Network-Controlled Repeater - An Introduction

In the fifth generation (5G) wireless cellular networks, millimeter wave spectrum opens room for several potential improvements in throughput, reliability, and 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 present the NCR concept, analyze its performance gains, and explore deployment options. Particularly, we present NCR aspects standardized by the third generation partnership project (3GPP) in Release 18, e.g., NCR architecture, NCR beamforming capability controlled by a gNodeB (gNB) and NCR-gNB side control information exchange. Furthermore, 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 gNBs may have.