Can quantization improve error performance in CDMA?

Hadar Efraim, Ori Shental, Nadav Yacov, Ido Kanter
2008 Journal of Physics A: Mathematical and Theoretical  
A K-user direct-sequence spread-spectrum code-division multiple-access (CDMA) system with (q log 2 K)-bit baseband signal quantization at the demodulator is considered. It is shown that additionally quantizing the K + 1 level output signal of the CDMA modulator into q bits improves significantly the average bit-error performance in a non-negligible regime of noise variance, σ 2 , and user load, β, under various system settings, like additive white Gaussian noise (AWGN), Rayleigh fading,
more » ... igh fading, single-user detection, multi-user detection, random and orthogonal spreading codes. For the case of single-user detection in random spreading AWGN-CDMA, this regime is identified explicitly as σ < γ (q) √ β, where γ (q) is a certain pre-factor depending on q, and the associated BER improvement is derived analytically for q = 1, 2. For the other examined system settings, computer simulations are provided, corroborating this interesting behavior.
doi:10.1088/1751-8113/41/36/365004 fatcat:2g4tvjxy3vgbnm3zeuopygqzli