System and method for digital memorized predistortion for wireless communication

In a wireless transmission system adapted for use with one or more portable mobile devices, a method for processing signals in preparation for wireless transmission, wherein the wireless transmission includes use of a power amplifier for transmitting a plurality of channels, the method comprising:

• operating the transmission system in a training mode,
• monitoring the operating characteristics of a power amplifier while operating in the training mode,
• computing values representative of nonlinearity in the power amplifier at a plurality of operating conditions and storing the computed nonlinearity values while operating in the training mode, the computing step comprising at least in part:
• squaring an in-phase component of a signal representative of power amplifier output to produce a squared in-phase output value;
• squaring a quadrature component of the signal representative of power amplifier output to produce a squared quadrature output value;
• squaring an in-phase component of a signal representative of an input signal to produce a squared in-phase input value;
• squaring a quadrature component of the signal representative of the input signal to produce a squared quadrature input value,
• determining an in-phase difference between the squared in-phase input value and the squared in-phase output value;
• and
• determining a quadrature difference between the squared quadrature input value and the squared quadrature output value, the distortion contributions being based on the in-phase difference and the quadrature difference;
• computing values of channel delay at a plurality of operating conditions and storing the computed channel delay values while operating in the training mode, and
• operating the transmission system in a normal operating mode and using the nonlinearity and channel delay values stored while in training mode to predistort input to the power amplifier so as to linearize the output of the power amplifier.