  Dual-functional radar-communication (DFRC) has attracted considerable
attention. This paper considers the frequency-selective multipath fading
environment and proposes DFRC waveform design strategies based on
multiple-input and multiple-output (MIMO) and orthogonal frequency division
multiplexing (OFDM) techniques. In the proposed waveform design strategies, the
Cramer-Rao bound (CRB) of the radar system, the inter-stream interference (ISI)
and the achievable rate of the communication system, are respectively
considered as the performance metrics. In this paper, we focus on the
performance trade-off between the radar system and the communication system,
and the optimization problems are formulated. In the ISI minimization based
waveform design strategy, the optimization problem is convex and can be easily
solved. In the achievable rate maximization based waveform design strategy, we
propose a water-filling (WF) and sequential quadratic programming (SQP) based
algorithm to derive the covariance matrix and the precoding matrix. Simulation
results validate the proposed DFRC waveform designs and show that the
achievable rate maximization based strategy has a better performance than the
ISI minimization based strategy.
