SCMA codebook design method based on maximization sum distance of constellation points

Abstract

The invention relates to an SCMA codebook design method based on the maximization sum distance of constellation points. The method comprises the following steps of: firstly, maximizing the sum distance among projection points of a rotated QPSK constellation on a coordinate axis, selecting an optimal rotation angle represented by a formula as shown in the specification, and taking the QPSK constellation having the rotation angle represented by a formula as shown in the specification as a mother constellation C+ after normalization processing; then, respectively rotating the projection of the mother constellation C+ on an X axis in alpha, beta and gamma, and constructing a constellation diagram that three users are stacked on a single resource block; on the premise that alpha is kept constant, maximizing a sum distance function f(alpha, beta, gamma) among the constellation points of the three users stacked on the single resource block so as to obtain optimized rotation angles beta and gamma; and finally, designing an operation factor matrix delta<j> according to alpha and the corresponding optimized angles beta and gamma, and furthermore, in combination with a mapping matrix V<j>, mapping the two-dimensional mother constellation C+ to obtain codebooks U<j> of six users, wherein j is 1, 2, ..., 6. According to the method disclosed by the invention, the sum distance among four constellation points of each user and the sum distance among the constellation points of three users stacked on each resource block are respectively maximized through optimal calculation for two times; and thus, the bit error rate performance of the system is improved.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, and relates to an SCMA codebook design method based on maximizing constellation points and distances. Background technique [0002] In mobile communication, multiple access technology is a technology used to solve the multi-user multiple access problem. From 1G to 4G, the development of each generation of mobile communication system is accompanied by the evolution of multiple access technology. Among them, the first generation mobile communication system (1G) that can only provide analog voice services uses Frequency Division Multiple Access (FDMA); the second generation mobile communication system (2G) uses Time Division Multiple Access ( Time Division Multiple Access, TDMA); can support digital voice services and low-speed data services; the third-generation mobile communication system (3G) uses code division multiple access to achieve multi-user access, and the peak rate of use...

AI Technical Summary

Problems solved by technology

Orthogonal Multiple Access (OMA) cannot meet the needs of 5G for large capacity, massive connections, and low-latency access because the number of access users is strictly limited by the available orthogonal resources.

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