FiberHome Ma Jun: Thoughts on the Development and Evolution of Optical Transmission Network


On June 16, at the 2021 Optinet China Conference held in Beijing, FiberHome expert Ma Jun delivered a keynote speech on " Thoughts on the Development and Evolution of Optical Transmission Networks". Ma Jun said: From the perspective of industrial development, the current optical network has constituted a solid foundation for the basic information and communication network, and has entered a new stage of smart optical network in terms of technological development. At the meeting, Ma Jun discussed the "speed and capacity development", "networking technology application and development", "network openness and disaggregation", and "application of AI in the transmission network" in the development and evolution of the optical transport network. The opinions of the hot topics after independent thinking were shared with the experts at the meeting, and aroused widespread resonance among industry experts.

● Can the single-wave rate be further improved after 400G?
Currently, single-wave 200G has been applied in existing networks, and single-carrier 400G, which supports long-distance transmission, has also been put on the agenda, and it is expected that it will gradually become commercially available around 2023. In the Internet field, driven by demand for traffic and cost, single-wave 800G applications supporting short distances (≈100km) have emerged, and it is believed that the future will continue to evolve to Tbit.
● In addition to modulation format and optical fiber, is there an effective way to increase the transmission distance of B100G?
Unlike 100G, the B100G system focuses on the product of capacity and distance, it needs to compromise between the two key indicators of spectrum efficiency and transmission distance to obtain an optimal solution. The improvement of the B100G transmission distance is a systematic project. The improvement of the fiber input power, the reduction of the optical fiber link loss and the reduction of the noise figure of the optical amplifier are three effective paths. At present, the industry has made progress in the research and application of signal modulation and reception, ultra-low loss and large effective area optical fiber. In the future, long-distance transmission of single-wave 400G should focus on the engineering application of intelligent Raman optical amplifiers. Under the same application conditions, the optical amplifier not only doubles the B100G non-electric transmission distance, but also solves the safety problem in the process of engineering application and maintenance. Its application prospects are worth expecting.
● Why band expansion is needed?
Unlike 10G and 100G DWDM systems that use 50GHz channel spacing, the B100G system will have 75GHz, 100GHz, and 150GHz channel spacing due to different single-wave rates and code types. In order to pursue the reduction of transmission cost per bit and continue the application habit of the 80-wave system, based on the conventional C-band and "C+L" extended application research is the current hot topic in the industry.

● How does the technology of transmission network evolve?
Optical transmission network networking technology has two technical routes based on ODUk electrical cross-connect and ROADM optical cross-connect. OTN electrical cross-connect has shifted from the past pursuit of cross-connect capacity improvement to adopting packet-enhanced OTN and OSU technology to support multi-service bearer. ROADM optical cross-connect focuses on the improvement of WSS dimensions and the research and application of OXC technology. Optoelectronic hybrid crossover is a mainstream technical solution commonly adopted by Chinese operators.
● What is the essence of OXC?
The essence of the current OXC is still a ROADM system based on WSS devices. Its innovation lies in the use of "optical backplane" technology to fix the external fibers between the ROADM nodes in different optical directions inside the equipment, simplifying the number of external fibers. Considering business requirements, cost and other factors, ROADM and OXC equipment deployment should be rationally selected according to the scale of network nodes in actual engineering applications (for example, conventional ROADM is recommended for nodes with less than 12 optical directions, and large and complex nodes with more than 12 optical directions can be considered OXC).
● How is OSU currently progressing and how will it evolve in the future?
From the perspective of operators to solve the needs of small unit services below GE, the packet-enhanced OTN and OSU technologies can meet the needs by different ways, and the difference lies in the internal implementation of the equipment. At present, the packet-enhanced OTN standard and technology are mature. With the development of the three major operators' OTN carrying government and enterprise services, they have been widely deployed and applied. OSU technology currently requires further research and advancement in the industry chain in terms of standards, technical solutions, and industry chain maturity. From a research perspective, it is recommended to deploy and research on a small scale at the user-side CPE and metro access convergence nodes.

● How to understand openness and disaggregation?
The openness of the network focuses on opening the network's resources and capabilities to internal and external users. With the application of SDN and AI technology, future network resource conditions and service differentiation can be clearly presented to customers, thereby enhancing customer perception and experience. The disaggregation of the network focuses on the organization and construction of the network. At present, there are closed "black box" solutions based on traditional equipment and management and control, and "white box" solutions that focus on modules and device-level interfaces in the Internet field are provided by equipment manufacturers. Equipment, and open capabilities according to standardized interfaces, allowing cross-vendor unified management of the "gray box" solution.
● Does the full disaggregation mode of the Internet apply to operators' large networks?
Internet manufacturers focus on cloud computing and application services, self-built networks for DC and POP point interconnection, simple network interfaces and topologies, and focus on low cost. Operators pay equal attention to network services and cloud computing services, and provide universal network services across the country. At the same time, the scale of the operator's network is huge, and the hierarchical and domain-specific construction schemes are generally adopted. Especially for the backbone network, considering factors such as modulation type, FEC, and line optimization, it is difficult to adopt a fully disaggregated scheme. In addition, due to the coexistence of different equipment vendors on the same subnet, the full disaggregation solution is difficult to locate equipment faults, so it cannot be applied to large operators’ networks.
● What is the enlightenment given to us by the deployment of government and enterprise networks in the province?
Judging from the recent practice of the government and enterprise private networks of various operators in the province, the CPE is fully disaggregated at the user access side, the "horizontal" forwarding level is divided into domains, and the "vertical" control level uses the "gray box" of SDN controller layers. The solution not only realizes the end-to-end characteristics of the service, but also avoids the excessive closure and openness of the network. It is a better realization idea for the current network construction.

● Does the optical network need AI?
With the increasing number of connections, number of nodes, number of wavelengths, number of time slots, number of ports, and number of routes, massive amounts of data will be generated during the operation of optical networks. On the one hand, AI needs to be introduced to improve the efficiency of network operation and maintenance. On the other hand, massive amounts of data laid the foundation of introduction of AI.
● What is the basis for the optical transmission network to load AI?
FiberHome believes that the digitization of the optical layer is the basis for the transmission network equipment to load AI. Through the real-time acquisition of self-developed DSP intermediate parameters, the introduction of online OTDR and the application of optical layer OAM, it can initially realize the digitization of the optical layer of the optical transmission network, which is the reasoning and real-time of AI. 
● How to promote the application of AI in the optical transmission network?
The current FiberHome Smart Optical Network App has successfully realized online interaction with the network management system, providing network topology, resource management, optimization settings, result analysis, service simulation, network reporting, equipment simulation, device simulation and other functions in the planning and operation of the network. In terms of network operation and maintenance, functions such as "performance trend prediction" and "fault data analysis" have been successfully applied to the live network, which has greatly improved the robustness of the network and the efficiency of operation and maintenance. In the future, network intelligence will be applied in the whole life cycle of "planning, construction, maintenance, optimization, and analysis".

Finally, in the roundtable discussion of the forum, Ma Jun discussed with the participants on the topic of "Optical Transmission Network Expansion and Upgrade Strategy", and discussed the time point of single-wave 400G application, the progress of FiberHome B100G research and application, the construction ideas of B100G and suggestion of implementation again.

FiberHome has always maintained its strategic strength in scientific research and innovation in the field of optical communications, and has deeply tapped the value of optical networks. FiberHome will continue to work with partners to seize opportunities, face challenges directly, build consensus, and coordinate industry to support the rapid development of the digital economy and accelerate the digital transformation of thousands of industries.

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