SoftBank and Toshiba Digital Solutions introduced Toshiba Digital Solutions’ Quantum Key Distribution (QKD) system into SoftBank’s optical wireless communication test environment and successfully demonstrated the operation of QKD combining optical fiber and optical wireless.
By combining optical wireless communication with quantum key distribution in addition to conventional optical fiber, QKD can be introduced at low cost and in a short period of time, leading to the expansion of QKD secure networks in urban areas. 
　　
By applying principles based on quantum mechanics to communication, QKD generates a common encryption key for both the data sender and receiver, and the information used to generate the common key is transmitted using photons (particles of light). Transmitted on the . Conventional QKD requires the use of optical fibers to connect locations in urban areas. Therefore, the introduction of QKD may be hindered at locations where it is difficult to install optical fibers, such as between buildings or between buildings across public roads, or locations where it takes a long time to install optical fibers.
SoftBank and Toshiba Digital Solutions conducted a demonstration experiment to solve this problem by adding optical wireless to the conventional QKD configuration.
In the future, QKD will be available in a short period of time without the need to install new optical fiber by installing and utilizing optical wireless communications on the rooftops of buildings.