Abstract：When 5G mobile communication technology is applied to sea coverage, it is not only to solve the problem of difficult station construction, but also to solve the parameter configuration and coverage distance estimation under ultra-far sea coverage. In this paper, firstly, the channel model of sea surface ultra-far coverage is built, and the equivalent earth model is given considering the influence of air permittivity change on radio wave propagation. Secondly, several key parameters affecting cell coverage radius in 5G are analyzed in detail. Finally, the main frequency bands of the three operators are simulated, and the relationship curves between the maximum coverage distance and the path loss in different frequency bands are given.

Abstract：With the continuous development of mobile communication network, operators have different frequency band resources at high, middle and low levels. Radio frequency band resources are valuable strategic resources, and how to use spectrum resources reasonably and efficiently is the primary issue that operators consider at present. Based on the comparative analysis of the coverage performance and service bearing of 5G NR 2.1 GHz and NR 3.5 GHz bands, this paper puts forward suggestions for networking and inter-carrier mobile strategy in different scenarios, providing an important basis for the subsequent construction of 5G networks.

Abstract：When building a large-scale 5G fronthaul network, operators have deployed a large number of CWDM passive coarse wavelength division multiplexing(CWDM）equipment in order to save fiber resources to realize 3-channel fronthaul transmission.In order to meet the needs of 5G multi-frequency networking and the joint construction and sharing of China Telecom and China Unicom, operators have proposed multi-channel solutions including medium wavelength division multiplexing(MWDM), LAN wavelength division multiplexing(LWDM), dense wavelength division multiplexing(DWDM) and other technologies.In this context, the research team innovatively proposed a multi-channel solution based on CWDM/circulator technology. This solution not only achieves industry chain sharing, has the highest localization capability, but also minimizes 5G fronthaul network construction cost. This article describes in detail the current network deployment plan of the CWDM/circulator solution and the existing problems.

Abstract：In the third year of 5G construction in 2021,the focus will be on the scale deployment of 5G indoor distribution system.The characteristics of low cost and low failure rate of passive indoor subsystem conform to the national construction and sharing strategy.Intersystem modulation interference has become an urgent problem to be solved in the construction of multi-system integration.Based on the in-depth analysis of the principle of IMI, this paper studied the possible IMI of 5G cell subband, proposed the solution of IMI of 5G cell subsystem, and combined with the case of a cell submodulation interference of Tower Company, put forward suggestions on how to solve the problem of IMI.

Abstract：With the commercial deployment and technological evolution of 5G networks, mobile communication networks are facing the coexistence of 2G/3G/4G/5G multi-mode networks, and the network structure is becoming increasingly complex. The distinctive features of 5G networks with multiple networking modes and multiple terminal categories further aggravate the complexity of network topology and boundary scenarios. How to ensure user′s mobility perception has become a crucial part that affects the reputation of the networks. This paper conducts in-depth research based on the solutions of 5G network mobile performance optimization, and introduces in detail the interoperability strategies of different terminals in different networking modes, so as to provide a theoretical basis for optimization of 5G network mobility and cooperative networking, and effectively promote 5G user′s perception improvement.