In millimeter-wave channels, most of the received energy is carried by a few paths. Traditional precoders sweep the angle-of-departure (AoD) and angle-of-arrival (AoA) space with directional precoders to identify directions with largest power. Such precoders are heuristic and lead to sub-optimal AoD/AoA estimation. We derive optimal precoders, minimizing the Cram\'{e}r-Rao bound (CRB) of the AoD/AoA, assuming a fully digital architecture at the transmitter and spatial filtering of a single path. The precoders are found by solving a suitable convex optimization problem. We demonstrate that the accuracy can be improved by at least a factor of two over traditional precoders, and show that there is an optimal number of distinct precoders beyond which the CRB does not improve.
@article{arxiv.1703.10978,
title = {Optimal Precoders for Tracking the AoD and AoA of a mm-Wave Path},
author = {Nil Garcia and Henk Wymeersch and Dirk Slock},
journal= {arXiv preprint arXiv:1703.10978},
year = {2018}
}
Comments
Resubmission to IEEE Trans. on Signal Processing. 12 pages and 9 figures