Waveform Design for MIMO ISAC Systems via Block Diagonalization Precoding

In this work, we investigate the waveform design scheme for multiple-input multiple-output (MIMO) integrated sensing and communication (ISAC) systems. We formulate two optimization problems: a communication-centric problem maximizing the signal-to-interference-plus-noise ratio (SINR) and a radar-centric problem maximizing the signal-to-clutter-plus-noise ratio (SCNR). To balance performance and computational complexity, we employ the block diagonalization (BD) method to mitigate interference, augmented by a precoding matrix that can be either multiplied or added to enhance design flexibility. Our analysis reveals that the multiplication-based approach better optimizes communication performance, whereas the addition-based approach preferentially improves sensing performance. Simulation results validate that the proposed schemes effectively enhance both communication and sensing performance.