Difficulty of Laying Optic Fiber in the Mountains
Smartphones and tablets allow us to watch movies and video and download music on the go. But there is a problem associated with this: many people find that their data allowance is used up before they know it.
Wireless base stations that transmit data for audio and video streaming are generally linked to one another via optic fiber. Optic fiber consists of very thin strands of glass or clear plastic encased in an outer sheath. It provides an efficient means of transmitting light over long distances, and is extensively used in the infrastructure that powers the Internet. However optic fiber networks can be difficult to construct in dense urban areas where there is a high concentration of buildings and structures, as well as in remote mountainous areas separated by physical barriers such as valleys and rivers. A wireless alternative to optic fiber is required—one that allows base stations to be installed in outdoor locations.
Data-rich wireless transmission uses a wide frequency bandwidth. The millimeter wave band (30–300 GHz) is ideal, given the relative lack of competing wireless applications in this frequency range. However the extremely high frequencies pose considerable design challenges as they are very close to the operational limitations of CMOS* integrated circuits. One of the key challenges has been to design a transmitter-receiver frequency modulation system capable of converting wide-band signals to a millimeter wave format without significant loss of quality. Another problem is the high losses incurred in the connection between the antenna and the CMOS integrated circuit.
* Complementary metal oxide semiconductor, one of the structural components of LSI (large-scale integration). CMOS has minimal power consumption and allows more compact designs and tighter integration.
World-record 56 GB/s Transmission Speeds
Fujitsu Laboratories and the Tokyo Institute of Technology have successfully developed a high-speed wireless transmitter operating across a broad 72–100 GHz frequency range. The transmitter employs a CMOS wireless chip that delivers high-speed signal processing with minimal loss. The technology is packaged as a module.
The Tokyo Institute of Technology contributed two main components: a modulation system where the data signal is split in half and converted to different frequencies that are then recombined for transmission, allowing for wider bandwidth and lower losses; and a booster unit that enables transmission of millimeter-wave frequency-converted signal in the form of radio signals. Fujitsu’s contribution was a printed substrate using a specially modified wiring pattern to provide an interface between impedance matched* wave guides and the substrate over an extremely wide frequency range, while at the same time substantially reducing signal loss in the designated frequency range.
Data transmission tests were conducted between two modules in the laboratory at a separation of 10 cm. Losses between the wave guides and the substrate were recorded at under 10%, while transmission speeds of up to 56 GB per second were achieved. This is currently the fastest transmission speed in the world.
* Impedance matching refers to alignment of the input and output resistance at the sending end of an electrical signal transmission path.
Enjoy Excellent Reception up in the Mountains
With data speeds like this, you can enjoy uncompressed 8K video streaming in real time. This technology can be used to set up high-speed wireless transmission networks in environments where optic fiber networks are considered unfeasible, such as built-up urban areas and remote mountains separated by rivers. Mountains can finally be interconnected, and it will not be long before we can provide relay services to support real-time wireless video transmission of sporting events in high resolution.
Fujitsu and the Tokyo Institute of Technology will continue developing technology to improve communication security and service standards, with a view to commercialization of wireless trunk lines for transmission between base stations such as smartphones by around 2020.