Title :
Analysis and minimization of loss of process gain with A/D conversion in DS-CDMA
Author :
Yagyu, Mitsuhiko ; Kinjo, Shigenori ; Yamaguchi, Hirohisa
Author_Institution :
Tsukuba R&D Center, Texas Instrum., Japan
Abstract :
This paper presents an analytical equation to estimate the process gain actually derived in the despreading process in DS-CDMA systems. The A/D converter (ADC) generates quantization and saturation noise, which reduces the process gain. The probability density function (PDF) of the ADC output is analytically expressed so that the PDF of the quantized and despread signal is shown. Then the SNR of the despread signal is obtained as the ratio of the expectation and the variance given by the PDF. Further by using the analytical equation, the optimum reference value of the AGC can be obtained without numerous computer simulations. In the wideband-CDMA system, the optimum reference value of the AGC is accurately estimated, which is confirmed in the computer simulation
Keywords :
analogue-digital conversion; automatic gain control; code division multiple access; minimisation; mobile radio; parameter estimation; probability; quantisation (signal); spread spectrum communication; A/D conversion; ADC; AGC; DS-CDMA; PDF; SNR; computer simulation; despreading process; expectation/variance ratio; minimization; mobile radio; optimum reference value; probability density function; process gain estimation; quantization noise; saturation noise; wideband-CDMA system; Computer simulation; Equations; Gain; Multiaccess communication; Noise reduction; Power amplifiers; Quantization; Sampling methods; Signal analysis; Signal to noise ratio;
Conference_Titel :
Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th
Conference_Location :
Amsterdam
Print_ISBN :
0-7803-5435-4
DOI :
10.1109/VETECF.1999.800127
