International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
www.irjet.net
Evaluation and Analysis of Modified Return to Zero Pulse Format (MDRZ) Over FSO in Comparison to Non Return to Zero and Return to Zero Linecodings Manpreet kaur1, Er.Amandeep kaur brar2 1M.tech
student 2Assistant professor Punjabi university Patiala ---------------------------------------------------------------------***--------------------------------------------------------------------Abstract - Free space optical communication is very popular nowadays, due its low cost and high speed applications. In this work, a 16 channel wavelength division multiplexed system is incorporated in FSO link at ultra dense frequency difference of 50 GHz. We successfully covered the transmission distance of 5000 km at 10 Gbps in this work without any amplification. Diverse advanced modulation and linecodings such as modified return to zero, Return to zero and non-return to zero are investigate in terms of Q factor at varied link lengths and data rates. Result revealed the MDRZ is best modulation format as compared to NRZ and RZ and recommended to use in future FSO systems.
like aperture averaging, diversity or amplification of signal uses optical amplifiers. Also, WDM technique puts drastic impact owing to the potential to pack large number of channels in one optical medium such as the fiber optic reliant network and by reducing the spacing between channels by using one FSO link. Numerous researches has been reported on FSO systems Till now, many research works has been reported to generate spectrum slices [6-8], to boost weak signal with amplifiers [9], beam divergence size [10] scintillation noise compensation [11]. Although, reported techniques are good but either supports less data rate or more complexity.
Key Words: Free space optical (FSO), Q factor, BER, WDM, MDRZ
In this research article, a high speed WDM-FSO system is presented using advanced modulation format and linecodings are investigated for distances and data rates. WDM channel with 16 transmitters at 50 GHz dense frequency spacing are considered for data rate 20 Gbps over 5 km.
1. INTRODUCTION Optical wireless communication is the engaging technology in the field of communication and provides us with the fastest transmission than microwave and RF technology [1]. Optical wireless communication is the special kind of optical communication that uses wireless medium to transmit the information to the destination. It basically uses the same concept as the laser communication technology FSO stands for free space optics where the medium of communication is optical wireless therefore FSO is named or recognized as Free space optical communication [2]. Free space uses line of sight technology that seeks to satisfy the need of higher band-width over short range. In this transmission, communication takes place through the atmosphere in place of glass fiber and transmission of these light pulses are in the narrow beam form [3]. Cost of FSO link is low and moreover it is simple such that easy to install it and no authentication like license approval is required to use FSO [4]. An important factor in FSO, is time and money saving because there is no need to lay fibers by digging the streets [5]. But the issue in FSO is, limited communication to short distances because of environmental interactions [6]. Due to atmospheric turbulences in the FSO channel or medium, the quality of signal degrades because FSO links are highly dependable on atmospheric conditions [7]. The atmospheric conditions like fog, smoke, rain and scintillation are the major cause for the reducing level of FSO performance [8]. To make the performance better of FSO, numerous methods are reported Š 2017, IRJET
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2. SYSTEM SETUP The purpose of this work is to investigate the system performance using diverse modulation formats such as MDRZ, MRZ and RZ. FSO transmission, named as the light based wireless transmission as well as are low cost, wideband and have persuasive profitable benefits, through the impending potential to cater data pace, cheap, and offers unregulated spectrum. In this wireless optical transmission, sender of data and recipient communicates with each other via air as shown in Figure 1.
Fig-1: shows the setup of 16-channel WDM-FSO link. ISO 9001:2008 Certified Journal
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