Efficient Dual-Beam Radar-Communications via Digital Array Look-Up Table

Digital array architectures are an enabling technology for dual-function radar-communication systems that produce multiple simultaneous transmit beams with different modulation structures. These spatially diverse emissions are produced by designing the independently generated waveforms produced by the digital array. Far-field radiated emission design (FFRED) is an optimization framework that can design a set of constantamplitude waveforms that produce the desired beam modulations in the desired spatial directions, but requires an optimization routine be performed on a pulse-by-pulse basis. By representing the waveforms transmitted by the digital array as a sequence of beamformers, the beam modulations can be implemented via a look-up table (LUT) according to the phase difference between the beam modulations. Here, this LUT is designed by formalizing an optimization problem to find the maximum power efficient set of LUT beamformers. It is found that the globally optimal (in terms of power efficiency) LUT beamformers can be found via the solution to the Lagrange dual problem for a wide variety of beam locations and powers.