Digitalizing Air Traffic Control

With a rich history spanning 2300 years, Chengdu in China’s central Sichuan province is a popular tourist destination, but the city’s Chengdu Shuangliu Airport has recently been overwhelmed with passengers. As a result, a second airport has been constructed — Tianfu International Airport — making Chengdu only the third city in China to have two airports, after Beijing and Shanghai.

While an additional airport brings obvious benefits to the city and its travelers, from a management perspective, it adds further complexity, since effective collaboration between the two airports must be established.

Air traffic control comprises multiple units, including the air traffic services reporting office, tower control, terminal (approach) control, area control, and the regional air traffic control bureau. Airport tower control is mainly responsible for field control, including clearance delivery, take-off, landing, and taxiing. Meanwhile, terminal control is responsible for managing aircraft landing at, or departing from, one or multiple airports in an area, and this also involves collaboration between air traffic control and the military.

The terminal area in Chengdu covers airports within a radius of approximately 100 km, including Mianyang, Yibin, Aba, and a Flight Academy. Area control is primarily responsible for the air traffic control of aircraft flying at a high altitude in a specific area, as well as handling requests and controlling and reporting flight forecasts and updates.

To achieve seamless collaboration between these units, Chengdu built four Optical Transport Networks (OTNs) to cover services at Shuangliu Airport, the Regional Control Center, the Terminal Control Center, and Tianfu Airport. As the new Tianfu Airport is more than 100 km away from Shuangliu, the Southwest Regional Air Traffic Management Bureau of the Civil Aviation Authority chose Huawei’s large-capacity OTN transmission solution to connect the four OTN networks and ensure the two airports operate effectively.

High-bandwidth, low-latency, and highly reliable all-optical base

The technological evolution of transportation has a two-fold effect. It offers a greater variety of travel options for passengers, but makes it increasingly difficult to predict passenger volume. According to VariFlight Technology’s Civil Aviation Operation Report of May 2020, the number of takeoffs and landings at Chengdu Shuangliu International Airport reached 25,300 in the month, and passenger throughput reached nearly three million.

Busy airports require efficient digital infrastructure to ensure seamless travel and operations. For this reason, the two airports in Chengdu are digitally equipped to build an intelligent transportation and air traffic control system, which improves the entire air travel experience. The application of High Definition (HD) video and digital-based tools requires high bandwidth, low latency, and highly reliable transport networks. Huawei’s OTN solution can accommodate such heavy infrastructure demands, guaranteeing 48 Tbit/s bandwidth over ten years. It provides one-hop connections at the optical layer, supports μs-level latency, implements protection switchover within 50 ms, and achieves zero interruptions.

Diverse service interfaces and physically isolated transport network

Air traffic control is vital to passenger safety. To ensure secure take-off and landing, the air traffic control center needs to obtain important flight and airport data in real-time, covering the weather, wind speeds, the temperature, and humidity levels, plus radar field, runway, and ground equipment information. This information is transmitted to the air traffic control center through different data collection and video security interfaces, which must be physically isolated from office network interfaces to ensure secure data transmission.

If a conventional optical fiber isolation solution were to be used in such a scenario, a large number of optical fiber resources would be wasted and management would be complicated. In contrast, Huawei’s OTN solution uses Dense Wavelength Division Multiplexing (DWDM) technology to provide 80 channels on a single fiber, equivalent to 80 independent physical pipes, with each pipe carrying multiple service types. Different services use independent Optical Data Unit-k (ODUk) sub-channels, with bandwidth kept exclusive and without interference.

The solution uses a four-in-one platform — Plesiochronous Digital Hierarchy (PDH), Synchronous Digital Hierarchy (SDH), Partition Knowledge Table (PKT), and OTN — that supports various service interfaces, such as PDH, SDH, Ethernet, video, and storage interfaces, to adapt to different scenarios. This reduces the number of required device types, reduces the physical space occupied by half, cuts power consumption by half, reduces network layers, and simplifies Operations and Maintenance (O&M).

Features of Huawei’s optical transmission solution

High capacity and low latency: Per-channel bandwidth of 100 to 800 Gbit/s, with each fiber providing 80 channels, delivering higher bandwidth with less fiber resources and future-proofed for the next five to ten years. The network is flattened, one-hop connections are achieved on the optical layer, and end-to-end latency is visualized, manageable, and guaranteed.

Multi-service support: Multi-Service Optical Transport Network (MS-OTN) architecture and a 4-in-1 platform support services of any rate, from 2 Mbit/s to 100 Gbit/s. PDH and SDH interfaces are compatible with legacy networks, protecting the investment of customers. Ethernet and HD video interfaces ensure smooth network evolution.

High security and reliability: Physical hard pipe isolation at fiber, wavelength, and ODUk levels, plus L1 encryption, ensure service transmission security. Protection at device and network levels ensures 99.999% availability and zero service interruptions.

Huawei’s all-optical transport OTN solution fulfils the requirements of air traffic control interconnection and provides infrastructure network assurance for future development of information technologies in air traffic control. The air traffic control project at Chengdu Tianfu International Airport successfully demonstrates the smooth construction of the transmission network, while the OTN transmission channel between Tianfu Airport and Shuangliu Airport ensures a safe, convenient, and intelligent flight experience.