Bit Error Rate Performance Analysis of Star-QAM Based SCMA Codebooks Design for HetNet

This article focused on research of bit error rate (BER) performance of systems which implements a Spread Code Multiple Access with using of Star-QAM based codebooks over Additive White Gaussian Noise (AWGN) channel. Message Passing Algorithm is used to separate different layers/users. BER from Signal-to-Noise (SNR) dependencies for different SCMA systems and for different Star-QAM based codebook design algorithms are presented. Motivated by the fact that authors of these algorithms don't give enough information such as design of constellation operators or design of mother constellation we provide all necessary information to repeat results of this article. As a result, we proposed optimum number of MPA algorithm iterations to maximize BER performance. Also, we show that correct design of constellation operators can significantly improves BER performance. For six user, four resources, two non-zero elements and four codewords in codebook correct choice can give an energy win from 2 dB up to 20 dB for BER 10-<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>.