FDD

FDD is an acronym that can refer to several different concepts depending on the context. The two most common meanings are Frequency Division Duplex, a method used in wireless communications, and Floppy Disk Drive, a data storage device used in personal computers in the late 20th century.

Frequency Division Duplex refers to a radio communication arrangement in which the uplink and downlink transmissions occur simultaneously but on separate frequency bands. This separation reduces interference and allows full-duplex operation, but it requires coordinated spectrum and duplex filters (duplexers). It is widely used in traditional cellular networks and fixed wireless systems, with coverage and efficiency dependent on spectrum availability and technology generation.

Floppy Disk Drive is a data storage device that reads and writes data on removable magnetic disks called floppy disks. Early 3.5- and 5.25-inch disks varied in capacity, from hundreds of kilobytes to about 1.44 megabytes on standard 3.5-inch disks. FDDs were common in personal computers from the 1980s through the 1990s, but have largely been supplanted by flash storage and optical media.

Other uses of the acronym exist in various fields, but Frequency Division Duplex and Floppy Disk Drive are the contexts most frequently encountered in technical and historical discussions.