scholarly journals Modulation Techniques of Free Space Optics using Various Link Ranges

2019 ◽  
Vol 9 (2) ◽  
pp. 2952-2955
Keyword(s):  
Free Space ◽  
Free Space Optics ◽  
Free Space Optical ◽  
Optical Links ◽  
Space Optics ◽  
Data Rates ◽  
Modulation Techniques ◽  
Efficient Communication ◽  
Link Budget ◽  
Attenuation Values

Free space optics is the present trend, which enables the communication to achieve the expected data rates for the increasing user demands. The utility of FSO in free space medium enables higher data rates than the conventional microwave links for efficient communication. Several researchers have performed the analysis of free space optics by use of different modulation techniques and optimization of the link budget in free space optical links. In this work, CW laser transmitting source ranging to 10dB of output level, link ranges of 500, 1000 and 1500 mts with attenuation values of 0.2, 0.7 and 0.9 dB/Km respectively are considered. The analysis of free space optics is carried out by using various modulation techniques such as ASK, PSK, FSK, MZ, EA, Dual Drive MZ and it is observed that Dual Drive MZ modulation performs well when compared with the other modulation techniques.

scholarly journals A Review On FSO By Using Different Modulation Techniques

2018 ◽  
Vol 7 (3.8) ◽  
pp. 136
Author(s):  
Rajan Miglani ◽  
Sachal Charak ◽  
Sandeep Kumar Arora ◽  
Mahedi Masud
Keyword(s):  
Free Space ◽  
Atmospheric Condition ◽  
Free Space Optics ◽  
Space Optics ◽  
Rf Communication ◽  
Modulation Techniques ◽  
Efficient Communication ◽  
Atmospheric Channel ◽  
Better Than

Now a days as we are seeing that the free space optics is one of the emerging technology used for the replacement of the radio frequency wireless communication, due to their advantages over it like cost, speed, bandwidth, minimum error as well as efficient communication. The quality of services provided by the FSO is far better than the RF communication network. The free space optics is unlicensed band which make it less costly than the licensed band technology. As the atmospheric channel is used for transmission the effects of atmospheric condition effects the communication. In this paper we try to discuss all the modulation schemes which help to improve the performances of the optic system. 

scholarly journals The Role and Challenges of Free-space Optical Systems

2014 ◽  
Vol 35 (4) ◽  
Author(s):  
Sushank Chaudhary ◽  
Angela Amphawan
Keyword(s):  
Free Space ◽  
Satellite Communications ◽  
Radio Networks ◽  
Optical Systems ◽  
Free Space Optics ◽  
Free Space Optical ◽  
Optical Carrier ◽  
High Data ◽  
Space Optics ◽  
Data Rates

AbstractComplementing wireless radio networks with free-space optics (FSO) achieves high data rates by modulating radio subcarriers over an optical carrier without expensive optical fiber cabling, enabling a pervasive platform for reaching underserved areas. In this paper, we review the main features of FSO for terrestrial and inter-satellite communications. Simulations of 1 Gbps data transmission through FSO links in both terrestrial and inter-satellite communications have been investigated to highlight potential atmospheric challenges in FSO.

Review on Wavelength Division Multiplexing Free Space Optics

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
S. Magidi ◽  
A. Jabeena
Keyword(s):  
Wavelength Division Multiplexing ◽  
Free Space ◽  
Access Network ◽  
Research Direction ◽  
Hybrid Network ◽  
Free Space Optics ◽  
Wavelength Division ◽  
Space Optics ◽  
Current State ◽  
Data Rates

AbstractWavelength division multiplexing-based free space optics (WDM FSO) has emerged as a potential communication network candidate for last-mile access among other applications. FSO has received much attention in the last few years as a complement as well as an alternative to radio frequency-based communication due to spectrum crisis among other reasons. On the other hand, WDM has been considered as one of the next-generation optical access network candidates for bandwidth efficiency and increased data rates. A hybrid network of these two technologies thus has emerged as another research direction. In this article, we present the background, progress and the current state of WDM FSO.

Mitigation of Atmospheric Turbulences Using Mode Division Multiplexing based on Decision Feedback Equalizer for Free Space Optics

2020 ◽  
Vol 41 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Abdullah Almogahed ◽  
Angela Amphawan ◽  
Yousef Fazea
Keyword(s):  
Free Space ◽  
Minimum Mean Square Error ◽  
Decision Feedback ◽  
Free Space Optics ◽  
Decision Feedback Equalizer ◽  
Free Space Optical ◽  
Space Optics ◽  
Link Distance ◽  
Mode Division Multiplexing ◽  
Simulation Results

AbstractIn mode division multiplexing (MDM) free space optical (FSO) communication system, the atmospheric turbulences such as fog, rain, and haze cause adverse effects on system performance. This paper investigates the mitigation of atmospheric turbulences of FSO using MDM and decision feedback equalizer (DFE) with minimum mean square error (MMSE) algorithm. The implementation of the MMSE algorithm is used to optimize both the feedforward and the feedback filter coefficients of DFE. The proposed system comprises three parallel 2.5Gbit/s channels using Hermite–Gaussian modes. A data rate of 7.5Gbit/s over 40 m, 800 m, 1400 m, and 2km under medium fog, rain, haze, and clear weather, respectively, has been achieved. In addition, it is noticed that the link distance is reduced while increasing the attenuation. The simulation results revealed that a DFE improves the performance MDM FSO system while maintaining high throughput and desired low bit error rate.

scholarly journals Performance Evaluation of Log-normal And Negative Exponential Channel Modeling Using Various Modulation Techniques in OFDM-FSO Communication

2005 ◽  
Vol 4 (2) ◽  
pp. 639-647
Author(s):  
Nitin Shankar Singh ◽  
Gurpartap Singh
Keyword(s):  
Phase Shift ◽  
Bit Error Rate ◽  
Error Rate ◽  
Free Space ◽  
Free Space Optics ◽  
Phase Shift Keying ◽  
Space Optics ◽  
Modulation Techniques ◽  
Shift Keying ◽  
Negative Exponential

Free Space Optics (FSO) is one of the emerging technology which is thoroughly being popular and is basically using optical signals for the communication. The paper evaluates the bit error rate performance of the Free space Optics (FSO) system. To design a high performance communication link for the atmospheric FSO channel, it is of great importance to characterize the channel with proper model. The performance of the highly efficient, high data rate system is limited by the certain constraints like scintillation effects and atmospheric turbulence. The FSO communication system using Orthogonal Frequency Division Multiplexing (OFDM) technique which is known for its increased robustness against frequency selective fading, narrow-band interference and high channel efficiency. The performance of the modulation techniques- Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK) and 8-PSK are studied in the Lognormal and Negative Exponential channel. The obtained results are the comparative study of Bit Error Rate (BER) vs. Signal to Noise Ratio (SNR), which is quite useful for analyse the system performance with different channel models for various modulation techniques.

scholarly journals Review on Free Space Optics

2013 ◽  
Vol 8 (1) ◽  
pp. 734-742 ◽  
Author(s):  
Er. Rajeev Thakur ◽  
Er. Sukhbir Singh ◽  
Er. Abhishek Sharma
Keyword(s):  
Free Space ◽  
High Speed ◽  
Free Space Optics ◽  
High Data ◽  
Space Optics ◽  
Free Spectrum ◽  
Data Rates ◽  
High Bandwidth ◽  
Bottle Neck ◽  
High Data Rates

Present era demands high bandwidth with high data rates especially for internet. For high data rates requires high speed transmission medium like optical fiber. To overcome the bottle neck of last mile communication free space optics has emerged as a better option for radio engineers. Using Infrared beams provides license free spectrum, high bandwidth with maximum data rates. In this paper different aspects for utilizing an FSO link are reviewed showing there advantages and disadvantages. 

scholarly journals Analysis of Rain Effects on Terrestrial Free Space Optics based on Data Measured in Tropical Climate

2012 ◽  
Vol 12 (5) ◽  
Author(s):  
Suriza Ahmad Zabidi ◽  
Md. Rafiqul Islam ◽  
Wajdi Al-Khateeb ◽  
Ahmed Wathik Naji
Keyword(s):  
Fiber Optics ◽  
Free Space ◽  
Prediction Models ◽  
Tropical Climate ◽  
Rain Attenuation ◽  
Free Space Optics ◽  
Tropical Region ◽  
Communication Link ◽  
Free Space Optical ◽  
Space Optics

Free Space Optics (FSO) shows a great alternative as the solution for last mile problem where fiber optics is unavailable due to deployment time and cost constraint.  However, the feasibility of using FSO system as communication link very much depends on local weather.  Since tropical region experiences heavy rainfall, rain with high intensity is expected to affect the FSO link severely. Few prediction models have been proposed by ITU-R based on France and Japan’s measurement. This paper has compared  rain attenuation predicted by  models and  data measured in Malaysia over Free Space Optical links for one year period. Prediction models are clearly unable to predict attenuation measured in tropical climate. ABSTRAK: Wayarles optik menjadi alternatif sebagai satu penyelesaian kepada masalah kesesakan terutama diakhir sesuatu talian dimana ianya tidak dapat diselesaikan dengan menggunakan gentian fiber akibat daripada kekangan masa pemasangan dan masalah kewangan.  Walaubagaimanapun, kejayaan untuk menggunakan wayarless optic ini amat bergantung kepada keadaan cuaca di sesuatu tempat.  Di rantau tropika  hujan lebat sentiasa dialami, oleh itu hujan dengan kepadatan tinggi adalah dijangkakan lebih memberi kesan kepada talian wayarles optic ini. Beberapa model yang telah dicadangkan oleh ITU-R berlandaskan kepada pengumpulan data yang dibuat di Perancis dan Jepun.  Kertas kajian ini akan membandingkan antara model-model yang telah digunapakai dengan data yang dikumpulkan di Malaysia selama setahun.  Jelasnya model yang telah digunapakai tidak dapat digunakan secara berkesan di rantau tropika.KEYWORDS: free space optics; rainfall rate; rain attenuation

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