Now 5G mainly requires time synchronization, which is more than 4G, mainly based on time synchronization. 4G requires 3 microseconds, 3 is UTC equivalent to 1.5, one to the left, the other to the right, and the maximum deviation is no more than 3. Know the definition of TE and TAE. 65NR is a special scenario. We have several points to calculate the distance accurately, and to compensate for it. It is no problem to satisfy the operation of automation machinery, and the transmission carrying rate is not large. Continuous narrow waves, including 130, have little impact. Our final consideration is the requirement of 260 ns and 3 microseconds. At the initial stage of 5G, the requirement is the same as that of 4G, and it is also 3 microseconds. The key is 260260, which is also the result of theoretical deduction.

ECPRI interface synchronization function, there are three functional modules to control the management plane and synchronization surface respectively, is a very important piece. Although it is a logical connection, for eCPRI, it has evolved from CPRI, and has taken into account the transmission of synchronization. Synchronous information can not be transmitted by private protocol of eCPRI, and eCPRI is its own delivery protocol. The middle is the relationship between eCPRI and 1588, and there is a new function. ECPRI can use the message in the PTP1588 protocol to carry out single measurement.

The timing principle of the 1588v2 protocol is very clear. From 10 trillion to 100 Gigabit Ethernet, we found that the timing capability was insufficient to do NTP. The time in our computer was obtained through NTP protocol. In 2008, a new version was released.

The PTP1588 protocol came out in 2002, and it has been in 2019 for a long time. The main reason is that the base stations require time synchronization. GPS may have some risks, including its failure rate and high cost. That's why the PTP1588 protocol is used. When it was used, it was mainly used locally, so China Unicom did not make it a three level architecture.

When 5G came, it also divided three businesses, one is the basic business, that is the demand of three microseconds mentioned just now. There are also collaborative businesses and new businesses, and demand will be higher. China Unicom's current plan should belong to a transitional program, because in the era of 4G, we have bought the core time servers, and the 4G network will also be passed down one by one through the core access to meet the early 1.5us of 5G. If there is demand for narrow wave polymerization in the future, the polymerization is not the aggregation of main network, but only part of the region. It can use NTP time server for some areas. Now the new dual frequency reception technology is received by the two frequency points of the satellite, so that the troposphere is more precise and the recovery time is more precise. At present, the common view method is used by manufacturers to make equipment. The accuracy is very high and can reach sub nanosecond level, but there are still some problems in application.

Beidou time service, China Unicom released a 5G+ Beidou and Chi Yan Research Institute's launching ceremony in Xiong an. Beidou is also a matter of national strategic level. When we are going to mention synchronization again, when we mention GNSS, we still need to mention BTS. The number of Beidou three generation satellites basically covers the whole world is no problem. But what is the performance of Beidou base station? In August last year, Wuhan also made a long-term test on HUAWEI's LTE base station and tracking Beidou's performance. You can see that the performance of Beidou is slightly better than that of GPS.

This is the base station of 5G, and Xiong an has deployed some 5G base stations. China Unicom also wants to cooperate with the May 10th press conference, and has also done some HUAWEI 5G base station tracking Beidou test. The upper right corner is time, the following frequency, 56 hours, it can be seen is also very stable. The average time signal is about 100 nanoseconds in average. In the future, 130 of the indicators can be satisfied, but there may be some problems with simple satellites. The lower left corner is maintained, and the GPS and Beidou are removed, and the base station is maintained for about 50 thousand seconds. When it stays, it will break 130 nanoseconds in only 6 minutes. At 1 microseconds, it can last for about 14 hours. In the future, if we rely entirely on satellites, we may not be able to support satellites for a day. When CA is used, it will not guarantee the accuracy requirement in 6 minutes.

The SYN2401 PTP clock is a high precision master clock device based on IEEE1588 V2 protocol, and supports dual mode clock synchronization of Beidou and GPS. When the dual-mode satellite is used as the reference clock, the precision of the SYN2401 PTP precision master clock tracking UTC is better than that of 100ns, which can provide a nanosecond time signal source through Ethernet.

With the development of wireless technology, synchronization is becoming more and more important. From the very beginning, we only asked for frequency synchronization, and now we need to be more precise in the project. This is a trend. If this strict synchronization is not guaranteed, it may have a great impact on the application of the industry, because it has not really tried yet, and there is no data in the end, such as vehicle networking and intelligent driving.Relying solely on GPS has potential political security risks, and for 5G's ultra high precision time synchronization demand, when the satellite fails, the base station's time keeping performance is not optimistic, we need to consider the 1588V2 technology based on the ground link transmission, and we also have some new technologies to track. One is Beidou, the other is 1588 to really use it. The worry is that when the network fails, it doesn't know how to locate it. But at present, it's basically not a big problem, so we have to push it up and use it to meet the needs of 5G in the future.

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