Signal processing algorithms for joint sensing and communication

Joint sensing and communication (JSC) systems can usher in a new era of mobile networks with pervasive sensing capabilities, by enabling precise user localization and non-collaborative objects detection. In this dissertation, several signal processing techniques for JSC systems are investigated and a comprehensive analysis of their sensing performance is presented by focusing on two main contributions. First, an analysis of orthogonal frequency division multiplexing (OFDM)-based JSC systems is performed by investigating the dominant factors that affect performance in the context of different radar settings when considering line-of-sight propagation conditions. Several signal-processing techniques for estimating target position and velocity are examined, with particular emphasis on multiple-input multiple-output systems. The sensing performance is first investigated in the presence of single and multiple point-like targets by considering monostatic and bistatic JSC systems with multibeam capabilities. Then, the analysis is extended by considering extended targets and a multistatic configuration with a single transmitter and two receivers to exploit spatial diversity for improved sensing performance. Furthermore, both near-field and far-field propagation conditions are considered to improve estimation performance when the target is close to the transmitter or receiver. The second part of this thesis investigates the performance of an orthogonal time frequency space (OTFS)-based JSC system. OTFS is a novel multicarrier modulation scheme that has shown promise for future mobile systems, particularly in JSC applications. However, it is associated with high computational complexity. Therefore, a novel low-complexity estimation and detection approach based on Dirichlet kernel analysis is presented by considering a monostatic JSC system. Through numerical simulations, it is proven that the proposed approximation technique effectively preserves the sensing performance while significantly reducing the computational complexity. The goal of this dissertation is to contribute to a deeper understanding of OFDM- and OTFS-based JSC systems and to provide innovative solutions to address key challenges.