106 research outputs found
Skip-Sliding Window Codes
Constrained coding is used widely in digital communication and storage
systems. In this paper, we study a generalized sliding window constraint called
the skip-sliding window. A skip-sliding window (SSW) code is defined in terms
of the length of a sliding window, skip length , and cost constraint
in each sliding window. Each valid codeword of length is determined by
windows of length where window starts at th symbol for
all non-negative integers such that ; and the cost constraint
in each window must be satisfied. In this work, two methods are given to
enumerate the size of SSW codes and further refinements are made to reduce the
enumeration complexity. Using the proposed enumeration methods, the noiseless
capacity of binary SSW codes is determined and observations such as greater
capacity than other classes of codes are made. Moreover, some noisy capacity
bounds are given. SSW coding constraints arise in various applications
including simultaneous energy and information transfer.Comment: 28 pages, 11 figure
Generalized Sphere-Packing Bound for Subblock-Constrained Codes
We apply the generalized sphere-packing bound to two classes of
subblock-constrained codes. A la Fazeli et al. (2015), we made use of
automorphism to significantly reduce the number of variables in the associated
linear programming problem. In particular, we study binary constant
subblock-composition codes (CSCCs), characterized by the property that the
number of ones in each subblock is constant, and binary subblock
energy-constrained codes (SECCs), characterized by the property that the number
of ones in each subblock exceeds a certain threshold. For CSCCs, we show that
the optimization problem is equivalent to finding the minimum of variables,
where is independent of the number of subblocks. We then provide
closed-form solutions for the generalized sphere-packing bounds for single- and
double-error correcting CSCCs. For SECCs, we provide closed-form solutions for
the generalized sphere-packing bounds for single errors in certain special
cases. We also obtain improved bounds on the optimal asymptotic rate for CSCCs
and SECCs, and provide numerical examples to highlight the improvement
PERFORMANCE LIMITS FOR ENERGY-CONSTRAINED COMMUNICATION SYSTEMS
Ph.DDOCTOR OF PHILOSOPH
Unary Coding Design for Simultaneous Wireless Information and Power Transfer with Practical M-QAM
Relying on the propagation of modulated radio-frequency (RF) signals, we can achieve simultaneous wireless information and power transfer (SWIPT) to support low-power communication devices. In this paper, we proposed a unary coding based SWIPT encoder by considering a practical M-QAM. Markov chains are exploited for characterising coherent binary information source and for modelling the generation process of modulated symbols. Therefore, both mutual information and the average energy harvesting performance at the SWIPT receiver are analysed in semi-closed-form. With the aid of the genetic algorithm, the sub-optimal codeword distribution of the coded information source is obtained by maximising the average energy harvesting performance, while satisfying the requirement of the mutual information. Simulation results demonstrate the advantage of the SWIPT encoder. Moreover, a higher-level unary code and a lower-order M-QAM results in higher WPT performance, when the maximum transmit power of the modulated symbol is fixed
Estimating the Sizes of Binary Error-Correcting Constrained Codes
In this paper, we study binary constrained codes that are resilient to
bit-flip errors and erasures. In our first approach, we compute the sizes of
constrained subcodes of linear codes. Since there exist well-known linear codes
that achieve vanishing probabilities of error over the binary symmetric channel
(which causes bit-flip errors) and the binary erasure channel, constrained
subcodes of such linear codes are also resilient to random bit-flip errors and
erasures. We employ a simple identity from the Fourier analysis of Boolean
functions, which transforms the problem of counting constrained codewords of
linear codes to a question about the structure of the dual code. We illustrate
the utility of our method in providing explicit values or efficient algorithms
for our counting problem, by showing that the Fourier transform of the
indicator function of the constraint is computable, for different constraints.
Our second approach is to obtain good upper bounds, using an extension of
Delsarte's linear program (LP), on the largest sizes of constrained codes that
can correct a fixed number of combinatorial errors or erasures. We observe that
the numerical values of our LP-based upper bounds beat the generalized sphere
packing bounds of Fazeli, Vardy, and Yaakobi (2015).Comment: 51 pages, 2 figures, 9 tables, to be submitted to the IEEE Journal on
Selected Areas in Information Theor
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