5G time synchronization demand is mainly reflected in three aspects: basic business time synchronization demand, collaborative business time synchronization demand and new business time synchronization demand.

The common requirement of time synchronization for 5G networks is still 1.5 s, which is not much different from 4G.However, with the development of network technology and the need of special application scenarios, a higher order of + 130nS requirement has been put forward. However, it is obvious that even the request of + 130nS, no matter the Beidou two generation or the Beidou three generation, can cope with it easily. The time for large-scale commercial 5G is expected to be completed in 2020, when the powerful, safe and reliable Beidou three generation has also been completed. Beidou's application in 5G network will come to a logical conclusion.

5G is a high-speed and efficient basic information network which is vital to the country and society. Its autonomy and security are self-evident. From the aspect of network synchronization and base station timing, the Beidou system or the Beidou /GPS dual mode instead of a single GPS system need to be put on schedule as soon as possible and implemented. In the future 5G scale expansion test, the NDRC 5G demonstration city project, and even the comprehensive business in 2020, we need to firmly implement and promote the application.

5G basic business time synchronization requirement is the common requirement of all TDD standard wireless systems, mainly to avoid up and down slot interference. The collaborative technologies such as MIMO, multi-point Cooperation (CoMP) and carrier aggregation (CA), which will be widely used in the 5G system, also have strict requirements for time synchronization. When the 5G network is carrying new services such as vehicle networking and industrial Internet, it needs to provide base station location service based on the time difference of arrival (TDOA). In the 3GPP protocol, the requirement for time synchronization under different scenarios is specified.