68 research outputs found
Probabilistic Shaping for Finite Blocklengths: Distribution Matching and Sphere Shaping
In this paper, we provide for the first time a systematic comparison of
distribution matching (DM) and sphere shaping (SpSh) algorithms for short
blocklength probabilistic amplitude shaping. For asymptotically large
blocklengths, constant composition distribution matching (CCDM) is known to
generate the target capacity-achieving distribution. As the blocklength
decreases, however, the resulting rate loss diminishes the efficiency of CCDM.
We claim that for such short blocklengths and over the additive white Gaussian
channel (AWGN), the objective of shaping should be reformulated as obtaining
the most energy-efficient signal space for a given rate (rather than matching
distributions). In light of this interpretation, multiset-partition DM (MPDM),
enumerative sphere shaping (ESS) and shell mapping (SM), are reviewed as
energy-efficient shaping techniques. Numerical results show that MPDM and SpSh
have smaller rate losses than CCDM. SpSh--whose sole objective is to maximize
the energy efficiency--is shown to have the minimum rate loss amongst all. We
provide simulation results of the end-to-end decoding performance showing that
up to 1 dB improvement in power efficiency over uniform signaling can be
obtained with MPDM and SpSh at blocklengths around 200. Finally, we present a
discussion on the complexity of these algorithms from the perspective of
latency, storage and computations.Comment: 18 pages, 10 figure
Partial Enumerative Sphere Shaping
The dependency between the Gaussianity of the input distribution for the
additive white Gaussian noise (AWGN) channel and the gap-to-capacity is
discussed. We show that a set of particular approximations to the
Maxwell-Boltzmann (MB) distribution virtually closes most of the shaping gap.
We relate these symbol-level distributions to bit-level distributions, and
demonstrate that they correspond to keeping some of the amplitude bit-levels
uniform and independent of the others. Then we propose partial enumerative
sphere shaping (P-ESS) to realize such distributions in the probabilistic
amplitude shaping (PAS) framework. Simulations over the AWGN channel exhibit
that shaping 2 amplitude bits of 16-ASK have almost the same performance as
shaping 3 bits, which is 1.3 dB more power-efficient than uniform signaling at
a rate of 3 bit/symbol. In this way, required storage and computational
complexity of shaping are reduced by factors of 6 and 3, respectively.Comment: 6 pages, 6 figure
Information Theoretical Analysis of Identification based on Active Content Fingerprinting
Content fingerprinting and digital watermarking are techniques that are used
for content protection and distribution monitoring. Over the past few years,
both techniques have been well studied and their shortcomings understood.
Recently, a new content fingerprinting scheme called {\em active content
fingerprinting} was introduced to overcome these shortcomings. Active content
fingerprinting aims to modify a content to extract robuster fingerprints than
the conventional content fingerprinting. Moreover, contrary to digital
watermarking, active content fingerprinting does not embed any message
independent of contents thus does not face host interference. The main goal of
this paper is to analyze fundamental limits of active content fingerprinting in
an information theoretical framework.Comment: 35th WIC Symposium on Information Theory in the Benelu
Achievable Information Rates for Probabilistic Amplitude Shaping: An Alternative Approach via Random Sign-Coding Arguments
Probabilistic amplitude shaping (PAS) is a coded modulation strategy in which
constellation shaping and channel coding are combined. PAS has attracted
considerable attention in both wireless and optical communications. Achievable
information rates (AIRs) of PAS have been investigated in the literature using
Gallager's error exponent approach. In particular, it has been shown that PAS
achieves the capacity of the additive white Gaussian noise channel (B\"ocherer,
2018). In this work, we revisit the capacity-achieving property of PAS and
derive AIRs using weak typicality. Our objective is to provide alternative
proofs based on random sign-coding arguments that are as constructive as
possible. Accordingly, in our proofs, only some signs of the channel inputs are
drawn from a random code, while the remaining signs and amplitudes are produced
constructively. We consider both symbol-metric and bit-metric decoding.Comment: 19 pages, 6 figures (v3: proofs of Theorems 3 and 4 are generalized
for M-ASK.
Enumerative Sphere Shaping for Rate Adaptation and Reach Increase in WDM Transmission Systems
The performance of enumerative sphere shaping (ESS), constant composition
distribution matching (CCDM), and uniform signalling are compared at the same
forward error correction rate. ESS is shown to offer a reach increase of
approximately 10% and 22% compared to CCDM and uniform signalling,
respectively.Comment: 4 Pages, 4 figure
First Experimental Demonstration of Probabilistic Enumerative Sphere Shaping in Optical Fiber Communications
We transmit probabilistic enumerative sphere shaped dual-polarization 64-QAM
at 350Gbit/s/channel over 1610km SSMF using a short blocklength of 200. A reach
increase of 15% over constant composition distribution matching with identical
blocklength is demonstrated
Thrombolysis with tissue plasminogen activator in acute myocardial infarction: no additional benefit from immediate percutaneous coronary angioplasty
A randomised trial of 367 patients with acute myocardial infarction was performed to determine whether an invasive strategy combining thrombolysis with recombinant tissue-type plasminogen activator (rTPA), heparin, and acetylsalicylic acid, and immediate percutaneous transluminal coronary angioplasty (PTCA) would be superior to a noninvasive strategy with the same medical treatment but without immediate angiography and PTCA. Intravenous infusion of 100 mg rTPA was started within 5 h after onset of symptoms (median 156 min). Angiography was performed 6-165 min later in 180 out of 183 patients allocated to the invasive strategy; 184 patients were allocated to the non-invasive strategy. Immediate PTCA reduced the percentage stenosis of the infarc
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