The merit of Infrared Communication System is as follows.

1. Throughput is high though it is wireless.
2. It does not depend on operational software and the driver is not needed. And the replacement of driver is not also needed.
3. Security is high because leakage to the outside of a room is low.
4. Huge numbers of personal computer are connectable without interference by segment division because leakage to neighboring area is low.
5. Coexistence with radio wave sensitive equipment for example medical electronics is possible.

But the data about throughput of Infrared Communication System was only rarely reported. So the following two items were evaluated about 100Mbps Infrared LAN System.

Data was offered by Victor Company of Japan, Limited, one of the members of ICSA.

Item 1. Maximum performance of Infrared LAN System as transmission line : How high speed of the signal can be transmitted through Infrared LAN System?

Result 1. Maximum performance of Infrared LAN System as transmission line

Smart Bits made by Netcom System Co. was used for the evaluation.

Evaluation Result frame size : 1518Byte    (maximum frame length)    (including header part) from node to HUB 93.28Mbps from HUB to node 95.20Mbps Cable System 98.72Mbps

Evaluation result contains 18 Byte header part and FCS code and moreover upper-layer header. So this transfer rate is the maximum value as Ethernet signal and is different from the value of the real file transfer. This is the result under the best condition in both cases of Cable System and Infrared LAN System.

Item 2. Comparison with the performance of Cable System
: How high performance can be achieved in file transfer under the real working condition?

Result 2. Comparison with the performance of Cable System

What is the difference in file transfer under the real working condition?

4 personal computers were used in this evaluation. Measured time is compared each other after the file transfer direction is decided. The time was measured with 2 personal computers though the limit value will be possible to be measured when many computers are used but the operation is difficult.

Evaluation system is as follows. A pair of 2 personal computers are used in down mode.

Throughput measurement of Cable System

Throughput measurement of Infrared LAN System

Total throughput is shown in the following graph. The result of Infrared LAN System bears comparison with Cable System.

Characteristics of personal computer OS : Windows 2000 MTU value : 1500Byte RWIN : 16kByte Data sending PC : Pentium �V 800MHz Data receiving PC : Celeron 500MHz

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This evaluation set uses the simple shared HUB not the high performance switching HUB for the comparison because ceiling mounted HUB is connected to the main line in many case and the communication traffic has a tendency to concentrate in the port of the main line (Communication Link 1,2). In such a system the throughput is better when the shared HUB is used compared to the switching HUB.