Phase Modulated Communications Embedded in Correlated FH-MIMO Radar Waveforms

Methods for embedding communication symbols into the emission of MIMO radar with orthogonal frequency hopping (FH) waveforms have been recently proposed. These methods require that the FH waveforms be orthogonal within each sub-pulse to enable symbol detection at the communication receiver. This orthogonality constraint puts a limit on the total number of communication symbols that can be embedded within each pulse. In this paper, we propose a new signaling strategy for embedding communication symbols into correlated FH-MIMO radar waveforms. It is shown that by relaxing the orthogonality constraint, either the FH code length or antenna number or both can be increased leading to higher data rates. We also propose a novel technique for communication symbol detection based on frame representation. To reduce the computational load associated with the proposed detector, a fast detection algorithm is presented. A method for optimal FH code design is formulated by jointly optimizing the radar and communication operations. The ambiguity function and spectral efficiency are utilized to examine the effectiveness of the proposed strategy. Simulation results demonstrate that the symbol error rate (SER) can be significantly reduced by optimally designing frequency hops among different antennas with improved spectrum efficiency.