5G-Advanced Powered Smart Metro: Empowering Passenger Services and Metro O&M

In a city, ensuring residents a high-quality living experience and a convenient, healthy living environment is crucial. The development of urban transportation plays a key role. Metro commuting offers an efficient and low-carbon choice amid escalating traffic congestion. The metro lines in Shanghai are approximately 936.17 km, with an average daily capacity of about 13 million passengers, ranking first in the world. The average commuting time on Shanghai metro is over 40 minutes, and passengers need stable and reliable Internet connections for social and entertainment. However, 5G network coverage on metro is less than 20%, and the actual network demand of passengers has been suppressed. In such a densely populated situation, translating passenger traffic into value creation is not only a critical challenge, but also a valuable opportunity to enhance the urban economy.

ZTE and China Telecom unveil a groundbreaking 5G-Advanced powered smart metro solution for Shanghai Metro Line 4. Since April 2023, the 34-kilometer Line 4 has been commercially deployed with this solution, handling 0.98 million daily passengers. ZTE introduces an industry-first 5G indoor solution with BBU + pRRU two-level architecture inside metro carriages. Additionally, 5G-Advanced AAUs are deployed in tunnels, achieving “high-speed backhaul” with up to 15 Gbps downlink and 2 Gbps uplink. This ensures extremely large bandwidth and high transmission capacity, providing passengers with a seamless and reliable 5G network for an enjoyable journey.

For metro operation, ensuring tunnel security is crucial. Previously, manual checks took three hours daily to eliminate potential risks and hazards in tunnel. Millimeter-wave technology’s high backhaul capacity enables real-time transmission of operating information from platforms and carriages to the metro control system. Pattern recognition and object detection can replace over 80% of daily manual checks for platforms, pantographs (electricity transfer from catenary to locomotive), and railways. This solution brings significant benefits to users, mobile operators, and metro operations.

Reducing Limitations on Mobile Network Infrastructure

In China, most metro systems were built with a distance of about 1 meter from tunnels to train carriages. However, a minimum of 1.2 meters is needed for installing new cables, considering isolation and security requirements. Insufficient power is another factor. To support 5G service and new signal sources (5G RRUs), the power supply needs to increase from 60 kW to at least 100 kW. The cable-based solution faces obstacles, with network signals significantly weakened inside the metro due to signal attenuation from dense metal carriages and the Doppler Effect caused by the train’s rapid movement.

The 5G-Advanced powered smart metro solution innovatively relocates network equipment deployment from tunnels to metro carriages, effectively addressing China Telecom’s space limitations and signal attenuation challenges caused by dense metal carriages.

Creating More Value for Mobile Operators

5G-Advanced powered smart metro is the most cutting-edge solution for specialized 5G network coverage. With a quadrupled average downlink speed, equivalent to upgrading from 480p to 1080p video quality, it achieves a 15 Gbps high-speed backhaul through the millimeter-wave technology. This technology supports approximately 75 channels of 8K HD camera live-streams simultaneously. Metro mobile users, on average, consume three times more payload. This unique solution allows for deployment across over 190 metro models, providing mobile operators with increased collaboration opportunities with various industrial partners. The achievement is attributed to its unique architecture and innovative products (Fig. 1).

• Easier deployment: The unique BBU + pRRU two-level architecture significantly simplifies metro network deployment. Specifically, slim BBU and Qcell (pRRU) are used for in-metro coverage, while 5G-Advanced AAUs deployed in tunnels serve as high-speed backhaul, receiving data from CPEs at both ends of the train simultaneously. Construction time has been reduced from one year to six months.
• Innovative products: The slim BBU, half the size of typical BBU and the industry’s only in-metro BBU, is the smallest in its field. It perfectly fits metro carriages, supporting up to 12×100 MHz Massive MIMO cells while weighing only half as much as a typical BBU. Despite its compact size to accommodate limited metro space, the slim BBU is powerful enough to ensure stable and seamless 5G coverage. Moreover, the 5G-Advanced AAU supports a 1.6 GHz bandwidth and can reach peak rates of up to 28 Gbps when used with NR-DC, making it the largest backhaul option.
• Lower investment and greener operation: For Metro Line 4 alone, the number of 5G network devices deployed has been reduced from 640 to 192, saving approximately $2.1 million. The energy consumption of the 5G network has decreased from 746 Kw to 169 Kw, representing a remarkable 78% reduction. This results in an annual savings of 3.7 million kWh, enough to power a community of 5,000 people for a year.

Empowering Smart Metro Operation

This 5G-Advanced powered smart metro solution based on 3GPP 5G standards offers high security, ultra-low latency (<5 ms), high bandwidth, and excellent reliability. Providing complete visibility and situational awareness of the entire metro line, it also integrates communication and perception, identifying objects as small as 20×20×20 (cm3). This enhances overall security and reliability for completely driverless driving.

Inspecting trains, rails and tunnels involves risks, such as gaps of up to 100 meters on both platform and non-platform tracks, with water accumulation. All inspections must be completed within a three-hour window at midnight. Machine vision and AI pattern recognition can cut down human inspections by 80%, enhancing employee safety, improving operating efficiency by 30%, and reducing night working by 50%.

Unprecedented Metro Experience Enhancement

The 5G-Advanced powered smart metro solution offers passengers an unparalleled gigabit experience, ensuring an enjoyable journey. Each metro has a network capacity of up to 15 Gbps, sufficient for 1800 people to watch HD video streams or play cloud games simultaneously without any Internet slowdown. The peak rate within the metro has tripled, reaching 2.1 Gbps from 600 Mbps, meeting passengers’ daily social and entertainment needs.

The mobile network infrastructure enhances user experience for various services. In Shanghai, the METRO app (available on both IOS and Android) provides real-time information on carriage arrival time and crowding levels, enabling passengers to plan optimal travel routes. After passengers disembark, the sub-meter-accuracy positioning guides passengers to the optimal route via the METRO app when GPS is unavailable, whether changing trains or exiting the station.

After the commercial launch on Line 4, deployment on Line 9 is underway, with plans for expansion to additional metro lines in Shanghai. The 5G-Advanced powered smart metro solution is applicable to at least 70 metro lines in medium- and large-sized cities like Beijing, Tsingtao, and Hangzhou in China, and aims to extend its reach globally.

Digitalization construction forms the foundation of a smart metro, focusing on safety, performance, comfort and reducing operational costs to support long-term, sustainable urban growth. ZTE is committed to advancing  5G-Advanced innovation in this digital economy era through collaboration with more industrial partners to create a brighter future.