Dithered probabilistic shaping

Nir Palgy, Rami Zamir

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Shaping is a practical method to approximate the optimal Gaussian input distribution for a power-constrained AWGN channel. The Shaping Gain is the reduction in average constellation energy, compared to a uniform (equi-probable) cubical constellation. The maximal Shaping Gain at high SNR is 1.53dB, which can be achieved by a constellation shape of a high dimensional ball with a uniform distribution. By freeing ourselves from the idea of equally probable symbols, we can reach the full shaping gain even with a one dimensional constellation. This idea has been studied before within the high SNR regime. We study and improve the system performance for medium SNRs (rates of 1-3 bit/1D) by inserting dither, and using MAP decoding to take into account the unequal probabilities. We also incorporate coding, and compare the system to regular coded uniform QAM signaling. The results show improvements of up to 0.6dB with respect to older works, and a total shaping gain of about 1dB.

Original languageEnglish
Title of host publication2012 IEEE 27th Convention of Electrical and Electronics Engineers in Israel, IEEEI 2012
DOIs
StatePublished - 2012
Event2012 IEEE 27th Convention of Electrical and Electronics Engineers in Israel, IEEEI 2012 - Eilat, Israel
Duration: 14 Nov 201217 Nov 2012

Publication series

Name2012 IEEE 27th Convention of Electrical and Electronics Engineers in Israel, IEEEI 2012

Conference

Conference2012 IEEE 27th Convention of Electrical and Electronics Engineers in Israel, IEEEI 2012
Country/TerritoryIsrael
CityEilat
Period14/11/1217/11/12

Keywords

  • Coset Coding
  • Dither
  • Information Theory
  • Map Decoding
  • Shaping
  • Unequal Modulation

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