Robust direction-of-arrival estimation and signal separation method for integrated sensing and communication

In this study, we designed a single-channel direction-of-arrival (DOA) estimation and signal separation algorithm based on a grouping scheme for the time-varying metasurfaces (TVMs) for integrated sensing and communication systems. In this scheme, the harmonic effect of the TVM was used to transform the received single-channel signal into a multichannel signal through an orthogonal Fourier coefficient matrix. After achieving multi-channel DOA estimation, the corresponding weighted beam pointing was designed for signal separation. By applying a periodic modulation function on the TVM to modulate the incident signal, the signal was mapped to a multi-dimensional received space to recover the multi-channel received signal. Thus, conventional multi-channel algorithms could be used on the single-channel signal for DOA estimation. Next, we designed a sub-surface weighted beam pointing to maximize the received signal signal-to-interference-plus-noise ratio. Simulation results revealed that the proposed scheme of DOA estimation can exhibit performances comparable to that of the conventional multichannel antenna array. Moreover, the signal separation scheme designed based on this method was robust and could maintain good signal separation ability under a low signal-to-noise ratio.