Shaping a Smarter Electromagnetic Landscape: IAB, NCR, and RIS in 5G Standard and Future 6G
Chao-Kai Wen, Lung-Sheng Tsai, Arman Shojaeifard, Pei-Kai Liao, Kai-Kit Wong, Chan-Byoung Chae
TL;DR
The paper surveys 3GPP-standardization efforts for IAB, NCR, and RIS in 5G and beyond, outlining architectures, resource allocation, and signaling mechanisms that enable flexible coverage and backhaul. It traces the evolution from Rel-16 through Rel-18, including mobile and vehicle-mounted relays, and highlights NCR’s side control information and RIS’s ETSI-led pre-standardization efforts. Key contributions include clarifying IAB/NCR architectures, HD/FD multiplexing approaches, and the RIS control paradigms being developed by ETSI ISG RIS, along with outlooks for phase 2 specifications. The findings underscore a converging trajectory toward UE-centric, cooperative, and environment-aware networks that blend gNBs, IABs, NCRs, and RIS for energy-efficient, scalable 6G-capable deployments.
Abstract
The main objective of 5G and beyond networks is to provide an optimal user experience in terms of throughput and reliability, irrespective of location and time. To achieve this, traditional fixed macro base station deployments are being replaced by more innovative and flexible solutions, such as wireless backhaul and relays. This article focuses on the evolution and standardization of these advancements, which are shaping the electromagnetic landscape. Specifically, we explore Integrated Access and Backhaul (IAB) nodes, which offer a cost-efficient and agile alternative to fiber backhaul. We also discuss Network-Controlled Repeaters (NCRs) and the emergence of Reconfigurable Intelligent Surfaces (RIS) actively adapting the wireless environment. The article provides an overview of the 5G features and ongoing developments in 3GPP Release 18 related to these intelligent EM entities, highlighting the expected evolution of future wireless networks in terms of architecture, operations, and control signals.