ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering (IJARCSEE) Volume 5, Issue 8, August 2016

Optical Wireless Transmitting Communications Based Satellite Orbit to Orbit Communication Systems Enhancement with EDFA Amplifiers Ahmed Nabih Zaki Rashed1* , Abd El–Naser A. Mohamed2, Hamdy A. Sharshar3, and Ehab Salah El-dien4

1,2,3,4

Electronics and Electrical Communications Engineering Department Faculty of Electronic Engineering, Menouf 32951, Menoufia University, EGYPT Abstract— This paper has demonstrated the effect of adding EDFA to satellite wireless optical communication system transmitter, also, demonstrated the effect of the change of length and characteristics of EDFA, telescope aperture length and input power in expanding the length of communication between two satellites in deferent orbits, then enhancing the output by using low pass filter. Optiwave 7 simulator was used to simulate the transmitter and receiver output. Modulation format used was NRZ (Non return to zero), the results was to compare the output of the receiver with different distance lengths between the satellites. As will as the output parameters such as BER, output power, Gain and the eye diagram was measured in the paper. Index Terms— EDFA, NRZ, Pumping power, Satellite orbit, and NRZ modulation format.

I. INTRODUCTION The optical wireless communication systems had taken evolved steps recent years because of the advantage of using light as a communication carrier and the free space as a wave guide. The advantages of such communication system are high capacity of information travelling between transmitter and receiver, lower bit error rate (BER) and agility of communication. The main losses in outer space are due to distance [1], other losses due to pink noise or cosmic rays are not studied in this paper. In satellite communication the satellites are placed in orbits around the earth named Low Earth Orbit (LEO) with altitude of 100 km to 5,000 km. Medium Earth Orbit (MEO) is from 10,000 km to 20,000 km as well as Geosynchronous Orbit (GEO) which has 36,000 km altitude from Earth. In free space optics there are four application groups they are: a. directed LOS, b. Non directed LOS, c. Diffuse and d. Tracked. Most satellite communications are using tracked application group in which satellites are passing signals between them and act as repeaters for each other to allow transmission over long distances [2]. But due to the complexity and cost of such approach the need of optical amplifiers appears to make the optical signals amplified optically without conversion and reduces the need of tracked satellites as repeaters. There are different types of optical amplifiers like Semiconductor Optical Amplifiers (SOA), rare earth element Erbium doped fiber amplifiers (EDFA) and RAMAN amplifiers [3]. EDFA is the most commercially used optical fiber amplifier and also it offers many merits [4]. The saturation effects in conjunction with the non-uniform gain spectrum of EDFAs lead to reduction of the optical signal to noise ratio and increase the signal power levels to acceptable values in the systems [5]. There are three optical pumping techniques [6] for EDFA namely co-pumping, counterpumping and bidirectional pumping [7],[8]. the change of the quality factor (Q) and bit error rate (BER) can be monitored with change of the input power, length and

forward pumping of the EDFA, eye diagram [9] will showing the ratio of (BER) and Q factor . II. SYSTEM STRUCTURE A communication system can be designed works in outer space with transmitter and receiver components to achieve a distance of 5000 Km which is the minimum distances between satellite orbits. Basic models has been demonstrated and investigated in [10] and [11] for inter satellite communication system, it was proved that as the input power increase the communication quality factor (Q) increases and (BER) increases, the maximum distance reached in [10] is 5000km with input power of 10dBm to 20dBm and input bit rate form (0.008 Gbps to 8 Gbps), also, the enhancement of communication output power when using optical amplifier at the transmitter and filter at the receiver. It was shown that minimum (BER) was achieved when using Bessel filter at the receiver rather than Gaussian filter [11]. II. 1. TRANSMITTER COMPONENTS: The transmitter part consists of: i) Pseudo-Random Bit Sequence Generator [12]: Generates a Pseudo Random Binary Sequence (PRBS) according to different operation modes. The bit sequence is designed to approximate the characteristics of random data. The output of the generator is ( bits/Sec, we are going to use in our paper a static value of 10Gbit/Sec. ii) NRZ Pulse Generator [12]: Generates a Non Return to Zero (NRZ) coded signal. According to the parameter Rectangle shape, this model can produce pulses with different edge shapes: Exponential, rectangle, Gaussian, leaner or sine. The sample rate used is Hz. iii) Continues Wave laser diode [12]: Generates a continuous wave (CW) optical signal, operates at 193.1 THz (or 1553 nm), input power (0.1, 0.15, and 0.2 Watt). iv) EDFA [12]: Designs Er-doped fiber amplifiers by considering numerical solutions of the rate and the propagation equations under stationary conditions. The model includes amplified spontaneous emission (ASE) as observed in the amplifier Erbium Doped Fiber. However, this module allows you to select forward and/or backward pump, as well as the pump power values. Parameters are given as from optiwave help files: Table(1) EDFA parameters Name and description Default value Unit Core radius 2.2 µm Er doping radius 2.2 µm Er metastable life time 10 ms Numerical aperture 0.24 -

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ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering (IJARCSEE) Volume 5, Issue 8, August 2016 between them diameter of apertures will be investigated for Er ion density (15cm and 20cm). Loss at 1550 nm 0.1 dB/cm II. 2. RECEIVER COMPONENTS: Loss at 980 nm 0.15 dB/cm vii) Photo detector APD [12]: Filter with a square cosine roll off Length of Er doped 5 to 10 m frequency transfer function. It detects the optical photons fiber and converts them into electrical pulses. The incoming optical signal and noise bins are filtered by an ideal rectangle Table(2) Pumping configuration filter to reduce the number of samples in the electrical signal. The new sample rate is defined by the parameter Sample Name and description Value unit rate. You can define the center frequency, or it can be Forward pump power 1000, 1500 mW calculated automatically by centering the filter at the optical and 2000 channel with maximum power. Backward pump power 0 mW If the noise calculation type in Numerical: Optical noise bins Forward pump 980 nm are converted to Gaussian noise inside of the signal wavelength bandwidth. The combined optical field is then converted to Backward pump 980 nm optical power. If the option Numerical - Convert Noise Bins wavelength is selected, the output noise and signal are combined. This v) Mach-Zehnder Modulator [12]: Simulates a Mach-Zehnder means that you cannot see the separate contributions of the modulator using an analytical model. The Mach-Zehnder noise. However, if you select Numerical only, the signal and modulator is an intensity modulator based on an noise are separated and you can select the different interferometric principle. It consists of two 3 dB couplers contributions of the noise. which are connected by two waveguides of equal length. Byviii) Low Pass Bessel Filter [12]: Filter with a Bessel frequency means of an electro-optic effect, an externally applied transfer function cutoff frequency (0.6 and 0.75 of bit rate). voltage can be used to vary the refractive indices in theix) 3R Regenerator [12]: This component regenerates an waveguide branches. The different paths can lead to electrical signal. It generates the original bit sequence, and a constructive and destructive interference at the output, modulated electrical signal to be used for BER analysis. It is depending on the applied voltage. Then the output intensity a subsystem based on the Data Recovery component and a can be modulated according to the voltage, using in this NRZ Pulse Generator. By using the 3R Regenerator, there is setup extinction ratio 30 dB. no need for connections between the transmitter and the vi) OWC Channel [12]: This component models an optical BER Analyzer. This is especially important for WDM wireless communication (OWC) channel. It is a subsystem systems, where you have with multiple transmitters, of two telescopes and the wireless communication channel receivers and BER Analyzers.

Figure (1) Model of system design as in optiwave 7 simulator input signal power, amount of erbium doping and pumping x) Eye diagram analyzer [10]: An eye diagram is generated on wavelength [3]. an oscilloscope using the data signal applied to the II. 3. 1 CO-PUMPING (FORWARD PUMPING): oscilloscope’s vertical input and a separate trigger signal is In this technique the two signals (pump and input) propagate applied to its trigger input. Ideally, the trigger signal is a in the same trend inside the optical fiber and they are repetitive waveform at the clock rate of the data, although collected using either pump co-coupler or wavelength the data signal itself can also be used as a trigger signal in selective coupler (WSC). Inside the optical fiber, at the input noncritical applications. of the amplifier pump energy is transferred to signal and at the output of it amplified signal is received. II.3 EDFA PUMPING CONFIGURATION II. 3.2 COUNTER-PUMPING (BACKWARD PUMPING): The EDFA consists of three basic components: length of This technique allows the pump and the input signals to erbium doped fiber, pump laser and Wavelength selective propagate within the fiber in opposite direction to each coupler to combine the signal and pump wavelengths the other. For amplification, the direction of both signals is not optimum fiber length used depends upon the pump power, important and they can travel in any trend.

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ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering (IJARCSEE) Volume 5, Issue 8, August 2016 II. 3.3 BIDIRECTIONAL PUMPING: Here both signals input and pump travel in single direction but there are inside the fiber two pump signals that are traveled. One of the two pumps travels in the same trend as the input signal and the other pump signal travels in the opposite direction of the input signal.

IV. SIMULATION RESULTS AND PERFORMANCE ANALYSIS: The effect of using different pumping configuration of EDFA Which are (forward pumping), (backward pumping) and bidirectional pumping can be compared and achieve the optimum configuration to maximize the transmission of signal, for modulation formats NRZ. The following simulation parameters shown to achieve this goal as shown in the following Table:

Table (3) system operating parameters Operating parameters Signal Input power Signal wavelength Frequency spacing Distance between Tx and Rx EDFA length Forward and backward Pumping wavelength Pumping power Aperture diameters Cutoff frequency

Value 0.1, 0.15, 0.2 W 1553 nm 0.5 nm 5000,10000 km 5, 10 m 980, 1480 nm 1,15, 2 W 15cm , 20cm 0.75, 0.60 of bit rate (br)

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.1 W 5000 km 5m 1000 mW 20cm 0.75*BR

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.1 W 10000 km 5m 1000 mW 20cm 0.60*BR

Case ( 1 )

Case ( 2 )

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ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering (IJARCSEE) Volume 5, Issue 8, August 2016

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.1 W 5000 km 10m 1000 mW 20cm 0.75*BR

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.15 W 5000 km 5m 1500 mW 15cm 0.75*BR

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.15 W 5000 km 5m 1500 mW 20cm 0.60*BR

Case ( 3 )

Case ( 4 )

Case ( 5 )

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ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering (IJARCSEE) Volume 5, Issue 8, August 2016

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.15 W 10000 km 5m 1500 mW 20cm 0.60*BR

Case ( 6 )

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ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering (IJARCSEE) Volume 5, Issue 8, August 2016

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.15 W 10000 km 15m 1500 mW 20cm 0.60*BR

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.2 W 5000 km 5m 2000 mW 20cm 0.60*BR

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.2 W 10000 km 5m 2000 mW 20cm 0.60*BR

Case (7)

Case (8)

Case (9)

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ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering (IJARCSEE) Volume 5, Issue 8, August 2016

Operating parameters Signal Input power Distance EDFA length Pumping power Aperture diameters Cutoff frequency

Value 0.2 W 10000 km 15m 2000 mW 20cm 0.60*BR

Case (10)

V. EVALUATING SYSTEM PERFORMANCE: As shown in the different cases illustrated above: i) In case (1) the input power was adjusted to (0.1W) and a change for the distance either (5000KM ) between transmitter and receiver telescopes, and the EDFA length was adjusted to (5m) the forward pumping power was used and adjusted to (1000mW ), other pumping powers ware set to zero, the result was fair good as in this case the eye diagram shows, the quality factor (Q) was (23.9) and bit error rate (BER) was (1.62x these values was measured with transmitter and receiver aperture diameter (20cm). ii) In case (2) distance between transmitter and receiver was increased to (10000km) the transmission was obviously degraded and quality factor (Q) was (7.6) and (BER) was (1.4x ), it was used the same system parameters in case (1) unless the cutoff frequency of the receiver filter was decreased from (75% of input bit rate) to (0.60% of input bit rate) to enhance output power by increasing selectivity of output frequency. iii) In case (3) the parameters were as same as case (1) but the change was made to the EDFA length was set to (10m), the output (Q) factor was (24) and BER was (2.06x ). iv) In Cases (4) changes had been made to input power which was set to (0.15W) and EDFA forward pumping power to (1500mW), distance between transmitter and receiver telescopes was 5000km, and EDFA length was (5m), also, the optical telescopes apertures were set to 15cm and the filter cutoff frequency at the receiver was 0.75 of the bite rate (10GB) the (Q) factor were equal to (12.79) and the BER was equal to (8.2x . v) Cases (5) the parameters was as same as case (4), but the change was in telescopes apertures (was set to (20cm)) and cutoff frequency in the filter at the receiver were set to (60% of input bit rate), the (Q) factor was (35.6) and BER was (2.8x .

vi)

In case (6) same parameters where used in case (5), but the distance was increased to 10000km, and the results was for (Q) factor was (11.11) and the BER was (5.4x . vii) In case (7) same parameters of case (6) were used, but a change in EDFA length were made the length was increased from (5m) to (15m), the results was for (Q) factor (11.14) and the BER was (3.8x . viii) Case (8) input power has been increased to (0.2W), EDFA pump power was set to (2000mW), EDFA length (5m), telescope apertures (20cm), filter cutoff frequency at the receiver (60%)of input bit rate), distance between transmitter and receiver was (5000km), the Q factor was (43.9) and BER was (0). ix) In case (9) the parameters were the same as in case (8) but distance had been increased to (10000km), the Q factor was (14.40) and BER was (2.28x ). x) In case (10) the parameters were set as case (9) but the change was in EDFA length which was set to (15m), the Q factor was (14.47) and BER was (8.63x ). IV. CONCLUSION In a summary, the quality factor which is related to the ratio of signal to noise ratio at the receiver is enhancing and increasing as the input power increases, also the (Q) factor increases with the increase of forward pumping power of the EDFA, Also, it was noticed that it was enhanced by increasing the apertures of the telescope diameters and decreasing the output cutoff frequency i.e. increasing filter selectivity. As well as the (Q) factor decreases with the increase of distance between the transmitter and receiver. In conjunction with this, the bit error rate (BER) which is the ratio of bits detected at the receiver to the bits transmitted, it was noticed also that Q factor and BER was not noticeably changed if the EDFA length was decreased. It is observed that (BER) increased if the distance between transmitter and receiver increases. REFERENCES [1] AIDA HASFIZA BINTI HASHIM "MODELING INTERSATELLITE OPTICAL WIRELESS

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ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering (IJARCSEE) Volume 5, Issue 8, August 2016 COMMUNICATION SYSTEM" 8-May-2009 PH. D. Thesis. [2] Bikram Beri, Neel Kamal "WDM BASED FSO LINK OPTIMIZING FOR 180KM USING BESSEL FILTER" IJRET eISSN: 2319-1163 pISSN: 2321-7308 Volume 03 Issue: 03 Mar-2014. [3] Ahmed Nabih Zaki Rashed, Abd El–Naser A. Mohamed, Mohammed S. Tabbour and Shimaa ElMeadawy 4 Different Pumping Categories of Erbium Doped Fiber Amplifiers Performance Signature With Both Wide Multiplexing and Modulation Techniques International Journal of Science, Engineering and Technology Research (IJSETR), Volume 5, Issue 3, March 2016. [4] Ramandeep Kaur Reg. "Performance Analysis of Hybrid Optical Amplifiers for multichannel WDM systems" No- 800961014. [5] A. Dhokar and S. D. Deshmukh, “Design and Performance analysis of Dynamic EDFA,” IOSR J. Eng., vol. 5, no. 7, pp. 23–33, Jul. 2015. [6] B. A. Hamida, S. M. Azooz, A. A. Jasim, T. Eltaif, H. Ahmad, S. Khan, and S. W. Harun, “Flat-gain wideband erbium doped fiber amplifier by combining two difference doped fibers,” J. Eur. Opt. Soc. Rapid Publ., vol. 10, no. 15015, pp. 1-5, Mar. 2015. [7] S. Singh and R. S. Kaler, “Performance optimization of EDFA – Raman hybrid optical amplifier using genetic algorithm,” Opt. Laser Technol., vol. 68, pp. 89–95, 2015. [8] M. S. Preeti Singh, “Comparative Analysis of EDFA based 32 channels WDM system for bidirectional and counter pumping techniques,” International Journal of Emerging Technologies in Computational and Applied Sciences, vol. 9, no. 1, pp. 66-70, June-August 2014. [9] Tektronix, “Anatomy of an Eye Diagram”. [10] K. Singh and Dr. M. S. Bhamrah " Investigations of Transmitted Power in Inter satellite Optical Wireless Communication" (IJCSITS), ISSN: 2249-9555 Vol. 2, No.3, June 2012. [11] B. Beri1, N. Kamal "WDM BASED FSO LINK OPTIMIZING FOR 180KM USING BESSEL FILTER" eISSN: 2319-1163 | pISSN: 2321-7308 [12] Optiwave corporation "optiamplifier 7.0 component library" 2007.

in linear or nonlinear passive or active in optical networks. His interesting research mainly focuses on transmission capacity, a data rate product and long transmission distances of passive and active optical communication networks, wireless communication, radio over fiber communication systems, and optical network security and management. He has published many high scientific research papers in high quality and technical international journals in the field of advanced communication systems, optoelectronic devices, and passive optical access communication networks. His areas of interest and experience in optical communication systems, advanced optical communication networks, wireless optical access networks, analog communication systems, optical filters and Sensors, digital communication systems, optoelectronics devices, and advanced material science, network management systems, multimedia data base, network security, encryption and optical access computing systems. As well as he is editorial board member in high academic scientific International research Journals. Moreover he is a reviewer member and editorial board member in high impact scientific research international journals in the field of electronics, electrical communication systems, optoelectronics, information technology and advanced optical communication systems and networks. His published paper under the title "High reliability optical interconnections for short range applications in high speed optical communication systems" has achieved most popular download articles in Optics and Laser Technology Journal, Elsevier Publisher in year 2013.

Author’s Profile Assoc. Prof. Dr. Ahmed Nabih Zaki Rashed was born in Menouf city, Menoufia State, Egypt country in 23 July, 1976. Received the B.Sc., M.Sc., Ph.D. and Assoc. Prof. scientific degrees in the Electronics and Electrical Communications Engineering Department from Faculty of Electronic Engineering, Menoufia University in 1999, 2005, and 2010, 2016 respectively. Currently, his job carrier is a scientific lecturer in Electronics and Electrical Communications Engineering Department, Faculty of Electronic Engineering, Menoufia university, Menouf. Postal Menouf city code: 32951, EGYPT. His scientific master science thesis has focused on polymer fibers in optical access communication systems. Moreover his scientific Ph. D. thesis has focused on recent applications

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