| Summary: | 碩士 === 國立中山大學 === 通訊工程研究所 === 107 === Sparse code multiple access (SCMA) is one of the competitive non-orthogonal multiple access techniques for the fifth generation communication systems. The key factor that affects the performance of SCMA lies in the design of codebooks. Following the first SCMA codebook design reported in several design proposals were further proposed in recent years. In other paper, the codebooks are designed by maximizing the minimum Euclidean distance (MED) value among the codeword pairs chosen from the mother codebook. By using multidimensional codebooks, the SCMA schemes are able to provide shaping gains and achieve better error performances when comparing to some other Non-Orthogonal Multiple Acess schemes. However, the design of optimal SCMA codebook has not been fully investigated. In this paper, we propose design criteria and procedures for near-optimal SCMA codebooks under various channel conditions, including the AWGN channel, the uplink fading channel, and the downlink fading channel. Numerical results show that the design SCMA codebooks provide significantly improvement in error performances, when compared to the codecooks provided in literature under various channel conditions.
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