Sparse code multiple access (SCMA) is a non-orthogonal multiple access scheme. In a downlink SCMA system, a message passing algorithm (MPA) is employed for multiuser detection. However, MPA detection has a problem of high computational complexity in downlink environment. In this study, we propose a method to reduce the computational complexity of MPA detection while maintaining the transmission rate and the number of simultaneously connectable users. First, we employ a codebook including symbols having only in-phase (I) or quadrature-phase (Q) component. Next, MPA detection is performed using a joint IQ factor graph in which real and imaginary parts of a symbol are treated separately as different subcarrier symbols. As a result, the number of superposed users in MPA detection is virtually reduced. Therefore, the proposed method can reduce the computational complexity. Numerical results show that the proposed method does not degrade the bit error rate performance compared to MPA using the conventional factor graph.
Complexity Reduction of MPA Detection Using Joint IQ Factor Graph in SCMA
01.05.2020
139346 byte
Aufsatz (Konferenz)
Elektronische Ressource
Englisch