Cramér–Rao Lower Bound on AoA Estimation Using an RF Lens-Embedded Antenna Array

In this letter, we investigate the Cramér-Rao lower bound (CRLB) on angle of arrival (AoA) estimation of an RF lens-embedded antenna array. We first derive an expression for the received signal, in terms of intrinsic lens characteristics, using an RF lens-embedded antenna array. As the AoA changes, the received signal through the RF lens also changes in amplitude. This differentiates the RF lens-embedded antenna array from a conventional uniform linear array (ULA) without an RF lens. Based on this property, we next derive the CRLB on AoA estimation and confirm that the CRLB of an RF lens-embedded antenna array may be better than the CRLB for a conventional ULA in a certain desired range. The results can be used as a guideline for designing RF lens-embedded antenna arrays in fifth generation localization.