The 5G fronthaul protocol comes out of the lab

Feixiang Network News (Ma Qiuyue / Text) Yesterday, the announcement of "China Telecom 5G prequel wave-division color light equipment (2022) collection and mining" attracted attention. The reason for the attention is that after China Telecom carried out the LWDM program 5G live network pilot last year, it was the first time that the collection and collection of fronthaul WDD IPL equipment was carried out at the group level.

In the construction of 5G, the traditional fiber direct drive and passive CWDM solutions have been commercialized on a large scale. The traditional optical fiber direct drive solution will lead to a huge consumption of optical fiber resources, which is one of the main bottlenecks in 5G construction; the passive CWDM fronthaul solution can solve the 6-wave single-fiber transmission more reasonably, but it is difficult to further improve the 12-wave single-fiber transmission and the later management and maintenance.

Therefore, it has become a consensus that 5G fronthaul chooses xWDM technology as the mainstay. The three major operators chose to establish different 5G fronthaul standards: China Mobile's Open-WDM/MWDM, China Telecom's LWDM and China Unicom's G.metro/DWDM solution.

At present, the 5G fronthaul solutions of the three major operators have basically gone through the experimental and test stage, and The collection of China Telecom's 5G fronthaul wavelength division color light equipment (2022) has opened a button for large-scale commercial use.

China Mobile: Semi-active Open-WDM/MWDM solutions have large-scale commercial capabilities

In order to solve the problem of fronthaul dumb resource management and fiber optic resource shortage, China Mobile pioneered the semi-active Open-WDM/MWDM solution, which solves the 12-wave single-fiber two-way transmission problem, realizes the single-fiber transmission of 5G base stations and DU machine rooms, and further improves the utilization rate of optical fiber, which has the advantages of manageable controllability and low cost.

It is reported that one of the Open-WDM/MWDM cores is a semi-active architecture, AAU side passive, DU side active, flexible deployment, can achieve low-cost management and control capabilities; the core two is based on CWDM expansion MWDM technology, the capacity increased by 1 times, can effectively save fiber resources.

Today, China Mobile has led the establishment of the X-haul transport working group (WG9) in O-RAN and served as the chairman of the working group, and the member units have expanded from 3 semi-active MWDM product research and development manufacturers in 2019 to 38, creating a whole industry chain covering chips, modules, equipment, and control systems. At the same time, 16 equipment manufacturers participate in the production of semi-active Open-WDM systems, which are applied on a large scale in Hubei, Fujian and other 4 provinces, and the core industry "optical chip + optical module" has the ability to mass production, realizing the localization of 25G MWDM optical chips.

As of September 2020, China Mobile's semi-active MWDM-based 5G fronthaul commercial network has been opened in 12 provinces. In December, ZTE completed the live network test of the MWDM semi-active fronthaul system organized by China Mobile, marking that the MWDM semi-active fronthaul solution led by China Mobile has the ability to be commercially available on a large scale.

In June this year, Li Han, the "chief expert" of China Mobile Group and director of the Network Technology Research Institute of China Mobile Research Institute, said in an interview with the media: Semi-active architecture will become the mainstream in the future, semi-active MWDM will be widely used in 5G prequel, and hopes to work with the industry to promote MTN2.0 related technologies, make the entire industry more sound, lower cost, and ensure the development of 5G fronthaul scale.

China Telecom: The pilot is running well The group opened the equipment collection

At the end of 2019, China Telecom proposed a 12×25 Gb/s LWDM fronthaul solution based on the O-band 800GHz fixed channel spacing, and jointly integrated the upstream and downstream of the industrial chain to jointly promote the rapid development of the industry.

In June 2020, the China Telecom Research Institute completed the first batch of LWDM solution tests, and then piloted the local network 5G live network in Beijing, Shenzhen, Nanjing, Yangzhou, Nantong, Hefei, Bozhou, Chengdu and other local networks, which are running well.

Yesterday, China Telecom issued an announcement that China Telecom's 5G prequel wavelength division IEL equipment (2022) centralized procurement project has been approved, the bidders are China Telecom Group Co., Ltd. and China Telecom Co., Ltd., the project has met the bidding conditions, and now the centralized pre-qualification is being carried out, and potential bidders who are interested in it are invited to submit centralized pre-qualification applications.

It is understood that there are 2 standard packages this time, namely: CWDM IE equipment kit and LWDM IPL equipment kit.

It is worth noting that after China Telecom carried out the LWDM program 5G live network pilot last year, for the first time at the group level, the collection and procurement of prequeue wavelength division IPL equipment was carried out.

China Unicom: G.metro optical industry chain has begun to take shape with large-scale commercial capabilities

China Unicom took the lead in formulating the G.metro standard based on DWDM tunable lasers, which defines the characteristics of wavelength adaptive configuration, ultra-low latency, transparent symmetrical transmission, etc., which can effectively realize the normalization of spare parts for fronthaul WDM optical modules, reduce the type of modules, arbitrarily connect between the combined splitters, and automatically identify wavelength matching, greatly improving O&M efficiency and reducing operator OPEX.

In 2014, the G.metro standard was successfully established in ITU-T, and in 2018 it was officially established as ITU-T G.698.4. In 2019, China Unicom took the lead in launching a standard revision in response to 5G transmission needs and adding a 25G rate definition.

As of the first half of 2021, China Unicom has led the completion of laboratory tests of a number of G.metro solutions (from Huawei/HiSilicon, Fiberhome, Hisense Broadband, Ruitai Technology, Greenwell, Zhenyou Technology, Xinnuo, Huahuan Electronics and other industry chain partners).

Since June 2021, China Unicom Research Institute, together with Jiangsu Liantong and Guangdong Unicom, has successfully completed the G.metro pilot project in Jiangning District, Nanjing, Jiangsu Province, and Jiangmen City, Guangdong Province, and realized business opening for the two typical architecture schemes of 25G G.metro passive and semi-active, and the implementation process of both schemes is that the technicians are on the station at one time, the optical module is plug and play, and the business is opened as it goes.

The success of a series of live network pilots means that the tunable laser has officially entered the commercial stage, and it also marks that the domestic G.metro optical industry chain has begun to take shape with large-scale commercial capabilities, which can support the coordinated development of the entire G.metro industry chain.