Circulating Code Array for a Dual-Function Radar-Communications System

It is possible to demodulate the embedded communication symbols from the transmitted base waveform by using the relationship between the transmitted base signal and the synthesized signal in the spatial domain of a circulating code array. The spatial-frequency modulation coefficient (SFMC) is firstly analyzed to determine the frequency band used for the communication user in a certain direction. Perturbation phase modulation (PM) term is attached to the certain time duration of a linear frequency modulation (LFM) signal to embed communication symbols. The perturbation PM term is designed to be a weighted sum of multiple orthogonal sub-PM terms and the communication symbols are carried out by the coefficients of different sub-PM terms. An adjustable weighted coefficient is applied to control the degree of the perturbation PM term to make a balance between radar performance and communication bit error rate (BER) performance. The designed dual-function radar-communications (DFRC) system has the following properties: 1) Multidimensional waveform design issue for a DFRC system based on multiple input multiple output (MIMO) is converted into a transmitted base waveform design issue; 2) the communication receiver can be located in any direction; 3) the effect of embedded communication symbols on radar performance can be effectively controlled while with a satisfactory BER performance.