IrDAIn 1993 the Infrared Data Association (IrDA) was founded to establish a common standard for infrared data communication. In 1994 the IrDA 1.0 standard was published which allowed a maximum data communication rate of 115 kBit/s. Because of this low data rate, the IrDA group announced IrDA 1.1 (Fast Infrared) in 1995 and VFIR (Very Fast Infrared) in 1999. IrDA 1.1 offers a data rate of 4 MBit/s and VFIR even of 16 MBit. Infrared (IR) communication is a popular and cheap way to transmit data without cables and wires. However, there is quite a difference between IR communication and radio-based communication. IR communication is based on infrared light, which needs a direct line of sight between the sender and the receiver. Due to the fact that the daylight contains parts of the infrared spectrum IR communication can be interrupted or blocked. While radio-based transmissions can permeate objects like walls, doors or clothes, IR transmissions are entirely blocked by such objects. The IR communication range is limited to a few meters whereas the radio-based communication ranges, generally, are higher (e.g. radio based WLAN with 100mW transmission power is limited to 100 meters). The limited communication range and the need for a direct line of sight between sender and receiver offers more privacy than radio-based networks. IR-based communication that is performed within a few meters is hard to intercept from outside. All modern operating systems support the IrDA standard and many mobile devices offer infrared ports. The IrDA standard is based on two substandards: IrDA Data: This substandard is responsible for data transmissions over infrared connections. IrDA Control: This substandard defines how input devices like keyboards, mice or joysticks can send control information over an infrared connection.Fig. 8 shows the IrDA protocol stack. At the bottom of the stack there is the infrared bit transport layer, which manages the encoding of data bits in infrared signals. The IrLAP layer (Infrared Link Access Protocol) is responsible for a reliable connection between sender and receiver. While the IrLAP layer supports only a single reliable channel, the IrLMP layer (Infrared Link Management Protocol) can manage multiple logical channels on a single physical connection. The IAS layer (Information Access Service) allows the discovery of services that are offered by other devices.The other protocol layers are optional and not necessarily implemented within every IrDA device. The Tiny TP layer (Tiny Transport Protocol) provides the possibility to transmit bigger messages through segmentation. IrLAN layer (Infrared Local Area Network) offers a bridge for connecting to a LAN. IrOBEX (Infrared Object Exchange Protocol) enables the exchange of complex messages such as v-cards, which is a protocol for the exchange of business cards. IrCOMM emulates a standard serial communication, which enables applications to communicate through a serial port.

SpecificationsIrPHYThe mandatory IrPHY (Infrared Physical Layer Specification) is the physical layer of the IrDA specifications. It comprises optical link definitions, modulation, coding, cyclic redundancy check (CRC) and the framer. Different data rates use different modulation/coding schemes:Some important characteristics are:Range: standard: 1 m; low power to low power: 0.2 m; standard to low power: 0.3 m, The 10 GigaIR also define new usage models that supports higher link distances up to several meters.Angle: minimum cone 15Speed: 2.4 kbit/s to 1 Gbit/sModulation: baseband, no carrierInfrared windowWavelength: 850900 nmThe frame size depends on the data rate mostly and varies between 64 byte and 64 kbyte. Additionally bigger blocks of data can be transferred by sending multiple frames consecutively. This can be adjusted with a parameter called Window Size (1127). Finally data blocks up to 8 Mbyte can be sent at once. Combined with a low bit error rate of generally