We consider a mixed analog-to-digital converter (ADC) based architecture for direction of arrival (DOA) estimation using a uniform linear array (ULA). We derive the Cram{\'e}r-Rao bound (CRB) of the DOA under the optimal time-varying threshold, and find that the asymptotic CRB is related to the arrangement of high-precision and one-bit ADCs for a fixed number of ADCs. Then, a new concept called ``mixed-precision arrangement" is proposed. It is proven that better performance for DOA estimation is achieved when high-precision ADCs are distributed evenly around the edges of the ULA. This result can be extended to a more general case where the ULA is equipped with various precision ADCs. Simulation results show the validity of the asymptotic CRB and better performance under the optimal mixed-precision arrangement.
@article{arxiv.2303.15112,
title = {Optimal Mixed-ADC arrangement for DOA Estimation via CRB using ULA},
author = {Xinnan Zhang and Yuanbo Cheng and Xiaolei Shang and Jun liu},
journal= {arXiv preprint arXiv:2303.15112},
year = {2023}
}