117 research outputs found
Hamming distance spectrum of DAC codes for equiprobable binary sources
Distributed Arithmetic Coding (DAC) is an effective technique for implementing Slepian-Wolf coding (SWC). It has been shown that a DAC code partitions source space into unequal-size codebooks, so that the overall performance of DAC codes depends on the cardinality and structure of these codebooks. The problem of DAC codebook cardinality has been solved by the so-called Codebook Cardinality Spectrum (CCS). This paper extends the previous work on CCS by studying the problem of DAC codebook structure.We define Hamming Distance Spectrum (HDS) to describe DAC codebook structure and propose a mathematical method to calculate the HDS of DAC codes. The theoretical analyses are verified by experimental results
Analysis on tailed distributed arithmetic codes for uniform binary sources
Distributed Arithmetic Coding (DAC) is a variant of Arithmetic Coding (AC) that can realise Slepian-Wolf Coding (SWC) in a nonlinear way. In the previous work, we defined Codebook Cardinality Spectrum (CCS) and Hamming Distance Spectrum (HDS) for DAC. In this paper, we make use of CCS and HDS to analyze tailed DAC, a form of DAC mapping the last few symbols of each source block onto non-overlapped intervals as traditional AC. We first derive the exact HDS formula for tailless DAC, a form of DAC mapping all symbols of each source block onto overlapped intervals, and show that the HDS formula previously given is actually an approximate version. Then the HDS formula is extended to tailed DAC. We also deduce the average codebook cardinality, which is closely related to decoding complexity, and rate loss of tailed DAC with the help of CCS. The effects of tail length are extensively analyzed. It is revealed that by increasing tail length to a value not close to the bitstream length, closely-spaced codewords within the same codebook can be removed at the cost of a higher decoding complexity and a larger rate loss. Finally, theoretical analyses are verified by experiments
Codebook cardinality spectrum of distributed arithmetic codes for stationary memoryless binary sources
It was demonstrated that, as a nonlinear implementation of Slepian-Wolf Coding, Distributed Arithmetic Coding (DAC) outperforms traditional Low-Density Parity-Check (LPDC) codes for short code length and biased sources. This fact triggers research efforts into theoretical analysis of DAC. In our previous work, we proposed two analytical tools, Codebook Cardinality Spectrum (CCS) and Hamming Distance Spectrum, to analyze DAC for independent and identically-distributed (i.i.d.) binary sources with uniform distribution. This article extends our work on CCS from uniform i.i.d. binary sources to biased i.i.d. binary sources. We begin with the final CCS and then deduce each level of CCS backwards by recursion. The main finding of this article is that the final CCS of biased i.i.d. binary sources is not uniformly distributed over [0, 1). This article derives the final CCS of biased i.i.d. binary sources and proposes a numerical algorithm for calculating CCS effectively in practice. All theoretical analyses are well verified by experimental results
Near-capacity joint source and channel coding of symbol values from an infinite source set using Elias Gamma Error correction codes
In this paper we propose a novel low-complexity Joint Source and Channel Code (JSCC), which we refer to as the Elias Gamma Error Correction (EGEC) code. Like the recently-proposed Unary Error Correction (UEC) code, this facilitates the practical near-capacity transmission of symbol values that are randomly selected from a set having an infinite cardinality, such as the set of all positive integers. However, in contrast to the UEC code, our EGEC code is a universal code, facilitating the transmission of symbol values that are randomly selected using any monotonic probability distribution. When the source symbols obey a particular zeta probability distribution, our EGEC scheme is shown to offer a 3.4 dB gain over a UEC benchmarker, when Quaternary Phase Shift Keying (QPSK) modulation is employed for transmission over an uncorrelated narrowband Rayleigh fading channel. In the case of another zeta probability distribution, our EGEC scheme offers a 1.9 dB gain over a Separate Source and Channel Coding (SSCC) benchmarker
Bridging Hamming Distance Spectrum with Coset Cardinality Spectrum for Overlapped Arithmetic Codes
Overlapped arithmetic codes, featured by overlapped intervals, are a variant
of arithmetic codes that can be used to implement Slepian-Wolf coding. To
analyze overlapped arithmetic codes, we have proposed two theoretical tools:
Coset Cardinality Spectrum (CCS) and Hamming Distance Spectrum (HDS). The
former describes how source space is partitioned into cosets (equally or
unequally), and the latter describes how codewords are structured within each
coset (densely or sparsely). However, until now, these two tools are almost
parallel to each other, and it seems that there is no intersection between
them. The main contribution of this paper is bridging HDS with CCS through a
rigorous mathematical proof. Specifically, HDS can be quickly and accurately
calculated with CCS in some cases. All theoretical analyses are perfectly
verified by simulation results
Multiuser Communication through Power Talk in DC MicroGrids
Power talk is a novel concept for communication among control units in
MicroGrids (MGs), carried out without a dedicated modem, but by using power
electronics that interface the common bus. The information is transmitted by
modulating the parameters of the primary control, incurring subtle power
deviations that can be detected by other units. In this paper, we develop power
talk communication strategies for DC MG systems with arbitrary number of
control units that carry out all-to-all communication. We investigate two
multiple access strategies: 1) TDMA, where only one unit transmits at a time,
and 2) full duplex, where all units transmit and receive simultaneously. We
introduce the notions of signaling space, where the power talk symbol
constellations are constructed, and detection space, where the demodulation of
the symbols is performed. The proposed communication technique is challenged by
the random changes of the bus parameters due to load variations in the system.
To this end, we employ a solution based on training sequences, which
re-establishes the signaling and detection spaces and thus enables reliable
information exchange. The presented results show that power talk is an
effective solution for reliable communication among units in DC MG systems.Comment: Multiuser extension of the power talk concept. Submitted to IEEE JSA
Partition Information and its Transmission over Boolean Multi-Access Channels
In this paper, we propose a novel partition reservation system to study the
partition information and its transmission over a noise-free Boolean
multi-access channel. The objective of transmission is not message restoration,
but to partition active users into distinct groups so that they can,
subsequently, transmit their messages without collision. We first calculate (by
mutual information) the amount of information needed for the partitioning
without channel effects, and then propose two different coding schemes to
obtain achievable transmission rates over the channel. The first one is the
brute force method, where the codebook design is based on centralized source
coding; the second method uses random coding where the codebook is generated
randomly and optimal Bayesian decoding is employed to reconstruct the
partition. Both methods shed light on the internal structure of the partition
problem. A novel hypergraph formulation is proposed for the random coding
scheme, which intuitively describes the information in terms of a strong
coloring of a hypergraph induced by a sequence of channel operations and
interactions between active users. An extended Fibonacci structure is found for
a simple, but non-trivial, case with two active users. A comparison between
these methods and group testing is conducted to demonstrate the uniqueness of
our problem.Comment: Submitted to IEEE Transactions on Information Theory, major revisio
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