We propose a method based on cluster expansion to study the optimal code with a given distance between codewords. Using this approach we find the Gilbert-Varshamov lower bound for the rate of largest code.
We propose a method based on cluster expansion to study the optimal code with a given distance between codewords. Using this approach we find the Gilbert-Varshamov lower bound for the rate of largest code.
The use of computer algebra is usually considered beneficial for mechanised reasoning in mathematical domains. We present a case study, in the application domain of coding theory, that supports this claim: the mechani...
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The use of computer algebra is usually considered beneficial for mechanised reasoning in mathematical domains. We present a case study, in the application domain of coding theory, that supports this claim: the mechanised proofs depend on non-trivial algorithms from computer algebra and increase the reasoning power of the theorem prover. The unsoundness of computer algebra systems is a major problem in interfacing them to theorem provers. Our approach to obtaining a sound overall system is not blanket distrust but based on the distinction between algorithms we call sound and ad hoc respectively. This distinction is blurred in most computer algebra systems. Our experimental interface therefore uses a computer algebra library. It is based on formal specifications for the algorithms, and links the computer algebra library Sumit to the prover Isabelle. We give details of the interface, the use of the computer algebra system on the tactic-level of Isabelle and its integration into proof procedures.
In a series of experiments color coding, intensity coding, and decluttering were compared in order to assess their potential benefits for accessing information from electronic map displays. Participants viewed electro...
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In a series of experiments color coding, intensity coding, and decluttering were compared in order to assess their potential benefits for accessing information from electronic map displays. Participants viewed electronic battlefield maps containing 5 classes of information discriminable by color or intensity, or, in the decluttering condition, displayed or removed entirely by a key press. Participants were asked questions requiring them to focus on objects within a class (objects presented at the same color or intensity) or to integrate data between objects in different classes (objects presented at different colors and intensities). The results suggested that the benefits of color and intensity coding appear to be in segregating the visual field rather than calling attention to the objects presented at a certain color or intensity. Interactivity proved to be a disadvantage;the time cost of information retrieval outweighed the time benefits of presenting less information on the display or even allowing map users to customize their displays. Potential applications of this research include a cost-benefit analysis for the use of 3 attentional filtering techniques and an attempt to quantitatively measure map complexity.
In this paper, a powerful approach is proposed for the design of two-dimensional two-channel perfect-reconstruction finite-duration impulse response filter banks employing diamond-shaped linear-phase filters. When one...
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In this paper, a powerful approach is proposed for the design of two-dimensional two-channel perfect-reconstruction finite-duration impulse response filter banks employing diamond-shaped linear-phase filters. When one of the analysis filter pair is properly designed, the condition of perfect reconstruction is formulated in a spatial-domain constraint equation for designing the other. The method is based on minimizing the integrated square error for the frequency response over the pass band and stop band while imposing the spatial-domain constraint. One numerical design example is given to demonstrate the perfect reconstruction for the proposed system.
E-VSB is a flexible, compatible outer coding enhancement to A TSC 8-VSB which trades payload bit rate for improved white noise and multipath performance when property equipped receivers are utilized. It is transparent...
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E-VSB is a flexible, compatible outer coding enhancement to A TSC 8-VSB which trades payload bit rate for improved white noise and multipath performance when property equipped receivers are utilized. It is transparent to legacy A TSC receivers. The coding method and experimental results are described.
Spatial scalable encoding of visual data has several applications, including browsing visual databases, querying multimedia databases, interactive multimedia communications, etc. To convert a compressed video sequence...
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Spatial scalable encoding of visual data has several applications, including browsing visual databases, querying multimedia databases, interactive multimedia communications, etc. To convert a compressed video sequence to a lower spatial resolution compressed video, it may decode the original bit-stream, down-sample each frame, and encode. The computation-intensive motion estimation will be included in the transcoder. The re-use of motion vectors extracted from incoming video bit-stream during transcoding has been widely accepted. This paper proposes a new algorithm to estimate the motion vector of the reduced low-resolution video by only using the original motion vectors and DC coefficients in the compressed bit-stream. By taking into account the spatial activity measurement to generate better prediction for the composed motion vector, higher quality and lower complexity than previous works are achieved by the proposed method.
In the United States Advanced Television Systems Committee (ATSC) standard for High Definition Television (HDTV), NTSC co-channel interference rejection may be performed by the comb filter, a filter with spectral null...
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In the United States Advanced Television Systems Committee (ATSC) standard for High Definition Television (HDTV), NTSC co-channel interference rejection may be performed by the comb filter, a filter with spectral nulls at or near the NTSC carriers, and only applied when NTSC interference is detected. In this paper, we discuss the influence of the comb filter in the trellis decoder performance. We then derive the closed form expression for the optimum trellis decoder metric when NTSC co-channel interference is detected and propose a recursive formula for its implementation.
In this paper, a rate 19/20 trellis code matched to the partial response (PR) channel is presented, Our trellis code is designed on a multidimensional Euclidean space for which the minimum free Euclidean distance is L...
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In this paper, a rate 19/20 trellis code matched to the partial response (PR) channel is presented, Our trellis code is designed on a multidimensional Euclidean space for which the minimum free Euclidean distance is Larger than conventional recording codes. By using this trellis coding, a trellis coded partial response (TCPR) system is defined for the enhanced extended class-4 partial response (E-2 PR4) channel. Further, the decoding method for this TCPR system is based on the syndrome-former trellis decoding. The number of add-compare-selects (ACS's) in our system is fewer than that of conventional Viterbi decoding. The result shows that TCPR system employing this rate 19/20 trellis code with the constraint length 7 for the E-2 PR4 has an excellent performance compared with the conventional 8/9 maximum transition run (MTR) coding system in high-density recording.
The problem of performing iterative detection (ID)-a technique originally introduced for the decoding of turbo codes-for systems having parametric uncertainty has received relatively little attention in the open liter...
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The problem of performing iterative detection (ID)-a technique originally introduced for the decoding of turbo codes-for systems having parametric uncertainty has received relatively little attention in the open literature. In this paper, the problem of adaptive ID (AID) for serial and parallel concatenated convolutional codes (SCCC's and PCCC's or turbo codes) in the presence of carrier-phase uncertainty is examined. Based on the theoretical framework in [1], [2], adaptive soft inverse (ASI) algorithms are developed for two commonly used blocks in turbo codes, leading to the adaptive soft-input soft-output (A-SISO) and the adaptive soft demodulator (A-SODEM) algorithms. Based on these algorithms, practical AID receivers are presented. Several design options are proposed and compared and the impact of parametric uncertainty on previously established results for iterative detection with perfect channel state information (CSI) is assessed.
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