This standard ARIB STD-91 specifies the radio equipment of radio station for UWB (Ultra-Wide Band) radio system defined in Article 4-4, Paragraph 2, Item 2 of the Regulations for Enforcement of the Radio Act.

The designated frequency bands are as follows:

　Indoor usage: 3.4GHz or above and below 4.8GHz, 7.25GHz or above and below

　　　　　　　　10.25GHz

　Outdoor usage: 7.587GHz or above and below 8.4GHz, 7.25GHz or above and

　　　　　　　　below 9GHz

UWB radio system enables such applications as short-range high-data-rate communication and precise distance measurement by spreading the electrical power over a wide bandwidth.

Made necessary revisions such as the expansion of the frequency bandwidth for the outdoor use, and the addition of the radiolocation use, corresponding to the development of the institutional framework by Ministry of Internal Affairs and Communications.

In addition, due to revisions of the major technical conditions, etc. of the wireless equipment, this revision was major and the version number was changed to 4.0.

Revisions corresponding to the development of the institutional framework by Ministry of Internal Affairs and Communications (MIC) to support the needs of using UWB radio systems outdoors, as in other countries.

Specifically, in addition to the conventional use of UWB radio systems indoors, the outdoor use is allowed at a part (7.587GHz or above, and below 8.4GHz) of the high band (7.25GHz or above, and below 10.25GHz). Although the technical requirements for outdoor usage are based on those for indoor usage, equivalent isotropic radiated power (EIRP) is required to allow for the use of smaller devices. The previous standard for indoor usage has been reorganized as Part 1, and the standard for outdoor usage has been added as Part 2.

Due to the significance of changes involving the reorganization of content structure to add technical requirements of radio equipment for outdoor usage, this revision is major and the version number is changed to 3.0.