the at least one configuration parameter of the phase rotator responsively to the estimated interference.

A method for wireless communications, comprising:

• receiving, processing and digitizing first and second signals transmitted over the air so as to generate first and second streams of input samples;
• filtering the first and second streams of input samples using respective first and second coefficients to generate respective first and second filtered outputs;
• applying a variable phase shift to one of the first and second filtered outputs using a phase rotator having at least one configuration parameter so as to generate a phase-shifted output compensating for a phase deviation between the first and second signals;
• summing the first and second filtered outputs so as to generate a third stream of output samples, which is representative of the first signal;
• estimating interference in the first signal due to the second signal;
• and
• setting the at least one configuration parameter of the phase rotator responsively to the estimated interference.