Joint Transmit and Receive Codebook Design for Self-Interference Suppression in a mmWave ISAC Terminal Device

We present a joint TX and RX codebook design method for self-interference (SI) suppression in a millimeter wave (mmWave) integrated sensing and communication (ISAC) terminal device. We formulate a signal-to-interference-and-noise ratio (SINR) maximization problem aiming at suppressing the near-field SI while maintaining the beamforming gain at a far-field sensing direction. The formulation considers the constant modulus (CM) constraints for the analog phase shifters and the TX beamforming gain constraint at the communication direction. When ignoring the constraints, we derive an engineering upper bound of the problem by solving it using an effective minimum variance distortionless response (MVDR) method. When considering the constraints, we solve the problem by an alternating optimization algorithm which jointly searches the TX and RX beams using CM gradient descent and the augmented Lagrangian method (ALM).