IrDA layered model
The IrDA layer model is a layer model specified by the Infrared Data Association (IrDA) for communication via infrared links. This IrDA layer model is supported by a mandatory and an optional protocol set. The general protocol set consists of the Physical Signalling Layer Protocol( IrPHY), the Link Access Protocol( IrLAP), the Link Management Protocol( IrLMP) and the Information Access Service( IAS).
The physical parameters of the infrared light and the modulation are defined on the physical layer. Bidirectional transmission over a distance of at least one meter is ensured. In a special low- power version, 20 cm to 30 cm is guaranteed. The maximum data transmission rateand range depend on the implementation. The lowest data rate version is Serial Infrared( SIR), which achieves data rates between 9.6 kbit/s and 115.2 kbit/s at a 30 degree beam angle. Medium Infrared( MIR) Medium Infrared has moderate data rates between 0. 576 Mbps and 1.152 Mbps. The next fastest versions are Fast Infrared( FIR) at 4 Mbit/s and Very Fast Infrared( VFIR) at 16 Mbit/s. Ultra Fast Infrared( UFIR) with 96 Mbit/s and Giga Infrared( GIR) with 512 Mbit/s and 1 Gbit/s were then developed. CRC procedures ensure protection of the transmitted data packets. Depending on the data transmission rates, the Cyclic Redundancy Checksum (CRC) works with 16, 32 or even 64 bits.
The link layer uses a procedure to support the detection of the addressed device and ensures the point-to-point connection between two devices at the selected transmission rate. At the link layer, multiplexing is supported by the IrDA Link Management Protocol (IrLMP). In addition, multiple channels can be operated on an IrLAP connection.
Optional protocols include IrDA Tiny Transport Protocol( IrTTP), which supports flow control on the IrLMP link with optional segmentation and reassembly.
IrCOMM, IrDA Communications, provides parallel and serial port emulation for communications applications, printers and modems. IrOBEX IrDA Object Exchange, supports object exchange services similar to HTTP. IrDA Lite supports methods to reduce the size of IrDA code while maintaining compatibility of the full implementation. IrTran-P is a protocol for capturing and exchanging images from digital cameras. IrMC, IrDA Mobile Communication, forms the specification for mobile exchange of information in mobile telephony and other mobile applications such as phone book, calendar and message data. IrLAN, IrDA Local Area Network, describes a protocol for wireless connection to local networks using infrared technology.