Cyclotomic Construction of Sparse Code Multiple Access With Improved Diversity

A number of studies focus on sparse code multiple access (SCMA) to increase the spectral efficiency and support the massive connectivity required for future wireless communications networks. This work reports an improved design for SCMA based on algebraic number field theory and cyclotomic construction of a lattice. The proposed constellation improves the diversity of the SCMA system, which supports the probability of decoding error. We show that the proposed constellation in the uplink transmission of SCMA supports the spectral efficiency by 1 dB gain in SNR when the error probability of SCMA is 0.001 as compared to the proposals in the literature.