A MODIFICATION OF FORNEY'S SCHEME INVOLVING DISTORTION

In an earlier paper (Gurdial and Taneja, 1975), the authors obtained bounds on the probability of erasure and error by modifying Forney's scheme for multiple decoding involving distortion. In this follow-up paper, bounds on distortion due to erasure and error have been obtained under the modified “maximum likelihood double decoding scheme involving distortion.”     

A complexity-reduced fast successive cancellation list decoder for polar codes

A multi-bit decision for polar codes based on a simplified successive cancellation (SSC) decoding algorithm can improve the throughput of polar decoding. A list algorithm is used to improve the error-correcting performance. However, list decoders are highly complex compared with decoders without a list algorithm. In this paper, a low-complexity list decoder is proposed, where path-splitting operations for a multi-bit decision can be avoided, if the decoding reliability exceeds a threshold. The threshold is determined based on the reliability of subchannels and positions of decoding nodes. Path splitting rules are designed for multi-bit decision processes, and a complexity-reduced list decoder is proposed based on this. Results show that the number of survival paths can be greatly reduced at the cost of negligible deterioration in block error performance. Thus, the computational complexity can be significantly reduced, especially for a high signal-to-noise ratio (SNR) region.     

A low-latency list decoder for polar codes

Successive cancellation (SC) is a low complexity serial decoding algorithm for polar codes, and successive cancellation list (SCL) can achieve excellent error-correcting performance. However, SCL decoder suffers from long decoding latency compared with belief propagation (BP) decoder. In this paper, a low-latency list decoder whose latency performance can approach that of BP deocder is proposed. A prunable subtree recognizing scheme based on H-Matrix check is proposed by taking the reliability of frozen bits into account. Then, a latency-reduced list decoder based on the prunable constituent codes is proposed. Simulation results show that the decoding latency of proposed list scheme can be reduced significantly, especially for high signal noise ratio (SNR) region.     

Adaptive rate coding using convolutional codes for asynchronous code division multiple access communications over slowly fading channels

This paper presents a method of code rate adaptation using punctured convolutional codes for direct sequence spread spectrum communication systems over slowly fading channels. A blind channel estimation technique is used to estimate the nature of the multi-user channel at the detector (before the decoder). The path gains obtained from the channel estimation technique are used to adapt the code rates. Punctured codes derived from a specific rate 1/2 (M = 4) mother code are used to provide error protection corresponding to the actual channel state. The upper and lower bounds on the bit error probability and the upper bound on the error event probability are derived for hard-decision and soft-decision decoding over Rayleigh and Rician fading channels. The throughput gains obtained using the adaptive scheme and the performances of the punctured codes are studied.     

Decoding design based on posterior probabilities in Ternary Error-Correcting Output Codes

Ternary Error-Correcting Output Codes (ECOC), which can unify most of the state-of-the-art decomposition frameworks such as one-versus-one, one-versus-all, sparse coding, dense coding, etc., is considered more flexible to model multiclass classification problems than Binary ECOC. Meanwhile, there are many corresponding decoding strategies that have been proposed for Ternary ECOC in earlier literatures. Note that there is few working by posterior probabilities, which can be considered as a Bayes decision rule and hence obtain a better performance in usual. Passerini et al. (2004) [16] have recently proposed a decoding strategy based on posterior probabilities. However, according to the analyses of this paper, Passerini et al.'s (2004) [16] method suffers some defects and result in bias. To overcome that, we proposed a variation of it by refining the decomposition process of probability to get smoother estimates. Our bias–variance analysis shows that the decrease in error by our variant is due to a decrease in variance. Besides, we extended an efficient method of obtaining posterior probabilities based on the linear rule for decoding process in Binary ECOC to Ternary ECOC. On ten benchmark datasets, we observe that the two decoding strategies based on posterior probabilities in this paper obtain better performance than other ones in earlier references.     

H.263视频编码中图像头标保护方法的研究

在H.263视频编码中,虽然图像头标只占视频数据流中极少的一部分,但其一旦丢失或出现错误,将给解码图像质量造成严重的影响,甚至不能解码,因此应当对其进行保护。该文对几种基于H.263句法结构的图像头标保护方法进行了分析研究,指出了它的优缺点。在此基础上,提出了一种改进的图像头标保护方法,给出了图像头标保护前后的出错概率分析,在信道出错概率为10-5时,图像头标出错概率由保护前的2.7×10-4降至8.1×10-9,并且不会造成编解码端的时间延迟。     

GRS解码在Fuzzy Vault中应用

将指纹细节点和密钥进行绑定,并用fuzzy vault方法对结果进行保护。在密钥恢复时,用GRS解码进行纠错处理。对GRS的传统解码和表单解码的效果进行了比较,实验表明表单解码比传统解码的密钥恢复效果更好。     

Generalized error-locating codes with component codes over the same alphabet

We consider generalized error locating (GEL) codes over the same alphabet for both component codes. We propose an algorithm for computing an upper bound on the decoding error probability under known input symbol error rate and code parameters. Is is used to construct an algorithm for selecting code parameters to maximize the code rate for a given construction and given input and output error probabilities. A lower bound on the decoding error probability is given. Examples of plots of decoding error probability versus input symbol error rate are given, and their behavior is explained.     

Error exponents for product convolutional codes

An upper bound on the error probability (first error event) of product convolutional codes over a memoryless binary symmetric channel, and the resulting error exponent are derived. The error exponent is estimated for two decoding procedures. It is shown that, for both decoding methods, the error probability exponentially decreasing with the constraint length of product convolutional codes can be attained with nonexponentially increasing decoding complexity. Both estimated error exponents are similar to those for woven convolutional codes with outer and inner warp.     

面向URLLC业务的MIMO上行系统线性接收机性能分析

针对5G超可靠低时延通信（URLLC）业务的应用需求,研究多输入多输出（MIMO）上行系统中匹配滤波接收机和迫零接收机的解码性能。在URLLC系统下,推导多用户MIMO上行链路在有限块长传输时两种接收机速率和解码错误率的表达式。采用基于随机矩阵理论的渐近等价分析方法和信道色散系数的泰勒展开式,分别获得高低信噪比场景下两种接收机解码错误率的解析式,据此分析两种接收机在URLLC业务下的性能差异,发现随着信噪比增加,迫零接收机解码错误率接近于零,而匹配滤波接收机解码错误率受限于基站天线数和用户数的比值。采用蒙特卡罗方法对所得理论表达式进行仿真验证,结果表明,随着信噪比增加,两种接收机速率和解码错误率的解析式与蒙特卡罗仿真结果十分接近,在低信噪比场景下解码错误率均高于10^-5,在高信噪比场景下满足URLLC业务的可靠性指标,并且迫零接收机可靠性明显优于匹配滤波接收机。     

一种能保证传输实时性和可靠性的工业无线通信网络编解码技术

针对工业控制网的实时性和可靠性要求，提出一种新的面向工业控制环境的无线通信 编解码技术，该技术混合了前向纠错和自动重复两种方法，信道编码采用纠错能力强的RS码 ．当信道特性不理想时，采用表决策略降低差错率，而基于截止时间松弛度的变冗余度编码 策略有效地提高了系统在干扰严重环境下的可靠性．     

A Modification of Forney's Scheme Involving Distortion

Abstract

The output sequences may be partitioned into different subsets and different decoders may be operating on these subsets. This is the idea of multiple decoding. The paper contains “Multiple decoding schemes involving distortion” for classical channels by modification of “maximum likelihood distortion ratio scheme with erasures.” Exponential bounds on the probability of error and erasure in terms of distortion are obtained.     

Particle swarm optimization and two solution representations for solving the capacitated vehicle routing problem

This paper presents two solution representations and the corresponding decoding methods for solving the capacitated vehicle routing problem (CVRP) using particle swarm optimization (PSO). The first solution representation (SR-1) is a (n + 2m)-dimensional particle for CVRP with n customers and m vehicles. The decoding method for this representation starts with the transformation of particle into a priority list of customer to enter route and a priority matrix of vehicle to serve each customer. The vehicle routes are then constructed based on the customer priority list and vehicle priority matrix. The second representation (SR-2) is a 3m-dimensional particle. The decoding method for this representation starts with the transformation of particle into the vehicle orientation points and the vehicle coverage radius. The vehicle routes are constructed based on these points and radius. The proposed representations are applied using GLNPSO, a PSO algorithm with multiple social learning structures, and tested using some benchmark problems. The computational result shows that representation SR-2 is better than representation SR-1 and also competitive with other methods for solving CVRP.     

Coding theorem for partial received information

Decoding schemes have been considered for making the decision on the basis of all the digits of a message received. In the present communication we consider the problem of decoding when only part of the transmitted message is received. An upper bound on the probability of decoding error for this case has been derived which as a special case includes the bound derived by Gallager (1965).     

New Approach to Estimation of the Decoding Error Probability

We suggest a new approach to constructing a lower bound on the decoding error probability in a discrete memoryless channel at zero transmission rate. This approach considerably simplifies derivation of the bound, making it more natural, and simultaneously improves the remainder term of the estimate for the decoding error exponent.     

A Note on Systematic Tailbiting Encoders

Tailbiting codes encoded by convolutional encoders are studied. An explanation is given for the fact that, at low signal-to-noise ratios, a systematic feedback encoder results in fewer decoding bit errors than a nonsystematic feedforward encoder for the same tailbiting code. The analysis is based on a recently introduced code property, namely, the weight density of distance-d codewords. For a given distance-d weight density, the decoding bit error probability depends on an encoder property, viz., the number of taps in the tap-minimal encoder pseudoinverse. Among all convolutional encoders that encode a given tailbiting code, the systematic one has the tap-minimal encoder pseudoinverse with fewest taps and, hence, gives the smallest bit error probability.     

A one-dimensional analysis for the probability of error of linear classifiers for normally distributed classes

Computing the probability of error is an important problem in evaluating classifiers. When dealing with normally distributed classes, this problem becomes intricate due to the fact that there is no closed-form expression for integrating the probability density function. In this paper, we derive lower and upper bounds for the probability of error for a linear classifier, where the random vectors representing the underlying classes obey the multivariate normal distribution. The expression of the error is derived in the one-dimensional space, independently of the dimensionality of the original problem. Based on the two bounds, we propose an approximating expression for the error of a generic linear classifier. In particular, we derive the corresponding bounds and the expression for approximating the error of Fisher's classifier. Our empirical results on synthetic data, including up to two-hundred-dimensional featured samples, show that the computations for the error are extremely fast and quite accurate; it differs from the actual error in at most ε=0.0184340683. The scheme has also been successfully tested on real-life data sets drawn from the UCI machine learning repository.     

基于有环因子图的密度进化理论分析

密度进化理论是分析低密度校验码的迭代译码性能的有效工具。本文在对密度进化理论进行研究的基础上,探讨了基于有环因子图的密度进化方法。首先讨论了有环因子图中环存在的情况,得到了环存在的概率表达式。然后研究了迭代译码算法中误码率的进化情况,在加入环存在对译码的影响因素后得到了迭代译码中误码率的进化表达式。在对该式讨论中,获得了有环情况下密度进化对信道奈件的要求,即译码门限。本文的研究表明,在考虑因子图中存在环的情况下进行密度进化分析时,其获得的译码门限要低于不考虑环存在的情况。     

Optimal probabilistic dense coding schemes

Dense coding with non-maximally entangled states has been investigated in many different scenarios. We revisit this problem for protocols adopting the standard encoding scheme. In this case, the set of possible classical messages cannot be perfectly distinguished due to the non-orthogonality of the quantum states carrying them. So far, the decoding process has been approached in two ways: (i) The message is always inferred, but with an associated (minimum) error; (ii) the message is inferred without error, but only sometimes; in case of failure, nothing else is done. Here, we generalize on these approaches and propose novel optimal probabilistic decoding schemes. The first uses quantum-state separation to increase the distinguishability of the messages with an optimal success probability. This scheme is shown to include (i) and (ii) as special cases and continuously interpolate between them, which enables the decoder to trade-off between the level of confidence desired to identify the received messages and the success probability for doing so. The second scheme, called multistage decoding, applies only for qudits (d-level quantum systems with \(d>2\)) and consists of further attempts in the state identification process in case of failure in the first one. We show that this scheme is advantageous over (ii) as it increases the mutual information between the sender and receiver.     

基于后验概率解码段模型的汉语语音数字串识别

通过对语音解码的分析指出了基于似然概率解码的连续语音识别的局限性,并给出了三种基于后验概率段模型（Segment Model,SM）的语音解码方法.这三种方法成功地运用于随机段模型（Stochastic Segment Model,SSM）,使误识率比基线系统下降了11%;与此同时还给出了段模型的快速算法,使算法的计算复杂度降到了与隐马尔可夫模型（Hidden Markov Model,HMM）相同的数量级,满足了实用要求.