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This slide shows introduction of this presentation.
We focused on two problems of OCDMA.
The first problem is the interference by the reflected light from the wall.
This problem occurs when the receiver is located near the wall in a room.
The reflected light from the wall causes delay distortion.
The delay distortion causes inter-symbol interference (ISI), which degrades
the bit error rate performance.
The second problem is the decrease in illumination due to the modulation method.
The major modulation methods of the OCDMA system are equal weight orthogonal (EWO)
modulation and pulse position modulation (PPM).
The EWO modulation can transmit only one bit per symbol, which becomes a problem
in terms of the speed of communication.
On the other hand, the PPM can improve the bit rate by dividing the symbol into multiple slots.
However, increasing the number of slots in the PPM-OCDMA means that
the LED emission time per symbol becomes shorter, which causes a decrease in the original
illumination brightness of the optical product.
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IEEE/ICACT20220102 Slide.02
[Big Slide]