This book provides detailed descriptions of downlink non-orthogonal multiple transmissions and uplink non-orthogonal multiple access (NOMA) from the aspects of majorly used 5G new radio scenarios and system performance. For the downlink, the discussion focuses on the candidate schemes in 3GPP standards which are not only applicable to unicast services but also to broadcast/multicast scenarios. For the uplink, the main target scenario is massive machine-type communications where grant-free transmission can reduce signaling overhead, power consumption of devices and access delays. The design principles of several uplink NOMA schemes are discussed in-depth, together with the analysis of their performances and receiver complexities. Devoted to the basic technologies of NOMA and its theoretical principles, data analysis, basic algorithms, evaluation methodology and simulation results, this book will be an essential read for researchers and students of digital communications, wireless communications engineers and those who are interested in mobile communications in general.