Transmitter and receiver for and method of transmitting and receiving symbols over an orthogonal time frequency space communication channel subject to doppler spread and multipath

Abstract

Pilot symbols and data symbols of a communication frame for an OTFS transmission system are two-dimensionally arranged along the points of a grid in the delay-Doppler domain. The pilot symbols are surrounded by guard symbols. The number of guard symbols in each direction of the Doppler domain is twice the number of the basis expansion modelling (BEM) basis functions used for modelling the communication channel in a receiver, and twice the maximum time delay in terms of delay bins in each direction of the delay domain. The receiver performs an initial pilot-aided channel estimation using BEM of a first BEM order and using the pilot signals, followed by an initial estimation of data symbols using the initial channel estimation, and iteratively performs data aided channel estimation using BEM of a second BEM order and at least the received data signals, until a termination criterion is met.