MIMO-OFDM ISAC with Spatial Multiplexing

For orthogonal frequency division multiplexing (OFDM) integrated sensing and communication (ISAC), in order to perform efficient delay and Doppler estimation, the equivalent data symbols on the time-frequency resource element need to be removed, so that the resulting signal obeys the manifold structure with phases linearly increasing across subcarriers/OFDM symbols. However, this task becomes more challenging for multiple-input and multiple-output (MIMO)-OFDM ISAC with spatial multiplexing, since the received equivalent data symbols in time-frequency resource element not only depend on the transmitted information-bearing symbols, but also depend on the transmit steering vectors and the precoding matrix. To address such challenges, this paper proposes an effective sensing signal processing method for MIMO-OFDM ISAC with spatial multiplexing. Specifically, we first estimate the angle of arrival, followed by channel matrix decomposition to obtain transmit steering vector, then reconstruct the equivalent symbol. After removing the equivalent symbol from the received signal, the classical periodogram algorithm can be used to estimate the range and Doppler of targets. Simulation results show that the proposed method achieves effective parameter estimation for MIMO-OFDM ISAC with spatial multiplexing.