# A Spatial Data Focusing and Generalized Time-invariant Frequency Diverse Array Approach for High Precision Range-angle-based Geocasting

## TL;DR

This paper introduces a unified FDA-SDF system for high-precision, time-invariant geocasting, combining spatial data focusing with frequency diverse array techniques to improve spatial accuracy and reduce system complexity.

## Contribution

It presents a novel generalized FDA-SDF approach with analytical design rules and demonstrates superior spatial focusing with fewer antennas compared to traditional methods.

## Key findings

- FDA-SDF achieves high spatial precision in geocasting.
- The system reduces antenna requirements significantly.
- Simulations validate the theoretical advantages.

## Abstract

A novel unified frequency diverse array (FDA) and spatial data focusing (SDF) approach is proposed to simultaneously overcome time-variance and precision constraints of conventional FDA in geocasting, i.e., spatially confined broadcasting, scenarios. This paper describes a free space FDA-based SDF (FDA-SDF) system model for 2-dimensional range-angle-based focusing, including a generalized multi-purpose baseband approach for time-invariant FDA, complemented by SDF processing for improved spatial focusing precision and reduced array size. Comprehensive analytical derivations - general for any frequency offset configuration - describe the geographical FDA-SDF properties and design rules, such as geocast delivery zone steering, location, uniqueness, and size. Simulations of the proposed scheme validate theoretical derivations and demonstrate FDA-SDF's superior spatial precision and minimal design complexity. In particular, using novel alternating logarithmic frequency offsets, a 3-antenna FDA-SDF setup is shown to match the radial and azimuthal precision of its beamforming-based FDA counterpart using, respectively, 64 and 24 antennas.