Concatenation Scheme Research Articles

Cancelable Face Template Protection using Transform Features for Cyberworld Security

Cyber world becomes a fundamental and vital component of the physical world with the increase of dependence on internet-connected devices in industry and government organizations. Provision of privacy and security of users during online communication offers unique cybersecurity challenges for industry and government. Intrusion is one of the crucial issues of cybersecurity, which can be overcome by providing the vigorous authentication solutions. Biometrics authentication is used in different cybersecurity systems for user authentication purpose. The cancelable biometric is a solution to rid of privacy problems in traditional biometric systems. This paper purposes a new cancelable face authentication method, which uses Hybrid Gabor PCA (HGPCA) descriptor for cyberworld security. The proposed method uses the wavelet transform for the extraction of the features of the face images by using Gabor filter and Principal Component Analysis (PCA). Later, both types of features have been ensemble by using the simple concatenation scheme. Then scrambling has been applied to the fused features by using the random key generated by the user. So finally, scrambled fused features has been stored in the database which are used for the cancelable biometric authentication as well as recovery. HGPCA achieves “cancelability” and increases the authentication accuracy. The proposed method has been tested on three standard face datasets. Experimental results of the proposed method have been compared with existing methods by using standard quantitative measures that show superiority over existing methods.

An Improved Concatenation Scheme of BCH-Polar Codes With Low-Latency Decoding Architecture

Polar codes have drawn much research attention in the last ten years for their capacity-achieving property. However, their conventional successive cancellation decoding method performs not well at a short or moderate length. In order to improve the performance, concatenation with other error-correction codes has been proved an effective approach, whereas current concatenation schemes using rate-optimized method are too complex to implement with long decoding latency. In this paper, we propose a critical set protected BCH-Polar code with its corresponding decoding architecture. In the proposed concatenation scheme, we only provide extra protection to partial information bits in the critical set, which is constructed based on the channel reliability. For its corresponding decoding architecture, we redesign some components and adopt the Look-up table decoding method for BCH codes, resulting in much degradation of decoding latency. Compared with existing decoders, the hardware implementation shows low decoding latency and high throughput-area efficiency.

Irregular LDPC‐polar concatenation scheme with designed scaling factors

In this Letter, a product concatenation scheme of systematic polar codes with irregular low-density parity check (LDPC) codes is proposed. The proposed scheme may take advantage of the good error-correction capability of irregular LDPC codes and superior error floor performance of polar codes. The joint belief propagation algorithm is employed, where scaling factors are introduced to manipulate the belief messages exchanged between constituent decoders, such that a fast convergence and a low BER performance may be achieved. Simulations are presented to validate its effectiveness.

Shipborne Underwater Acoustic Communication System and Sea Trials with Submersible Shenhai Yongshi

The Shipborne acoustic communication system of the submersible Shenhai Yongshi works in vertical, horizontal and slant channels according to the relative positions. For ease of use, an array combined by a vertical-cone directional transducer and a horizontal-toroid one is installed on the mothership. Improved techniques are proposed to combat adverse channel conditions, such as frequency selectivity, non-stationary ship noise, and Doppler effects of the platform’s nonlinear movement. For coherent modulation, a turbo-coded single-carrier scheme is used. In the receiver, the sparse decision-directed Normalized Least-Mean-Square soft equalizer automatically adjusts the tap pattern and weights according to the multipath structure, the two receivers’ asymmetry, the signal’s frequency selectivity and the noise’s spectrum fluctuation. The use of turbo code in turbo equalization significantly suppresses the error floor and decreases the equalizer’s iteration times, which is verified by both the extrinsic information transfer charts and bit-error-rate performance. For noncoherent modulation, a concatenated error correction scheme of nonbinary convolutional code and Hadamard code is adopted to utilize full frequency diversity. Robust and low-complexity synchronization techniques in the time and Doppler domains are proposed. Sea trials with the submersible to a maximum depth of over 4500 m show that the shipborne communication system performs robustly during the adverse conditions. From the ten-thousand communication records in the 28 dives in 2017, the failure rate of the coherent frames and that of the noncoherent packets are both below 10%, where both synchronization errors and decoding errors are taken into account.

CRC Location Design for Polar Codes

Polar codes concatenated with cyclic redundancy check (CRC) can achieve a competitive performance compared with the state-of-the-art codes. In this letter, we propose a criterion for designing concatenation structure based on an error pattern matrix. According to this criterion, we rearrange the location of CRC bits for polar codes to further improve the decoding performance. Meanwhile, the optimal CRC searching complexity of the proposed concatenation structure is significantly less than that of the standard CRC-polar concatenation scheme. Simulation results show that the proposed concatenation scheme outperforms the standard scheme whether they use the identical standard CRC or their respective optimal CRCs.

A dictionary learning algorithm for multi-subject fMRI analysis based on a hybrid concatenation scheme

Analysis of functional magnetic resonance imaging (fMRI) data from multiple subjects is at the heart of many medical imaging studies, and recently, the approaches based on dictionary learning (DL) are noted as promising solutions to the problem. However, the DL-based methods for fMRI analysis proposed to date do not naturally extend to multi-subject analysis. In this paper, we propose a DL algorithm for multi-subject fMRI data analysis which is derived using a hybrid (temporal and spatial) concatenation scheme. It differs from existing DL methods in both its sparse coding and dictionary update stages. It has the advantage of learning a dictionary common to all subjects as well as a set of subject-specific dictionaries, as a result, it is able to generate both group-level spatial activation maps as well as group-level temporal dynamics, which are particularly attractive for task-based fMRI studies. In addition, by simultaneously learning multiple sub-specific dictionaries, it also provides us with unique sub-specific features as well. Performance of the proposed DL method is illustrated using simulated and real fMRI datasets. The results show that it can successfully extract common as well as sub-specific latent components.

Serial concatenation of a block code and a 2D convolutional code

In this paper we study two different concatenation schemes of twodimensional (2D) convolutional codes. We consider Fornasini–Marchesini state space representation of 2D linear systems to describe our concatenated codes. Also we present upper and lower bounds on the distance of the proposed concatenated codes.

Topological Qubits from Valence Bond Solids.

Topological qubits based on SU(N)-symmetric valence-bond solid models are constructed. A logical topological qubit is the ground subspace with twofold degeneracy, which is due to the spontaneous breaking of a global parity symmetry. A logical Z rotation by an angle 2π/N, for any integer N>2, is provided by a global twist operation, which is of a topological nature and protected by the energy gap. A general concatenation scheme with standard quantum error-correction codes is also proposed, which can lead to better codes. Generic error-correction properties of symmetry-protected topological order are also demonstrated.

High Performance Short Polar Codes: A Concatenation Scheme Using Spinal Codes as the Outer Code

An innovative scheme for concatenating the polar codes with the recently proposed spinal codes is presented in this paper. The primary objective is to improve the performance of the polar codes in the finite-length regime. One effective used way is to concatenate the polar codes with short outer codes. Essentially, the short outer codes that have as high performance as possible is required for concatenation. To this end, the newly invented spinal codes are used as the outer codes, which are characterized by its great error correcting capability even when the message length is short. First, the proposed codes, named spinal-polar, is implemented through an interleaved concatenation scheme. A joint iterative decoding algorithm is proposed accordingly, and the decoding complexity of the algorithm is also analyzed. Second, in order to reduce the decoding complexity of the full concatenation while maintaining the BER performance, the partial concatenation scheme is presented. Finally, we propose a rate allocation algorithm to further improve the BER performance of the designed concatenated codes. Extensive simulations results indicate that the proposed spinal-polar codes have significant performance improvement over the stand-alone polar codes, and the other improvement strategies mentioned earlier have also been proved to be effective.

On the Concatenations of Polar Codes and Non-Binary LDPC Codes

An interleaved concatenation scheme of polar codes with non-binary low-density parity check (NBLDPC) codes is proposed in this paper to improve the error-correcting performance of polar codes with finite code length. The information blocks of inner polar codes are split into several information sub-blocks, and several segment successive cancellation list (S-SCL) decoders are carried out in parallel for all inner polar codes. Moreover, for a better error-correcting performance, an improved SCL decoder with a selective extension is proposed for the concatenated polar codes, which will be referred to selective extended segment SCL (SES-SCL) decoder. The SES-SCL decoder uses soft information of some unreliable information sub-blocks for the decoding of subsequent sub-blocks so as to mitigate the error propagation of premature hard decision of S-SCL decoder. Simulation results show that NBLDPC-polar codes can outperform Reed Solomon -polar codes. The NBLDPC-polar codes with the proposed SES-SCL algorithm can also be comparable with pure polar codes with cyclic redundancy check aided successive cancellation list (CA-SCL) decoding with list size $L=4$ in the high SNR, but require lower decoding storage. Therefore, the NBLDPC-polar codes may strike a better balance between memory space and performance compared with the state-of-the-art schemes in the finite length regime.

End-to-End Error-Correcting Codes on Networks With Worst-Case Bit Errors

In highly dynamic wireless networks, communications face several challenges. In the first place, noise levels between nodes might be difficult to predict a priori . Besides, a Byzantine attacker hidden in the network, with knowledge of the network topology and observation of all transmissions, can choose arbitrary locations to inject corrupted packets. Considering that transmissions are usually in bits and hardware in wireless networks usually use modulation schemes with the size of modulation alphabet being powers of two, e.g. BPSK, QPSK, 16-QAM, 64-QAM, and so on, to address the above problem, we study coding for networks experiencing worst case bit errors, and with network codes over binary extension fields. We demonstrate that in this setup prior network error-correcting schemes can be arbitrarily far from achieving the optimal network throughput. A new transform metric for errors under the considered model is proposed. Using this metric, we replicate many of the classical results from coding theory. Specifically, new Hamming-type , Plotkin-type , and Elias-Bassalygo-type upper bounds on the network capacity are derived. A commensurate lower bound is shown based on Gilbert–Varshamov (GV)-type codes for error-correction. The GV codes used to attain the lower bound can be non-coherent, that is, they require neither prior knowledge of the network topology nor network coding kernels. We also propose a computationally efficient concatenation scheme. The rate achieved by our concatenated codes is characterized by a Zyablov-type lower bound. We provide a generalized minimum-distance decoding algorithm which decodes up to half the minimum distance of the concatenated codes. The end-to-end nature of our design enables our codes to be overlaid on the classical distributed random linear network codes. The other advantage of the end-to-end strategy over the link-by-link error-correction is that it reduces the computational cost at the internal nodes for performing error-correction.

PC-CC: An advancement in forward error correction using polar and convolutional codes for MIMO-OFDM system

Multiple-input multiple-output (MIMO) antennas integrated with orthogonal frequency division multiplexing (OFDM) gains high interest due to its potential reduction on interference as well as efficient data transmission. However, the rapid growth of voluminous data and their diverse characteristics necessitate the effectiveness of error correction schemes in the recent past. The conventional error correction schemes suffer from its compatibility over the diverse data. Despite the concatenated error correction schemes meet the requirements, the precision remains uncertain under data and image transmission. This paper intends to develop an error correction scheme with the combination of Polar Coding (PC), which is an advanced coding scheme, and the renowned Convolution coding (CC). The competiveness of the proposed error correction scheme is experimented under extensive simulation constraints. Accordingly, this paper simulates MIMO-OFDM system with three antenna configurations (2 × 2), (2 × 4) and (4 × 4), which are subjected to experimentation under three modulation schemes such as Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM)-16 and QAM-64. Three practical channel models such as Additive White Gaussian Noise (AWGN), Rayleigh and Rician channel models are used in the proposed study. The performance of the proposed coding scheme is compared against the traditional error correction schemes such as CC, Reed Solomon Code (RSC)-CC, Low-Density Parity Check (LDPC)-CC and turbo-CC. The study is also extended by transmitting the data as well as image to ensure the fairness on diversity of the data characteristics. The study discloses the effectiveness of the proposed error correction scheme over the conventional error correction schemes in terms of BER (Bit Error Rate) and PSNR (Peak Signal to Noise Ratio), when data and images are transmitted, respectively. The proposed method is compared with the conventional techniques and the results have shown that the PSNR performance of the proposed PC-CC method is 37.95% better than CC, 31.73% better than RSC-CC, 24.52% better than LDPC-CC and 14.12% better than turbo-CC method.

Sample Preparation for Endopeptidomic Analysis in Human Cerebrospinal Fluid.

This protocol describes a method developed to identify endogenous peptides in human cerebrospinal fluid (CSF). For this purpose, a previously developed method based on molecular weight cut-off (MWCO) filtration and mass spectrometric analysis was combined with an offline high-pH reverse phase HPLC pre-fractionation step. Secretion into CSF is the main pathway for removal of molecules shed by cells of the central nervous system. Thus, many processes in the central nervous system are reflected in the CSF, rendering it a valuable diagnostic fluid. CSF has a complex composition, containing proteins that span a concentration range of 8 - 9 orders of magnitude. Besides proteins, previous studies have also demonstrated the presence of a large number of endogenous peptides. While less extensively studied than proteins, these may also hold potential interest as biomarkers. Endogenous peptides were separated from the CSF protein content through MWCO filtration. By removing a majority of the protein content from the sample, it is possible to increase the sample volume studied and thereby also the total amount of the endogenous peptides. The complexity of the filtrated peptide mixture was addressed by including a reverse phase (RP) HPLC pre-fractionation step at alkaline pH prior to LC-MS analysis. The fractionation was combined with a simple concatenation scheme where 60 fractions were pooled into 12, analysis time consumption could thereby be reduced while still largely avoiding co-elution. Automated peptide identification was performed by using three different peptide/protein identification software programs and subsequently combining the results. The different programs were complementary rather than comparable with less than 15% of the identifications overlapped between the three.

Multi-core virtual concatenation scheme considering inter-core crosstalk in spatial division multiplexing enabled elastic optical networks

Spatial division multiplexing enabled elastic optical networks (SDM-EONs) are the potential implementation form of future optical transport networks, because it can curve the physical limitation of achievable transmission capacity in single-mode fiber and single-core fiber. However, spectrum fragmentation issue becomes more serious in SDM-EONs compared with simple elastic optical networks (EONs) with single mode fiber or single core fiber. In this paper, multi-core virtual concatenation (MCVC) scheme is first proposed considering inter-core crosstalk to solve the spectrum fragmentation issue in SDM-EONs. Simulation results show that the proposed MCVC scheme can achieve better performance compared with the baseline scheme, i.e., single-core virtual concatenation (SCVC) scheme, in terms of blocking probability and spectrum utilization.

Error suppression via complementary gauge choices in Reed-Muller codes

Concatenation of two quantum error-correcting codes with complementary sets of transversal gates can provide a means toward universal fault-tolerant quantum computation. We first show that it is generally preferable to choose the inner code with the higher pseudo-threshold to achieve lower logical failure rates. We then explore the threshold properties of a wide range of concatenation schemes. Notably, we demonstrate that the concatenation of complementary sets of Reed-Muller codes can increase the code capacity threshold under depolarizing noise when compared to extensions of previously proposed concatenation models. We also analyze the properties of logical errors under circuit-level noise, showing that smaller codes perform better for all sampled physical error rates. Our work provides new insights into the performance of universal concatenated quantum codes for both code capacity and circuit-level noise.

High-Threshold Low-Overhead Fault-Tolerant Classical Computation and the Replacement of Measurements with Unitary Quantum Gates.

von Neumann's classic "multiplexing" method is unique in achieving high-threshold fault-tolerant classical computation (FTCC), but has several significant barriers to implementation: (i)the extremely complex circuits required by randomized connections, (ii)the difficulty of calculating its performance in practical regimes of both code size and logical error rate, and (iii)the (perceived) need for large code sizes. Here we present numerical results indicating that the third assertion is false, and introduce a novel scheme that eliminates the two remaining problems while retaining a threshold very close to von Neumann's ideal of 1/6. We present a simple, highly ordered wiring structure that vastly reduces the circuit complexity, demonstrates that randomization is unnecessary, and provides a feasible method to calculate the performance. This in turn allows us to show that the scheme requires only moderate code sizes, vastly outperforms concatenation schemes, and under a standard error model a unitary implementation realizes universal FTCC with an accuracy threshold of p<5.5%, in which p is the error probability for 3-qubit gates. FTCC is a key component in realizing measurement-free protocols for quantum information processing. In view of this, we use our scheme to show that all-unitary quantum circuits can reproduce any measurement-based feedback process in which the asymptotic error probabilities for the measurement and feedback are (32/63)p≈0.51p and 1.51p, respectively.

Concatenation of convolutional codes and rank metric codes for multi-shot network coding

In this paper we present a novel coding approach to deal with the transmission of information over a network. In particular we make use of the network several times (multi-shot) and impose correlation in the information symbols over time. We propose to encode the information via an inner and an outer code, namely, a Hamming metric convolutional code as an outer code and a rank metric code as an inner code. We show how this simple concatenation scheme can exploit the potential of both codes to produce a code that can correct a large number of error patterns.

An Improved Concatenation Scheme of Polar Codes With Reed–Solomon Codes

An improved Reed–Solomon (RS)-polar code concatenation scheme with a threshold is proposed. It applies successive cancellation list and hard-decision decoding based on the low-complexity chase algorithm. A new multiplicity assignment module is proposed to make it possible to realize the RS-polar code concatenation and facilitate hardware decoder design. The proposed scheme achieves high decoding performance, low decoding complexity, and short latency. The simulation results show that the improved concatenation scheme gives a coding gain reaching about 0.4 dB compared with the traditional RS-polar scheme. Moreover, it can reduce the average number of RS codewords to be decoded in a concatenated code by 65% and decrease the decoding latency by 50% when the signal-to-noise ratio is 1.75 dB.

Crosstalk‐aware cross‐core virtual concatenation in spatial division multiplexing elastic optical networks

Spatial division multiplexing elastic optical networks (SDM-EONs) will become the most important form of future optical transport networks, because it can break the physical limit of achievable capacity in single-mode and single-core fibre. However, spectrum fragmentation issue becomes more serious in SDM-EONs compared with in single EON. Crosstalk-aware cross-core virtual concatenation (CCVC) scheme is first proposed to solve the spectrum fragmentation issue in SDM-EONs. Simulation results show that CCVC can achieve lower blocking probability and higher spectrum utilisation compared with single-core virtual concatenation scheme.

Interleaved Concatenations of Polar Codes With BCH and Convolutional Codes

We analyze interleaved concatenation schemes of polar codes with outer binary BCH codes and convolutional codes. We show that both BCH-polar and Conv-polar codes can have a frame error rate that decays exponentially with the code length for all rates up to capacity, which is a substantial improvement in the error exponent over stand-alone polar codes. Interleaved concatenation with long constraint length convolutional codes is an effective way to leverage the fact that polarization increases the cutoff rate of the channel. Simulation results show that Conv-polar codes when decoded with the proposed soft-output multistage iterative decoding algorithm can outperform stand-alone polar codes decoded with successive cancellation or belief propagation decoding. It may be comparable to stand-alone polar codes with list decoding in the high SNR regime. In addition to this, we show that the proposed concatenation scheme requires lower memory and decoding complexity in comparison to belief propagation and list decoding of polar codes. Practically, the scheme enables rate compatible outer codes which ease hardware implementation. Our results suggest that the proposed method may strike a better balance between performance and complexity compared to existing methods in the finite-length regime.