Radio frequency control for communication systems

A method for performing frequency correction in a wireless terminal comprising:

• calibrating a local oscillator that produces a local oscillation;
• entering a tracking mode that includes:
• receiving an Rx RF information signal;
• mixing the Rx RF information signal with the local oscillation to produce an Rx baseband signal;
• determining an Rx frequency error of the Rx baseband signal;
• based upon the Rx frequency error, determining an Rx frequency offset command and a Tx frequency offset command;
• based upon the Rx frequency offset command, phase rotating complex symbols of the Rx baseband signal to frequency correct the Rx baseband signal;
• based upon the Tx frequency offset command, phase rotating complex symbols of a Tx baseband signal to frequency correct the Tx baseband signal;
• and
• up converting the Tx baseband signal based upon the local oscillation to produce a Tx RF information signal;
• and
• when the Rx frequency error exceeds a threshold, adjusting operation of the local oscillator based upon the Rx frequency error.

A wireless terminal comprising:

• an RF front end operable to receive an Rx RF information signal;
• a local oscillator operable to produce a local oscillation;
• a down converter operable to down convert the Rx RF information signal based upon the local oscillation to produce an Rx baseband signal;
• a frequency error estimator operable to determine an Rx frequency error of the Rx baseband signal;
• automatic frequency control operable to, based upon the Rx frequency error, determine an Rx frequency offset command and a Tx frequency offset command;
• a downlink phase rotator operable to, based upon the Rx frequency offset command, phase rotate complex symbols of the Rx baseband signal to frequency correct the Rx baseband signal;
• an uplink phase rotator operable to, based upon the Tx frequency offset command, phase rotate complex symbols of a Tx baseband signal to frequency correct the Tx baseband signal;
• and
• an up converter operable to up convert the Tx baseband signal based upon the local oscillation to produce a Tx RF information signal.

A wireless terminal comprising:

• an RF front end operable to receive an Rx RF information signal;
• a local oscillator operable to produce a local oscillation;
• a down converter operable to down convert the Rx RF information signal based upon the local oscillation to produce an Rx baseband signal;
• a frequency error estimator operable to determine an Rx frequency error of the Rx baseband signal;
• automatic frequency control operable to:
• determine an Rx frequency offset command based upon the Rx frequency error;
• determine a Tx frequency offset command based upon the Rx frequency error;
• and
• adjust operation of the local oscillator based upon the Rx frequency error when the Rx frequency error exceeds a threshold;
• a downlink phase rotator operable to, based upon the Rx frequency offset command, phase rotate complex symbols of the Rx baseband signal to frequency correct the Rx baseband signal;
• an uplink phase rotator operable to, based upon the Tx frequency offset command, phase rotate complex symbols of a Tx baseband signal to frequency correct the Tx baseband signal;
• and
• an up converter operable to up convert the Tx baseband signal based upon the local oscillation to produce a Tx RF information signal.