Blind Recognition of Non-Binary LDPC Codes Based on Ant Colony Optimization

This paper introduces a novel blind recognition of non-binary low-density parity-check(LDPC)codes without a candidate set,using ant colony optimization(ACO)algorithm over additive white Gaussian noise(AWGN)channels.Specifically,the scheme that effectively combines the ACO algorithm and the non-binary elements over finite fields is proposed.Furthermore,an improved,simplified elitist ACO algorithm based on soft decision reliability is introduced to recognize the parity-check matrix over noisy channels.Simulation results show that the recognition rate continuously increases with an increased signalto-noise ratio(SNR)over the AWGN channel.

PCGC码低复杂度译码算法的研究

PCGC是一种将LDPC码运用于并行级联编码形式的信道编码,它的译码采用的是修改后的双层迭代BP(beliefpropagation,置信传播)译码算法.这种译码算法的性能较好,但运算复杂度高,不利于硬件实现.该文介绍两种低复杂度的PCGC迭代译码算法,并通过仿真验证了算法具有非常好的性能.

基于PEG算法的多进制PCGC码

PCGC码是一种以LDPC码作为分量码的新型级联码,它在继承LDPC码优越的误比特率性能的同时,还拥有比LDPC码更低的编码复杂度。研究了多进制PCGC,并将PEG算法引入其分量码的设计构造中。仿真结果表明:短帧情况下,通过合理的设计分量码,四进制PCGC码性能好于四进制LDPC码,且四进制PCGC码性能也略好于二进制的PCGC码。通过合理设计的四进制PCGC码在未来数字通信系统中具有重要的实用价值。

GPU-Based Non-Binary LDPC Decoder with Weighted Bit-Reliability Based Algorithm

In this paper, we present a graphics processing unit(GPU)-based implementation of a weighted bit-reliability based(w BRB) decoder for non-binary LDPC(NB-LDPC) codes. To achieve coalesced memory accesses, an efficient data structure for the w BRB algorithm is proposed. Based on the Single-Instruction Multiple-Threads(SIMT) programming model, a novel mapping strategy with high intra-frame parallelism is presented to improve the latency and throughput performance. Moreover, by using Single-Instruction Multiple-Data(SIMD) intrinsics, four 8-bit message elements are packed into a 32-bit unit and simultaneously processed. Experimental results show that the proposed w BRB decoder provides good tradeoff between error performance and throughput for the codes with relatively large column degrees or high rates.

基于准循环分量码构造的多进制PCGC码

PCGC码是一种以LDPC码作为分量码的级联码。它在继承LDPC码优越的误比特率性能的同时,还拥有比LDPC码更低的编码复杂度。对多进制PCGC码进行了研究,同时将采用准循环算法构造的校验矩阵引入其分量码的设计中。用准循环方法构造的PCGC码,在编码端采用一组移位寄存器即可完成编码,大大降低了PCGC码的编码复杂度。仿真结果表明:短帧情况下,通过准循环构造分量码矩阵编码,四进制PCGC码性能优于同进制LDPC码。因此,基于准循环分量码构造的多进制PCGC码在未来数字通信系统中具有重要的应用价值。

基于EXIT图的PCGC码子码校验矩阵研究及仿真分析

传统的PCGC(Parallel Concatenated Gallager Code,并行级联Gallager码)在设计子码时主要依据子码的MCW(Mean Column Weight,平均列重)参数,没有考虑信息节点的度分布的影响。利用基于互信息的EXIT(Extrinsic Information Transfer,边信息转移)图工具,通过计算机仿真,分析获得子码输出增益曲线,并通过构造迭代轨迹来对比分析校验矩阵信息节点度分布对译码性能的影响。仿真结果表明,传统的LDPC(Low Density Parity Check,低密度奇偶校验)码校验矩阵设计的设计准则在PCGC子码设计中并不适用。

Research on encoding and decoding of non-binary polar codes over GF(2m)

Binary Polar Codes (BPCs) have advantages of high-efficiency and capacity-achieving but suffer from large latency due to the Successive-Cancellation List (SCL) decoding. Non-Binary Polar Codes (NBPCs) have been investigated to obtain the performance gains and reduce latency under the implementation of parallel architectures for multi-bit decoding. However, most of the existing works only focus on the Reed-Solomon matrix-based NBPCs and the probability domain-based non-binary polar decoding, which lack flexible structure and have a large computation amount in the decoding process, while little attention has been paid to general non-binary kernel-based NBPCs and Log-Likelihood Ratio (LLR) based decoding methods. In this paper, we consider a scheme of NBPCs with a general structure over GF(2m). Specifically, we pursue a detailed Monte-Carlo simulation implementation to determine the construction for proposed NBPCs. For non-binary polar decoding, an SCL decoding based on LLRs is proposed for NBPCs, which can be implemented with non-binary kernels of arbitrary size. Moreover, we propose a Perfect Polarization-Based SCL (PPB-SCL) algorithm based on LLRs to reduce decoding complexity by deriving a new update function of path metric for NBPCs and eliminating the path splitting process at perfect polarized (i.e., highly reliable) positions. Simulation results show that the bit error rate of the proposed NBPCs significantly outperforms that of BPCs. In addition, the proposed PPB-SCL decoding obtains about a 40% complexity reduction of SCL decoding for NBPCs.

Partial Parallel Encoding and Algorithmic Construction of Non-Binary Structured IRA Codes

The non-binary(NB) Irregular Repeat Accumulate(IRA) codes, as a subclass of NB LDPC codes, potentially have an excellent error-correcting performance. They are also known to provide linear complexity of encoding, but the basic encoding method with the serial rate-1 accumulator significantly limits the encoder throughput. Then the objective of the research presented in this paper is to develop an encoding method pro- viding significantly increased throughput of an NB-IRA encoder altogether with a flexible code construction methods for the structured(S-NB-IRA) codes eligible for the proposed encoding method. For this purpose, we reformulate the classic encoding algorithm to fit into the partial parallel encoder architecture. We propose the S-NB-IRA encoder block diagram and show that its estimated throughput is proportional to the submatrix size of the parity check matrix, which guarantees a wide complexity- throughput tradeoff. Then, in order to facilitate the S-NB-IRA coding systems design, we present a computer search algorithm for the construction of good S-NB-IRA codes. The algorithm aims at optimizing the code graph topology along with selecting an appropriate non-binary elements in the parity check matrix. Numerical results show that the constructed S-NB-IRA codes significantly outperform the binary IRA and S-IRA codes, while their performance is similar to the best unstructured NB-LDPC codes.

A High Spectral Efficient Non-Binary TCM Scheme-Based Novel Decoding Algorithm for 4G Systems

This paper deals with the MIMO-OFDM technique that is applied to the fourth generation (4G) of the wireless communication systems, this technique can provide high data rate transmission without increasing transmit power and expanding bandwidth, it can also efficiently use space resources and has a bright future. It presents the channel coding assisted STBC-OFDM systems, and employs the Coded Modulation techniques (CM), since the signal bandwidth available for wireless communications is limited. The proposed system deals with Non-binary error control coding of the TCM-aided STBC-OFDM scheme for transmissions over the Rayleigh channel. A new non-binary decoding method, Yaletharatalhussein decoding algorithm, is designed and implemented for decoding non-binary convolutional codes, which is based on the trellis diagram representing the convolutional encoder. Yaletharatalhussein decoding algorithm outperforms the Viterbi algorithm and other algorithms in its simplicity, very small computational complexity, decoding reliability for high states TCM codes that are suitable for Fourth-Generation (4G), decreasing errors with increasing word length, and easy to implement with real-time applications. The simulation results show that the performance of the non-binary TCM-based Yaletharatalhussein decoding algorithm-assisted STBC-OFDM scheme outperforms the binary and non-binary decoding methods.

A Novel Decoding Method for Non-Binary TCM Codes

A new non-binary decoding method, which is called Yaletharatalhussein decoding algorithm, is designed and implemented for decoding non-binary convolutional codes which is based on the trellis diagram representing the convolutional encoder. Yaletharatalhussein decoding algorithm outperforms the Viterbi algorithm and other algorithms in its simplicity, very small computational complexity, decoding reliability for high states TCM codes that suitable for Fourth-Generation (4G), decreasing errors with increasing word length, and easy to implement with real-time applications. The proposed Yaletharatalhussein decoding algorithm deals with non-binary error control coding of the convolutional and TCM codes. Convolutional codes differ from block codes in that a block code takes a fixed message length and encodes it, whereas a convolutional code can encode a continuous stream of data, and a hard-decision decoding can easily be realized using the Yaletharatalhussein algorithm. The idea of non-binary codes has been extended for symbols defined over rings of integers, which outperform binary codes with only a small increase in decoding complexity. The simulation results show that the performance of the nonbinary TCM-based Yaletharatalhussein algorithm outperforms the binary and non-binary decoding methods.

并行级联LDPC码译码迭代终止准则研究

提出了两种低复杂度的终止准则,以用于降低PCGC(并行级联Gallager码,parallel concatenated gallager code)的译码器运算量。这两种准则通过观察边信息方差的改变情况,来判断是否终止译码器迭代。计算机仿真结果证明,这些终止准则可有效地降低译码器运算量,且不影响译码器误比特率性能。

并行级联Gallager码的动态最大外迭代次数译码方案的研究

PCGC(Parallel Concatenated Gallager Code,并行级联Gallager码)是将LDPC(Low Density Parity Check,低密度奇偶校验)码运用于并行级联编码形式而得到的一种新型编码,它的译码器采用双层迭代的形式。传统的PCGC译码器采用FMSIN(Fixed Maximum Super Iteration Number,固定最大外迭代次数)的方案,在信道SNR(Signal-to-NoiseRatio,信噪比)较低时会导致译码器平均迭代次数,也即译码器复杂度偏高。针对于此,本文提出一种根据信道信噪比状况动态调整译码器中最大外迭代次数的方案,并通过计算机仿真,验证了运用此方案后,译码器复杂度可得到较大程度的降低。

Decoding on Adaptively Pruned Trellis for Correcting Synchronization Errors

Forward-backward algorithm, used by watermark decoder for correcting non-binary synchronization errors, requires to traverse a very large scale trellis in order to achieve the proper posterior probability, leading to high computational complexity. In order to reduce the number of the states involved in the computation, an adaptive pruning method for the trellis is proposed. In this scheme, we prune the states which have the low forward-backward quantities below a carefully-chosen threshold. Thus, a wandering trellis with much less states is achieved, which contains most of the states with quite high probability. Simulation results reveal that, with the proper scaling factor, significant complexity reduction in the forward-backward algorithm is achieved at the expense of slight performance degradation.

生物标志物单体放射性碳同位素分析技术的发展

自Eglinton等(1996)首次将单体放射性碳同位素分析技术(CSRA)应用于海洋沉积物中生物标志物14C研究以来,该技术发展迅速,广泛应用于海洋科学、生物地球化学和古气候学等领域。但是,自然环境样品中生物标志物大多含量低、干扰基质复杂而且难以分离。因此,如何从基质组成复杂的样品中分离富集高纯度的目标化合物已经成为限制CSRA技术发展和应用的瓶颈。近些年来,不断改进的色谱分离富集技术不仅提高了目标化合物分离的纯度和回收效率,同时也扩展了生物标志物的碳同位素示踪应用。综合介绍了自然环境研究中单体化合物放射性碳同位素分析技术中常见生物标志物单体分离纯化的技术方法以及发展现状。

Low complexity NB-LDPC decoder based on shared comparator architecture for ECN/EVN

Non-binary low density parity check （NB-LDPC） codes are considered as preferred candidate in conditions where short/medium codeword length codes and better performance at low signal to noise ratios （SNR） are required. They have better burst error correcting performance, especially with high order Galois fields （GF）. A shared comparator （SCOMP） architecture for elementary of check node （ECN）/elementary of variable node （EVN） to reduce decoder complexity is introduced because high complexity of check node （CN） and variable node （VN） prevent NB-LDPC decoder from widely applications. The decoder over GF（16） is based on the extended rain-sum （EMS） algorithm. The decoder matrix is an irregular structure as it can provide better performance than regular ones. In order to provide higher throughput and increase the parallel processing efficiency, the clock which is 8 times of the system frequency is adopted in this paper to drive the CN/VN modules. The decoder complexity can be reduced by 28% from traditional decoder when SCOMP architecture is introduced. The result of synthesis software shows that the throughput can achieve 34 Mbit/s at 10 iterations. The proposed architecture can be conveniently extended to GF such as GF（64） or GF（256）. Compared with previous works, the decoder proposed in this paper has better hardware efficiency for practical applications.