  The design of modular, passive, and static artificial metasurfaces to be used
as electromagnetic skins (EMSs) of buildings for improving the coverage in
urban millimeter-wave communication scenarios is addressed. Towards this end,
an ad-hoc design strategy is presented to determine optimal trade-off
implementative solutions that assure a suitable coverage of the areas of
interest, where the signal from the base station is too weak, with the minimum
complexity. More specifically, the admissible surface in the building facade is
first partitioned into tiles, which are the minimum-size elements of the
artificial coating (i.e., the building block of an EMS). Then, the search for
the optimal EMS layout (i.e., the minimum number and the positions of the tiles
to be installed) is carried out with a binary multi-objective optimization
method. Representative numerical results are reported and discussed to point
out the features and the potentialities of the EMS solution in the smart
electromagnetic environment (SEME) as well as the effectiveness of the proposed
design method.
