Field Tests of a Random-Padded OTFSM Waveform in a Joint Sensing and Communication System

This work presents the results from field tests of a recently proposed Random-Padded Orthogonal Time Frequency Space Modulated (RP-OTFSM) waveform designed for integrated short-range sensing and telecommunication (ISAC) systems. The system consists of two nodes. The first is a software-defined radio (SDR)-based transmitter working at a carrier frequency of 5.8 GHz with 20 MHz bandwidth, which sends 4-QAM modulated data in the delay-Doppler domain of OTFS. The second is a digital SDR-based receiver with two antennas, one for reference and another for surveillance, built from two parts: a digital data decoder for communication purposes and a passive radar workstation for sensing applications. The main aim of the sensing radar module is to estimate the range and velocity of vehicles moving in the surrounding urban environment. The paper briefly summarizes the generation, transmission, and decoding of the RP-OTFSM waveform. It is shown that both tasks of the system are successfully completed in the receiver: 1) after channel estimation and correction, digital data are recovered, and 2) cars driven nearby are correctly detected. Using experimental results, the benefits and limitations of using the OTFSM waveform in ISAC systems are presented.