For the coexistent radar and communications system, the radar can receive the communications-path signal, i.e., the target return due to the transmission from the communications. The communications-path signal can be exploited to improve the radar detection performance when it has high signal to noise ratio (SNR). To show this, the statistical signal model at the radar receiver is developed, and then the generalized likelihood ratio test (GLRT) for the coexistent radar and communications system is derived in this paper. The derived GLRT has constant false alarm rate (CFAR). Finally, several numerical examples are presented to verify the performance gain by exploiting the communications-path signal with high SNR.

Coexistent radar and communications; GLRT; radar detection; constant false alarm rate