PRESS RELEASE: As 5G networks continue to expand across the globe, China Telecom is making significant strides in tackling one of the major challenges in 5G deployment: Signal Bar for Metro.
While outdoor 5G coverage in China has exceeded 95%, metro systems remain less connected, with only 55% coverage across the country’s 308 metro lines. These lines span over 10,000 kilometers, many of which were built before 5G technology came into existence, presenting technical and infrastructure limitations.
Challenges in Metro 5G Deployment
Yang Xin, Mobile Network Expert of China Telecom Shanghai Branch, highlighted several challenges to expanding 5G in metro systems. One key limitation is the type of cables currently in place, which support frequencies between 800MHz and 2.3GHz, while 5G requires higher bands like 2.6GHz and 3.5GHz. Additionally, space constraints in tunnels, power supply limitations, and the need for upgrades to existing infrastructure further slowdown the deployment process.
Due to these complexities, metro coverage lags behind outdoor 5G rollout, and more innovative approaches are required to overcome obstacles like signal attenuation from dense metal carriages and the Doppler Effect caused by fast-moving trains.
“The metro lines in Shanghai are approximately 936.17km, with an average daily passengers around 13 million, both are the world most. Passengers require stable, high-speed internet access during their average 40-minute commutes for social interaction and entertainment.” Yang Xin added.
Customized Metro Solution: 5G-in-train Smart Metro
To address these challenges, China Telecom, in collaboration with its partner ZTE, has developed a customized 5G solution for metros, including the deployment of millimeter wave backhaul in tunnels and 5G Qcell (Pico site solution) in metro carriages.
This system delivers high-speed data transfer with downlink rates of up to 15Gbps and uplink speeds of 2Gbps for backhaul. Meanwhile, Qcell ensures seamless coverage within metro carriages, providing uninterrupted connectivity for passengers. The average downlink speed rate for metro passenger has tripled from 600Mbps to 2.1Gbps, while the entire capacity is an increase of 16-fold, enabling over 1800 passengers to stream high-definition video or to cloud games at the same time.
The 3GPP-based system enhances data security compared to existing Metro operation system with Wi-Fi and LTE-M systems, allowing for both passengers and operational use on metro systems.
Successful Deployment and Energy Efficiency
China Telecom deployed the 5G-in-train Metro system on Shanghai Metro Line 4, achieving full 5G coverage over the 34km line. This deployment not only boosted connectivity but also lowered energy consumption by 75.6% and reduced investment costs by 20%, saving nearly $2 million.
The installation duration of the millimeter wave backhaul system in tunnels is approximately six months, whereas the cable solution necessitates over one year. 3,700,000+ kWh will be saved for 5G network yearly, which is enough to provide electricity for a community of 5,000 people for a year.
The upgraded network is for use by both passengers and metro operations. A dedicated app (Metro) as well as screens on station platforms display arrival timings for all lines, the real-time occupancy levels of carriages and carriage temperature.
A Vision for the Future
Yang Xin emphasized that 5G-in-train metro solution can be applied to more than 90% of China’s metro lines and has already been tested on 190 different models. With flexible frame structure adaptation, the solution enables quick adjustments to 5G service requirements, allowing operators to maximize millimeter wave wide bandwidth across various scenarios.
China Telecom predicts that within two years, China’s metro systems will achieve the same level of 5G coverage as outdoor networks. This advancement will significantly enhance both passenger experiences and metro operations, furthering China’s leadership in global 5G deployment.