Browsing by Author "Wang, Chung-Hsuan"

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A Low-complexity Power Allocation for Cooperative Bit-interleaved Coded Modulation Systems with Adaptive Decode-and-Forward Relaying
(2011)
Yu, Tsang-Wei
;
Sheen, Wern-Ho
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Wang, Chung-Hsuan
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電機工程學系
;
Department of Electrical and Computer Engineering
Transmit power allocation between source and relays is a critical design issue in a cooperative relaying system where source and relays are powered by batteries. In this paper, a low-complexity power allocation method is proposed for a 3-node cooperative bit-interleaved coded modulation system with adaptive decode-and-forward relaying, aiming to minimize the bit-error-rate at the destination. The key novelty of the method lies in transforming the power allocation into a max-min optimization problem which can be solved in a first-order equation with very low-complexity. Computer simulations show that the proposed method outperforms the equal gain power allocation with large margins in different channel conditions.
A Pragmatic Labeling Design of MIMO BICM-ID Systems Based on EXIT Chart
(2009)
Yu, Tsang-Wei
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Wang, Chung-Hsuan
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Sheen, Wern-Ho
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電信工程研究所
;
Institute of Communications Engineering
We propose a pragmatic labeling design based on the extrinsic information transfer (EXIT) chart for bit-interleaved coded modulation with iterative decoding on multiple-input-multiple-output channels. In our design, the EXIT chart is used to determine a candidate set of labelings which have representative demapper transfer curves. Then, a procedure to generate these labelings is provided based on the genetic algorithm. Given fixed channel code and signal-to-noise ratio (SNR), we can search within this candidate set for a most-suitable labeling to minimize the bit-error-rate (BER) with low complexity. Simulation results show that the labeling chosen from the candidate set exhibits a controllable BER performance gap compared to the optimal labeling found through exhaustive search. Besides, even though the channel code or the SNR is changed, the same candidate set can still be directly adopted to reduce the time on re-searching a new labeling.
Address Generation Apparatus And Method For Quadratic Permutation Polynomial Interleaver De-Interleaver
(2011-03-17)
Lee, Shuenn-Gi
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Wang, Chung-Hsuan
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Sheen, Wern-Ho
An address generation apparatus for a quadratic permutation polynomial (QPP) interleaver is provided. It comprises a basic recursive unit, and L recursive units represented by first recursive unit up to Lth recursive units. The apparatus inputs a plurality of configurable parameters according to a QPP function Π(i)=(f1i+f2i2) mod k, generates a plurality of interleaver addresses in serial via the basic recursive unit, and generates L groups of corresponding interleaver addresses via the first up to the Lth recursive units, wherein Π(i) is the i-th interleaver address generated by the apparatus, f1 and f2 are QPP coefficients, and k is information block length of an input sequence, 0≦i≦k−1.
An Error-Floor Reduction Technique for Short-Length LT Codes
(2014-01-01)
Chang, Li-Jen
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Wang, Chung-Hsuan
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Zao, John K.
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資訊工程學系
;
電機資訊學士班
Luby transform (LT) codes are often employed during best-effort packet transfers to offer rateless erasure protection. Efficient as they are, these randomized codes with a small number of input symbols often post an inevitable performance trade-off between the decoding failure rates in their waterfall and error-floor regions. In order to surmount this trade-off, we propose a new encoding strategy that requires a portion of the high-degree output symbols of an LT code to abandon the conventional equally-probable input selection strategy; instead, connect themselves to some specially selected low-degree input symbols. Our simulation results show that shortlength LT codes with merely 10(3) input symbols yield significantly lower symboVhlock failure rates at a small overhead of reception as they employ the proposed strategy. These performanceenhanced rateless codes can have potential applications in realtime multimedia broadcasting.
An Iterative Soft-decision Decoding Algorithm for Reed-Solomon Codes
(2017-01-01)
Lee, Huang-Chang
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Wu, Jyun-Han
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Wang, Chung-Hsuan
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Ueng, Yeong-Luh
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電機工程學系
This paper proposes an iterative soft-decision decoding algorithm for Reed-Solomon (RS) codes. The proposed decoding algorithm combines the concepts of adapting the parity-check matrix and informed dynamic scheduling decoding. The parity-check matrix is re-arranged before each iteration, where the systematic part is mapped to the least reliable bits, consequently reducing their influence on the other bits. Using dynamic scheduling, the more important decoding messages are updated to these least reliable bits, meaning that the majority of the error bits with low reliability can be corrected. When the proposed integrated decoding is applied to (255, 239) RS code, the difference between its frame error rate performance (FER) and the maximum-likelihood (ML) bound can be reduced to 0.8 dB, and a gain of about 0.1 dB is achieved compared to all the previously recorded soft-decision decoding for RS codes.
BCH Code Selection and Iterative Decoding for BCH and LDPC Concatenated Coding System
(2013-05-01)
Chen, Pin-Han
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Weng, Jian-Jia
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Wang, Chung-Hsuan
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Chen, Po-Ning
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電機資訊學士班
In this letter, we consider a concatenated BCH and QC-LDPC coding system for potential use of data protection on flash memory. Two issues are studied, and strategies to resolve them are proposed. First, in order to guarantee that the concatenated coding system is free from undesired error floor, we propose a strategy to select the outer BCH codes according to the error patterns of inner QC-LDPC code. We next present an iterative decoding algorithm between inner QC-LDPC and outer BCH codes to alleviate the performance degradation in the waterfall region due to code-concatenation rate loss. The two proposals jointly provide a feasible design for the concatenated BCH and QC-LDPC coding system. Simulations to verify the performance of the proposed concatenated coding system design are given at the end.
Bilateral Exchange of Soft-Information for Iterative Reliability-Based Decoding with Adaptive Belief Propagation
(2009-09-01)
Wang, Chung-Hsuan
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Hsieh, Yu-Min
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Kuo, Hsin-Chuan
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電信工程研究所
;
Institute of Communications Engineering
For linear block codes without a sparse graph representation, there exists an iterative decoding algorithm which combines the traditional reliability-based decoding (RBD) with adaptive belief propagation (ABP) to achieve a good trade-off between the error performance and decoding complexity. However, in the original design of the iterative scheme, only a one-way flow of soft-information from the ABP-part to the RBD-part is available, hence limiting the performance of iterative processing. In this study, several low-complexity schemes are presented for the RBD-part to produce desirable soft-outputs such that decoded results can be bilaterally exchanged between both of the RBD and ABP parts. Simulation results also verify the superiority of the proposed idea over the conventional design.
Canonical Convolutional Encoders for Unequal Error Protection
(2008)
Wang, Chung-Hsuan
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Chao, Chi-chao
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電信工程研究所
;
Institute of Communications Engineering
In this paper, canonical convolutional encoders are studied for unequal error protection (UEP) from an algebraic theoretical viewpoint. We show that for any convolutional code there exists at least a canonical generator matrix which has the greatest separation vector, and hence the optimal UEP capability, among all canonical ones. A procedure for obtaining such desirable generator matrices is also proposed.
Combined puncturing and path pruning for convolutional codes and the application to unequal error protection
(2008-09-01)
Wang, Chung-Hsuan
;
Lin, Yi-Hsin
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電信工程研究所
;
Institute of Communications Engineering
In this paper, puncturing and path pruning are combined for convolutional codes to construct a new coding scheme for unequal error protection (UEP), called the hybrid punctured and path-pruned convolutional codes. From an algebraic viewpoint, we show that the hybrid codes not only inherit all the advantages of the conventional rate-compatible punctured convolutional codes and path-compatible pruned convolutional codes but also can provide more flexible choices of protection capability for UEP. In addition, a data-multiplexing scheme originally proposed for path-pruned codes which can guarantee smooth transition between rates without additional zero-padding for frame termination is proven applicable to the hybrid codes to improve the system throughput.
Complete Complementary Codes and Generalized Reed-Muller Codes
(2008-11-01)
Chen, Chao-Yu
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Wang, Chung-Hsuan
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Chao, Chi-Chao
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電信工程研究所
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Institute of Communications Engineering
Due to ideal autocorrelation and cross-correlation properties, complete complementary codes (CCCs) can be employed in CDMA systems to eliminate the multiple-access interference. In this letter, we propose a direct general construction of CCCs from cosets; of the first-order Reed-Muller codes, which includes previous results as a special case. The larger number of CCCs constructed by our method can provide advantages in applications to cellular CDMA systems.
Decoding of LDPC Convolutional Codes with Rational Parity-Check Matrices from a New Graphical Perspective
(2010)
Weng, Jian-Jia
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Lai, Chih-Chieh
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Wang, Chung-Hsuan
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電機工程學系
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Department of Electrical and Computer Engineering
Previous studies on low-density parity-check convolutional codes (LDPC-CC) reveal that LDPC-CC with rational parity-check matrices (RPCM) suffer from the unaffordable decoding latency/complexity due to the infinite memory order and the poor bit-error-rate performance due to the existence of length-4 cycles in the Tanner graph. However, in this paper, we show that every LDPC-CC with RPCM can be associated with an equivalent Tanner graph which can avoid the infinite memory order and undesired short length cycles but still implements the same constraints specified by the RPCM. Together with the iterative decoding based on belief propagation with proper scheduling, simulation results indicate that LDPC-CC with RPCM can also provide satisfactory decoding performance.
Decoding Scheduling for Unequal Error Protection Quasi-Cyclic Low-Density Parity-Check Codes
(2019-01-01)
Wu, Jia-Jyun
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Wang, Chung-Hsuan
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Chao, Chi-chao
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電信工程研究所
;
Institute of Communications Engineering
Algebraic constructions of quasi-cyclic (QC) low-density parity-check (LDPC) codes with unequal error protection (UEP) capabilities have recently been proposed, which can provide different error-correcting capabilities for different parts of the coded bits. However, conventional decoding algorithms are not designed for LDPC codes with UEP. In this paper, we propose three decoding schemes for UEP QC-LDPC codes extended from existing scheduling strategies, tailored to the special structures of the parity-check matrices. Simulation results show that the proposed schemes can provide improved error rate performance especially for coded bits on low protection levels. The decoding convergence can also be accelerated, thereby reducing the computational complexity.
Design and Analysis of Unequal Missing Protection for the Grouping of RFID Tags
(2015-11-01)
Su, Yi-Sheng
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Wang, Chung-Hsuan
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電機資訊學士班
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Undergraduate Honors Program of Electrical Engineering and Computer Science
In this paper, we address the issue of unequalmissing protection (UMP) for the design of grouping of radio-frequency identification (RFID) tags. While relying on group generation matrices, grouping of RFID tags allows verifying the integrity of a collection of tags without the requirement for accessing external systems, and can be extended to identify missing tags. Motivated by application needs that call for UMP among the tags, we first introduce the concepts of UMP for grouping of RFID tags and its extended counterpart, with which missing tags with high missing protection levels are more easily counted or identified than those with low missing protection levels. We then present simple yet effective schemes to realize grouping of RFID tags with UMP and its extended counterpart. The proposed schemes not only can easily fulfill the requirement of UMP among the tags, but also offer flexibility in constructing UMP group generation matrices. We also characterize key objects in order to further study grouping of RFID tags with UMP and its extended counterpart, called consistent and unidentifiable sets, respectively. This characterization in turn enables theoretical analysis of the error rate from the perspective of a tag. Theoretical and simulation results are presented to demonstrate the efficiencies of the proposed schemes for the design of grouping of RFID tags with UMP.
Dynamic Scheduling-Aided Decoding Strategies for LDPC Convolutional Codes with Rational Parity-Check Matrices
(2011)
Weng, Jian-Jia
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Wu, Mu-Chen
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Wang, Chung-Hsuan
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Su, Yi-Sheng
;
Wu, Tsung-Cheng
In this paper, decoding of LDPC convolutional codes with rational parity-check matrices (LDPC-CC-RPCM) is investigated. We show that Tanner graph of every LDPC-CC-RPCM can always be transformed into an equivalent one with enlarged girth and finite memory order suitable for practical pipeline decoder. Based on the transformed graph, a dynamic scheduling-aided decoding scheme with the enhancement of signal perturbation and error cancellation is presented to improve the convergence speed and bit-error-rate performance in both of the waterfall and error-floor regions. Simulation results also reveal that LDPC-CC-RPCM may outperform ordinary LDPC-CC with polynomial parity-check matrices in some cases under the same code rate and decoding complexity.
Further Exploration of Convolutional Encoders for Unequal Error Protection and New UEP Convolutional Codes
(2016-09)
Tang, Hung-Hua
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Wang, Chung-Hsuan
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Lin, Mao-Chao
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電機學院
;
College of Electrical and Computer Engineering
In this paper, the unequal error protection (UEP) capability of convolutional encoders, in terms of the separation vector, is studied from an algebraic viewpoint. A simple procedure is presented for constructing a generator matrix, which is basic and has the largest separation vector for every convolutional code. Such a generator matrix would be desirable, since the corresponding encoder not only achieves UEP optimality, but also avoids undesired catastrophic error propagation. In addition, canonical generator matrices, which are both basic and reduced, are even more preferable for encoding, since they attain the lowest complexity for Viterbi decoding. However, the direct transformation from a UEP-optimal generator matrix to a canonical generator matrix may come with an unexpected loss of the separation vector. We also propose a specific type of transformation matrix that reduces the external degrees of the generator matrices, from which canonical generator matrices can be constructed that include the mitigated degradation of the separation vector. Finally, beneficial UEP convolutional codes that achieve the maximum free distances for the given code parameters are provided.
Generation of Two-Dimensional Optical Reference Signals Based on Parametric Minimum Cross Entropy
(2011-06-15)
Su, Yi-Sheng
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Wu, Tsung-Cheng
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Wang, Chung-Hsuan
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Chang, Min-Kuan
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電機工程學系
In this letter, a novel design of two-dimensional (2-D) zero reference codes (ZRCs) based on parametric minimum cross entropy (PMCE) is proposed to generate 2-D optical zero reference signals (ZRSs) with low second maximum for grating alignment systems. An optical ZRS is necessary to obtain an absolute measurement in grating alignment systems. A method to acquire an optical ZRS is by means of illuminating two identical superimposed ZRCs. Because the movement between the two ZRCs is in two-axis, 2-D ZRCs are required. However, they are hard to design due to the high computational complexity, especially for large codes. The proposed PMCE method not only reduces the second maximum of 2-D optical ZRSs, but also decreases the computational complexity. Simulation results indicate that there are 8.33%similar to 22.22% reductions in the second maximum of several 2-D optical ZRSs, as compared with those of the recently proposed cross-entropy (CE) method. The PMCE method proves to be a powerful tool for the design of 2-D ZRCs.
Irregular puncturing for convolutional codes and the application to unequal error protection
(2006)
Wang, Chung-Hsuan
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Wang, Shih-Chieh
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Chang, Yun-Liang
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電信工程研究所
;
Institute of Communications Engineering
In this paper, convolutional codes are studied for puncturing with irregular puncturing periods. Irregular puncturing can generate punctured codes with more available rates and better bit-error-rate performance compared with the conventional scheme with a single puncturing period. For the application to unequal error protection, a new multiplexing scheme is also proposed for rate-compatible punctured convolutional (RCPC) codes which can guarantee smooth transition between rates without extra overheads. Finally, families of good RCPC codes with irregular puncturing tables are given by a computer search.
Iterative Soft-decision Decoding of Reed-Solomon Codes Using Informed Dynamic Scheduling
(2015)
Lee, Huang-Chang
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Huang, Guan-Xuan
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Wang, Chung-Hsuan
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Ueng, Yeong-Luh
;
傳播研究所
In this paper, an iterative soft-decision decoding algorithm is proposed for Reed-Solomon (RS) codes. The proposed decoding algorithm combines the concepts of adapting the parity-check matrix and informed dynamic scheduling. Before each iteration, the parity-check matrix is re-arranged according to the reliability of the codeword bits, meaning that the influence of the least reliable variable nodes on the decoding process can be reduced. Consequently, the important decoding messages can be scheduled to be updated first, and the reliability of the least reliable bits can be enhanced. The simulation results show that the proposed decoding algorithm can provide significant improvement in the error-rate performance. By using the proposed algorithm, a gain of 0.5 dB can be achieved compared to the conventional adapting belief propagation algorithm.
MULTIPLEXING METHOD AND APPARATUS THEREOF FOR DATA SWITCHING
(2009-01-15)
Wang, Chung-Hsuan
;
Lee, Shuenn-Gi
A multiplexing method for data switching is disclosed. In the method, a continuous data is received, and the continuous data includes a plurality of super frames, and each super frame includes a plurality of frames. These super frames are divided into a set of even super frames and a set of odd super frames. The frames included in the set of odd super frames are sorted by corresponding required bit error rate of each frame decreasingly or increasingly. The frames included in the set of even super frames are sorted by the required bit error rate of each frame increasingly or decreasingly. An encoder is used to encode these sorted super frames.
New Construction of LDPC Convolutional Codes
(2008)
Wu, Chi-Jen
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Chou, Yi-Chun
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Wang, Chung-Hsuan
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Chao, Chi-Chao
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電信工程研究所
In this paper, we propose a new construction of (3,t)-regular low-density parity-check convolutional codes by properly including binomial entries in the parity-check matrices. Both of the upper and lower bounds on free distance are derived for the new codes. Compared with previous constructions, our design can not only avoid codes of girth less than 8 but also provide enlarged free distances for some code rates. Simulation results show that the codes based on the new construction can achieve better bit-error-rate performance and lower error floor.