Optsim Example FTTH Application Note

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OptSim™ Application Note

FTTH System with Broadband PON AccessArchitecture

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OptSim™ Application Note: FTTH System with Broadband PON Access Architecture p. o! "



#$ample: FTTH System with Broadband PONaccess architecture.

Design and deployment activities for FTTH (fiber-to-the-home) and FTTP (fiber-to-the-premises) accessnetworks are on the rise and rapidly growing in order to support the increasing demands and delivery of

new multimedia services to the customer premises such as interactive video voice and high-speed internet!

There are many types of FTTH technologies" the most popular one is based on the concept of using a

passive fiber distribution network known as a passive optical network (P#$)! FTTH employing P#$access architecture is the accepted choice of delivery channel for triple-play services (voice video and

data) from service providers to the home and business users! Three ma%or P#$ technologies are currently

under consideration as the basis for FTTH deployments& 'roadband P#$ ('P#$) igabit P#$ (P#$)

and thernet P#$ (P#$)!

'roadband P#$ is the most mature and widely used among them to the date! 'P#$ is a set of standards

that specify the service capabilities and network protocols for broadband services over fiber access! *t is

specified by the *T+-T and published in the !,.!/ series of *T+-T recommendations!*n a P#$ the active optoelectronics are situated on either ends of the passive network! 0n optical line

termination (#1T) device is installed in the central office (2#) and an optical network termination (#$T)

device is installed on the other end in or near each home or business site! Fiber distribution is done using a

tree-and-branch architecture! 0 single fiber connected to the #1T can be split up to .3 times and connectedto multiple #$Ts!

Figure 1. Layout for FTTH BPON system.

OptSim™ Application Note: FTTH System with Broadband PON Access Architecture p. % o! "



2urrent simulation e/ample models a typical 'P#$ FTTH design with .3 subscribers and 34-km reach!

Figure 5 depicts the OptSim schematic for e/ample layout! The 2entral #ffice is connected through a 56-

km standard single-mode fiber to the first 7emote $ode with a 5&8 splitter! ach of the four outputs goes

through another 8!6-km fiber and then enters the 7emote $ode with a 5& splitter! #utputs from the 5&splitter are connected to eight end-users at the #$T though drop-off cables of length varying from 544 to

,44 feet!

Figure 2. Output spectrum from Central Office.

Figure 3. Signal constellation left! an" #$le%el logical signal rig&t! at 1'$()* enco"er.

The triple-play service is reali9ed as a combination of data voice and video signals! To optimi9e the bandwidth in 'P#$ the transmission through the optical fiber path employs the 2:D; techni<ue with

data and voice component transmitted at wavelengths in the range of 584-5644 nm and video within the

5664-56=4 nm range! The high-speed internet component is represented by a data link with 5!36 b>s

OptSim™ Application Note: FTTH System with Broadband PON Access Architecture p. & o! "



downstream bandwidth! The voice component can be represented as ?#*P service (voice over *P packet-

switched protocol) which is gaining popularity as an alternative to traditional P@T$ (public switched

telephone network) with P#T@ (plain old telephone service) at the customer end! The video component is

represented as a 5=-A0; subcarrier multiple/ed (@2;) system! 0ctually =8-A0; is more typicalmodulation scheme used to carry digital video>data stream in 7F channels but we used 5=-A0; for

simplicity! 0lso for simplicity purpose this simulation e/ample models only a downstream link with one

#$T unit attached! 0s an e/ercise the reader can add more #$T units and re-run the simulations!

Figure #. +ecei%e" eye "iagram for "ata signal

Figure ,. +ecei%e" eye "iagram for "ata signal

Figure 3 shows the signal spectrum output from #1T with data>voice signal at 5644 nm and video signal at

5664 nm! Figure . demonstrates 8-level logical signal and signal constellation plot for 5=-A0; encoder!

The signal from the central office travels though a 34-km long fiber distribution network and arrives atoptical network termination unit! The optical spectrum at the input to #$T is shown at Figure 8! Here the

OptSim™ Application Note: FTTH System with Broadband PON Access Architecture p. ' o! "



optical signal first demultiple/ed into data>voice and video components! The data component goes to the

optical receiver P*$! #ptical power meters inserted after transmitters and before receivers shows that total

attenuation from fiber spans and splitters is about 3, d' and input power to the receiver is about B36 d'm!

The receiver eye diagram for data signal is given at Figure 6! The video component of the received signalenters 5=-A0; decoder! Figure = shows 8-level logical signal and signal constellation plot at the received

side of 5=-A0; decoder! Figure C shows multi-level eye-pattern and electrical signal 7F waveform at 5=-

A0; decoder!

Figure '. Signal constellation left! an" #$le%el logical signal rig&t! at 1'$()* enco"er.

Figure -. ye$pattern left! an" output electrical signal rig&t! at 1'$()* enco"er.

*n conclusion the given e/ample allows user to study various performance characteristics and its

dependence of components characteristics and layouts specifics in physical layer design for 'P#$ FTTH

network!

OptSim™ Application Note: FTTH System with Broadband PON Access Architecture p. " o! "

Optsim Example FTTH Application Note

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