Huawei, in collaboration with the China Telecom branch in Shaanxi Province, has commercially deployed 32T32R FDD Massive MIMO technology on the Shu-Lan and Yinxi high-speed railway lines. This equipment operates simultaneously on 1.8 GHz and 2.1 GHz frequencies.
Huawei states that this is the first commercial use of FDD Massive MIMO in a high-speed railway environment in China. High-speed rail networks present significant challenges for mobile coverage due to the large distance between towers, train speeds up to 350 km/h, and penetration losses caused by metal carriages.
Massive MIMO technology, which is often used to increase capacity in densely populated urban areas, forms narrower beams compared to traditional wide-beam antennas. Huawei asserts that this beam shape is suitable for a linear route: the beams can be directed along the tracks, follow the train through cells, and adapt to compensate for the Doppler effect, which could degrade the connection.
The company highlighted three key design aspects for railway application. Adaptive beams are designed to limit frequency shift effects at high speeds. Inter-cell beam tracking and coordinated planning aim to reduce the number of handovers when a train crosses multiple cells. Furthermore, broadcast beams and pilots are configured to ensure linear coverage so that energy remains within the corridor rather than scattering in open terrain.
According to the statement, measurements conducted on the Yinxi section in Shaanxi showed an approximate 200-meter expansion of cell coverage after modernization, a 24% increase in average 5G uplink speed, and an increase in average downlink speed of over 50%. User experience improvements were even more pronounced: uplink speed at the zone boundary increased by 95%, and downlink speed by over 100%.
Although FDD Massive MIMO has long served as a tool for increasing capacity in urban macrocells, deploying 32 transmit and 32 receive chains on a high-speed corridor represents an attempt to apply this urban capacity model to a fast-moving linear cell. Huawei and Shaanxi Telecom present the deployment in Shaanxi as an operational commercial network, not a laboratory experiment. It should be noted that all claimed gains in coverage and throughput are assertions made by the company and operator from the announcement in October and have not undergone independent verification.
