g layers as virtual users, the data is split into multiple parallel layers New Radio Access Physical Layer Aspects (Part 1) 367 for each user. The complexity of multi-layer RSMA is higher than that of single-layer RSMA. The RSMA uses hybrid short-code spreading and long-code scrambling as the MA signatures. The generation of scrambling sequences can be UE-group and/or cell specific, wherein the sequence ID of scrambling code is a function of the cell ID and UE-group ID. One or multiple UE groups can be configured in a cell. The sequences used for scrambling code can be Gold sequences, Zadoff-Chu sequences, or a combina- tion of the two [12,23]. In Welch bound equality (WBE)-based spreading schemes such as RSMA, the design metric for the signature vectors is the total squared cross- correlation The lower bound on the total squared cross-correlation of any set of K vectors of length N is K2/N . The WBE sequences are designed to meet the bound on the total squared cross-correlations of the vector set with equality The spreading-based NOMA schemes use non-orthogonal short spreading sequences with relatively low cross-correlation, for distinguishing multiple users, and the spreading sequences are non-sparse. The spreading sequences and the decoding algorithm are dif- ferent for this category of NOMA schemes. In MUSA, modulation symbols of multiple users are spread by specially designed short sequences. All spreading symbols are trans- mitted over the same time-frequency resources. Multiple spreading sequences constitute a pool from which each user can randomly select. The spreading sequences of MUSA are complex-valued, in which the real part and imaginary part are both drawn from a real- valued multi-level set with uniform distribution. At the receiver, the codeword-level SIC detection is used to separate the target UE signal from the overlapped signals [23]. The average mutual information19 can be used as a performance metric to compare the spectral efficiencies of various NOMA schemes with OFDMA. This performance me