Optimal quantization for third-generation CDMA transmitters

Due to the need for pulse-shaping and channel aggregation for improved spectral efficiency, pulse-amplitude modulation is used extensively in digital wireless systems. An example of such a system is the third-generation code-division multiple access (CDMA) system derived from the IS-95 standard, known as cdma2000. In this work, optimal quantization of pulse amplitude-modulated systems is analyzed and applied to a cdma2000 reverse link transmitter. Of particular interest is how reverse link channels are scaled prior to subsequent quantization as a result of digital-to-analog conversion. Through analysis, two methods of quantization are proposed-fixed and adaptive. Simulations are provided which show that adaptive quantization provides a performance benefit over fixed methods in terms of emissions.