Position and Velocity Estimation Accuracy in MIMO-OFDM ISAC Networks: A Fisher Information Analysis

Integrated sensing and communication (ISAC) is a core technology for future wireless networks, enabling high-resolution sensing and reliable data transmission within a unified radio platform. This paper develops a theoretical framework to assess the estimation accuracy of target position and velocity in heterogeneous orthogonal frequency division multiplexing (OFDM)-based ISAC networks with multiple cooperative and distributed multiple-input multiple-output (MIMO) base stations (BSs). Using Fisher information analysis, we first derive closed-form Cram\'er-Rao lower bounds (CRLBs) for target localization in single monostatic and bistatic configurations. We then analyze the benefits of BS cooperation by deriving CRLBs for joint position and velocity estimation in a general setting that encompasses multiple cooperating monostatic systems and multistatic networks with multiple transmitters (Txs) and receivers (Rxs). The influence of key system parameters, including the number of BSs, bandwidth, antenna array configuration, and network geometry, is systematically examined. Numerical results highlight the performance gains enabled by cooperative sensing and provide insights to guide the design of future ISAC systems.

Jamming Detection in MIMO-OFDM ISAC Systems Using Variational Autoencoders

This paper introduces a novel unsupervised jamming detection framework designed specifically for monostatic multiple-input multiple-output (MIMO)-orthogonal frequency-division multiplexing (OFDM) radar systems. The framework leverages echo signals captured at the base station (BS) and employs the latent data representation learning capability of variational autoencoders (VAEs). The VAE-based detector is trained on echo signals received from a real target in the absence of jamming, enabling it to learn an optimal latent representation of normal network operation. During testing, in the presence of a jammer, the detector identifies anomalous signals by their inability to conform to the learned latent space. We assess the performance of the proposed method in a typical integrated sensing and communication (ISAC)-enabled 5G wireless network, even comparing it with a conventional autoencoder.