Multi Dimensional SCMA Codebook Design Based on Constellation Rotation and Interleaving
Sparse code multiple access (SCMA) is a new non orthogonal multiple access scheme, which effectively exploits the shaping gain of multi dimensional codebook. In this paper, a multi dimensional SCMA (MD SCMA) codebook design based on constellation rotation and interleaving method is proposed for downlink SCMA systems. In particular, the first dimension of mother constellation is constructed by subset of lattice Z2. Then the other dimensions are obtained by rotating the first dimension. Further, the interleaving is used for even dimensions to improve the performance in fading channels. In this way, we can design different codebooks for the aim of spectral efficiency or power efficiency. And the simulation results show that the bit error rate (BER) performance of MD SCMA codebooks outperforms that of the existing SCMA codebooks and low density signature (LDS) in downlink Rayleigh fading channels.
2016 IEEE 83rd Vehicular Technology Conference (VTC Spring)