  Joint radar and communication (RadCom) systems have been proposed to
integrate radar and communication into one platform and achieve spectrum
sharing in recent years. However, the joint RadCom systems cause the clutter
modulation and the performance degradation of radar. Therefore, it's very
essential to improve the performance of radar when designing joint RadCom
systems. This paper deals with the clutter mitigation for joint RadCom systems
based on spatial modulation. The communication information embedding introduces
variation of transmit beampatterns in a coherent processing interval (CPI) and
causes the clutter modulation and spreading of the clutter spectrum. This paper
propose a reduced dimension spatial temporal adaptive processing (RD-STAP)
method, i.e., we firstly perform time domain filtering and then perform spatial
domain filtering on received data. As for time domain filtering, this paper
mitigates the extended clutter by subspace projection (SP) and proposes a more
effective eigen-decomposition algorithm based on Power method than singular
value decomposition (SVD) to obtain clutter subspace basis vectors. And the
matched filter is performed on the data after clutter mitigation to display the
moving target. And receive beamforming is utilized for spatial domain
filtering. Simulation results highlight the effectiveness of the proposed
RD-STAP method and the eigen-decomposition algorithm.
