imulation of fiber to the home triple play services at 2 Gbit/s using GE-PONrchitecture for 56 ONUs
eeksha Kochera, R.S. Kalera, Rajneesh Randhawab,∗
Electronics & Communication Engineering Department, Thapar University, Patiala 147004, IndiaPunjabi University, Patiala, India
r t i c l e i n f o
rticle history:eceived 27 September 2012ccepted 3 March 2013
a b s t r a c t
This paper evaluates and compares FTTH (Fiber To The Home) GEPON (Gigabit Ethernet Passive OpticalNetwork) link design for 56 subscribers at 20 km reach at 2 Gbps bit rate. A 1:56 splitter is used asa PON (Passive Optical Network) element which creates communication between a Central Office todifferent users and. A boosting amplifier is employed before fiber length which tends to decrease BER
eywords:NUONTTHTTP
and allows more users to accommodate. This architecture is investigated for different values of datarate from a CO (Central Office) to the PON in terms of BER (Bit Error Rate). The simulation work reportsBER of 4.5246e−009 at 2 Gbit/s systems for the case of 56 users and if we further increase data rate ofsystem say 5 Gbps, then we observe a sharp increase in BER. Similarly in the variation of BER with respectto transmission distance, we observe that BER shows an increase in its value as transmission distance
bps increases.
. Introduction
The next generation technology is required to be compatibleith today’s bandwidth needs and to also offer bandwidth ease
o support future growth based on network expansion and newpplication development. Since optical technology has proven toave large bandwidth capacity, it appears to be the proper choiceo solve the complexities of access networks [1]. Thus, several fiber-o-the-home (FTTH) or fiber-to-the-premises (FTTP) networks haveeen proposed to provide broadband services to the end user. FTTH
s simply the 100% deployment of optical fiber in today’s accessetworks [2]. However, access networks have three great require-ents; they must meet high reliability, performance, and be cost
fficient. Therefore, it is important to understand which of the pro-osed FTTH networks meet these requirements better.
To meet the low cost and reliability requirement, FTTH networksave employed passive optical components at the customerremises and therefore they are known with as Passive Opticaletworks (PON) [3]. PON’s have a tree topology in order to maxi-ize their coverage with minimum network splits, thus reducing
ptical power. Several architectures have been proposed of Timeivision Multiplexing PON (TDM-PON) provides Broadband PON
BPON) with downstream of 622 Mbps [4], Ethernet PON with.25 Gbps downstream, and Gigabit PON (GPON) with 2.5 Gbpsownstream. Gigabit-capable passive optical network (GPON) is
the basic technology to support the structure of the next-generationfiber to the home (FTTH) system and supports multi-speed rates,full services, high efficiency and other advantages, and considersthe suggestions of service providers at the same time [5]. GPON isregarded as one of the best choices for broadband access networkin the future.
The cost benefits have enabled increasing deployment of pas-sive optical network delivering fiber to the home. However, inmany cases, extended reach requires some form of amplification toovercome the additional losses [6]. In order to increase transmis-sion distance of a system, an amplifier is introduced somewherebetween the transmitter and the splitter. Analysis of the effective-ness of the amplifier can be determined by evaluating the Q factoror BER of the system.
Erik Weis et al. [7] reported a FTTH field trial with GPON(Gigabit-capable passive optical network) technology in the net-work of Deutsche Telekom in the region of the cities of Berlinand Potsdam. Focus of this trial was to gain practical experienceregarding GPON technology, fiber installation in existing ducts withmicro duct technology, fiber cabling in customer buildings andimpact on operational processes. Their main target was to obtainpractical deployment and operation experiences with fiber-basedaccess networks and to provide broadband access to a part of thecity formerly not servable by DSL (digital subscriber line) technol-ogy.
Bernard HL Lee et al. [8] investigated the performance of a novel2.5Gbps FTTH-PON Network architecture which employs a passiveoptical booster configuration for future user scaling. The passivebooster configuration used an NxN AWG and exploits its cyclical
Fig. 2. Simulation Setup for 56 users GEPON based FTTH architecture.
008 D. Kocher et al. / Op
outing table which was made possible by the device’s Free Spec-ral Range (FSR) property configuration for future user and servicescaling. The new configuration was compared with a conventionalccess network.
Junichi Kani et al. [9] proposed a novel and simply configuredroad-band optical access network that uses coherence multiple-ing (CM) and half-duplex bidirectional transmission. It allowedhe on-demand use of broad bandwidth on existing fiber-to-the-ome (FTTH) access lines. The study showed that the capacity ofxisting FTTH access lines that employ star couplers can be signif-cantly enhanced.
Till now we observe that the number of users used in FTTH sim-lations are maximum 32. Considering [7], we see that 1 OLT isonnected to a maximum of 10 users. Similarly in [8,9] an errorree transmission over a 25 km link with 32 optical splitting andith a 7-km 9-dB standard access line, 12 users at rate of 155 Mb/sas found to be acceptable.
This research work examines the FTTH with GEPON architectureor a bit rate of 2 Gbit/s using booster amplifier for 56 users andorrespondingly BER is determined for different number of usersike 48, 32, 64 etc. Simulation results show that up to 56 users, anptimized value of BER is obtained. Gigabit Ethernet provides theidirectional transmission at the data rate of 2 Gbps. The maxi-um transmission distance of GEPON is 20 km and splitting ratio
s of 1:56. To provide the longer distance transmission and moreplitting ratios we have used the booster amplifier. This system istilizing fifty six 2 Gbps signals By using this technique the per-ormance of the system can be improved. The proposed scheme isromising for future deployment of PON with high quality of serviceQoS).
. Simulation setup
To optimize the BER in PON, the transmission through the opti-al fiber path employs the CWDM (Coarse Wavelength Divisionultiplexing) technique with data/voice component transmitted
t wavelengths in the range of 1480–1500 nm, and video withinhe 1550–1560 nm range. Fig. 1 depicts the block diagram for sim-lation setup for GEPON architecture.
Fig. 2 shows the simulation setup for the system. CO OLT (Opti-al Line Terminal) block which is the transmitter block consistsf Data/VOIP and Video components. The Data/VOIP transmitter isodeled with pseudo-random data generator (PRBS), NRZ modu-
ator driver and direct-modulated laser.The video component is modeled as RF SCM (sub-currier multi-
lexed) link with only two tones (channels) for simplicity. RF videoransmitter consists of two Electrical Signal Generators, summernd direct-modulated laser as shown in Fig. 3.
ig. 1. Block diagram for simulation setup for 56 users GEPON based FTTH architec-ure.
Fig. 3. OLT components for GEPON based architecture.
Next, Data/Voice and Video signals are multiplexed at Multi-plexer and launched into 20-km fiber span. Before traveling overfiber, a booster amplifier is used to boost the incoming signal whichimproves BER. Amplifier is having a constant gain of 30 dB. Out-put from the fiber trunk goes through the 1:56 splitter and then toindividual users. User’s ONT consists of splitter and data and videoreceivers. Data receiver configured with optical filter, PIN receiver,and BER Tester. The video signal receiver consists of optical fil-ter, PIN receiver, electrical filters and measurement instrumentsto visualize to link’s optical spectrum, waveforms, eye diagrams,
etc. as shown in Fig. 4.
To convert the data and video again in the original form, weuse a high sensitivity receiver or detector which performs boththe function, the first one is to detect whether data or voice is
Fig. 4. ONT components for GEPON based architecture.
nd again converted in the form of the electrical signal. The samehenomena is repeated or done simultaneously for different userst the same time. To measure the spectrum of the voice and datat the user’s end we use spectrum analyzer. But as we know thatata is transmitted in the digital domain or also in the light pulseso in transmission on the fiber such type of noise also produced e.g.nter symbol interference, noise so in the effect of such things errorhould be occurred. So to measure the error we applied an instru-ent called BER Tester, as we know some standard also made to
ccept that type of error by ITU-T standard. Now at the end of theeceiver side every ONT has a particular receiver for both the recep-ion of the voice and the data. Before the reception a splitter is usedo differentiate the particular user.
Optical splitter component simulates an “Ideal” optical splitter.t works as a balanced splitter with the same attenuation on eachutput. Attenuation is set to a default value of 0 dB, so this compo-ent implements an ideal splitter without any insertion loss, i.e. aomponent that perfectly splits the input signals.
Photodiode considered as a PIN photodiode. The output cur-ent generated by the photo detection process depends on thenput optical power and on the dark current. Its parametersre 193.42 THz/1590 nm/1650 nm reference freq/wavelength, 0.80uantum efficiency, 0.99 A/W responsively and zero dark current.
. Results and discussions
GEPON works for transmission technology of the optical fiberccording to which optical fiber generates from the Central Officehich is terminated to the user premises for providing a higher
andwidth. As we know that we use optical splitter as a passiveevice, so on the basis of these factors some experimental resultsave been obtained. FTTH has separate channels for the data andhe video so it has two spectra one for the voice and one for the data.ata is transmitted at the wavelength of 1490 nm and the video is
ransmitted at the wavelength of 1550 nm. Both the wavelengthsre selected because these wavelengths window has certain advan-age i.e. it is low attenuation window. So each user has separater slightly different wavelength spectra for video and the data. Asumber of ONUs increases some errors have also occurred so BER
s calculated, a graph is showing the effect the number of users onhe BER.
Fig. 5 represents the frequency spectrum of received voice andata signal for user 1. These spectra are observed at the receiver
ide as data and video are modulated by NRZ modulator and thenransmitted over the optical fiber so optical medium also insertedome error in the form of noise.
ig. 5. Received voice and data signal frequency spectrum at 20 km for 2 Gbps dataate system.
Fig. 6. Received frequency spectrum of video signal at 20 km for 2 Gbps data ratesystem.
Table 1 shows the values of BER for different number of users inthis architecture when boosting amplifier is installed in path andit is shown that for 16 users with data rate of 2 Gbps we obtainedBER of 6.1073e−009 without amplifier and with amplifier the sameBER decreases to 4.1443e−013 for same specifications.
Similar to Fig. 5, we obtain received frequency spectrum of videosignal for user1 as shown in Figs. 6 and 7 shows the OLT outputoptical waveforms for data and video signal.
The data and video are modulated by NRZ modulator and thentransmitted over the optical fiber so optical medium also insertedsome error in the form of noise at the receiver side. From the abovediagram, it is clear that for the video transmission 1550 nm is mostsuitable while for the data transmission 1490 nm is most suitable. Inthe above architecture different users are separated by the opticalsplitter. Fig. 8 depicts the eye diagram for data and voice in case of56 users. Eye diagram shows the width and height of the eye open-ing. Thus the width and height of the eye opening is large whichmeans that reception of the signal is very much clear. The width ofeye opening defines the time interval over which received signalcan be sampled without interference and distortion. The height ofeye opening shows the noise margin of the signal.
Basically, we extended or increased the number of users using a
passive device named as optical splitter. This simulation describesthe relation between the users and BER, if we increase the number
Fig. 7. OLT output optical waveforms for data and video signal for 2 Gbps data ratesystem.
5010 D. Kocher et al. / Optik 124
Fig. 8. Data and voice signal output eye diagram of 56 users at 20 km for 2 Gbps datarate system.
Fig. 9. Comparison of system BER at various data rates at 20 km.
oF
bBe4a8t
Is
[
[
[
[
[
[
[
[
Fig. 10. Distance Vs BER for 2 Gbps data rate system.
f users then our data and voice distorted and become error full.ig. 9 represents the BER versus the users.
Here we see that if we increase data rate, BER increases sharplyut it accommodates less users and if we decrease the data rate,ER decreases and more number of users get Accommodated. Forxample for data rate of 1.25 Gbps at 56 users we have BER value.7992e−018, for 2 Gbps system BER of 4.5246e−009 for same usersnd then we observe a sudden increase in BER of 4.5046e−005 and.8212e−002 at data rate of 2.5 Gbps and 5 Gbps respectively. So
here is a trade-off between bit error rate and data rate of system.
Fig. 10 shows the variation of distance and BER for various users.t is seen that if we increase distance, Bit Error Rate increases veryharply.
[
(2013) 5007– 5010
For example, for 16 users at 20 km we receive BER value of4.1443e−013 and then for same users at distance of 50 km, BER of4.7512e−006. Similarly for 56 users, we obtain BER of 4.5246e−009and 3.1128e−002 at distance of 20 km and 50 km respectively. Thisproves that there is a tradeoff between number of users, distanceand BER.
4. Conclusion
This implementation simulated an optimized GE-PON basedFTTH access network to provide residential subscribers with tripleplay services. We described the requirements of GE-PON accessnetwork with considerations of services and PON specific layeredfunctions. To satisfy those requirements, we simulated an opti-mized architecture and describe the detailed functions of majorelements. Finally, we consider the major technical issues i.e. BERto realize the GEPON based FTTH access network. The results at2 Gbit/s system between the BER and different number of usersillustrate that as the number of users increases beyond 56 usersthe BER comes to unacceptable level and if further increase datarate of system say 5 Gbps, then we observe a sharp increase in BER.
FTTH is a driver for the development of advances optoelectronicstechnologies, and the great volume in production of optical mod-ules will also accelerate the reduction in cost. We described that byusing a boosting amplifier can decrease BER up to a certain extentand hence more users can be accommodated.
References
1] R. Randhawa, S. Singh, J.S. Sohal, R.S. Kaler, Wavelength converter using semi-conductoroptical amplifier Mach-Zehnder interferometer based on XPM at 40Gb/s forfuture transport networks, Fiber and Integrated Optics 28 (2) (2009)154–169.
2] Rajneesh Kaler, Pradeep Teotia, R.S. Kaler, Simulation of FTTH at 10 Gbit/s for 8OTU by GE-PON architecture, Optik 122 (2011) 1985–1989.
3] R.S. Kaler, T.S. Kamal, A.K. Sharma, Approximateand exact small signal anal-ysis for single-mode fiber near zero dispersionwavelength with higher orderdispersion, Fiber and Integrated Optics 21 (5) (2002) 391–415.
4] S. Singh, R.S. kaler, Simulationof DWDM signals using optimum span schemewith cascaded optimized semiconductoroptical amplifiers, Optik 118 (2) (2007)74–82.
5] S. Singh, R.S. Kaler, Alloptical wavelength converters based on cross phasemodulation in SOA-MZIconfiguration, Optik-International Journal for Light andElectron Optics 118 (8) (2007) 390–394.
6] S. Singh, R.S. Kaler, 1190 kmWDM transmission of 20× 10 Gb/s RZ-DPSK signalsusing cascaded in-linesemiconductor optical amplifier, International Conferenceon Optics &Optoelectronics (ICOL-05) (2005) 11–15.
7] Erik Weis, Rainer Holzl, Dirk Breuer, Christoph Lange, GPON FTTH trial-lessonslearned, in: SPIE-OSA-IEEE Asia Communications and Photonics, vol. 7633, 2009,6330J-1–6330J-7.
8] Sahrul Hilm, Bernard H.L. Lee, Kaharu din Dimyatt, Unlimited FTTH-PON scaling by exploiting the AWG free spectral range, in: IEEE 7th
Malaysia International Conference on Communication, vol. 1, 2005,pp. 491–495.
9] Jun-ichi Kani, Katsumi Iwatsuki, Noboru Takachio, Nobuo Fujii, A simple broad-band coherence multiplexed optical access network and its scalability, IEEE J.Light Wave Technol. 19 (April (4)) (2001) 456–464.
