Frequency Diverse Array Spatial Data Focusing for High Precision Range-angle-based Geocasting

A unified frequency diverse array (FDA) and spatial data focusing (SDF) system, or FDA-SDF, is proposed as a novel approach to perform spatially confined broadcasting of information, i.e. geocasting. It is shown that SDF processing exploits FDA range-angle-dependency more effectively than conventional power focusing implementations, resulting in improved spatial focusing precision and reduced array size. Additionally, the time-variance flaw in conventional FDAs is addressed and mitigated by introducing a generalized baseband FDA model. This paper describes the FDA-SDF system model in free space, including dedicated SDF precoding, beamsteering, and equalization, exploiting FDA multi-frequency transmission for 2-dimensional range-angle-based time-invariant geocasting. Simulations of the FDA-SDF system illustrate compatibility with conventional FDA frequency offset schemes and highlight degrees of freedom for geocast delivery zone manipulation. Finally, FDA-SDF's superior spatial precision is demonstrated: a 3-antenna FDA-SDF setup matches the radial and angular precision of a conventional FDA using, respectively, 13 and 23 antennas.