Two new schemes are presented to improve the error performances of coding and modulation on slow fading channels. The first scheme consists of permuting coordinates of multidimensional modulation and trellis coded mod...
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Two new schemes are presented to improve the error performances of coding and modulation on slow fading channels. The first scheme consists of permuting coordinates of multidimensional modulation and trellis coded modulation (TCM) on interleaved channels. Theoretical and simulation results show that this simple permutation may provide gains of 3.8 dB on slow Rayleigh fading channels for uncoded modulation. It also improves by 5 dB the performance of fully interleaved 16-QAM TCM. The second scheme consists of using coded frequency diversity. Without bandwidth expansion, the signal is spread over different independent fading channels. For two very slow fading channels, where interleaving is impractical and coding usually does not provide any gain, coded diversity and 16-QAM TCM provides gains of 13 dB at a BER of 10(-4).
Increasing demand for high-speed interchip interconnects requires faster links that consume less power. The Shannon limit for the capacity of these links is at least an order of magnitude higher than the data rate of ...
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Increasing demand for high-speed interchip interconnects requires faster links that consume less power. The Shannon limit for the capacity of these links is at least an order of magnitude higher than the data rate of the current state-of-the-art designs. Channel coding can be used to approach the theoretical Shannon limit. Although there are numerous capacity-approaching codes in the literature, the complexity of these codes prohibits their use in high-speed interchip applications. This work studies several suitable coding schemes for chip-to-chip communication and back-plane application. These coding schemes achieve 3-dB coding gain in the case of an additive white Gaussian noise (AWGN) model for the channel. In addition, a more realistic model for the channel is developed here that takes into account the effect of crosstalk, jitter, reflection, inter-symbol interference (ISI), and AWGN. Interestingly, the proposed signaling schemes are significantly less sensitive to such interference. Simulation results show coding gains of 5-8 dB for these methods with three typical channel models. In addition, low-complexity decoding architectures for implementation of these schemes are presented. Finally, circuit simulation results confirm that the high-speed implementations of these methods are feasible.
Although spiking neural network (SNN) has the advantages of strong brain-likeness and low energy consumption due to the use of discrete spikes for information representation and transmission, its performance still nee...
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Although spiking neural network (SNN) has the advantages of strong brain-likeness and low energy consumption due to the use of discrete spikes for information representation and transmission, its performance still needs to be improved. This article improves SNN in terms of the coding process and the spike response function by invoking fuzzy sets. In terms of coding, a new fuzzy C-means coding (FCMC) method is proposed, which breaks the limitation of uniformly distributed receptive fields of existing coding methods and automatically determines suitable receptive fields that reflect the density distribution of the input data for encoding through the fuzzy C-means clustering. In terms of spike response function, triangular fuzzy numbers instead of the commonly used alpha-type function are used as the spike response function. Different from other functions of fixed shape, width parameters of the proposed function are learnt in the iterative way like weights of synapses do. Experimental results obtained on seven benchmark datasets and two real-world datasets with eleven approaches demonstrate that SNN with triangular spike response functions (abbreviated as T-SNN) combining FCMC can achieve improved performance in terms of accuracy, F-measure, AUC, required epochs, running time, and stability.
A new method for coding graphic information is proposed. The method is based on the change in the color of each image symbol according to a pseudorandom law. Artificially designed self-oscillatory systems are used for...
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A new method for coding graphic information is proposed. The method is based on the change in the color of each image symbol according to a pseudorandom law. Artificially designed self-oscillatory systems are used for generating a pseudorandom sequence of numbers. Results of studying the employed pseudorandom-signal generators and of encoding/decoding a color image are presented. The effect of damage in an encoded image on the restoration process is considered.
With the advancement of computer graphics in the recent years, an increasing number of pictures, video and 3D content is generated by synthesis processing rather than acquired with capture devices such as cameras or s...
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With the advancement of computer graphics in the recent years, an increasing number of pictures, video and 3D content is generated by synthesis processing rather than acquired with capture devices such as cameras or scanners. Several techniques have been developed for compression of discrete (i.e. piece-wise planar) 3D models, in the form of 3D polygonal meshes. However, no important attempt has been made to compress the smooth surfaces of artificially generated 3D models, that are most often represented as parametric surfaces, of which Non-Uniform Rational B-Spline (NURBS) is a popular form. This paper presents a method for compressing NURBS 3D models with a small and controllable loss. The scheme uses a differential pulse coded modulation coder with different predictors for knot values and control points, coupled with a uniform scalar quantizer, followed by a bitplane arithmetic entropy coder. The multiplicity of knots is preserved by the use of a multiplicity map. The rate-distortion characteristics of the proposed scheme are evaluated on various models. When compared to MPEG-4 (ISO/IEC 14496-2:1999: information technology-coding of audio-visual objects-Part 2: Visual, December 1999;ISO/IEC 14496-2:1999/Amd 1:2000: visual extensions, August 2000) and Touma-Gotsman (Proceedings of the 24th Conference on Graphics Interface (GI-98), Morgan Kaufmann, Los Altos, CA, San Francisco, CA, June 1998, pp. 26-34) compressed triangular meshes, the proposed scheme achieves more than five times better compression, for equivalent L-2 error and much better visual quality. (C) 2002 Elsevier Science B.V. All rights reserved.
The dramatic growth in new designs of microprocessor relays has led to a growth in the use digital communications for protection. Unfortunately in any communication system there will always be some corruption of the r...
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The dramatic growth in new designs of microprocessor relays has led to a growth in the use digital communications for protection. Unfortunately in any communication system there will always be some corruption of the received data. Part of the art and science of relay design is therefore to take this into account. This paper examines coding techniques designed to minimise the probability of corrupted data being declared as healthy. Message size, coding techniques and interleaving are examined with respect to the choice of a coding strategy for a secure data communication system for unit protection.
A reliable high-speed bus employing low-swing signaling can be designed by encoding the bus to prevent crosstalk and provide error correction. coding for on-chip buses requires additional bus wires and codec circuits....
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A reliable high-speed bus employing low-swing signaling can be designed by encoding the bus to prevent crosstalk and provide error correction. coding for on-chip buses requires additional bus wires and codec circuits. In this paper, fundamental bounds on the number of wires required to provide joint crosstalk avoidance and error correction using memoryless codes are presented. The authors propose a code construction that results in practical codec circuits with the number of wires being within 35% of the fundamental bounds. When applied to a 10-mm 32-bit bus in a 0.13-mu m CMOS technology with low-swing signaling, one of the proposed codes provides 2.14 x speedup and 27.5% energy savings at the cost of 2.1 x area overhead, but without any loss in reliability.
We consider the problem of encoding an i.i.d. source into a set of symbols or messages that may be altered by an adversary while en route to the decoder. We focus in particular on the regime in which the number of mes...
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We consider the problem of encoding an i.i.d. source into a set of symbols or messages that may be altered by an adversary while en route to the decoder. We focus in particular on the regime in which the number of messages is fixed while the blocklength of the source and the size of each message tend to infinity. For this fixed-blocklength, "large alphabet" channel, we show that combining an optimal rate-distortion code with an optimal error-correction code yields an optimal overall code for Gaussian sources with quadratic distortion and binary uniform sources with Hamming distortion but that it can be suboptimal by an arbitrarily large factor in general. We also consider the scenario in which the distortion constraint that the decoder must satisfy depends on the number of errors that occur. We show that the problem can be reduced operationally to one with erasures instead of errors in two special cases: one involving lossless reproduction of functions of the source and one in which the encoder and decoder share common randomness.
We develop a qualitative measure for the completeness and complementarity of sets of local features in terms of covering relevant image information. The idea is to interpret feature detection and description as image ...
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We develop a qualitative measure for the completeness and complementarity of sets of local features in terms of covering relevant image information. The idea is to interpret feature detection and description as image coding, and relate it to classical coding schemes like JPEG. Given an image, we derive a feature density from a set of local features, and measure its distance to an entropy density computed from the power spectrum of local image patches over scale. Our measure is meant to be complementary to existing ones: After task usefulness of a set of detectors has been determined regarding robustness and sparseness of the features, the scheme can be used for comparing their completeness and assessing effects of combining multiple detectors. The approach has several advantages over a simple comparison of image coverage: It favors response on structured image parts, penalizes features in purely homogeneous areas, and accounts for features appearing at the same location on different scales. Combinations of complementary features tend to converge towards the entropy, while an increased amount of random features does not. We analyse the complementarity of popular feature detectors over different image categories and investigate the completeness of combinations. The derived entropy distribution leads to a new scale and rotation invariant window detector, which uses a fractal image model to take pixel correlations into account. The results of our empirical investigations reflect the theoretical concepts of the detectors.
This paper presents a source-coding framework for the design of coding schemes to reduce transition activity. These schemes are suited for high-capacitance busses where the extra power dissipation due to the encoder a...
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This paper presents a source-coding framework for the design of coding schemes to reduce transition activity. These schemes are suited for high-capacitance busses where the extra power dissipation due to the encoder and decoder circuitry is offset by the power savings at the bus. In this framework, a data source (characterized in a probabilistic manner) is first passed through a decorrelating function f(1). Next, a variant of entropy coding function f(2) is employed, which reduces the transition activity. The framework is then employed to derive novel encoding schemes whereby practical forms for f(1) and f(2) are proposed. Simulation results with an encoding scheme for data busses indicate an average reduction in transition activity of 36%. This translates into a reduction in total power dissipation for bus capacitances greater than 14 pF/b in 1.2-mu m CMOS technology. For a typical value for bus capacitance of 50 pF/b, there is a 36% reduction in power dissipation and eight times more power savings compared to existing schemes. Simulation results with an encoding scheme for instruction address busses indicate an average reduction in transition activity by a factor of 1.5 times over known coding schemes.
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