*Article* **Cognitive Frequency-Hopping Waveform Design for Dual-Function MIMO Radar-Communications System**

**Yu Yao 1,\*, Xuan Li <sup>1</sup> and Lenan Wu <sup>2</sup>**


Received: 30 November 2019; Accepted: 8 January 2020; Published: 11 January 2020

**Abstract:** A frequency-hopping (FH)-based dual-function multiple-input multiple-output (MIMO) radar communications system enables implementation of a primary radar operation and a secondary communication function simultaneously. The set of transmit waveforms employed to perform the MIMO radar task is generated using FH codes. For each transmit antenna, the communication operation can be realized by embedding one phase symbol during each FH interval. However, as the radar channel is time-variant, it is necessary for a successive waveform optimization scheme to continually obtain target feature information. This research work aims at enhancing the target detection and feature estimation performance by maximizing the mutual information (MI) between the target response and the target returns, and then minimizing the MI between successive target-scattering signals. The two-step cognitive waveform design strategy is based upon continuous learning from the radar scene. The dynamic information about the target feature is utilized to design FH codes. Simulation results show an improvement in target response extraction, target detection probability and delay-Doppler resolution as the number of iterations increases, while still maintaining high data rate with low bit error rates between the proposed system nodes.

**Keywords:** multiple-input multiple-output (MIMO); frequency-hopping code; dual-function radar-communications; information embedding; mutual information (mi); waveform optimization
