This paper presents a technique to scale up an LDPC code to any desired block length. Under certain constraints, the scaled LDPC code results in a special case of globally-coupled-LDPC code. The proposed scheme can co...
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ISBN:
(纸本)9781538670484
This paper presents a technique to scale up an LDPC code to any desired block length. Under certain constraints, the scaled LDPC code results in a special case of globally-coupled-LDPC code. The proposed scheme can construct globally-coupled-LDPC codes from any short LDPC codes. A design example targeting for NAND flash memory applications is addressed and simulated. The results show the feasibility of constructing a structural long LDPC code by scaling from a short code.
Reconciliation is a crucial procedure in post-processing of continuous-variable quantum key distribution (CV-QKD) system, which is used to make two distant legitimate parties share identical corrected keys. The adapti...
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Reconciliation is a crucial procedure in post-processing of continuous-variable quantum key distribution (CV-QKD) system, which is used to make two distant legitimate parties share identical corrected keys. The adaptive reconciliation is necessary for practical systems to cope with the variable channel. Many researchers adopt fixed-rate error correction codes to implement adaptive reconciliation, such as the punctured LDPC code;however such protocol can achieve high efficiency only in a small range of signal-to-noise ratios (SNRs). In this paper, the spinal-based rateless reconciliation protocol for CV-QKD is first proposed. The proposed adaptive reconciliation protocol can achieve high efficiency in a much larger range of SNRs. Because the protocol we propose uses the code with short length and simple encoding/decoding structure, the design and implementation complexities of our protocol are greatly decreased. Meanwhile, its parallel attribute makes it suitable for hardware implementation, which means it has the potential of achieving high-throughput reconciliation. Moreover, the security of proposed protocol is investigated and proved. Experimental results show that the reconciliation efficiency of the spinal-based protocol maintains around 95% in a larger SNR range (0,0.5), and even exceeds 96.5% at extremely low SNR (<= 0.032) with quite low frame error rate (FER) (<= 5.2%). Both the theoretical analysis and experimental results demonstrate that the proposed adaptive reconciliation protocol is a suitable candidate for the long-distance CV-QKD systems.
In this study, the authors propose a new feedback-channel-free distributed video coding algorithm using local rank transform (LRT). The encoder computes LRT by considering selected neighbourhood pixels of Wyner-Ziv (W...
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In this study, the authors propose a new feedback-channel-free distributed video coding algorithm using local rank transform (LRT). The encoder computes LRT by considering selected neighbourhood pixels of Wyner-Ziv (WZ) frame. These LRT values are merged, and their positions are entropy coded and sent to the decoder. In addition, means of each block of WZ frame are also transmitted to assist motion estimation (ME). Using these measurements, the decoder generates side information (SI) by implementing ME and compensation in LRT domain. An iterative algorithm is executed on SI using LRT to reconstruct the WZ frame. Experimental results show that the coding efficiency of the authors' codec is close to the efficiency of pixel domain distributed video coders based on low-densityparitycheck and accumulate or turbo codes, with less encoder and decoder complexity.
The authors propose a novel turbo detection scheme based on the factor graph (FG) serial-schedule belief propagation equalisation algorithm with low complexity for single-carrier faster-than-Nyquist (SC-FTN) and multi...
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The authors propose a novel turbo detection scheme based on the factor graph (FG) serial-schedule belief propagation equalisation algorithm with low complexity for single-carrier faster-than-Nyquist (SC-FTN) and multi-carrier FTN (MC-FTN) signalling. In this work, the additive white Gaussian noise channel and multi-path fading channels are both considered. The iterative FG-based equalisation algorithm can deal with severe intersymbol interference and intercarrier interference introduced by the generation of SC and MC-FTN signals, as well as the effect of multi-path fading. With the application of Gaussian approximation, the complexity of the proposed equalisation algorithm is significantly reduced. In the turbo detection, low-density parity check code is employed. The simulation results demonstrate that the FG-based turbo detection method can achieve satisfactory performance with low complexity.
Joint sparse graph for code division multiple access systems (JSG-CDMA) combines multiple accessing (low-density signature) and forward error correction (low-density parity check code) techniques, and it achieves sati...
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Joint sparse graph for code division multiple access systems (JSG-CDMA) combines multiple accessing (low-density signature) and forward error correction (low-density parity check code) techniques, and it achieves satisfactory performance under overloaded conditions. In this study, the authors carry on the research on the joint detection and decoding for JSG-CDMA, and analyse the syndrome effect of message passing on the JSG by the extrinsic information transfer (EXIT) chart. An improved algorithm for joint detection and decoding on the JSG-CDMA receiver is proposed, and the convergence behaviour of the algorithm is analysed by EXIT chart. Simulation results show that improved algorithm enhance the system performance significantly with a marginal increase of the computational complexity.
Shuffled belief propagation (SBP), as a sequential belief propagation (BP) algorithm, speeds up the convergence of BP decoding, and maintains the least complexity of flooding BP. However, its performance is remarkably...
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Shuffled belief propagation (SBP), as a sequential belief propagation (BP) algorithm, speeds up the convergence of BP decoding, and maintains the least complexity of flooding BP. However, its performance is remarkably inferior to informed dynamic scheduling (IDS) BP algorithms. The authors design an informed dynamic location method, based on the residuals of variable node log-likelihood ratio values, to reorder variable nodes of SBP to be updated. The location method significantly accelerates the convergence of SBP algorithm from two aspects: the unstable variable node with the largest residual to be updated first, and selecting the largest residual locally. Simulation results show that the proposed algorithm performs nearly the same as the best performance of IDS BP algorithms, and behaves prominently at high signal-to-noise ratios.
Burst error occurs due to various factors and degrades the system performance. In this paper, we propose a burst error sensing scheme for page-oriented data. Using this scheme, the proposed method can sense a two-dime...
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ISBN:
(纸本)9781509013258
Burst error occurs due to various factors and degrades the system performance. In this paper, we propose a burst error sensing scheme for page-oriented data. Using this scheme, the proposed method can sense a two-dimensional burst error location. In addition, it is possible to improve the performance by using erasure decoding on the sensed burst error position.
The next generation broadcast wireless (NGB-W) system is aimed to provide high-speed, ubiquitous, and secure tri-play services to massive users. In this paper, a new terrestrial broadcast solution for the NGB-W system...
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ISBN:
(纸本)9781467363051
The next generation broadcast wireless (NGB-W) system is aimed to provide high-speed, ubiquitous, and secure tri-play services to massive users. In this paper, a new terrestrial broadcast solution for the NGB-W system is proposed. The system and the key techniques of the proposed solution are introduced. The performance of the proposed solution is evaluated by simulations. It is shown that the performance of the proposed solution is better than that of the second generation terrestrial broadcast systems of Digital Video Broadcasting (DVB).
Physical layer (PHY) security has aroused great research interest in recent years, exploiting physical uncertainty of wireless channels to provide communication secrecy without placing any computational restrictions o...
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ISBN:
(纸本)9781450338325
Physical layer (PHY) security has aroused great research interest in recent years, exploiting physical uncertainty of wireless channels to provide communication secrecy without placing any computational restrictions on the adversaries under the information-theoretic security model. Particularly, researches have been focused on investigating Wyner's Wiretap Channel for constructing practical wiretap codes that can achieve simultaneous transmission secrecy and reliability. While theoretically sound, PHY security through the wiretap channel has never been realized in practice, and the feasibility and physical limitations of implementing such channels in the real world are yet to be well understood. In this paper, we design and implement a practical opportunistic secret communication system over the wireless wiretap channel for the first time to our best knowledge. We show that, our system can achieve nearly perfect secrecy given a fixed codeword length by carefully controlling the structure of the parity-check matrix of wiretap codes to strike the proper balance between the transmission rate and secrecy. Our system is implemented and evaluated extensively on a USRP N210-based testbed. The experimental results demonstrate the physical limitations and the feasibility of building practical wiretap channels in both the worst channel case and the case where the sender has only the knowledge of instantaneous channel capacities. Our system design and implementation successfully attempts towards bridging the gap between the theoretical wiretap channel and its practice, alleviating the unrealistic and strong assumptions imposed by the theoretical model.
This paper proposes a new construction of quantum low-densityparitycheck (LDPC) codes that belong to the class of general stabilizer (non-CSS) codes. The method constructs a binary check matrix associated with the s...
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This paper proposes a new construction of quantum low-densityparitycheck (LDPC) codes that belong to the class of general stabilizer (non-CSS) codes. The method constructs a binary check matrix associated with the stabilizer generators of a quantum LDPC code. The binary check matrix is obtained from a large bipartite graph built by combining several small bipartite graphs called seed graphs. Computer simulation results show that the proposed code has similar or better performance than other quantum LDPC codes, and can be improved by exploiting the degenerate effect of quantum error-correcting codes.
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