Patent ID: 7499501
Filing Date: 2009-03-03
Classification: H03F,H04B

Abstract:
1. In a wireless data communication system, an apparatus for pre-compensating input data symbols to proactively mitigate distortions caused by signal amplification, the apparatus comprising: a pulse-shaping module configured to pulse-shape input data symbols; a compensator configured to adjust the pulse-shaped data symbols; a digital-to-analog converter configured to convert the adjusted data symbols to analog signals, wherein the compensator is coupled among the pulse-shaping module and the digital-to-analog converter; a radio frequency (RF) converter configured to convert the analog signals to RF signals; a power amplifier configured to amplify the RF signals for transmission; a monitor receiver configured to estimate data symbols based on the amplified RF signals; and a compensation estimator configured to compute a set of compensation parameters, based on the estimated data symbols, wherein the compensation estimator is coupled among the monitor receiver and the compensator, and wherein the compensator employs the set of compensation parameters for adjusting the data symbols; and, wherein the compensation estimator and compensator are configured to adaptively optimize compensation of the data symbols to minimize a mean square error (MSE) of adjusted data symbols with a stochastic update algorithm, where the algorithm repeatedly disturbs a compensation mapping in two opposite and random directions and chooses a direction minimizing the MSE until the MSE reaches a stable state at a local minimum.