Infrared Communication can be observed from many viewpoints. This paper is the merit of Infrared Communication observed from the viewpoint of "deployment place".

● Deployment Place : factory, hospital, school, department store, family restaurant, office

In factory there are many cases that the machine works under the control of remote controller and the machine was formerly connected to controller with cable. But the construction work of cable is complicated and the cable contains the danger. So radio wave method is introduced because of the convenience, but it contains the problem.

In factory many kinds of electromagnetic wave are generated from the spark of the electric welder and the motor of the crane. And the radio wave is used for the control of unattended forklift and the communication of workers. Effective radio wave will interfere with harmful electromagnetic wave and the interference will cause many troubles. Moreover radio wave is used for the communication between maintenance room and working room.

Infrared Communication is also useful for the communication method in such a wide area.

● Comparison of cable, radio wave and infrared

Now let's compare with cable, radio wave and infrared each other.

Item	Cable	Radio Wave	Infrared
Mobility	×	◎	○
Effective Speed	◎	△	◎
Signal Quality	◎	△	◎
Interference	◎	×	◎
Security	◎	△	◎
Electromagnetic Damage	◎	×	◎

◎: excellent  ○: good  △: inferior  ×: bad

• Cable is the most stable communication method except the portability.
• Radio Wave has the merit to be portable anywhere.
• Infrared is not suitable for the portability. But it is the communication method of the best safety for the security and is useful because it is not sensitive against the electromagnetic noise if the purpose and the deployment place are considered correctly.

When radio wave is reflected by wall, the signal error happens sometimes because of the interference of the reflected radio wave and the communication is interrupted because the signal fades due to the transmission distance. Signal speed is reduced because of the repeat transmission after the interruption. So the effective signal speed of Radio Wave is 5〜6Mbps in spite of the nominal signal speed 11Mbps. In the case of Infrared the effective signal speed is maintained 80〜90% of the nominal value. The signal speed is maximum when the receiver faces to the transmitter directly.

Comparison of effective signal speed (extracted from ASCII network PRO September 2000)

● Infrared Communication applied in such a place

Infrared is not so suitable for the portability as mobile telephone and is not convenient while walking outside. On the contrary Radio Wave is not stable for the communication quality and is difficult to transmit the important data. Infrared is the best for the mobile terminal in the finite space of the building.

Factory	Correct performance in the congested information and no influence of electromagnetic wave
Hospital	Read from / write in the chart the patient information while visiting the patients
School	Free layout of school room and no influence of the precision equipment in college laboratory
Department Store	Both direction transmission of sales information and floor information
Family Restaurant	Sum up of sales by the transmission of accept order data from portable terminal
Office	Mount in personal computer and portability from own seat to conference room

<schoolroom>	<HUB and node>
	In the communication world, radio wave interference, electromagnetic interruption and security are the important points. Infrared is high speed and inexpensive. We consider simply the layout and the purpose. Please tell us the idea about "Infrared Communication applied in such a place".