Quasi-cyclic LDPC (QC-LDPC) codes have been accepted as the standard of 5G enhanced mobile broadband data channel. These are designed to support multiple lifting sizes and possess rate-compatible property, which can help adapt various information lengths code rates well. In this paper, we propose an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">algebra-assisted</i> method for constructing QC-LDPC with such properties. We will first review...

Semantic communication is an emerging approach that enhances transmission efficiency by conveying the semantic content of information more effectively. It has garnered significant attention in recent years. However, existing systems for image typically adopt direct features or uniformly compress before transmission. They have not yet considered differential impact on recovery at receiver end and issue bandwidth limitations during actual This paper shows non-uniform processing leads to better...

The Alternating Direction Method of Multipliers (ADMM) has proven to be an efficient approach for implementing linear programming (LP) decoding low-density parity-check (LDPC) codes. By introducing penalty terms into the LP model’s objective function, ADMM-based variable node penalized effectively mitigates non-integral solutions, thereby improving frame error rate (FER) performance, especially in low signal-to-noise ratio (SNR) region. In this paper, we leverage ADMM framework derive...

In this letter, we study the construction of quasi-cyclic (QC) low-density parity-check (LDPC) codes by array dispersion and masking. We first propose a class arrays circulant permutation matrices (CPMs) arbitrary size obtained dispersion. Based on CPMs, QC-LDPC is constructed. For these resulting codes, analyze their cycle structure derive numbers, which indicate how many cycles pass through each CPM in matrices. Following indication numbers with order from largest to smallest, replace...

Girth is an important structural property of low-density parity-check (LDPC) codes. Motivated by the works on girth Tanner (3, 5), 7), 11), and (5, 7) quasi-cyclic (QC) LDPC codes, we, in this paper, study 13) QC-LDPC codes length <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$13p$ </tex-math></inline-formula> for notation="LaTeX">$p$ being a prime form notation="LaTeX">$(39m+1)$ . First, cycle structure...

In this letter, we present an efficient method for constructing a family of quasi-cyclic low-density parity-check (QC-LDPC) codes specified only by one single exponent matrix that can support multiple lifting sizes. Our adopts the small-lifting-size-first design strategy and resulting larger size has non-decreasing girth. Numerical results show all constituent perform as well (outperform) CCSDS (5G) LDPC over AWGN channel with iterative decoding algorithms. This fact demonstrates feasibility...

In this letter, we consider the construction of q-ary low-density parity-check (LDPC) codes by jointly optimizing girth and number shortest cycles in frame superposition. We begin with constructing binary quasi-cyclic LDPC By replacing nonzero entries matrices resulting elements GF(q), a class is obtained. Furthermore, analyze cycle structure constructed for given degree distribution code length, present search algorithm finding few length g, where g optimized value. Simulation results show...

This paper presents a nonbinary low-density parity-check (LDPC) coded spatial modulation (CSM) for multiple-input multiple-output communication systems, in which the information bits choosing active transmit antennas and constellation signals are protected by LDPC code. We apply many-to-one mapping known as Gallager to signal constellation, resulting an improved design CSM system. Furthermore, we propose mapping-based scheme solve problem of system with arbitrary antennas, is used map index...

Girth plays an important role in the design of low-density parity-check (LDPC) codes. Motivated by works on girth some classes Tanner quasi-cyclic (QC) LDPC codes, e.g., (3, 5), 7), 11), and (5, 7) we, this paper, study <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(J,L)$ </tex-math></inline-formula> QC-LDPC codes where notation="LaTeX">$J$ notation="LaTeX">$L$ can be any two positive integers. According...

Quasi‐cyclic (QC) LDPC codes play an important role in 5G communications and have been chosen as the standard for enhanced mobile broadband (eMBB) data channel. In this paper, we study construction of QC based on arbitrary given expansion factor (or lifting degree). First, analyze cycle structure give necessary sufficient condition existence short cycles. Based fundamental theorem arithmetic number theory, divide integer factorization into three cases present classes accordingly....

Sparse code multiple access (SCMA) is a promising technique to meet the requirements for massive capacity in 5G communications. In this paper, nonbinary LDPC- coded SCMA system with turbo receiver proposed. We also provide heuristic approach based on Cartesian product and Euclidean distance construct codebook, which greatly reduces detection complexity can be easily extended large-size constellations. Furthermore, codebook design large systems presented, sparse structure optimized via...

There exist lots of (3, L)-regular quasi-cyclic (QC) LDPC codes constructed from finite fields, protographs, array codes, and computer search under some design rules. For a given code length rate, how to select the best one these is considerable. In this paper, we study QC perspective graph isomorphism, non-isomorphic are determined. By analyzing cycle structures resulting an efficient algorithm for counting cycles presented. Also proposed simplified exhaustive free less than g <sub...

In this paper, we present a method for constructing LDPC codes from resolvable group divisible designs (RGDDs). According to the incidence matrices (or their submatrices) of RGDDs, class regular can be constructed. Since parity-check matrix resulting code satisfies row-column constraint, girth proposed is at least six. Furthermore, based on design, obtain sequence with various lengths and rates, which perform well over AWGN channel iterative decoding have low error floors.

As a class of capacity-approaching codes, nonbinary low-density parity-check (LDPC) codes have attracted much attention because noticeable performance. Nonbinary LDPC-coded modulation systems which excellent performance for high-spectral efficiency transmission are also potential schemes in the future communication system. In this paper, we propose new construction method quasi-cyclic LDPC codes. Furthermore, comparative study about various coded over AWGN channel and high-mobility is...

In this paper, we investigate the application of nonbinary LDPC codes to spatial modulation, and a coded modulation (NBLDPC- SM) system is proposed. system, symbols for choosing active antennas constellation signals are protected by code. Furthermore, combine NBLDPC-SM with Gallager mapping, method shaping, improve spectral efficiency. We demonstrate that such can achieve low probability bit error at near SM capacity. Several communication scenarios investigated verify good performance...

In this paper, we focus on short-block nonbinary LDPC (NB-LDPC) codes based cyclic codes. Based Tanner graphs' isomorphism, present an efficient search algorithm for finding non-isomorphic binary Notice that the parity-check matrix H of resulting code is square and not full rank, its row weight column are same. By replacing ones in same with a nonzero element finite fields GF(q), class NB-LDPC over GF(q) obtained. Numerical results show constructed perform well AWGN channel have fast...

This paper presents a family of rate‐compatible (RC) globally coupled low‐density parity‐check (GC‐LDPC) codes, which is constructed by combining algebraic construction method and graph extension. Specifically, the highest rate code using codes lower rates are formed successively extending higher codes. The proposed provide more flexibility in guarantee structural property construction. It confirmed, numerical simulations over AWGN channel, that have better performances than their...

Data collection is an essential operation in wireless sensor networks (WSNs). Topology control and duty-cycle are two popular schemes WSNs to improve the utilization of various network resource. The problem low-cost topology investigated this paper. Due each sensor's awake/sleep schedule, topological graphs changed over time. A space-time graph model presented describe dynamics a series graphs. new spacetime defined, then heuristic algorithms proposed find structures, which connectivity from...

In space communications, there exist two prominent issues: large Doppler spread and limited pilot resources, which will result in poor performance for a pilot-aided (PA) traditional carrier synchronization mode (TCSM) with serial processing. view of this, we propose frequency-phase decoupling method (FPDM) based on an unbiased auto-correlation (AC) operator variable correlation delay length. By using this method, new (NCSM) is developed parallel Taking the classical maximum likelihood (ML)...

We consider a low-density parity-check (LDPC) coded non-recursive Gaussian minimum shift keying (GMSK) scheme for space communications subject to low signal-to-noise ratio (SNR), limited power, and spectrum resources. First, we design continuous-phase encoder (NRCPE)-based GMSK modulator alleviate the impact of error propagation existed in recursive CPE (RCPE)-based one. Then, corresponding pilot-aided quasi-coherent demodulation algorithm (PA-QCDA) is developed improving performance...