Abstract—In Multiuser Multiple Input Multiple Output (MU-MIMO) system, Block Diagonalization (BD) and Regularized Block Diagonalization (RBD) are schemes which completely suppress Inter-User Interference (IUI). BD and RBD use the same number of RF chains and transmit antennas as the number of data streams in general. This paper proposes a RBD precoding transmission scheme using relay in Non-orthogonal Multiple Access (NOMA) system to reduce complexity of transmitter structure. The proposed scheme uses only half the number of RF chains and transmit antennas compared to the conventional RBD scheme. The number of Singular Value Decomposition (SVD) of the proposed scheme is also reduced compared to the conventional RBD, while Successive Interference Cancellation (SIC) is needed additionally. However, the proposed algorithm can achieve low computational complexity since SIC is simpler than SVD. However, the proposed scheme has poor BER performance compared to the conventional RBD. Therefore, further study is needed to increase the BER performance while the complexity is reduced. 

Index Terms—multiuser MIMO, Regularized Block Diagonalization (RBD), relay, Non-orthogonal Multiple Access (NOMA), precoding

Cite: Hyun-Sun Hwang, Ji-Hwan Kim, and Hyoung-Kyu Song, "Regularized Block Diagonalization Precoding Transmission Scheme Using Relay in NOMA," International Journal of Signal Processing Systems, Vol. 8, No. 4, pp. 74-77, December 2020. doi: 10.18178/ijsps.8.4.74-77