scholarly journals Blind Detection for Serial Relays in Free Space Optical Communication Systems

2018 ◽  
Vol 8 (11) ◽  
pp. 2074 ◽  
Author(s):  
Mohamed Elbawab ◽  
Mohamed Abaza ◽  
Moustafa H. Aly
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Free Space ◽  
Communication Systems ◽  
Signal To Noise Ratio ◽  
Blind Detection ◽  
Free Space Optical ◽  
Observation Window ◽  
Space Optical Communication ◽  
Average Bit Error Rate

Free-space optical (FSO) communication systems have attracted considerable research interest owing to its high transmission rates and its efficient solution for the last mile problem. Atmospheric turbulence degrades the performance of FSO systems. To estimate the received signal, Channel State Information (CSI) or blind detection is used. The blind detection estimates the received signal without the need for pilot signals which reduce the throughput and increase the complexity of the signal. In this paper, we have proposed a relay technique which utilizes the blind detection method for FSO communications. This proposed technique would improve the performance of the FSO system compared to the direct link method. It is observed that the proposed method achieves a signal-to-noise ratio (SNR) close to the SNR reported by CSI method maintaining the same average bit error rate, provided that only a small observation window is employed. Moreover, Monte Carlo simulation results are further provided to demonstrate the validity of the derived approximated average bit error rate.

Analytical Evaluation of Bit Error Rate Performance of a Free-Space Optical Communication System with Receive Diversity Impaired by Pointing Error

2015 ◽  
Vol 36 (2) ◽  
Author(s):  
A. K. M. Nazrul Islam ◽  
S. P. Majumder
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Free Space ◽  
Signal To Noise Ratio ◽  
Free Space Optical ◽  
Pointing Error ◽  
Receive Diversity ◽  
Multiple Receivers ◽  
Space Optical Communication ◽  
Performance Results

AbstractAnalysis is carried out to evaluate the conditional bit error rate conditioned on a given value of pointing error for a Free Space Optical (FSO) link with multiple receivers using Equal Gain Combining (EGC). The probability density function (pdf) of output signal to noise ratio (SNR) is also derived in presence of pointing error with EGC. The average BER of a SISO and SIMO FSO links are analytically evaluated by averaging the conditional BER over the pdf of the output SNR. The BER performance results are evaluated for several values of pointing jitter parameters and number of IM/DD receivers. The results show that, the FSO system suffers significant power penalty due to pointing error and can be reduced by increasing in the number of receivers at a given value of pointing error. The improvement of receiver sensitivity over SISO is about 4 dB and 9 dB when the number of photodetector is 2 and 4 at a BER of 10

scholarly journals Calculations of Signal to Noise Ratio (SNR) for Free Space Optical Communication Systems

2008 ◽  
Vol 5 (1) ◽  
pp. 95-100
Author(s):  
Baghdad Science Journal
Keyword(s):  
Optical Communication ◽  
Free Space ◽  
Communication Systems ◽  
Signal To Noise Ratio ◽  
Full Duplex ◽  
Free Space Optical ◽  
Signal To Noise ◽  
Optical Communication Systems ◽  
Space Optical Communication ◽  
Noise Ratio

In this paper, we calculate and measure the SNR theoretically and experimental for digital full duplex optical communication systems for different ranges in free space, the system consists of transmitter and receiver in each side. The semiconductor laser (pointer) was used as a carrier wave in free space with the specification is 5mW power and 650nm wavelength. The type of optical detector was used a PIN with area 1mm2 and responsively 0.4A/W for this wavelength. The results show a high quality optical communication system for different range from (300-1300)m with different bit rat (60-140)kbit/sec is achieved with best values of the signal to noise ratio (SNR).

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