Performance of 1-D and 2-D OCDMA systems in presence of atmospheric turbulence and various weather conditions

2017 ◽  
Vol 11 (9) ◽  
pp. 1416-1422 ◽  
Author(s):  
Ajay Yadav ◽  
Subrat Kar ◽  
Virander Kumar Jain
Keyword(s):  
Atmospheric Turbulence ◽  
Weather Conditions

Performance Analysis of FSO Links in Turbulent Atmosphere

2020 ◽  
pp. 100-156
Author(s):  
Banibrata Bag ◽  
Akinchan Das ◽  
Aniruddha Chandra ◽  
Rastislav Róka
Keyword(s):  
Atmospheric Turbulence ◽  
Communication Systems ◽  
Weather Conditions ◽  
Free Space Optical ◽  
Wireless Optical Communication ◽  
Adverse Weather Conditions ◽  
Adverse Weather ◽  
Optical Communication Systems ◽  
Active Research ◽  
Atmospheric Channel

The free-space optical communications technology is emerging as an attractive substitute to RF communications. It can satisfy the current demands for higher bandwidth to the customer. Atmospheric turbulence is a major obstacle in wireless optical communication systems. To fully utilize the terabit capacity of FSO system, it has to overcome various challenges offered by the heterogeneous nature of the atmospheric channel. Currently, FSO communication through atmospheric turbulence under adverse weather conditions is an active research topic. A lot of studies and experiments have been carried out on the effect of attenuation due to atmospheric turbulence; but still, much more research is necessary for fulfilling the current demands and commercial needs for implementing this technology successfully. This chapter discussed the various limitations of FSO system which are faced during data transmission through the atmospheric channel and various ways to improve the performance regarding BER, outage probability, and channel capacity.

Capacity of Optical Wireless System over Log-Normal Channels with Spatial Diversity in Presence of Atmospheric Losses

2018 ◽  
Vol 39 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Rahul Kaushik ◽  
Vineet Khandelwal ◽  
R.C. Jain
Keyword(s):  
Atmospheric Turbulence ◽  
Channel Capacity ◽  
Random Variable ◽  
Weather Conditions ◽  
Spatial Diversity ◽  
Closed Form Expression ◽  
Atmospheric Conditions ◽  
Optical Wireless ◽  
Diversity Techniques ◽  
Log Normal

Abstract In this paper, average channel capacity of optical wireless communication system is evaluated under the combined effect of geometrical loss, attenuation due to weather conditions and weak atmospheric turbulence using a simple closed form expression. Fading induced due to atmospheric turbulence is modeled by log-normal distribution. Considering the fact that the sum of log-normal random variables can be well approximated by another log-normal random variable, the proposed expression has been utilized to compute the channel capacity for spatial diversity reception employing maximum ratio combining and equal gain combining over uncorrelated turbulence-induced fading conditions. It is shown that spatial diversity is an effective technique to mitigate the impairments caused by various atmospheric conditions such as haze, rain and fog. The quantitative improvement in channel capacity achieved by using diversity techniques is investigated and compared. Accuracy of the results is validated with exact results computed using Monte Carlo simulation.

scholarly journals Performance Investigation of OFDM-FSO System under Diverse Weather Conditions of Bangladesh

2018 ◽  
Vol 8 (5) ◽  
pp. 3722
Author(s):  
Maliha Sultana ◽  
Agnila Barua ◽  
Jobaida Akhtar ◽  
Mohammad Istiaque Reja
Keyword(s):  
Atmospheric Turbulence ◽  
Communication Systems ◽  
Weather Conditions ◽  
Index Structure ◽  
Propagation Path ◽  
Free Space Optical ◽  
Atmospheric Attenuation ◽  
Suitable Alternative ◽  
Pointing Error ◽  
Free Spectrum

Free space optical (FSO) communication systems which are deployed for last mile access, being considered as a suitable alternative technology for optical fiber networks. It is one of the emerging technologies for broadband wireless connectivity which has also been receiving growing attention due to high data rate transmission capability with low installation cost and license free spectrum. However, the widespread use of FSO technology has been hampered by the randomly time varying characteristics of propagation path mainly due to atmospheric turbulence, sensitivity to diverse weather conditions and the nonlinear responsivity of laser diode. This paper presents the performance investigation of an OFDM-FSO system over atmospheric turbulence channels under diverse weather conditions of Bangladesh. The channel is modeled with gamma-gamma distribution using 16-QAM modulation format and 4×4 multiple transceiver FSO system. All possible challenges are imposed on the system performance such as atmospheric attenuation, turbulence, pointing error, geometric loss etc. The refractive index structure parameter and atmospheric attenuation coefficient for different weather conditions are calculated by using the data, collected from Bangladesh Meteorological Department. The acquired results can be fruitful for scheming, forecasting and assessing the OFDM-FSO system’s ability to transmit wireless services over turbulent FSO links under actual conditions of Bangladesh.

Performance Analysis of a STBC FDM FSO Communication System with Direct Detection Receiver under Turbulent Condition

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Bobby Barua ◽  
S. P. Majumder
Keyword(s):  
Atmospheric Turbulence ◽  
Channel Capacity ◽  
Communication System ◽  
Direct Detection ◽  
Weather Conditions ◽  
Optical Receiver ◽  
Communication Link ◽  
Link Distance ◽  
Receive Diversity ◽  
Turbulent Condition

AbstractWeather conditions are severely degraded the performance of FSO communication link. Atmospheric turbulence is one of the important weather conditions that degrade the performance even under clear sky condition. In this paper, we provide a noble analytical approach to evaluate the performance of STBC coded FDM FSO communication system with direct detection optical receiver under turbulent condition. Analysis is carried out to find the channel capacity of RF subcarrier modulation taking into consideration the effect of strong atmospheric turbulence which is modeled as gamma-gamma distribution and the probability density function of the conditional CNR, conditioned on a given turbulence-induced fading is derived considering equal gain receive diversity combining technique with direct detection optical receiver followed by RF synchronous demodulation. Results are evaluated numerically in terms of average CNR, BER and channel capacity for several system parameters like turbulence variance, link distance, data rate, etc.

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