Abstract: In the decade of mobile communication, 2G provides voice and low-speed data services, 3G provides voice and basic mobile multimedia services, 4G provides mobile broadband services, and 5G opens everything interconnection. After the Ministry of Industry and InformationTechnology issues the basic telecommunications business operation license, mobile communication in China has officially entered the stage of coexistence of 2G/3G/4G/5G network, and the network is be coming more and more complex. Then the terminal should support more frequency band and RAT, the complexity of the terminal is also increasing, and the cost of the terminal is getting higher and higher. This paper focuses on the current situation and development trend of global mobile communication network, the necessity of simplifying multiRATnetwork and reducing the complexity of terminals, then givesomesuggestions for the development of network and terminal simplification.

Key words: 5G, multiRATnetwork, terminals