China Mobile Proposes Open WDM Solution For 5G Fronthaul

At the “2019 China Optical Network Seminar” held on June 12 by Communications World News (CWW), Li Han, deputy director of network and information technology research of China Mobile Research Institute, said that China Mobile will be in Beijing by the end of September this year. 5G continuous coverage in 8 cities including Shanghai, Hangzhou, Suzhou, Wuhan, Guangzhou, Chengdu and Xiongan. The new SPN method will be adopted to deploy tens of thousands of stations on a scale of deployment, and the remaining small-scale coverage will be carried by PTN expansion. A large-scale 5G network will be deployed next year.

The current stage is the stage of large-scale deployment of SPN. Although the technology is very advanced, the cost and economics of large-scale deployment are topics of great concern to the industry. Li Han said that China Mobile has conducted many trials and taken many measures to ensure low-cost large-scale deployment. Mainly the access layer adopts 50G PAM4 single-fiber bidirectional optical module; the convergence layer and the core layer adopt the lighting + simple OADM solution; the SR-MPLS technical solution is adopted, which is backward compatible with PTN and forward compatible with IPv6 evolution; single-fiber bidirectional realization of ultra-high Precision time synchronization. Finally, it is concluded that the SPN access layer uses 50G PAM4 BiDi optical modules to better meet the bandwidth and synchronization indicators. It is necessary to further promote industry maturity and reduce costs. The SPN convergence and core layer use low-cost N*100G coherent color optical modules. And lightweight OADM system, providing large-bandwidth comprehensive service carrying capacity.

Li Han revealed that SPN has passed laboratory tests and live network trials, and has established projects in major standards organizations such as ITU-T. With the joint efforts of the industry chain, SPN technology has matured and is ready for the upcoming first year of 5G scale deployment.

Speaking of the 5G fronthaul transmission network, Li Han pointed out that C-RAN will be an important scenario for 5G construction, and the construction scale is expected to account for 30 to 90%; in addition, C-RAN is expected to be mainly small and medium-sized, based on 10 physical stations Focusing on the fact that the computer room needs 120-core optical fiber, WDM technology needs to be introduced to ease the pressure on optical fiber resources.

Li Han also analyzed the pain points of the current passive WDM technology. He pointed out that DU/AAU is mainly equipped with color optical modules, but lacks management means; the ability to sense fiber link failures is weak; optical module operation and maintenance are difficult, mainly relying on manual labor .

In addition, Li Han pointed out that in order to better meet the needs of 5G fronthaul, reduce fiber resource requirements and have fronthaul management and control capabilities, China Mobile proposed an Open-WDM solution. It is understood that Open-WDM is a semi-active system, as long as it includes AAU color light modules, AAU-side passive wavelength division multiplexers, and DU-side active WDM equipment to form a unified control and control fronthaul network. Open-WDM has "three new" features:

The new management division is conducive to the division of maintenance interface and management domain by wireless and transmission;