Zak-OTFS with Interleaved Pilots to Extend the Region of Predictable Operation

TL;DR

This paper proposes a novel pilot design framework for Zak-OTFS in the delay-Doppler domain, enabling support for diverse user characteristics and extending the predictable operation region.

Contribution

It introduces an interleaved pilot scheme in the delay-Doppler domain that allows reconstruction of the input-output relation for multiple users with different channel characteristics.

Findings

Supports users with diverse delay-Doppler profiles

Enables reconstruction of channel response from minimal pilots

Extends the operational region of Zak-OTFS systems

Abstract

When the delay period of the Zak-OTFS carrier is greater than the delay spread of the channel, and the Doppler period of the carrier is greater than the Doppler spread of the channel, the effective channel filter taps can simply be read off from the response to a single pilot carrier waveform. The input-output (I/O) relation can then be reconstructed for a sampled system that operates under finite duration and bandwidth constraints. We introduce a framework for pilot design in the delay-Doppler (DD) domain which makes it possible to support users with very different delay-Doppler characteristics when it is not possible to choose a single delay and Doppler period to support all users. The method is to interleave single pilots in the DD domain, and to choose the pilot spacing so that the I/O relation can be reconstructed by solving a small linear system of equations.