A new probabilistic algorithm for decoding one received word from a set of many given received words, into a codeword such that the Hamming distance between the received word and the codeword is at most t, is proposed...
详细信息
A new probabilistic algorithm for decoding one received word from a set of many given received words, into a codeword such that the Hamming distance between the received word and the codeword is at most t, is proposed. The new algorithm is applicable to several cryptographic problems, such as the Stern identification scheme, the McEliece public-key cryptosystem, and in correlation attacks on stream ciphers. When applicable, it runs significantly faster than previous algorithms used for attacks on these cryptosystems.
We describe an efficient algorithm for successive errors-and-erasures decoding of BCH codes, The decoding algorithm consists of finding all necessary error locator polynomials and errata evaluator polynomials, choosin...
详细信息
We describe an efficient algorithm for successive errors-and-erasures decoding of BCH codes, The decoding algorithm consists of finding all necessary error locator polynomials and errata evaluator polynomials, choosing the most appropriate error locator polynomial and errata evaluator polynomial, using these two polynomials to compute a candidate codeword for the decoder output, and testing the candidate for optimality,ia an originally developed acceptance criterion, Even in the most stringent case possible, the acceptance criterion is only a little more stringent than Forney's criterion for GMD decoding, We present simulation results on the error performance of our decoding algorithm for binary antipodal signals over an AWGN channel and a Rayleigh fading channel, The number of calculations of elements in a finite field that are required by our algorithm is only slightly greater than that required by hard-decision decoding, while error performance is almost as good as that achieved with GMD decoding, The presented algorithm is also applicable to efficient decoding of product RS codes.
Recent mobile devices, which adopted Eureka-147, terrestrial-digital multimedia broadcasting (T-DMB) systems, are developed as integrated circuit. As a result, the space of memory expands hardly on mobile handheld. Th...
详细信息
Recent mobile devices, which adopted Eureka-147, terrestrial-digital multimedia broadcasting (T-DMB) systems, are developed as integrated circuit. As a result, the space of memory expands hardly on mobile handheld. Therefore most mobile handheld must operate a lot of application on limited memory. To solve the problem, most of the mobile devices use some kind of compression algorithms to overcome the memory shortage. Among such algorithms, Huffman algorithm is most widely used. In this study, the authors present a novel binary tree expression of the Huffman decoding algorithm which reduces the memory use approximately by 50% and increases the decoding speed up to 30%. The authors experiment the decoding speed on an evaluation kit (SMDK 6400), which is a T-DMB mobile handheld with an advanced risk machine processor. Later to enhance the decoding speed, the authors present an optimum Huffman decoder based on hardware implementation.
The neocortex is by far one of the most complex regions of the mammalian brain, characterized by an extraordinary diversity of neuronal and non-neuronal cell types, whose coordinated development and function guarantee...
详细信息
The neocortex is by far one of the most complex regions of the mammalian brain, characterized by an extraordinary diversity of neuronal and non-neuronal cell types, whose coordinated development and function guarantee the execution of high order cognitive, sensory, and motor behaviours. decoding its heterogeneity and understanding the molecular strategies upon which the cerebral cortex is built during development have been at the core of neuroscientists' work for decades. Here, we will focus on the current classification of neuronal types (both excitatory and inhibitory) of the neocortex in light of the insights provided by recent single-cell omit technologies, which have offered with unprecedented resolution an extended framework to interpret cortical diversity and its developmental origin. We will cover the impact of neuronal subtype identity on generating specific neuronal networks (neuron-to-neuron interaction), as well as their effect on the development of the non-neuronal populations in the cerebral cortex.
Speech recognition in noisy conditions is a major challenge for computer systems, but the human brain performs it routinely and accurately. Automatic speech recognition (ASR) systems that are inspired by neuroscience ...
详细信息
Speech recognition in noisy conditions is a major challenge for computer systems, but the human brain performs it routinely and accurately. Automatic speech recognition (ASR) systems that are inspired by neuroscience can potentially bridge the performance gap between humans and machines. We present a system for noise-robust isolated word recognition that works by decoding sequences of spikes from a population of simulated auditory feature-detecting neurons. Each neuron is trained to respond selectively to a brief spectrotemporal pattern, or feature, drawn from the simulated auditory nerve response to speech. The neural population conveys the time-dependent structure of a sound by its sequence of spikes. We compare two methods for decoding the spike sequencesone using a hidden Markov model-based recognizer, the other using a novel template-based recognition scheme. In the latter case, words are recognized by comparing their spike sequences to template sequences obtained from clean training data, using a similarity measure based on the length of the longest common sub-sequence. Using isolated spoken digits from the AURORA-2 database, we show that our combined system outperforms a state-of-the-art robust speech recognizer at low signal-to-noise ratios. Both the spike-based encoding scheme and the template-based decoding offer gains in noise robustness over traditional speech recognition methods. Our system highlights potential advantages of spike-based acoustic coding and provides a biologically motivated framework for robust ASR development.
Pyramidal neurons recorded from the rat hippocampus and entorhinal cortex, such as place and grid cells, have diverse receptive fields, which are either unimodal or multimodal. Spiking activity from these cells encode...
详细信息
Pyramidal neurons recorded from the rat hippocampus and entorhinal cortex, such as place and grid cells, have diverse receptive fields, which are either unimodal or multimodal. Spiking activity from these cells encodes information about the spatial position of a freely foraging rat. At fine timescales, a neuron's spike activity also depends significantly on its own spike history. However, due to limitations of current parametric modeling approaches, it remains a challenge to estimate complex, multimodal neuronal receptive fields while incorporating spike history dependence. Furthermore, efforts to decode the rat's trajectory in one- or two-dimensional space from hippocampal ensemble spiking activity have mainly focused on spike history-independent neuronal encoding models. In this letter, we address these two important issues by extending a recently introduced nonparametric neural encoding framework that allows modeling both complex spatial receptive fields and spike history dependencies. Using this extended nonparametric approach, we develop novel algorithms for decoding a rat's trajectory based on recordings of hippocampal place cells and entorhinal grid cells. Results show that both encoding and decoding models derived from our new method performed significantly better than state-of-the-art encoding and decoding models on 6 minutes of test data. In addition, our model's performance remains invariant to the apparent modality of the neuron's receptive field.
A novel soft-decision algorithm is presented for Reed-Solomon (RS) codes, based on the reordering of the symbols of the received word according to some measure of reliability. The simulation results show that improvem...
详细信息
A novel soft-decision algorithm is presented for Reed-Solomon (RS) codes, based on the reordering of the symbols of the received word according to some measure of reliability. The simulation results show that improvements in coding gain of > 1 dB are possible when compared to similar decoding algorithms using unsorted received words.
We propose a fast decoding algorithm for the p-ary first-order Reed-Muller code guaranteeing correction of up to left perpendicularn/4 sin(p-1/2p)right perpendicular errors and having complexity proportional to n log ...
详细信息
We propose a fast decoding algorithm for the p-ary first-order Reed-Muller code guaranteeing correction of up to left perpendicularn/4 sin(p-1/2p)right perpendicular errors and having complexity proportional to n log n, where n = p(m) is the code length and p is an odd prime. This algorithm is an extension in the complex domain of the fast Hadamard transform decoding algorithm applicable to the binary case.
Neural systems are inherently noisy. One well-studied example of a noise reduction mechanism in the brain is the population code, where representing a variable with multiple neurons allows the encoded variable to be r...
详细信息
Neural systems are inherently noisy. One well-studied example of a noise reduction mechanism in the brain is the population code, where representing a variable with multiple neurons allows the encoded variable to be recovered with fewer errors. Studies have assumed ideal observer models for decoding population codes, and the manner in which information in the neural population can be retrieved remains elusive. This letter addresses a mechanism by which realistic neural circuits can recover encoded variables. Specifically, the decoding problem of recovering a spatial location from populations of grid cells is studied using belief propagation. We extend the belief propagation decoding algorithm in two aspects. First, beliefs are approximated rather than being calculated exactly. Second, decoding noises are introduced into the decoding circuits. Numerical simulations demonstrate that beliefs can be effectively approximated by combining polynomial nonlinearities with divisive normalization. This approximate belief propagation algorithm is tolerant to decoding noises. Thus, this letter presents a realistic model for decoding neural population codes and investigates fault-tolerant information retrieval mechanisms in the brain.
We generalize Sudan's results for Reed-Solomon codes to the class of algebraic-geometric codes, designing algorithms for list decoding of algebraic geometric codes which can decode beyond the conventional error-co...
详细信息
We generalize Sudan's results for Reed-Solomon codes to the class of algebraic-geometric codes, designing algorithms for list decoding of algebraic geometric codes which can decode beyond the conventional error-correction bound (d - 1)/2, d being the minimum distance of the code. Our main algorithm is based on an interpolation scheme and factorization of polynomials over algebraic function fields, For the latter problem we design a polynomial-time algorithm and show that the resulting overall list-decoding algorithm runs in polynomial time under some mild conditions. Several examples are included.
暂无评论