BER Analysis of SCMA Systems With Codebooks Based on Star-QAM Signaling Constellations

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 the BER performance in SCMA system, we derive a theoretical expression for the BER performance based on the statistics of the phase angle in SCMA constellations. Numerical and simulation results corroborate the proposed analysis.