A Codebook Generation Method for Sparse Code Division Multiple Access

Abstract

The invention discloses a method for generating an SCMA (Sparse Code Multiple Access) codebook. The method comprises the steps of: building a factor matrix according to a subcarrier number K and a user number J as well as a predetermined dimension number L of a unit matrix; selecting a QAM (Quadrature Amplitude Modulation) master constellation diagram according to the user number actually transmitted by each subcarrier, optimizing the QAM master constellation diagram by aiming at maximizing the minimum euclidean distance between constellation points, dividing the QAM master constellation diagram by the method of equally dividing the constellation points to obtain sub-constellation diagrams with preset number; and randomly replacing non-zero elements in the factor matrix with the differentsub-constellation diagrams to form a constellation matrix, and generating a codebook according to the constellation matrix and coordinates of the constellation points in the sub-constellation diagrams. The method of the invention can be used for generating the SCMA codebook, and enables the minimum euclidean distance between the constellation points in the constellation diagram corresponding to users to be maximized, thereby reducing error rate of a transmission system using the codebook under the condition of wireless transmission, and achieving high wireless communication application value.

Description

technical field [0001] The invention belongs to the technical field of digital communication, and in particular relates to a sparse code division multiple access (Sparse Code Multiple Access, SCMA) codebook generation method. Background technique [0002] With the development of mobile communication technology, mobile data traffic will experience explosive growth. It is estimated that by 2020, the global mobile data traffic will increase by more than 200 times. As the two main forces of future mobile communication development, the mobile Internet and the Internet of Things provide broad application prospects for the fifth generation mobile communication (5G). The connection requirements of massive devices bring challenges to the generation of 5G systems. Moreover, the multiple access methods used in existing communications are all orthogonal, that is, multiple users access by orthogonally dividing resources in different dimensions such as time division, frequency division,...

AI Technical Summary

Problems solved by technology

The disadvantage is that when faced with high-order modulation requirements, the Euclidean distance of the user's corresponding constellation points in the constellation diagram must be very small, and the bit error rate during decoding is relatively high.

Traditionally, each user constellation is obtained by using subset segmentation in trellis coded modulation, and finally the codebook is obtained by combining low-density spread spectrum sequences. The bit error rate will increase with the increase of overload.

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