Codebook

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

Multiple input multiple output communication system and a method of adaptively generating codebook

Abstract: A Multiple-Input Multiple-Output (MIMO) communication system and a method of adaptively generating a codebook are provided. A terminal includes a channel estimator to estimate a channel formed between a base station and the terminal to calculate a channel matrix and a codebook generator to adaptively generate a codebook based on a spatial correlation matrix of the channel matrix.

Iterative split-and-merge algorithm for VQ codebook generation

Abstract: We propose a new iterative algorithm for the generation of a codebook in vectorquantization. The algorithm starts with an initial codebook that is improved by acombination of merge and split operations. By merging small neighboring clusters,additional resources (codevectors) will be released. These extra codevectors can bereallocated by splitting large clusters. This process can be iterated until no furtherimprovement is achieved in the distortion of the codebook. Experimental results showthat the proposed method performs well in comparison to other tested methods,including the GLA and two hierarchical methods. 1. Introduction We consider the codebook generation problem involved in the design of a vectorquantizer [1]. The aim is to find M codevectors (codebook) for a given set of N trainingvectors (training set) by minimizing the average pairwise distance between the trainingvectors and their representative codevectors. The vectors are assumed to belong to aK-dimensional Euclidean space. The question of the proper choice for the training set isnot addressed here; the motivation is simply to select the best possible codebook for agiven training set.There are several established methods for generating a codebook [1]. The most cited andwidely used is the generalized Lloyd algorithm (GLA) [2]. It starts with an initialsolution, which can be chosen arbitrarily. The existing solution is then improvediteratively using two optimality criteria in turn until a local minimum is reached. Thealgorithm is relatively easy to implement and it gives reasonable results in most cases.Unfortunately the algorithm makes only local changes to the original codebook and itthus gets stuck at the first local minimum. The quality of the final codebook is thereforehighly dependent on the initialization.A different approach is to build the codebook hierarchically. An iterative splittingalgorithm [3, 4] starts with a codebook of size 1 where the only codevector is thecentroid of the entire training set. The codebook is then iteratively enlarged by asplitting procedure until it reaches the desired size. This top-down process gives resultssimilar to or even better than the GLA, with a faster algorithm [4]. A drawback of this

The American Working Conditions Survey Data: Codebook and Data Description

Abstract: This codebook describes the content and structure of the American Working Conditions Survey data (AWCS) which was fielded on the RAND American Life Panel (ALP) in 2015.

Multimode coding of speech-like and non-speech-like signals

Abstract: The invention relates to the coding of audio signals that may include both speech-like and non-speech-like signal components. It describes methods and apparatus for code excited linear prediction (CELP) audio encoding and decoding that employ linear predictive coding (LPC) synthesis filters controlled by LPC parameters, a plurality of codebooks each having codevectors, at least one codebook providing an excitation more appropriate for non-speech-like signals and at least one codebook providing an excitation more appropriate for speech-like signals, and a plurality of gain factors, each associated with a codebook. The encoding methods and apparatus select from the codebooks codevectors and/or associated gain factors by minimizing a measure of the difference between the audio signal and a reconstruction of the audio signal derived from the codebook excitations. The decoding methods and apparatus generate a reconstructed output signal from the LPC parameters, codevectors, and gain factors.

Modular VLSI architectures for real-time full-search-based vector quantization

Abstract: Vector quantization (VQ) has become feasible to be employed for real-time applications by using VLSI technology. In this paper, the authors propose modular linearly connected VLSI architectures for VQ that can support real-time image processing applications. Each processing element in the design consists of an adder and a shift register instead of a multiplier. The designs require fixed I/O bandwidth with the host and allow codebook changes. The throughput is independent of the codebook size. These designs can be extended to the case when a fixed number of processors are available. A number of VQ schemes-single-stage and multistage VQ, classified VQ, etc.-can be implemented using this approach. >