  In this paper, we study lattice coding for Rician fading wireless channels.
This is motivated in particular by preliminary studies suggesting the Rician
fading model for millimeter-wavelength wireless communications. We restrict to
lattice codes arising from rotations of $\mathbb{Z}^n$, and to a single-input
single-output (SISO) channel. We observe that several lattice design criteria
suggest the optimality of Hadamard rotations. For instance, we prove that
Hadamard rotations maximize the diamond-packing density among all rotated
$\mathbb{Z}^n$ lattices. Finally, we provide simulations to show that Hadamard
rotations outperform optimal algebraic rotations and cross-packing lattices in
the Rician channel.
