High efficiency, remotely reconfigurable remote radio head unit system and method for wireless communications

A remote radio head unit comprising:

• an input interface configured to receive an input signal;
• a digital module comprising digital predistortion logic configured to predistort the input signal;
• a power amplifier configured to output an amplified output signal that is a representation of the predistorted input signal;
• and
• a feedback path comprising:
• a directional coupler for sampling the amplified output signal;
• a mixer for frequency translating the sampled output signal to an intermediate-frequency (IF) signal comprising nonlinear distortions of the amplified output signal including in-band distortions and out-of-band distortions;
• and
• a band pass filter for capturing the out-of-band distortions,
• wherein the digital module determines dynamic parameters of the predistorted input signal in response to the out-of-band distortions.

A dual-channel remote radio head unit comprising:

• a first transmit path including a first power amplifier configured to receive a first input signal at a first frequency band and output a first amplified output signal;
• a second transmit path including a second power amplifier configured to receive a second input signal at a second frequency band separated from the first frequency band and output a second amplified output signal;
• a duplexer configured to combine the first and second amplified output signals and provide the combined first and second amplified output signals to an antenna;
• a first feedback path including a first feedback signal associated with first distortions of the first amplified output signal;
• a second feedback path including a second feedback signal associated with second distortions of the second amplified output signal;
• digital logic configured to predistort the first input signal in response to the first feedback signal and predistort the second input signal in response to the second feedback signal.

A method comprising:

• receiving an input signal;
• predistorting the input signal by digital predistortion logic;
• amplifying the predistorted input signal by a power amplifier to obtain an amplified output signal;
• obtaining a feedback signal including in-band distortions and out-of-band distortions of the amplified output signal;
• determining dynamic parameters of the digital predistortion logic in response to the out-of-band distortions.