Abstract: Due to the limited number of RRUs connected by BBUs and limited remote signal distance of optical fibers between BBUs and RRUs in the 5G-R system, and in view of the difficulties in the construction and maintenance of long tunnels, the 5G-R system coverage scheme for long tunnels deserves special attention under the condition of no BBU in the tunnel. On the basis of a survey of the equipment manufacturers and an analysis of the published technical conditions of the 5G-R system, this paper firstly analyzes the characteristics and networking method of 5G-R base stations. It then studies the link budget of and proposes a RRU setting interval for the 5G-R system in tunnels. In view of the scenarios of long tunnels of different lengths, it finally provides suggestions on the coverage scheme for the 5G-R system in tunnels of different lengths under the condition of no BBU in the tunnel.

Key words: 5G-R, long tunnel, coverage scheme, link budget, star networking

摘要： 由于5G-R系统BBU连接RRU数量以及BBU与RRU之间的光纤拉远距离均有所限制，考虑到长大隧道施工及维护不便，在隧道内不设置BBU的情况下，长大隧道内5G-R覆盖方案值得重点研究。通过对各5G-R系统设备厂家进行调研，结合5G-R已发布的技术条件，首先对5G-R基站特点及组网方式进行分析，其次对5G-R隧道链路预算进行研究，提出隧道内5G-R RRU的设置间距；最后，结合不同长度的长大隧道场景，在隧道内不设置BBU设备的情况下，提出不同长度隧道下的5G-R的覆盖方案建议。

关键词: 5G-R, 长大隧道, 覆盖方案, 链路预算, 星型组网