Circularly pulse-shaped orthogonal time frequency space modulation

Abstract

Orthogonal time-frequency space (OTFS) modulation is a recently proposed waveform for efficient data transfer in high-speed vehicular scenario. Use of rectangular pulse shape in OTFS results in high out of band (OoB) radiation, which is undesirable for multi-user scenarios. In this work, the authors present a circular pulse shaped framework for OTFS for reducing the OoB. The authors also design a low complexity transmitter for such a system. They argue in favour of orthogonal transmission for low complexity transceiver structure. The authors establish that frequency-localised circulant Dirichlet pulse is one of the possible pulses having this desirable unitary property, which can reduce OoB radiation significantly (by around 50 dB) without any loss in BER. They also show that the proposed pulse-shaped OTFS has a lower peak to average power ratio than conventional OTFS system.