The equipment is able to deliver high-speed communications in excess of 10 Gbps, as required by 5G mobile communication formats. The use of 5G is premised on deployment of base stations with comparatively small coverage areas placed every few tens of meters. Given this, it will be necessary to have equipment of a compact size that can be deployed anywhere.
Conventional 5G system structures require use of an antenna panel for each terminal when simultaneously transmitting to multiple terminals. Now, by controlling with high accuracy the phase (angle) of signals separately emitted from 128 antenna elements, Fujitsu has been able to suppress the interference between signals, enabling simultaneous communications in four directions using only one antenna panel.
The company said that it can vary signals in both horizontal and vertical directions, successfully expanding the communications area.
With these developments, components can now be fitted on a single 13 cm2 printed circuit board, instead of two or more antenna panels required with conventional technology. This will enable the deployment of compact base stations and high-speed 5G communications in locations where many people gather, such as around train stations and in stadiums.
The development of 5G, which uses the millimeter wave band to secure a wide frequency band, is being carried out globally but while 5G can provide high-speed, high-capacity communications in excess of 10 Gbps, its radio waves are very one-directional and blocked by obstacles. As result, the use of a method called small cells, where base stations are deployed every few meters, is anticipated.
Commercialisation will require compact equipment that can be easily installed in any location.
5G base stations make use of a technology called beam-forming, which controls the phase of signals emitted from the multiple antenna elements on the antenna panel and concentrates the radio waves in the desired direction. This divides and multiplexes beams, to handle simultaneous communications with multiple users.
To avoid radio wave interference during communications with multiple users, base stations have been configured to use a number of antenna panels corresponding to the number of concurrent users. To miniaturise the equipment so that it can be deployed anywhere, the best option is to provide multi-directional transmissions from a single antenna panel.
Fujitsu has developed a phased array chip using a technology that can regulate the phase of a signal propagated from an antenna element with accuracy of one degree or less and built into the panel one phased array chip per eight antenna elements.
The company also uses circuitry that detects the differences in phase between phased array chips, which enables highly accurate phase control for any size antenna panel that has between 64 and 256 antenna elements.
As a result, by holding the difference in undesired emissions intruding between one radio wave communicating with a device and another radio wave with another device to 20dB or more, it makes it possible for a single antenna panel to carry out high-capacity communications of 10 Gbps or more. Detecting the phase differences from the signals produced by each antenna element and controlling the phase with high accuracy to concentrate the signal in the desired direction, will result in more compact equipment capable of transmitting to four users simultaneously with just one antenna panel. The equipment propagates radio waves on two axes, including horizontal and vertical directions, enabling wide-area communications with users.
Fujitsu has confirmed that a single antenna panel can deliver high-speed transmissions of 2.5 Gbps per person, for a total of 10 Gbps, and carry out beam multiplexing in four directions. By using this antenna panel, it will be possible to build small, energy efficient 5G base stations.
