Implementation of the Unidirectional and Bidirectional Optical Wireless Communication System
Date Issued
2010
Date
2010
Author(s)
Wang, Chin-Min
Abstract
The optical wireless communication system is a newly risen communication system. Both high transmission capacity and low equipment cost are main advantages of the optical wireless communication system, and result in an ideal solution for the last mile problem. Because the transmission of light is directional, we can only connect both transmitter and receiver when the line of sight is available. On the other hand, the light power will decrease when transmitting light in the atmosphere. The power attenuation can reach over 100dB/km if the visibility is extremely low. The main factors caused power attenuation are: absorption, scattering and turbulence. The scattering effect is the most significant effect of them. At the wavelength of 1.55μm, we can use Mie scattering theory to analyze the attenuation effect.
This thesis composed by three major parts: The first one is to analyze power attenuation by Mie scattering theory. The second part introduces a 8-channel unidirectional optical wireless communication system with 785 meters and each channel rate up to 10Gb/s. From the experiment result we can found that in bad weather condition, such as raining, decrease the bit error rate performance , but the result is still acceptable. The last part shows a 4-channel bidirectional optical wireless communication system with 785 meters and each channel rate up to 10Gb/s and measure the bit error rate. The bit error rate performance of the bidirectional system is almost the same as the unidirectional system.
Because of the high transmission rate and low hardware cost, the optical wireless communication system is a suitable solution for the last mile problem. Even more, this system is easy to setup, so it is a good method for emergency communication situation. We believe that optical wireless communication system is a high potential wireless communication technology.
Subjects
optical wireless
free space optical
wavelength division multiplexing
bidirectional transmission
wireless communication
Type
thesis
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