Movable Antenna Enhanced Wireless Sensing Via Antenna Position Optimization
arxiv(2024)
摘要
In this paper, we propose a new wireless sensing system equipped with the
movable-antenna (MA) array, which can flexibly adjust the positions of antenna
elements for improving the sensing performance over conventional antenna arrays
with fixed-position antennas (FPAs). First, we show that the angle estimation
performance in wireless sensing is fundamentally determined by the array
geometry, where the Cramer-Rao bound (CRB) of the mean square error (MSE) for
angle of arrival (AoA) estimation is derived as a function of the antennas'
positions for both one-dimensional (1D) and two-dimensional (2D) MA arrays.
Then, for the case of 1D MA array, we obtain a globally optimal solution for
the MAs' positions in closed form to minimize the CRB of AoA estimation MSE.
While in the case of 2D MA array, we aim to achieve the minimum of maximum
(min-max) CRBs of estimation MSE for the two AoAs with respect to the
horizontal and vertical axes, respectively. In particular, for the special case
of circular antenna movement region, an optimal solution for the MAs' positions
is derived under certain numbers of MAs and circle radii. Thereby, both the
lower- and upper-bounds of the min-max CRB are obtained for the antenna
movement region with arbitrary shapes. Moreover, we develop an efficient
alternating optimization algorithm to obtain a locally optimal solution for
MAs' positions by iteratively optimizing one between their horizontal and
vertical coordinates with the other being fixed. Numerical results demonstrate
that our proposed 1D/2D MA arrays can significantly decrease the CRB of AoA
estimation MSE as well as the actual MSE compared to conventional uniform
linear arrays (ULAs)/uniform planar arrays (UPAs) with different values of
uniform inter-antenna spacing.
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