Decoding Message Research Articles

Robust Communication: How Math Is Used to Encode and Decode Messages

Coding theory uses linear and abstract algebra to protect messages against corruption when sending them over a channel. This paper examines the mathematics behind coding theory and how it is used to ensure reliable communication.

Non-binary codes approach on the performance of short-packet full-duplex transmissions

This paper illustrates the enhancement of the performance of short-packet full-duplex (FD) transmission by taking the approach of non-binary low density parity check (NB-LDPC) codes over higher Galois field. For the purpose of reducing the impacts of self-interference (SI), high order of modulation, complexity, and latency decoder, a blind feedback process composed of channels estimation and decoding algorithm is implemented. In particular, this method uses an iterative process to simultaneously suppress SI component of FD transmission, estimate intended channel, and decode messages. The results indicate that the proposed technique provides a better solution than both the NB-LDPC without feedback and the binary LDPC feedback algorithms. Indeed, it can significantly improve the performance of overall system in two important factors, which are bit-error-rate (BER) and <a name="_Hlk155778233"></a>mean square error (MSE), especially in high order of modulation. The suggested algorithm also shows a robustness in reliability and power consumption for both short-packet FD transmissions and high order modulation communications.

Vibrational Radar Backscatter Communications Theory and Bound

Vibrational radar backscatter communication (VRBC) utilizes millimeter-wave radar vibrometry to receive message signals from vibrating surfaces. So long as multiple transponding surfaces are separable by the system radar in angle and/or range, VRBC can simultaneously detect, isolate, and decode messages from these multiple sources. For anything-to-vehicle communications, VRBC is therefore a scalable, low-latency approach which leverages existing automotive radars to increase situational awareness without requiring any additional use of the RF spectrum. In this paper, we describe the modeling and processing of VRBC signals. We show that knowledge of surface resonances and coding constraints can be used to improve system performance by incorporating them into a Markov model. We provide insight into the rate capabilities of VRBC by providing a theoretical upper bound that incorporates the presence of intersymbol interference (ISI). Simulation results compare our upper bound to achievable communication rates using single symbol vs sequence detection maximum likelihood methods for a given symbol length, set of symbol excitations, and VRBC radar pulse repetition interval (PRI).

Four-channels optical chaos secure communications with the rate of 400 Gb/s using optical reservoir computing based on two quantum dot spin-VCSELs

In this work, we utilize four parallel reservoirs to model the chaotic dynamics of the output four polarization components (PCs) from a driving QD spin-VCSEL. Here, the four parallel reservoirs are implemented using the four PCs of a reservoir QD spin-VCSEL. High-quality chaos synchronizations of four pairs of PCs can be realized by using the four parallel reservoirs based on a reservoir QD spin-VCSEL. Under these high-quality synchronizations, we successfully implement four-channel secure communications with 4 × 100 Gb/s 16 QAM messages under guaranteeing. We further discuss the performances of the bit error ratios (BERs) for four decoding messages under different parameters. We show that all BERs via different parameters are less than 7 × 10−3, denoting that high-quality data-transmissions can be potentially obtained in the system. Moreover, we prove that our proposed multi-channel optical chaotic communication scheme has the same level of security as the traditional schemes. Our findings show that the delay-based optical reservoir computing based on a QD spin-VCSEL provides an effective method for realization of multi-channel optical secure communication.

Low Complexity Decoding Algorithm for Uplink SCMA Based on Aerial Spherical Decoding

As a new non-orthogonal multiple access technology for 5G massive machine type communication scenario, the sparse code multiple access (SCMA) has greatly improved the spectrum efficiency due to the high connection density. SCMA combines QAM (Quadrature Amplitude Modulation) modulation and sparse spreading into a codebook set to obtain forming gain. The user binary bit data is directly mapped into multi-dimensional codewords in the transmitter. The receiver uses the message passing algorithm (MPA) for multi-user detection to achieve efficient decoding. However, MPA is a good solution for SCMA, though its high complexity limits the application in practical systems. In order to reduce the complexity of MPA, this paper proposed a low-complexity decoding algorithm based on the serial spherical decoding message passing algorithm (SSD-MPA), which greatly enhanced the practicability of the SCMA system. The SSD-MPA took into account the distribution characteristics of the Gaussian noise and the reliability of the constellation points, and only updates the trusted constellation point messages of nodes within the spherical radius. At the same time, it used a serial strategy to speed up the convergence rate. The simulation results have shown that when the radius sets properly, the algorithm reduces the complexity by about 2/3 compared with the original MPA, and the performance was almost lossless.

A Deep Learning Assisted Node-Classified Redundant Decoding Algorithm for BCH Codes

This paper proposes a node-classified redundant decoding (NC-RD) algorithm based on the received sequence’s channel reliability for high-density parity-check (HDPC) codes. Two preprocessing steps are proposed prior decoding. The variable nodes of the parity-check matrix are firstly classified by the $k$ -median algorithm based on the number of shortest cycles associated with each variable node before decoding. Then, by searching among the automorphism group of the HDPC codes, we generate a list of permutations for bit positions by computing and sorting the permutation reliability metrics. The redundant decoder conducts the message-passing decoding according to the sorted permutations, which limit the unreliable information propagation for each permutation. Besides proposing a list decoding algorithm on top of the NC-RD algorithm to augment the decoder’s performance, we show that the NC-RD algorithm can be transformed into a neural network system. More specifically, multiplicative tuneable weights are attached to the decoding messages to optimize the decoding performance. Simulation results of BCH codes over the AWGN channels show that the NC-RD algorithm provides a performance gain compared to the random redundant decoding algorithm. Additional decoding performance gain can be obtained by both the list decoding method and the neural network “learned” NC-RD algorithm.

Low-Power Non-Binary LDPC Decoder Design via Adaptive Message Length Control Exploiting Domain-Specific Information

With the enhanced performance and convergence speed than their binary counterparts, NB-LDPC codes have been considered for emerging wireless communication and storage applications. However, one challenging issue to apply NB-LDPC codes in low-power embedded applications is the high decoding complexities. In this paper, we propose a comprehensive message length control technique that adaptively truncates decoding messages according to the domain-specific information. The number of arithmetic operations and memory accesses can be greatly reduced with shorter decoding messages. To implement the proposed technique, we propose a sequential decoder architecture which controls the decoding message length. Evaluation results show that the proposed technique can achieve significant power reduction than the conventional techniques while maintaining the same decoding performance.

Analysis of TDMP Algorithm of LDPC Codes Based on Density Evolution and Gaussian Approximation.

Based on density evolution analysis of the existing belief propagation (BP) algorithm, the Turbo Decoding Message Passing (TDMP) algorithm was analyzed from the perspective of density evolution and Gaussian approximation, and the theoretical analysis process of TDMP algorithm was given. When calculating the prior message of each layer of the TDMP algorithm, the check message of the previous iteration should be subtracted. Therefore, the result will not be convergent, if the TDMP algorithm is directly analyzed based on density evolution and Gaussian approximation. We researched the TDMP algorithm based on the symmetry conditions to obtain the convergent result. When using density evolution (DE) and Gaussian approximation to analyze the decoding convergence of the TDMP algorithm, we can provide a theoretical basis for proving the superiority of the algorithm. Then, based on the DE theory, we calculated the probability density function (PDF) of the check-to-variable information of TDMP and its simplified algorithm, and then gave it a calculation based on the process of the normalization factor. Simulation results show that the decoding convergence speed of the TDMP algorithm was faster and the iterations were smaller compared to the BP algorithm under the same conditions.

An improved multidimensional reconciliation algorithm for continuous-variable quantum key distribution

Reconciliation is a crucial procedure for continuous-variable quantum key distribution (CV-QKD) systems since it directly affects the performance of practical system including processing speed, secret key rate, and maximal transmission distance. In this paper, we proposed a novel initial decoding message computation method for multidimensional reconciliation with low density parity check code, which does not need the norm information from the encoder. Both theoretical analysis and simulation results demonstrate that the improved scheme can greatly decrease the communication traffic and storage resource consumption of the reconciliation procedure almost without degradation in the reconciliation efficiency. What is more, the improved scheme can decrease the secure key consumption for classical channel authentication, then increase the secure key rate, and also be conducive to the realization of high-speed CV-QKD systems.

Lattice Codes for Many-to-One Interference Channels With and Without Cognitive Messages

A new achievable rate region is given for the Gaussian cognitive many-to-one interference channel. The proposed novel coding scheme is based on the compute-and-forward approach with lattice codes. Using the idea of decoding sums of codewords, our scheme improves considerably upon the conventional coding schemes which treat interference as noise or decode messages simultaneously. Our strategy also extends directly to the usual many-to-one interference channels without cognitive messages. Comparing to the usual compute-and-forward scheme where a fixed lattice is used for the code construction, the novel scheme employs scaled lattices and also encompasses key ingredients of the existing schemes for the cognitive interference channel. With this new component, our scheme achieves a larger rate region in general. For some symmetric channel settings, new constant gap or capacity results are established, which are independent of the number of users in the system.

The Research on TDMP Merged Decoding Algorithm of LDPC Codes Based on DVB-S2 Standard

DVB-S2 is the second generation of Digital Video Broadcasting-Satellite and LDPC (Low Density Parity Code) is the key technology in which the decoding plays an important role in determining the performance of DVB-S2 system. According to the research on the characteristics of DVB-S2 standard, this paper reports on the improvement of the Turbo Decoding Message Passing (TDMP) algorithm by adopting the idea of merging. The component codes which don’t have public nodes are regarded as a new component. By changing the decoding order of component codes and removing useless waiting time, the message capacity transmitted between two adjacent component codes is increased. The performance of the proposed TDMP merged decoding algorithm is evaluated by simulation experiments. We measure decoding performance, convergence rate and the average decoding time to evaluate the system performance. The results obtained show that the TDMP merged decoding algorithm ensures the performance of decoding and good convergence, and also improves the average decoding speed and throughput.

Mapper and Demapper for LDPC-Coded Systems

Low Density Parity Check (LDPC) codes are state-of-art error correcting codes, included in several standards for broadcast transmissions. Iterative softdecision decoding algorithms for LDPC codes reach excellent error correction capability; their performance, however, is strongly affected by finite-precision issues in the representation of inner variables. Great attention has been paid, in recent literature, to the topic of quantization for LDPC decoders, but mostly focusing on binary modulations and analyzing finite precision effects in a disaggregrated manner, i.e., considering separately each block of the receiver. Modern telecommunication standards, instead, often adopt high order modulation schemes, e.g. M-QAM, with the aim to achieve large spectral efficiency. This puts additional quantization problems, that have been poorly debated in previous literature. This paper discusses the choice of suitable quantization characteristics for both the decoder messages and the received samples in LDPC-coded systems using M-QAM schemes. The analysis involves also the demapper block, that provides initial likelihood values for the decoder, by relating its quantization strategy with that of the decoder. A signal label for a signal in a 2m-ary modulation scheme is simply the m-bit pattern assigned to the signal. A mapping strategy refers to the grouping of bits within a codeword, where each mbit group is used to select a 2m-ary signal in accordance with the signal labels. The most obvious mapping strategy is to use each group of m consecutive bits to select a signal. . We will call this the consecutive-bit (CB) mapping strategy. An alternative strategy is the bit-reliability (BR) mapping strategy which will be described below. A new demapper version, based on approximate expressions, is also presented, that introduces a slight deviation from the ideal case but yields a low complexity hardware implementation.

Efficient Power Allocation for LDPC-Coded MIMO Systems

In this papers an efficient ordering scheme for an ordered successive interference cancellation detector is determined under the bit error rate minimization criterion for multiple-input multiple-output(MIMO) communication systems using transmission power control. From the convexity of the Q-function, we evaluate the choice of suitable quantization characteristics for both the decoder messages and the received samples in Low Density Parity Check (LDPC)-coded systems using M-QAM schemes. We derive the ordering strategy that makes the channel gains converge to their geometric mean. Based on this approach, the fixed ordering algorithm is first designed, for which the geometric mean is used for a constant threshold using correlation among ordering results.

Bandwidth-Efficient Modulation Codes Based on Nonbinary Irregular Repeat–Accumulate Codes

Using nonbinary low-density parity-check (LDPC) codes with random-coset mapping, Bennatan and Burshtein constructed bandwidth-efficient modulation codes with remarkable performance under belief propagation (BP) decoding. However, due to the random nature of LDPC codes, most of the good LDPC codes found in the literature do not have a simple encoding structure. Thus, the encoding complexity of those LDPC codes can be as high as O(N 2), where N is the codeword length. To reduce the encoding complexity, in this paper, nonbinary irregular repeat-accumulate (IRA) codes with time-varying characteristic and random-coset mapping are proposed for bandwidth-efficient modulation schemes. The time-varying characteristic and random-coset mapping result in both permutation-invariance and symmetry properties, respectively, in the densities of decoder messages. The permutation-invariance and symmetry properties of the proposed codes enable the approximations of densities of decoder messages using Gaussian distributions. Under the Gaussian approximation, extrinsic information transfer (EXIT) charts for nonbinary IRA codes are developed and several codes of different spectral efficiencies are designed based on EXIT charts. In addition, by proper selection of nonuniform signal constellations, the constructed codes are inherently capable of obtaining shaping gains, even without separate shaping codes. Simulation results indicate that the proposed codes not only have simple encoding schemes, but also have remarkable performance that is even better than that constructed using nonbinary LDPC codes.

Design of a Multimode QC-LDPC Decoder Based on Shift-Routing Network

A reconfigurable message-passing network is proposed to facilitate message transportation in decoding multimode quasi-cyclic low-density parity-check (QC-LDPC) codes. By exploiting the shift-routing network (SRN) features, the decoding messages are routed in parallel to fully support those specific 19 and 3 submatrix sizes defined in IEEE 802.16e and IEEE 802.11n applications with less hardware complexity. A 6.22- mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> QC-LDPC decoder with SRN is implemented in a 90-nm 1-Poly 9-Metal (1P9M) CMOS process. Postlayout simulation results show that the operation frequency can achieve 300 MHz, which is sufficient to process the 212-Mb/s 2304-bit and 178-Mb/s 1944-bit codeword streams for IEEE 802.16e and IEEE 802.11n systems, respectively.

La competencia intercultural como llave para el desarrollo del Perú

The term «intercultural competence» originally referred to the conscious skills and attitudes that the student and everyone involved in teaching a foreign language had to develop to understand the sociocultural context and decode messages from the language they were teaching-learning, meaning is no longer exclusive to this area. This article is about how the implementation of intercultural competence has become very important in international relations, international cooperation, education and business; it allows optimizing the communication between different countries and cultures. Also, focus on its application to the national situation. Finally, gives an example of what can be a good practice of «intercultural competence» with the Chinese culture as a reference

Finite-Precision Analysis of Demappers and Decoders for LDPC-Coded M-QAM Systems

LDPC codes are state-of-art error correcting codes, included in several standards for broadcast transmissions. Iterative soft-decision decoding algorithms for LDPC codes reach excellent error correction capability; their performance, however, is strongly affected by finite-precision issues in the representation of inner variables. Great attention has been paid, in recent literature, to the topic of quantization for LDPC decoders, but mostly focusing on binary modulations and analysing finite precision effects in a disaggregrated manner, i.e., considering separately each block of the receiver. Modern telecommunication standards, instead, often adopt high order modulation schemes, e.g. M-QAM, with the aim to achieve large spectral efficiency. This puts additional quantization problems, that have been poorly debated in previous literature. This paper discusses the choice of suitable quantization characteristics for both the decoder messages and the received samples in LDPC-coded systems using M-QAM schemes. The analysis involves also the demapper block, that provides initial likelihood values for the decoder, by relating its quantization strategy with that of the decoder. A new demapper version, based on approximate expressions, is also presented, that introduces a slight deviation from the ideal case but yields a low complexity hardware implementation.

Design and analysis of nonbinary LDPC codes for arbitrary discrete-memoryless channels

We present an analysis under the iterative decoding of coset low-density parity-check (LDPC) codes over GF(q), designed for use over arbitrary discrete-memoryless channels (particularly nonbinary and asymmetric channels). We use a random- coset analysis to produce an effect that is similar to output symmetry with binary channels. We show that the random selection of the nonzero elements of the GF(q) parity-check matrix induces a permutation-invariance property on the densities of the decoder messages, which simplifies their analysis and approximation. We generalize several properties, including symmetry and stability from the analysis of binary LDPC codes. We show that under a Gaussian approximation, the entire q-1-dimensional distribution of the vector messages is described by a single scalar parameter (like the distributions of binary LDPC messages). We apply this property to develop extrinsic information transfer (EXIT) charts for our codes. We use appropriately designed signal constellations to obtain substantial shaping gains. Simulation results indicate that our codes outperform multilevel codes at short block lengths. We also present simulation results for the additive white Gaussian noise (AWGN) channel, including results within 0.56 dB of the unrestricted Shannon limit (i.e., not restricted to any signal constellation) at a spectral efficiency of 6 bits/s/Hz.

The dialogic model: representing human diversity in messages to extraterrestrials

A Dialogic Model of constructing a unified reply message is suggested in which differences between perspectives are valued, rather than minimized. In this model, a diversity of views is seen as a virtue. Consensus in the broad sense of agreeing to include multiple perspectives is encouraged, while consensus in the narrow sense of everyone agreeing about all parts of the message is seen as overly restrictive, if not impossible. In the Dialogic Model, even perspectives that are irreconcilable with one another might be included in a single reply. Drawing upon multiple perspectives allows us to expand beyond our own preconceptions, gives extraterrestrials several ways to understand our views of the world, and portrays the breadth of human concerns. Seven benefits of beginning work on a reply message immediately are identified: (1) concretely understanding the challenge of creating an adequate reply; (2) helping decode messages from extraterrestrials; (3) creating interstellar compositions as a new form of art; (4) having a reply ready in case we receive a message; (5) providing a sense of concrete accomplishment; (6) preparing for an active search strategy; and (7) gaining public support for SETI.

Role of the Carrier Frequency in the Territorial Songs of Oscines

AbstractBirds cannot emit acoustic signals of very low frequencies. To code a message with such signals they shift them upwards by using a frequency modulation. The new frequency chosen for transmission is the carrier. Its value is adapted to the phonetic and sensory capacities of the bird, as well as to the characteristics of the channel.The code does not give any significance to the carrier alone, but determines its value. Modulation and demodulation must be applied to carriers of the same value.The code also determines the carrier wave shape, i.e. its spectrum. Any alteration of this shape reduces decoding possibilities.To code and decode messages with frequency modulated signals, birds use the same strategies as humans.