Joint Communication and Sensing for MIMO Systems with Overlapped OFDM and FMCW

In this paper, we design a Joint Communication and Sensing (JCAS) waveform for Multiple Input Multiple Output (MIMO) wireless systems. The JCAS waveform is formed by combining Frequency Modulated Continuous Wave (FMCW) and Orthogonal Frequency Division Multiplexing (OFDM) wave-forms. Specifically, it can be viewed as a combined MIMO-OFDM and MIMO-Radar waveform. The proposed waveform is used by the Base Station (BS) of the JCAS system, which consists of communication and sensing subsystems. The communication subsystem is used to transmit information to the desired user equipment (UE), while the sensing subsystem is used to detect multiple objects in the vicinity of the BS. For the communication subsystem, OFDM sub-carriers are used to carry UE's data, while the FMCW acts as pilot signals and enable frequency domain channel estimation. For the sensing subsystem, after receiving the echos of JCAS signal, we remove the OFDM part of it and then form a Radar virtual array at the BS. The data from the virtual array is used to estimate the target parameters of interest, i.e., distance and velocity. Numerical results are presented to demonstrate the performance of both communication and sensing subsystems with the proposed JCAS waveform.