6 A 131mW 6.4Gbps 256×32 Multi-User MIMO OTFS Detector for Next-Gen Communication Systems

Future wireless systems are expected to accommodate a variety of devices with high-mobility 1, such as high-speed rail, unmanned aerial vehicle (UAV), and low-earth-orbit (LEO) satellite, as shown in Fig. 2.6.1. Under such fast time-varying channel conditions, however, the performance of current orthogonal frequency-division multiplexing (OFDM) systems degrades due to inter-carrier interference caused by severe Doppler spread. The orthogonal time-frequency space (OTFS) system has been recognized as a promising solution to high-mobility communication 1. Unlike OFDM that multiplexes data symbols in the time-frequency (TF) domain, OTFS multiplexes data symbols in the delay-Doppler (DD) domain. In the OTFS system, the transmitted data are modulated through an inverse symplectic finite Fourier transform (ISFFT) and Heisenberg transform. The received data are demodulated through symplectic finite Fourier transform (SFFT) and Wigner transform 1. The equivalent DD domain channel indicates the physical geometry of the wireless environment, enabling high resilience against Doppler spread. Integration of OTFS technology and massive multi-user multi-input multi-output (MU-MIMO) is envisioned to meet the growing demand for future high-throughput, high-mobility communication systems.