416,018 research outputs found
Explicit Constructions of Quasi-Uniform Codes from Groups
We address the question of constructing explicitly quasi-uniform codes from
groups. We determine the size of the codebook, the alphabet and the minimum
distance as a function of the corresponding group, both for abelian and some
nonabelian groups. Potentials applications comprise the design of almost affine
codes and non-linear network codes
Protograph-Based LDPC Code Design for Probabilistic Shaping with On-Off Keying
This work investigates protograph-based LDPC codes for the AWGN channel with
OOK modulation. A non-uniform distribution of the OOK modulation symbols is
considered to improve the power efficiency especially for low SNRs. To this
end, a specific transmitter architecture based on time sharing is proposed that
allows probabilistic shaping of (some) OOK modulation symbols. Tailored
protograph-based LDPC code designs outperform standard schemes with uniform
signaling and off-the-shelf codes by 1.1 dB for a transmission rate of 0.25
bits/channel use.Comment: Invited Paper for CISS 201
Perfect Space–Time Block Codes
In this paper, we introduce the notion of perfect space–time block codes (STBCs). These codes have full-rate, full-diversity, nonvanishing constant minimum determinant for increasing spectral efficiency, uniform average transmitted energy per antenna and good shaping. We present algebraic constructions of perfect STBCs for 2, 3, 4, and 6 antennas
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