Asymmetric Quantizers Are Better at Low SNR

2011/01/05 by Tobias Koch, Koch, Tobias, Amos Lapidoth +1
Computer Science · Mathematics · #FOS: Computer and information sciences #Information Theory (cs.IT) #cs.IT #math.IT

paper · pdf · doi:10.48550/arxiv.1101.0970

5 pages. To be presented at the 2011 IEEE International Symposium on Information Theory (ISIT) in Saint Petersburg, Russia. Replaced with version that will appear in the proceedings

arxiv created 2011/05/30 · arxiv updated 2011/06/01

Abstract

We study the behavior of channel capacity when a one-bit quantizer is employed at the output of the discrete-time average-power-limited Gaussian channel. We focus on the low signal-to-noise ratio regime, where communication at very low spectral efficiencies takes place, as in Spread-Spectrum and Ultra-Wideband communications. It is well know that, in this regime, a symmetric one-bit quantizer reduces capacity by 2/pi, which translates to a power loss of approximately two decibels. Here we show that if an asymmetric one-bit quantizer is employed, and if asymmetric signal constellations are used, then these two decibels can be recovered in full.

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