Fundamental Limits of MIMO-OFDM Sensing

This chapter explores the fundamental performance limits of MIMO-OFDM-based sensing in ISAC systems. We begin by analyzing the information-theoretic bounds on the accuracy of position and velocity estimation in far-field and near-field propagation scenarios. In the latter cases, it is crucial to consider the spherical nature of wavefronts, particularly when dealing with extremely large aperture arrays (ELAA). Next, we examine cooperative ISAC setups, deriving lower bounds on position and velocity estimation errors when multiple sensing nodes collaborate. Based on these insights and case studies, we discuss how these fundamental limits can inform design principles for network topology and resource allocation (including power, bandwidth, and time) for future sensing-enabled radio systems.