Systems, methods, and instrumentalities are described herein that may be used for NOMA resource selection. Different types of NOMA resources may be configured by a network and selected by a WTRU based on rules, priorities, fairness, overloading factors, multiple access signature sizes, measurement results, payload sizes, and/or the like. Single-NOMA operations may be performed using DFT-invariant codewords. Multiple NOMA schemes may coexist with different codeword types and/or codeword sizes.