  In fifth generation (5G) wireless cellular networks, millimeter wave spectrum
opens room for several potential improvements in throughput, reliability,
latency, among other aspects. However, it also brings challenges, such as a
higher influence of blockage which may significantly limit the coverage. In
this context, network-controlled repeaters (NCRs) are network nodes with low
complexity that represent a technique to overcome coverage problems. In this
paper, we introduce the NCR concept and study its performance gains and
deployment options. Particularly, presenting the main specifications of NCR as
agreed in 3rd generation partnership project (3GPP) Rel-18, we analyze
different NCR deployments in an urban scenario and compare its performance with
alternative deployments. As demonstrated, with a proper network planning and
beamforming design, NCR is an attractive solution to cover blind spots the base
stations (BSs) may have.
