US Patent 11343823 Orthogonal multiple access and non-orthogonal multiple access

A transmitter in a wireless communication network encodes data bits of a first layer to produce a set of coded symbols; spreads the coded symbols using discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM); and modulates the spread symbols onto a set of OFDM subcarrier frequencies to produce a discrete-time OFDM signal. Spreading is configured to map the coded symbols to a first sparse DFT-s-OFDM code space in a DFT-s-OFDM symbol, wherein the first sparse DFT-s-OFDM code space is different from a second sparse DFT-s-OFDM code space in the DFT-s-OFDM symbol, the second sparse DFT-s-OFDM code space being employed by a second layer.