MIMO OTFS in 5G NR Resource Grid

Although orthogonal time frequency space (OTFS) is shown to outperform orthogonal frequency division multiplexing (OFDM), yet it has not been incorporated into the multiple input multiple output (MIMO) OFDM based resource grid of 5G new radio (NR) physical-layer (PHY). In this letter, we describe a method for transmitting MIMO OTFS in 5G NR resource grid without any modification to the 5G NR pilot and the resource grid structure. We present the corresponding receiver which uses channel estimates obtained from the demodulation reference signal (DMRS) pilots of 5G NR PHY. The receiver performs iterative component wise conditionally unbiased MIMO LMMSE equalization using the channel decoder’s soft output. We find that the coded error performance of OTFS mapped to 5G NR resource grid is superior to that of the existing OFDM based 5G NR by 3 dB or more. This creates an opportunity for beyond 5G systems (6G) to have OTFS as the waveform for air interface.