Recently, China Telecom successfully conducted the first existing network test of 5G OTN fronthaul carrying equipment in Beijing. This is the first time in the world to verify the 5G fronthaul carrying OTN equipment with 25G rate eCPRI interface based on the existing network environment, which can effectively solve the problem of insufficient fiber core of forward optical cable in 5g deployment.
The test was started in late November 2018, and China Telecom and Huawei conducted the test in Yizhuang pilot area of Beijing Telecom 5G test network. Three kinds of 5G fronthaul carrying schemes are compared in the current network test, including traditional single fiber unidirectional fiber direct drive (fiber demand is 2 fiber / sector, 6 fiber / station), new single fiber bidirectional (BiDi) fiber direct drive (fiber demand is 1 fiber / sector, 3 fiber / site) and new OTN equipment bearing (fiber demand is 1 fiber / site), the results show that the three schemes can well support 5G fronthaul carrying requirements. Delay, delay jitter, synchronization and other key technical indicators meet the needs of typical 5G applications such as uRLLC, eRLLC and mMTC.
The 5G fronthaul carrying OTN equipment used in the current network test uses single fiber bidirectional transmission mode to provide a total transmission capacity of 100GB / s. Only one optical fiber can solve the forward transmission demand of a 5G site (three sectors), and can also provide 25Gb / s additional transmission bandwidth, which can be used for 3G / 4G bearer or government enterprise dedicated line access; even in the extreme case of no new fiber core, the existed 4G front end can be used It can also meet the requirements of 4G and 5G fronthaul transmission at the same time. The new 5G fronthaul transmission carrier OTN FO (outdoor unit) supports industrial temperature, AC or DC power supply and low power (about 100W), which is convenient for installation; it supports loop back test, OAM management, power failure alarm and other remote control, which is convenient for operation and maintenance.
Dr. Li Junjie of China Telecom said that the current network test shows that OTN fronthaul transmission equipment has basically commercial capacity; the scheme is especially suitable for the scenario where optical fiber is extremely scarce, and only one fiber is needed to realize the fronthaul carrying of a 5G base station. As an important supplement to the optical fiber direct drive scheme, this scheme will greatly reduce the pressure of 5G scale deployment on the forward optical fiber and cable resources. It is of great significance to accelerate the application of 5G in China.