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In this letter, the average bit error rate (BER) performance of sparse code multiple access (SCMA) systems with codebooks based on star quadrature amplitude modulation (star-QAM) signaling constellations over the additive white Gaussian noise channel is analyzed and evaluated. Motivated by the fact that the phase rotation plays an important role in designing codebooks and thus can significantly affect...
In this paper, an optimized codebook design based on rotated angles and extrinsic information transfer (EXIT) chart for a non-orthogonal multiple access scheme, called irregular sparse code multiple access (IrSCMA), is presented. Unlike regular SCMA, in IrSCMA, the defined degree of layer's resource nodes is different, which is beneficial to system performance.It is demonstrated that the new codebook...
In this paper, an optimized codebook design for a non-orthogonal multiple access scheme, called sparse code multiple access (SCMA), is presented. Unlike the low density signature (LDS) systems, in SCMA systems, the procedure of bits to QAM symbol mapping and spreading are combined together, and the incoming bits are directly mapped to the codewords of the SCMA codebook sets. Each layer or user has...
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