Multi-RAT Spectrum Sharing (MRSS) should remain the baseline approach for 5G-6G migration, but more evidence around its efficiency, implementation feasibility, performance capabilities and hardware requirements is still required, according to the Next Generation Mobile Networks Alliance (NGMN).
Following on from the release of its ‘6G Architecture and Migration Options – An Operator View’ publication in June 2026, NGMN’s updated operator guidance has been issued in conjunction with the upcoming 3GPP plenary meeting in Spain (14-18 September).
NGMN has highlighted that several important areas still need to be addressed to ensure MRSS’ suitability as the preferred solution for 6G migration. NGMN further recommends that, should migration options beyond MRSS be needed, these should be guided by deployment need, hardware impact, implementation feasibility, total cost of ownership (TCO) implications and overall commercial viability to justify the additional standardisation, implementation, and operational complexity introduced by other migration options.
In addition, NGMN’s latest guidance urges the industry to consider whether 6G Core (6GC) is an evolution of 5G Core (5GC) or a more distinct architecture, and how this affects user equipment (UE), radio access network (RAN), operational complexity and the relative value of migration options.
Laurent Leboucher, Chairman of the NGMN Alliance Board and Orange Group CTO and EVP Networks, commented: “The 5G to 6G migration path is an essential component of the 6G design, because it will determine the cost of the 6G deployment and hence the economic viability of the associated new features and capabilities. MRSS is the most promising mechanism as it allows flexible reuse of the legacy 5G spectrum for deploying 6G services, with limited impact on 5G capacity and user experience.
“Nevertheless, to be deployable, the MRSS design has to satisfy a number of criteria, including low control signalling overhead and working efficiently with the 5G hardware already in the field. With this guidance, NGMN emphasises the important criteria to take into account in the design of the 5G-6G migration solutions, from the perspective of both the impact on end-users and the severe business implications for operators and the industry.”
Guangyi Liu, Chief Expert of China Mobile and NGMN Board Director, said: “5G taught us a hard lesson: too many migration options led to fragmentation, delayed rollouts, and costly retrofits. For 6G, let’s not repeat that – with 6G Standalone as the target, MRSS should be our baseline, and any alternative needs to prove it is worth the extra complexity.”
Luke Ibbetson, Head of R&D at Vodafone and NGMN Board Director, added: “6G must build on the strong foundations of 5G and not trigger unnecessary replacement of deployed infrastructure. Efficient spectrum sharing allows new 6G radio capabilities to be introduced as a smooth, software driven upgrade in existing frequency bands. MRSS technology is fundamental to this goal, and it must be delivered with low operational overhead and a demonstrable ability to maximise hardware reuse.”
NGMN contributes operator-driven requirements to standards organisations (SDOs) and provides industry guidance to enable sustainable and affordable mobile telecommunications services.
NGMN’s latest guidance can be downloaded here.
Further information and all NGMN publications can be found on the website at ngmn.org.
