Impact of Both Nonzero Boresight and Jitter Pointing Error on Outage Capacity of FSO Communication Systems Over Strong Turbulence

In free space optical (FSO) communication systems limited by atmospheric turbulence, the use of non-adaptive decision thresholds to determine the transmitted bits results in bit error rate (BER) floors at high BER values in all turbulence regimes. Practically implementing an adaptive decision threshold that can properly track the fluctuations due to atmospheric turbulence is challenging, therefore, devising ways of optimising the non-adaptive decision threshold used by FSO designers is necessary. In this paper, the investigation of gain saturated pre-amplified FSO communication systems using non-adaptive decision thresholds in the presence of atmospheric turbulence, pointing errors (PEs), geometric spread (GS) and amplified spontaneous emission noise is carried out by applying analytical methods and Monte Carlo (MC) simulation techniques. System performance is carried out for various turbulence regimes, normalised beam widths, normalised PE standard deviations and small signal gains using fixed gain and gain saturated optical amplifiers (OAs). Results obtained show that in the presence of atmospheric turbulence, PE and GS, optimal BER performances are obtained with OA input powers higher than the internal saturation power of the OA. Also, by using high gain OAs and varying the decision threshold level, acceptable BER performances can be obtained in strong turbulence regimes with a non-adaptive decision threshold.

Download Full-text

Performance analysis of dual-hop optical wireless communication systems over k-distribution turbulence channel with pointing error

10.1063/1.4984158 ◽

2017 ◽

Author(s):

Neha Mishra ◽

Sriram Kumar D. ◽

Pranav Kumar Jha

Keyword(s):

Performance Analysis ◽

Wireless Communication ◽

Communication Systems ◽

Wireless Communication Systems ◽

Optical Wireless Communication ◽

Optical Wireless ◽

Pointing Error

Download Full-text

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

International Journal of Electrical and Computer Engineering (IJECE) ◽

10.11591/ijece.v8i5.pp3722-3731 ◽

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.

Download Full-text

Impact of pointing error on SISO/MISO drones swarm-based free space optical system in weak turbulence regime

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v23.i2.pp918-926 ◽

2021 ◽

Vol 23 (2) ◽

pp. 918

Author(s):

Abdullah Jameel Mahdi ◽

Wamidh Jalil Mazher ◽

Osman Nuri Ucan

Keyword(s):

Free Space ◽

Communication Systems ◽

High Performance ◽

Signal To Noise Ratio ◽

Weather Conditions ◽

Free Space Optical ◽

Single Input Single Output ◽

Pointing Error ◽

Single Output ◽

Link Distance

Applying the drone-based free space optical (FSO) technology is recent in communication systems. The FSO technology hashigh-security features dueto narrow beamwidth, insusceptible to interferences, free license and landline connection is not appropriate. However, these advantages face many obstacles that affect the system's performance, such as random weather conditions and misalignment. The pointing error Hpis one of the critical factors of the channel gain H. The related parameters of the Hp factor: the pointing error angles θr and the path length Z, were manipulated to extract the applicable values at various receiver diameter values. The proposed system has two topologies: single input single output (SISO) and multiple input single output (MISO), flying in weak atmospheric turbulence. The simulation was done using MATLAB software 2020. The average bit error rate (ABER) for the system versus signal-to-noise ratio (SNR) were verified and analyzed. The results showed that at θr=10−3rad, Z increased in the range 10~100m for each one-centimeter increase of DR. At θr=10−2rad, the applicable Z was nearly 10% of the link distance Z when θr=10−3rad was applied. Consequently, an increase in θr must correspond decrease in Z and vice versa to maintain the system at high performance.

Download Full-text