  Hybrid reconfigurable intelligent surfaces (HRIS) are RIS architectures
having both active and passive elements. The received signal-to-noise ratio
(SNR) in HRIS-assisted communication systems depends on the placement of active
elements. In this paper, we show that received SNR can be improved with a
channel-aware placement of the active elements. We jointly design the transmit
precoder, the RIS coefficients, and the location of active and passive elements
of the HRIS to maximize the SNR. We solve the underlying combinatorial
nonconvex optimization problem using alternating optimization and propose a
low-complexity solver, which is provably nearly optimal. Through numerical
simulations, we demonstrate that the proposed method offers significantly
improved performance compared to communication systems having a fully passive
RIS array or a hybrid RIS array with channel agnostic active element placement
and performance comparable to that of communication systems with a fully active
RIS array.
