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1

CG-SCMA Codebook Design Based on Maximized Euclidian Distance

Mohamed Sura S., Abdullah Hikmat N.

Journal of Telecommunications and Information Technology

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2023

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nr 1

18--24

EN

Sparse code multiple access (SCMA) is a multi-dimensional codebook based on a class of non-orthogonal multiple access (NOMA) technologies enabling the delivery of non-orthogonal resource elements to numerous users in 5G wireless communications without increasing complexity. This paper proposes a computer-generated sparse code multiple access (CG-SCMA) technique, where the minimum Euclidian distance (MED) of a star 16-point quadrature amplitude modulation is maximized by CG-SCMA, thus creating a complex SCMA codebook based on optimizing the difference between the first and other radiuses over rotated constellations. To specify the most suitable values for this constellation, it is divided into four sub-constellations using trellis coded modulation (TCM) in an effort to optimize MED. The new codebook has four sub-constellations with MED values of 3.85, 2.26, 2.26, and 3.85, respectively. Application of the message passing algorithm (MPA) ensures low complexity of the decoding process

2

BOVW For Classification In Geometrics Shapes

Zurita Baldemar, Luna Luís, Hernández José, Ramírez Federico

Applied Computer Science

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2018

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Vol. 14, no 4

5--11

EN

The classification of forms is a process used in various areas, to perform a classification based on the manipulation of shape contours it is necessary to extract certain common characteristics, it is proposed to use the bag of visual words model, this method consists of three phases: detection and extraction of characteristics, representation of the image and finally the classification. In the first phase of detection and extraction the SIFT and SURF methods will be used, later in the second phase a dictionary of words will be created through a process of clustering using K-means, EM, K-means in combination with EM, finally in the Classification will be compared algorithms of SVM, Bayes, KNN, RF, DT, AdaBoost, NN, to determine the performance and accuracy of the proposed method.

3

Fast VQ Codebook Generation Method Using Codeword Stability Check and Finite State Concept

Tsai P., Hu Y-C., Yeh H-L.

Fundamenta Informaticae

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2008

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Vol. 87, nr 3-4

447-463

EN

The codebook design in the vector quantization scheme is important because it affects the image quality of the encoded image. The Linde-Buzo-Gray (LBG) codebook generation algorithm is well known and a popular choice among codebook users. However, a heavy computational complexity is consumed for the iteratively clustering process in the LBG algorithm. In this paper, the similarity of codewords in consecutive rounds of the LBG algorithm is exploited to reduce the computational complexity. By checking the stability of codewords, the status of each codeword in the codebook can be determined. Only the unstable codewords are refined to generate the new codebook. The proposed method can be further improved by cooperating with the finite state technique. Experimental results show that the computational complexity of the proposed method is reduced to about 4% of the LBG algorithm while achieving a slightly worse image quality.

4

Vector Quantisation

Rak R.J.

Fundamenta Informaticae

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1998

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Vol. 34, nr 4

397-412

EN

In the last few years Vector Quantisation has become an important technique in speech and image compression and recognition. The jump from one dimension to the multiple ones allows wealth of new ideas, concepts, techniques and applications. In this paper there is enclosed a desription of vector quantisation idea, the design techniques, optimization methods and practical implementations.