IrDA

IrDA stands for Infrared Data Association, a consortium formed in the early 1990s to standardize infrared communications between consumer electronics. The IrDA specification defines a stack of protocols for short-range wireless data exchange, including the physical layer (IrPHY), the link layer (IrLAP and IrLMP), and higher-level data protocols. The standard supports multiple speed classes, commonly referred to as SIR (Serial Infrared), MIR (Medium Infrared), and FIR (Fast Infrared), with data rates ranging from a few kilobits per second to several megabits per second, depending on the class used. The physical layer uses near-infrared light in the 850-900 nanometer range and requires light emission from an infrared LED and detection by a photodiode.

Connections are typically short-range, usually a single device-to-device link, and generally require line-of-sight geometry; devices are connected by an infrared port or accessory adapter. The IrDA protocol stack handles device discovery, session establishment, data transfer, and error control, enabling simple file transfers, printing, synchronization, and other tasks between PCs, mobile devices, printers, and peripherals.

IrDA gained broad adoption in the late 1990s and early 2000s, especially in laptops, PDAs, and mobile phones, as a standard method for wireless data transfer before Bluetooth became prevalent. Following the success of Bluetooth and later Wi-Fi, IrDA usage declined in consumer devices, though some specialized equipment and older devices still include IrDA interfaces for compatibility.