Bistatic MIMO DFRC System Waveform Design via Fractional Programming

The Cramér-Rao lower bound (CRLB) and sum-rate (SR) are widely-used metrics in the radar parameter estimation performance evaluation and communication quality-of-service (QoS) assessment, respectively. In this paper, we adopt these two metrics in waveform design for bistatic multiple-input multiple-output dual-function radar-communication (MIMO DFRC) systems, which is different from existing methods where only suboptimal optimization criteria are employed. However, both of the design formulations result in nonconvex and nonlinear fractional programming (FP) problems with complex fractional constraint and objective function. Especially, the CRLB for direction-of-departure (DOD) and direction-of-arrival (DOA) in bistatic DFRC MIMO system is a fraction with quadratic polynomial in the numerator and quartic polynomial in the denominator; whereas the SR expression corresponds to a summation-log-fraction function. By fractional function transformation and convexification, complex function design and simplification, and summation-log-fraction function separation, this article derives an FP framework to solve these complicated problems. Numerical results demonstrate the excellent performance of our design solutions.