CA2347725A1 - Cdma transmit peak power reduction - Google Patents

Abstract

A peak power regulator is disclosed that functions within a Code Division Multiple Access (CDMA) transmitter to reduce peak power spikes within baseband signals while maintaining the average output power consistent with the average input power, controlling the out-of-band emissions, and maintaining the in-band signal quality within an acceptable degradation. In-phase and quadrature baseband signals are input to a delay block and an envelope magnitude predictor within the peak power regulator. The envelope magnitude predictor outputs an estimate for the magnitude of the envelope that will be generated when the inputted baseband signals are modulated. This estimate is input to a multiplier that generates a ratio by dividing the estimate by a maximum acceptable envelope magnitude. The ratio is subsequently input to a mapping table that outputs a scaling factor sufficient for reducing peak power spikes. The scaling factor is subsequently input to an optional mean power regulator that generates an instantaneous gain value sufficient to maintain the average output power level at the average input power level. This gain value is applied to two multipliers that are also input with delayed versions of the in-phase and quadrature baseband input signals. The outputs from these two multipliers, after being filtered within lowpass filters to remove out-of-band emissions caused by the scaling, are output from the peak power regulator. These peak power reduced outputs have any peak power spikes scale reduced while maintaining the average power constant.