The current IrDA Physical Layer was revised to Ver. 1.4 in 2001, and has been established up to a 16Mbps transfer rate, referred to as "VFIR"
•Optical wireless communication using infrared light with a wavelength between 850 and 900nm
| •Communication distance |
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In general, the standards approximate a communication distance of 1m. However, taking into consideration the life of batteries for portable terminal equipment, a "Low Power Standard" was recently issued, defining a communication distance of 20cm.
Low Power 20cm
Standard 100cm
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| •Communication range |
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In order to perform communications using infrared light, the communication area must be restricted. Communication is possible within the range of a 30º circular cone with respect to the axis of communication. However, according to the actual standard, the communication distance is defined by stipulating the relationship between the strength of the transmitted light (emissive power) and the reception sensitivity.
Each of the standard values is illustrated below. |
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| •Communication speed |
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The communication speed is defined as follows for each of the standards.
All of these standards are prescribed with backward compatibility.
The standards are defined such that communication is first performed at 9.6kbps for third party device confirmation.
SIR : 2.4k, 9.6k, 19.2k, 38.4k, 57.6k, 115.2kbps
MIR : 0.576, 1.152Mbps
FIR : 4Mbps
VFIR : 16Mbps
UFIR : 100Mbps(Standards under formulation) |
| •Communication method |
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Half-duplex
When information is being transmitted, it cannot be simultaneously received.
However, two-way communication is possible by alternately repeating transmission and reception.
Modulation method |
SIR,MIR (<1.152Mbps) RZI modulation
SIR and MIR use a modulation and demodulation method called the "RZI" method shown in the figure below. |
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FIR (4Mbps) 4PPM modulation
FIR uses a modulation and demodulation method called the "4PPM" method shown in the figure below. |
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| VFIR (16Mbps) HHH(1,13)CODE |
In order to enable IrDA infrared communication, it is necessary to satisfy not only the physical standards defined by IrPHY, but also the software requirements.
The IrDA standards are hierarchical such that physical standards are ranked low, standards for data linking are ranked above physical standards, and application standards are positioned above data link standards.
IrDA communication defines software standards up to the following fundamental data link protocols so that communication is possible for any set in which an IrDA module is mounted:
・IrLAP (IrDA Link Access Protocol)
・IrLMP (IrDA Link Management Protocol)
"IrLAP" is a standard for realizing intercommunication between all types of equipment using physical communication media based on half-duplex serial infrared light.
In order to transfer data with certainty, it is necessary to not simply transmit and receive data itself, but rather to regulate the confirmation of the physical connection with the other party as well as detect and correct data transfer errors.
Examples of the main IrDA standards and applications are described below.
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IrPHY IrDA Physical Layer
Hardware standards for infrared communication used for physical connections.
These standards regulate the infrared light specifications, communication distance, angle, speed, data modulation method, and pulse width for IrDA communication. Guidelines for resistance against external factors such as optical noise are also described.
IrLAP IrDA Link Access Protocol
Standards for the data link level in the communications protocol.
These standards search for third party equipment then determine the transfer rate as well as the data and window sizes.
A half-duplex method based on HDLC frames is used.
IrLMP IrDA Link Management Protocol
Management protocol for efficiently performing communications in which IrLAP is used for various upper layer levels.
These are standards for connection diversification/station information in which logical connections are performed so that multiple applications can be communicated simultaneously without interference.
Tiny TP IrDA Transport Protocol
Standards for flow control
Flow is controlled by managing buffers for each logical connection point.
Transmission data is divided and reception data is assembled such that data exceeding the data size of the data link level can be handled.
IrCOMM Infrared Communication Protocol
Application protocol for serial communication.
This protocol emulates RS232C/parallel.
IrOBEX Infrared Object Exchange Protocol
Standards for transferring objects that operate in the IrDA protocol.
The attributes of objects are unified using headers, enabling the transfer of objects between all types of equipment.
IrTran-P Infrared Transfer Protocol
Image communication protocol for use in infrared communications.
UPF is used as the format for image files.
IrMC Infrared Mobile Communication
Definition of the object exchange function in mobile communications terminals.
In order to transfer information such as address widths, calendars, e-mail, or memos, the IrOBEX protocol is used to regulate the format of objects.
IrFM Infrared Financial Messaging
Application protocol for electronic payment using IrDA.
IrLAN Infraed LAN
Application protocol for determining infrared LAN connections.
IrSC Infrared Simple Connect
Application protocol for efficiently transferring large data or images.
3.5MB)
Uses