Turbo Bi-Static Radar in OTFS-Based Joint Communications and Sensing

In joint communications and sensing (JCS), the same waveform delivers data to communication receiver in the forward propagation of electromagnetic (EM) wave and fetches information of significant reflectors (radar targets) in the backward propagation. For both communications and sensing, there are pressing needs to identify the significant reflectors, for both communication channel estimation and radar target sensing, which share common information of the reflector positions and velocities. In this paper, the JCS transceiver and communication receiver are considered as a bi-static radar, which can exchange information via the communication links (data channel from the JCS transceiver to the communication receiver and reverse control channel from the the communication receiver to the JCS transceiver). Due to the common information, the target sensing in JCS is carried out in a turbo manner, through the mechanism of message passing and within the framework of Kalman filtering for the dynamics of reflectors. The validity of the proposed turbo sensing scheme is demonstrated by numerical simulations.