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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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Journal ArticleDOI
TL;DR: This paper proposes a codebook-based OIA, in which the weight vectors are chosen from a predefined codebook with a finite size so that information of the weight vector can be sent to the belonging BS with limited feedforward, and derives the codebook size required to achieve the same user scaling condition as the SVD- based OIA case for both Grassmannian and random codebooks.
Abstract: For the multiple-input multiple-output interfering multiple-access channels (IMACs), opportunistic interference alignment (OIA) using the singular value decomposition (SVD)-based beamforming at each user fundamentally reduces the user scaling condition required to achieve any target DoF, compared to that for the single-input multiple-output IMAC. In this paper, we tackle two practical challenges of the existing SVD-based OIA: 1) the need of full feedforward of the selected users’ beamforming weight vectors and 2) a low rate achieved based on the exiting zero-forcing receiver. We first propose a codebook-based OIA, in which the weight vectors are chosen from a predefined codebook with a finite size so that information of the weight vectors can be sent to the belonging BS with limited feedforward. We derive the codebook size required to achieve the same user scaling condition as the SVD-based OIA case for both Grassmannian and random codebooks. Surprisingly, it is shown that the derived codebook size is the same for the two codebook methods. Second, we introduce an enhanced receiver at the base stations (BSs) in pursuit of further improving the achievable rate. Assuming no collaboration between the BSs, the interfering links between a BS and the selected users in neighboring cells are difficult to be acquired at the belonging BS. We propose the use of a simple minimum Euclidean distance receiver operating with no information of the interfering links. With the help of the OIA, we show that this new receiver asymptotically achieves the channel capacity as the number of users increases.

29 citations

PatentDOI
TL;DR: An adaptive pitch pulse enhancer and method, adaptive to a voicing measure of input speech, for modifying the adaptive codebook of a CELP search loop to enhance the pitch pulse structure was proposed in this paper.
Abstract: An adaptive pitch pulse enhancer and method, adaptive to a voicing measure of input speech, for modifying the adaptive codebook of a CELP search loop to enhance the pitch pulse structure of the adaptive codebook. The adaptive pitch pulse enhancer determines a voicing measure of an input signal, the voicing measure being voiced when the input signal includes voiced speech and the voicing measure being unvoiced when the input signal does not include voiced speech, modifies a total excitation vector produced by the CELP search loop in accordance with the voicing measure of the input signal, and updates the adaptive codebook of the CELP search loop by storing the modified total excitation vector in the adaptive codebook.

29 citations

Journal ArticleDOI
TL;DR: In this paper, a concatenated coding construction for U-RA on the AWGN channel is presented, in which a sparse regression code (SPARC) is used as an inner code to create an effective outer OR-channel, and an outer code is used to resolve the multiple access interference in the OR-MAC.
Abstract: Unsourced random-access (U-RA) is a type of grant-free random access with a virtually unlimited number of users, of which only a certain number $K_{a}$ are active on the same time slot. Users employ exactly the same codebook, and the task of the receiver is to decode the list of transmitted messages. We present a concatenated coding construction for U-RA on the AWGN channel, in which a sparse regression code (SPARC) is used as an inner code to create an effective outer OR-channel. Then an outer code is used to resolve the multiple-access interference in the OR-MAC. We propose a modified version of the approximate message passing (AMP) algorithm as an inner decoder and give a precise asymptotic analysis of the error probabilities of the AMP decoder and of a hypothetical optimal inner MAP decoder. This analysis shows that the concatenated construction under optimal decoding can achieve a vanishing per-user error probability in the limit of large blocklength and a large number of active users at sum-rates up to the symmetric Shannon capacity, i.e. as long as $K_{a}R . This extends previous point-to-point optimality results about SPARCs to the unsourced multiuser scenario. Furthermore, we give an optimization algorithm to find the power allocation for the inner SPARC code that minimizes the ${\mathsf {SNR}}$ required to achieve a given target per-user error probability with the AMP decoder.

29 citations

Proceedings ArticleDOI
16 Sep 1996
TL;DR: Results show that codebooks with isometries offer no advantages in terms of fidelity-in contrast to the prevalent belief.
Abstract: In fractal image compression an image is partitioned into a set of image blocks, called ranges. The ranges are matched with blocks taken from a codebook of filtered and subsampled domain image blocks up to an affine transformation of intensity values. It is common practise in fractal image compression to include all 8 isometric versions of a codebook block in the codebook. It is reasoned that such enlarged domain pools yield better rate-distortion curves. However, this is not a valid argument supporting the use of isometries. A fair test must compare the performance of the method using a codebook including isometries with that obtained when using a plain codebook of the same size. We have performed such analysis and our results show that codebooks with isometries offer no advantages in terms of fidelity-in contrast to the prevalent belief. A similar study is carried out for the effects of including respectively excluding negative scaling factors in the fractal code.

29 citations

Proceedings ArticleDOI
15 Apr 2007
TL;DR: A data hiding method based on dither quantization is used for speech bandwidth extension and results show that compared with using non-classified codebook, the propose scheme have a better bandwidth extension performance in terms of log spectral distortion (LSD).
Abstract: Speech bandwidth extension can be defined as the deliberate process of expanding the frequency range (bandwidth) for speech transmission. Its significant advancement in recent years has led to the technology being adopted commercially in several areas including psychoacoustic bass enhancement of small loudspeakers and the high frequency enhancement of perceptually coded audio. In this paper, a data hiding method based on dither quantization is used for speech bandwidth extension. More specifically, the out-of-band information is encoded and embedded into the narrowband speech without degrading the quality of the bandlimited signal. At the receiver, when the out-of-band information is extracted from the hidden channel, it can be used to combine with the bandlimited signal, providing a signal with a wider bandwidth. To encode the out-of-band speech more efficiently, acoustic phonetic classification is employed to generate three linear prediction (LP) codebook. The simulation results show that compared with using non-classified codebook, the propose scheme have a better bandwidth extension performance in terms of log spectral distortion (LSD).

29 citations


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