  To support faster and more efficient networks, mobile operators and service
providers are bringing 5G millimeter wave (mmWave) networks indoors. However,
due to their high directionality, mmWave links are extremely vulnerable to
blockage by walls and human mobility. To address these challenges, we exploit
advances in artificially engineered metamaterials, introducing a wall-mounted
smart metasurface, called mmWall, that enables a fast mmWave beam relay through
the wall and redirects the beam power to another direction when a human body
blocks a line-of-sight path. Moreover, our mmWall supports multiple users and
fast beam alignment by generating multi-armed beams. We sketch the design of a
real-time system by considering (1) how to design a programmable,
metamaterial-based surface that refracts the incoming signal to one or more
arbitrary directions, and (2) how to split an incoming mmWave beam into
multiple outgoing beams and arbitrarily control the beam energy between these
beams. Preliminary results show the mmWall metasurface steers the outgoing beam
in a full 360-degrees, with an 89.8% single-beam efficiency and 74.5%
double-beam efficiency.
