Dynamic spectrum sharing (DSS) played an important role in the 4G-to-5G transition by allowing 5G new radio (NR) to reuse legacy spectrum without immediate static refarming. Yet practical deployments also exposed the cost of coexistence of NR with long-term evolution (LTE), including overheads, control-channel bottlenecks, neighbor-cell interference, etc. As 6G begins to take shape, spectrum scarcity below 7 GHz is again making 5G-6G spectrum sharing a migration tool of interest. Multi radio access technology spectrum sharing (MRSS) is being considered by the 3rd generation partnership project (3GPP) as a key mechanism for 5G-6G coexistence. This article reviews the lessons learned from LTE-NR DSS and examines how those lessons should shape MRSS design. The main challenge is no longer basic coexistence feasibility, but coexistence efficiency which determines whether MRSS will become a broadly usable framework for 5G-to-6G spectrum migration.

翻译：动态频谱共享（DSS）在4G向5G过渡中发挥了重要作用，它允许5G新空口（NR）复用传统频谱，无需立即进行静态重耕。然而实际部署也暴露出NR与长期演进（LTE）共存的代价，包括开销、控制信道瓶颈、邻区干扰等问题。随着6G初具雏形，7 GHz以下频段的频谱稀缺性再次使5G-6G频谱共享成为值得关注的迁移工具。第三代合作伙伴计划（3GPP）正将多无线接入技术频谱共享（MRSS）视为5G-6G共存的关键机制。本文回顾了从LTE-NR DSS中汲取的经验教训，并探讨这些经验应如何指导MRSS设计。当前的主要挑战已不再是基本的共存可行性，而是共存效率——这决定了MRSS能否成为5G向6G频谱迁移的通用框架。