Stable high-capacity communication using millimeter waves even at high speeds [2:58]

For autonomous vehicles and next-generation railways in the Beyond 5G era, stable high-capacity communication is required to achieve a more valuable mobility experience.

NEC developed technology to stabilize communication quality during high-speed movement by utilizing millimeter waves capable of high-capacity communication, and conducted a joint demonstration experiment with NTT and NTT DOCOMO.

In this experiment, a 40 GHz band millimeter-wave equipment developed by NEC was used to conduct communication tests during high-speed movement. Three base station antennas were installed at 150-meter intervals along the test course and connected using analog radio-over-fiber technology developed by NTT.

In the experiment, a vehicle equipped with a terminal antenna moved at a speed of 100 km/h, maintaining communication while switching between the base station antennas.

First, a driving test using conventional communication technology was conducted.

During the switch between antennas, the transmission throughput significantly decreased.
In millimeter wave communication during high-speed movement, a significant frequency shift known as the "Doppler shift" occurs.

This is particularly problematic during antenna switching, where abrupt frequency changes happen, leading to a decrease in throughput.

Next, the newly developed technology is applied.

With this technology, the base station pre-compensates the frequency shift before transmission, ensuring the radio waves are delivered to the terminal at the normal frequency.

Furthermore, pre-compensation of timing is applied at the base station, ensuring the radio waves from different antennas reach the terminal simultaneously.

With this technology, stable frequency and timing are maintained even after antenna switching, throughput degradation is significantly reduced.

Moving forward, digital twin world of the exprimental space, created by NTT DOCOMO, can realize validation beyond real-world limits.

NEC will continue to collaborate with NTT and NTT DOCOMO to enhance the value of the mobile experience.
A future where cars and trains are more than just "moving spaces" is approaching.

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