System and method for digital memorized predistortion for wireless communication

A portable electronic device having wireless communication capabilities, the portable electronic device comprising:

• a processor for executing commands that direct operations of the portable electronic device;
• a wireless transmission stage that includes a power amplifier having nonlinear characteristics;
• memory for storing digitally-indexed data including digitally-indexed information that reflects nonlinear characteristics of the power amplifier;
• and
• code stored in the memory that directs the processor to:
• determine, given a first signal that includes information to be communicated wirelessly, a correction contribution based on the first signal and on the digitally-indexed information that reflects the nonlinear characteristics of the power amplifier;
• and
• pre-compensate for the nonlinear characteristics of the power amplifier, based on the correction contribution, to obtain a second signal, wherein the wireless transmission stage will transmit wirelessly a signal based on the second signal.

In a portable mobile device, a method for processing signals in preparation for wireless transmission, wherein the wireless transmission includes use of a power amplifier, the method comprising:

• maintaining a lookup table that contains pre-computed distortion contributions, the distortion contributions being for distorting of signals to thereby pre-compensate the signals for nonlinear characteristics of the power amplifier;
• accepting a value that reflects information to be communicated, the value hereinafter referred to as an original value;
• generating a lookup-table key based on the original value, wherein the lookup-table key is digital;
• retrieving from the lookup table, using the lookup-table key, a pre-computed distortion contribution for the original value;
• distorting the original value based on the pre-computed distortion contribution to obtain a distorted value to pre-compensate for the nonlinear characteristics of the power amplifier;
• wirelessly transmitting a pre-distorted signal based on the distorted value;
• establishing the pre-computed distortion contributions by training based on errors observed from feedback based on output of the power amplifier wherein the feedback is hereinafter referred to as pre-compensation training feedback, the establishing step comprising:
• storing information, hereinafter referred to as reference information, that models characteristics, hereinafter referred to as reference characteristics, that are more linear than the nonlinear characteristics, and
• establishing the reference information by training based on errors observed from feedback, hereinafter referred to as reference training feedback, based on output of the power amplifier;
• wherein the errors observed from the pre-compensation training feedback comprise an error between the pre-compensation training feedback and the reference information.