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Codebook

About: Codebook is a research topic. Over the lifetime, 8492 publications have been published within this topic receiving 115995 citations.


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Proceedings ArticleDOI
27 Jun 2004
TL;DR: By choosing the size of the codebook large enough, the rate that is reliably realized by the strategy can be made to approach arbitrarily closely the mutual information between channel input and output induced by the user-chosen input distribution.
Abstract: We present a strategy for the reliable communication of a message, in a variable number of channel uses, over an unknown discrete memoryless channel (DMC). The decoder periodically tests the received sequence and, when it can decode, sends an acknowledgment to the transmitter, which then stops transmitting. By choosing the size of the codebook large enough, the rate that is reliably realized by the strategy can be made to approach arbitrarily closely the mutual information between channel input and output induced by the user-chosen input distribution. The strategy presented can be considered as a generalization to arbitrary unknown DMCs of earlier variable length coding schemes, such as digital fountain codes for binary erasure channels (BECs), and a coding strategy for binary symmetric channels (BSCs) presented by Tchamkerten and Telatar

47 citations

PatentDOI
Bruce Alan Fette1
TL;DR: A method of operating a vocoder so that a variable frame rate results while maintaining a constant bit rate is disclosed, and vector quantization operations producing larger, more spectrally accurate outputs are selected when fewer subframes are included within a base frame.
Abstract: A method of operating a vocoder so that a variable frame rate results while maintaining a constant bit rate is disclosed. A base frame rate remains constant. However, spectral change is measured to determine an appropriate subframe rate within the base frame. Only one of a plurality of separate vector quantization processes is selected in response to spectral change for performance of a vector quantization operation on LPC spectrum coefficients. Each of the plurality of vector quantization operations utilizes its own codebook that contains a different quantity of reference patterns from that contained in the other codebooks. Each vector quantization operation produces a reference pattern descriptor code that contains a different number of bits from that produced by the other vector quantization processes. Vector quantization operations producing smaller, less spectrally accurate outputs are selected when more subframes are included with a base frame, and vector quantization operations producing larger, more spectrally accurate outputs are selected when fewer subframes are included within a base frame.

47 citations

Journal ArticleDOI
TL;DR: This paper designs the multiuser codebook and the advanced decoding from the perspective of the theoretical capacity and the system feasibility, and proposes an iterative joint detection and decoding scheme with only partial inner iterations, which exhibits significant performance gain over the traditional one with separate detection and decode.
Abstract: Sparse code multiple access (SCMA) is a promising non-orthogonal air-interface technology for its ability to support massive connections. In this paper, we design the multiuser codebook and the advanced decoding from the perspective of the theoretical capacity and the system feasibility. First, different from the lattice-based constellation in point-to-point channels, we propose a novel codebook for maximizing the constellation constrained capacity. We optimize a series of 1-D superimposed constellations to construct multi-dimensional codewords. An effective dimensional permutation switching algorithm is proposed to further obtain the capacity gain. Consequently, it shows that the performance of the proposed codebook approaches the Shannon limit and achieves significant gains over the other existing ones. Furthermore, we provide a symbol-based extrinsic information transfer tool to analyze the convergence of SCMA iterative detection, where the complex codewords are considered in modeling the a priori probabilities instead of assuming the binary inputs in previous literature. Finally, to approach the capacity, we develop a low-density parity-check code-based SCMA receiver. Most importantly, by utilizing the EXIT charts, we propose an iterative joint detection and decoding scheme with only partial inner iterations, which exhibits significant performance gain over the traditional one with separate detection and decoding.

47 citations

Proceedings Article
01 Jan 1997
TL;DR: Through the evaluation by the spectral distance measure, it was found that the proposed method achieved a lower spectral distortion than the other methods.
Abstract: This paper proposes a recovery method of broadband speech form narrowband speech based on piecewise linear mapping. In this method, narrowband spectrum envelope of input speech is transformed to broadband spectrum envelope using linearly transformed matrices which are associated with several spectrum spaces. These matrices were estimated by speech training data, so as to minimize the mean square error between the transformed and the original spectra. This algorithm is compared the following other methods, (1)the codebook mapping, (2)the neural network. Through the evaluation by the spectral distance measure, it was found that the proposed method achieved a lower spectral distortion than the other methods. Perceptual experiments indicates a good performance for the reconstructed broadband speech.

47 citations

Patent
Amitav Das1
23 Sep 1998
TL;DR: A multi-path, split, multi-stage vector quantizer (MPSMS-VQ) was proposed in this article, which has multiple paths between stages to achieve robust and flexible quanitizer.
Abstract: A multi-path, split, multi-stage vector quantizer (MPSMS-VQ) having multiple paths between stages which result in a robust and flexible quanitizer. By varying parameters, the MPSMS-VQ meets design requirements, such as: (1) the number of bits used to represent the input vector (i.e., uses the same or less total bits than the given number of bits, N); (2) the dimension of the input vector, the performance (distortion as noted by WMSE or SD); (3) complexity (i.e., total complexity can be adjusted to be within a complexity constraint); and (4) memory usage (i.e., total number of words M in the codebook memory can be adjusted to be equal to, or less than, the memory constraint M d ). Therefore, the disclosed method and apparatus works well in many conditions (i.e., offers a very robust performance across a wide range of inputs).

47 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023217
2022495
2021237
2020383
2019432
2018364