Physical Layer Waveform Design for High Mobility Wireless Channels

With the advent of high-speed trains, unmanned aerial vehicles, and drones, reliable communications in high mobility wireless channels have become necessary for next-generation wireless networks. Orthogonal frequency division multiplexing (OFDM) has been the standard physical-layer modulation scheme deployed in 4G and 5G mobile systems but suffers from severe performance degradation in high-mobility environments. Hence, robust modulation techniques in both slow and fast time-varying channels are needed to solve the 'reliable communications' problem in such channels. This thesis investigates new physical layer techniques for high-mobility wireless channels, focusing on a recently proposed waveform known as orthogonal time frequency space (OTFS) modulation.