  Network-controlled repeaters (NCR) and reconfigurable intelligent surfaces
(RIS) are being considered by the third generation partnership project (3GPP)
as valid candidates for range extension in millimeter-wave (mmW, 30-300 GHz
frequency) 5G and 6G networks, to counteract large path and penetration losses.
Nowadays, there is no definite answer on which of the two technologies is
better for coverage extension, since existing comparative studies focused
either on communication-related metrics only or on very large-scale analysis,
without physical layer details or environmental considerations. This paper aims
at comparing NCR and RIS solutions in terms of coverage in an urban scenario.
Numerical results suggest a possible usage of both technologies, showing that
preferring RIS or NCR depends not only on their physical capabilities and cost
(e.g., the number of antenna elements, the angular separation between panels
for NCR, etc.) but also on environment geometry.
