“98kmh, 198kmhh 390kmh, 431kmh”, the magnetic levitation car inside the display, the numbers are beating, passengers feel the speed and passion it brings, have taken pictures. “102Mbps, 230Mbps 371Mbps, 405Mbps”, in the high-speed maglev train, technicians stare at the test terminal screen, watching the 5G rate continue to soar.
For the first time in the world, the world’s fastest land transportation and the fastest mobile communication technology have come together.
Recently, Shanghai Telecom joint zte launched the world’s first 5G maglev high-speed line commercial network test, in the fast-moving maglev train, 5G performance is stable, marking 5G network for magnetic levitation trains to provide an ideal broadband communication service.
With the further improvement of maglev 5G network coverage, in the near future will provide passengers with stable high-rate data access services in the fast journey, but also for a variety of high-speed railway and maglev lines to provide 5G services set a model, solid foundation.
The intersection of the fastest speed and the fastest mobile speed
Series from Line 2 Longyang Road Station and Shanghai Pudong International Airport, 30 kilometers distance can be reached in 8 minutes, since its inception in 2002, magnetic levitation has become a symbol of Shanghai’s speed, certified by Guinness as “the world’s fastest land transportation.”
What would be the experience of the intersection of 5G and magnetic levitation?
On the morning of December 9, the reporter and ZTE technicians came to Longyang Road together to experience the 5G speed on the spot on the maglev train.
The start-up speed and acceleration of the maglev train are extremely fast, and on the display inside the car, the beat frequency of the second number is obviously not keeping up with the speed increase. At that time, when the speed reached 300 kilometers, when encountering a turn can also feel centrifugal force, the carrier will also have a significant tilt.
In high-speed trains, technicians hold mobile phones and computers to test 5G speed and stability. Computer screen, test software in real time in the monitoring of mobile phone 5G Internet data: network speed, location, signaling, signal strength …
“The result is also, performance is stable. “At this point, the maglev travels faster and faster, with the cabin shaking slightly, the technician says while keeping his body stable. Reporters on the computer screen saw that 5G speed reached 405Mbps.
Even more “amazing” is that the technician’s on-site fixed-point test results show a peak rate of 959Mbps at a peak rate of 959Mbps, with an average rate of 857Mbps.
“With the continuous improvement and continuous optimization of network construction, the peak rate can reach 1Gbp. It’s worth noting that we’re using a 3.5GHz high band, which is more challenging than the lower band, and the lower band has an advantage in the same networking. 3.5G is the global 5G mainstream band, where we have a wide range of demonstration effects for high-speed linear coverage performance verification. The technician added.
Cracking the “fast speed, car body thickness, switch frequency” puzzle
Providing high-quality network coverage for high-speed trains is a common challenge for operators and equipment manufacturers around the world, not to mention providing the most advanced 5G network service for maglev trains, the world’s fastest land transportation.
ZTE and Shanghai Telecom technical personnel after many discussions, continuous experiments, through the “speed fast, car body thickness, switch frequency” these three gates, to solve the magnetic levitation train high-speed movement caused by the Doppler frequency shift, train metal body and a larger thickness to bring a significant attenuation of the signal, the user terminal and base station frequency switchthese these difficult problems.
Compensation “Doppler” frequency shift “speaking on the same channel”
In our daily lives, we often hear the phrase “I’m not on the same channel as you”, describing the difficulty of communicating. This is especially true in mobile communication, where signal transmission and reception between terminals and base stations need to be transmitted at the same frequency in order to communicate normally.
However, because of the Doppler effect, the faster the movement, the greater the frequency deviation between the terminal and the base station, so in the high-speed motion of magnetic levitation, want the terminal and base station to keep the “same channel” on the call is not easy.
ZTE can detect and compensate Doppler bias in high-speed movement of the terminal through the patented frequency-bias compensation algorithm, allowing the terminal and base station to send and receive signals at the same frequency, thus greatly improving the performance of the wireless link.
“Amplifier” solves the big problem of signal attenuation
When covering maglev 5G, the second problem encountered is that the train has a thick metal body, which produces a great signal attenuation.
To address this problem, technicians take a high-gain antenna, which is like a megaphone, amplifying the sound outside so that people in the room can hear it. “There are still no small challenges in the middle, such as which antenna we should choose, how much gain is needed, what the angle of the antenna should be, etc., need to be accurately calculated and comprehensive judgment, need to accuratelink budget.” “
Base station “merge” significantly reduces signal switching frequency
The base station has a certain coverage, and there will be overlapping coverage between the two base stations.
When the user is in a low-speed state of movement, there is enough time to complete the switchover in the overlapping coverage area of the two base stations, the phone can easily switch from one base station cell to another, thus maintaining uninterrupted communication.
However, in a high-speed mobile state, the mobile phone through the overlap between the two base stations will be a short coverage area time, when the time required to switch can not be met, the switch will fail, the phone will drop.
In order to solve this problem, the technician adopted the “base station consolidation” approach, the multiple base stations “turned into” one base station.
“Physically, these base station cells are independent, but through background parameter settings, these base stations logically become a larger cell.” “The technician introduced.
In this way, can greatly reduce the number of cell switching, and between the two communities to increase the overlap coverage, leaving enough time, so that the mobile phone can smoothly switch to the next cell, so as to solve the problem of frequent signal switching, to ensure the user experience.
To the future!
Pushing 5G towards high-speed rail
At present, high-speed rail transit has entered a period of rapid development, the global high-speed rail mileage has exceeded 40000 kilometers. In China, high-speed rail passenger traffic reached 2.03 billion in 2018, more than three times that of civil aviation.
When people travel on high-speed rail, there is a general demand for high-speed Internet access, high-quality broadband network can not only bring better experience for passengers, but also enhance the brand competitiveness of operators.
Shanghai Maglev train is the world’s first and only magnetic levitation train commercial operation line, the top speed is the world’s commercial operation of high-speed trains. Moreover, this 5G network solution for maglev lines provides a complete set of network equipment for high-speed train broadband communications, and the base station family supports the global mainstream 5G band, which means that it can be extended to a wide range of high-speed rail and maglev lines with huge market potential.
At present, ZTE and China Telecom have joined forces to provide 4G coverage for several high-speed rail lines, the next step is to continue to optimize the commercial performance of 5G networks, combined with specific business characteristics, steadily promote various test verification, to provide ubiquitous high-speed broadband access.