An application of 8-APSK modulation for the uplink using SVD-SCMA

In recent years SCMA has been proposed as a strong candidate to perform as access technique for fifth-generation mobile communications systems; usually for the uplink, bit pairs are mapped directly to code words and MPA is used in the receiver. In this work, we proposed to encode three bits to increase the capacity of data transmission in the uplink using singular value decomposition of the initial mother constellation to generate the codewords. In the receiver, the detection and decoding of data is more complex than its predecessors with two bits, since the symbols in the IQ constellation are closer to each other, so a receiver based on neural networks is proposed to perform these tasks. The experimental performance of this proposal was evaluated by implementing a software defined radio platform. The results show that, even under unfavorable SNR conditions, it is possible to use 8-APSK as a modulation technique with low error rate in the detection and decoding of SCMA signals.