International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
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Enhancing FSO link performance in turbulent environment using Fiber bundle based receiver Prakash Chandra jat1, Dr Pranay joshi2, Dr Sunil joshi3 1M.Tech.
Student, Department of Electronics and Communication, CTAE, Udaipur, Rajasthan, India 2Assistant Professor, Madhav University, Abu Road, Sirohi, Rajasthan, India 3Professor & Head, Department of Electronics and Communication, CTAE, Udaipur, Rajasthan, India ---------------------------------------------------------------------***--------------------------------------------------------------------Abstract - Free space optical (FSO) communication uses infrared (IR) or visible wavelengths to broadcast high-speed data wirelessly through the atmospheric turbulence channel. The performance of FSO communications is mainly dependent on the random atmospheric turbulence. The presence of turbulence, create received power fluctuation of the laser beam between the transmitter and receiver lead to performance degradation of the communication link. To mitigate this effect, The fiber bundle based receiver design is simulated in OptiSystem which consists of a hexagonal array of fiber to capture light. These fiber allow more power to be collected that would be less to a standard receiver due to turbulence. The simulation results show that some reduction in bit error rate (BER) by introducing fiber bundle based receiver in FSO system and increase in Q- factor.
FSO is that contrary to wireless RF communications, no license is required for transmission in FSO [2]. Thirdly, in some rural areas where current wireless RF technology and inaccessible such as hilly terrains and areas far from radio base stations, FSO technology may be integrated with existing mobile cellular radio technology to promote more rapid deployment of a universal wireless architecture [3] as well as mobile environment also [4]. Although (FSO) guarantees high-speed data rates, there are some challenges such as scintillations and atmospheric turbulences which need to be addressed in order to improve the performance of the FSO link. In this paper, we have simulated the performance of Fiber bundle based receiver design under the effect of scintillation by varying channel’s refractive index structure parameter (CR2) for different link range. Qfactor and received powers are analysed over different link ranges.
Key Words: Free space optical (FSO), bit error rate (BER), Q-factor, Gamma-Gamma Channel Model, Atmospheric Turbulence, Fiber bundle based receiver.
Section 2 denotes basics of FSO link. Section 3 describes the mathematical analysis of atmospheric turbulence channel. Section 4 introduces fiber bundle based receiver design and sections 5 and 6 give simulation results and conclusion to new receiver design.
1. INTRODUCTION The last decade has seen tremendous development in the growth of broadband access networks around the globe. The interest for faster data rates in the evolution towards 5G wireless systems has brought rapid innovation in new optical technologies to accommodate the rise in a number of subscribers. The growth of Internet traffic together with an increase in the number and range of new services have placed pressure on legacy low-speed optical networks. This calls for effective modern optical communication systems that support high transmission rates and enhanced coverage. It has been very hard for the International Telecom Unions (ITU) to allocate the limited radio frequency (RF) Spectrum among the operators due to the explosive growth of subscribers every year. The ITU has reported 7.5 billion cellular subscribers in 2013 [1]. FSO is a promising technology for increasing broadband penetration, enabling transmission of multiple signals via a high-speed optical carrier without expensive optical fiber cabling or licensing for radio frequency (RF) solutions. In FSO links, transportation of signals is carried out through the atmosphere instead of an expensive optical fiber, thus eliminating the need for costly cabling of fiber optics in sparsely-populated rural areas. Another main advantage of
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2. FSO System The basic concept of FSO communication is similar to RF communications in terms of data generation, modulation, transmission, propagation through the unguided channel, reception, and recovery of data. A generic FSO communication system consists of three main blocks; an optical transmitter, an optical receiver separated by an atmospheric channel as described in Fig1. An FSO link requires a line-of-sight communication (LOS) without any obstacles between the transmitter and receiver.
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