CHAPTER 4 LINK POWER ESTIMATION FOR 10Gbps …shodhganga.inflibnet.ac.in/bitstream/10603/39358/9/09_chapter 4.pdf · 70 CHAPTER 4 LINK POWER ESTIMATION FOR 10Gbps GIGABIT ETHERNET

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CHAPTER 4

LINK POWER ESTIMATION FOR 10Gbps GIGABIT

ETHERNET PON (GPON) ARCHITECTURE

4.1 INTRODUCTION

Recently, a group of researchers has proposed the architecture for

extending the transmission rate from 1 Gbps to 10 Gbps (Optical Broadband

Working Group 2006). They adopted the burst mode operations in two ways.

The first is the asymmetric mode of operation with 10 Gbps as downstream

data and with 1Gbps as upstream data link. The second is the symmetric

10 Gbps data for both upstream and downstream. For economic feasibility

and to overcome the limitations of Wi- Fi and Wi-Max, research articles

point out that the FTTX technology with P2MP topology is optimal for

broadcast triple play services (data, voice and video) including IP based TV

using 10 Gbps GPON access service (Frank Effenberger et al 2007).

In this chapter, how DBA controlling is to be taken care by novel

link power budget of 10Gbps GPON downstream link with important fiber

optical network parameters has been considered. The analyses of GPON have

been measured for flexibility and scalability which provide 10 Gbps at low

cost for more than 64 users and up to 1024 end users. The innovative link

power estimation of 10 Gbps GPON modeling design has been considered at

RN component which is having M stage 1xN power splitters with optical

amplifiers to extend its scalability performance. Also analyses were made for

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extending GPON architecture to handle data from 1.25 Gbps to 10 Gbps

through simulation results.

4.2 EXISTING GPON ARCHITECTURE

Many types of GPON structure have been analyzed in literature

review. In the past half decade, most of GPON architecture attempted to

transmit 2.5 Gbps and 1.25 Gbps downstream and upstream respectively

except a few types demonstrated 10Gbps and above. The link length using

SMF has been considered from 20 km and maximum of 135 km with splitting

ratio 1x 4, 1x8 and 1x32 at RN (Davey et al 2006, Genay et al 2007). But the

power penalty is varied in all types by varying the splitting ratio in 10Gbps

GPON.

4.2.1 GPON standard and power penalty issues

The main characteristics of GPON based on FSAN group G.984,

ITU-T, in 2003 are (Henrique and da Silva 2005)

1. Physical reaches at least 20 km and up to 60 km

2. Symmetric link at 622Mb/s or 1.25Gbps, or

2.5 Gbps downstream with 1.25Gbps upstream

3. Multicast operation of PON needs security in protocol level

in downstream traffic.

Optical power budget using DFB laser source operating 1550nm at

0 dBm power is not sufficient at 16km distance located of SMF and

Multimode Fiber (MMF). MMF will suffer more loss in power gain which is

compensated by SOA. A CW laser source with minimum of 2 dBm power

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penalty to achieve the maximum gain during link power between OLT and

splitter- ONUs was considered. The 50/50 power splitting between upstream

and downstream which gives power loss is 7dB where fiber loss variations are

almost less than 4dB. Therefore, any practical PON system, power loss of

entire transmission between RN and ONUs is due to distributions of fiber

distance differences (Optical Broadband Working Group 2006 and Farbod

Tabatabai 2007). Based on the above issues, the standard value of fiber

parameters was considered such as splicing loss, coupling loss, feeder loss are

shown in Table 4.1(GarrettCom).

Table 4.1 Details of OPB comparative study for Power budget

calculation as model for Power budget 22.5 dB

Speed Mb/s

Fiber mode

Std.km fdx

Wave

length nm

TXpmin

dB RXpmin

dB

Worst

OPB dB

Worst Distance km, fdx

Typical OPB

dB

Typical

Distance km,fdx

100 Multi 2 1310 -19 -31 12 4 16 5.7

100 single 40 1310 -5 -34 29 58 32.5 65

100 single 100 1550 -5 -36 31 116 33 124

1000 multi 0.55 850 -9.5 -17 5.5 2 12.5 4

1000 single 10 1310 -9.5 -20 8.5 17 10.5 21

1000 single 25 1310 -4.0 -21 15 38 17.5 43

1000 single 40 1550 -4.0 -21 15 60 17.5 70

1000 single 70 1550 -3.0 -23 18 90 20.5 102

1000 single 120 1550 0.0 -32 28 126 29.5 133.5

where km – kilometer, fdx- full-duplex mode

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4.3 PERFORMANCE AND ANALYSIS OF PROPOSED GPON

ARCHITECTURE

Based on the above existing GPON architecture impairments, in

this chapter, a novel 10Gbps DBA scheme was proposed using GPON

architecture. In the proposed model, RN design was reconsidered specifically

to simplify the splitting ratio and complexity to obtain 10 Gbps per end user

and also obtain better improvement in power penalty requirements by SPO

techniques. The proposed novel model for 10 Gbps GPON is classified in the

Figure 4.1.

10 Gbps GPON

EDFA

10 Stage 1x2 Splitter


EDFASOA

SOA

With Splittingloss

Without Splitting loss

6 Stage 1x2 -without Optical Amplifier

With Splittingloss


With Splittingloss


With Splittingloss


10 Gbps GPON

EDFA



EDFASOA

SOA

With Splittingloss


6 Stage 1x2 -without Optical Amplifier

With Splittingloss


With Splittingloss


With Splittingloss


Figure 4.1 Classifications and proposed various design modeling of

Link power estimation for 10 Gbps GPON

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4.3.1 Using 6 stages 1×2 Splitter at RN without optical Amplifier –

Proposed design

In the proposed GEPON architecture design as shown in Figure 4.2,

the selected SONET standard OC-192 (10 Gbps) has been taken for analysis.

OLT

FR-FT

FR-FT

FR-FT

ONU 1

ONU 2

ONU 63

ONU 64

10 Gbps

TT/TL/TF

TR/TAPD

FR-FT

MZI Modulator

RN (6 stage 1x2 splitter)

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C1

1550nm

OLT

FR-FT

FR-FT

FR-FT

ONU 1

ONU 2

ONU 63

ONU 64

10 Gbps

TT/TL/TF

TR/TAPD

TT/TL/TF

TR/TAPD

FR-FT

MZI Modulator

RN (6 stage 1x2 splitter)

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C

1X2S / C1

1550nm

Figure 4.2 Model proposed for 10Gbps GPON structured with TF

(OLT), 6 - Stage 1x2 Splitter (64 ONUs)

A single wavelength 1550.92 nm carrying 10 Gbps electrical signal

is modulated using MZI modulator with PRBS signals and NRZ encoding

signal format. The DFB laser source is used to produce the wavelength and it

has operated with input optical power for the range of -7.5 to 10 dBm at the

OLT side and APD as photo detector at ONUs side. The power transfer

function of MZI is expressed in (4.1) (Rajiv Ramaswamy and Srinivasan

2002).

(i) Power transfer function of MZI measurement is

calculated by

2 211 12T (f ) sin ( L / 2) T (f ) cos ( L / 2) (4.1)

where eff2 n / eff i in L / m / 2

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Remote nodes have been constructed with 1 × 2 with six stages of

splitters. 64 users or 64 ONUs can avail the services with total bandwidth of

160 Gbps. The following parameters have been estimated with the

expressions (4.2) to (4.5) from the reference (Franz and Jain 2000, Rong

Zhang and Daryouush Habibi 2002, Zeng Yun et al 2006))

(ii) link power budget Estimation to be estimated with power

margin as

Power margin Pm = (Pt – Pr – LSf – NLff - L - Lfd) dB (4.2)

where, Pt is the transmitted power, Pr is the minimum received power, N is the

number of splices, Lsf source to fibre loss, Lff is fiber to fiber coupling loss,

L is the attenuation loss, Lfd is fiber to detector loss. In this chapter the

power margin is assumed more than 4dB for the simulation.

(iii) Received Power at Splitter stage Estimation

Similarly with reference to two stage splitter operations, the optical

power received by ONU was received in six stages i.e. 1×64 splitters usage is

by the modified expression (4.3)

Pr = Pt – (S1 + S2 + … + S6 + f* (L1a + L2b +…+ L6f)

+ con+ 10 log 10 (A * B … E * F) + Ms (4.3)

where, S1 to S6 are the six stages of splitters excess losses respectively,

f is fiber cable loss in km, L1a is first splitter to the Ath second stage

splitters, L2.b is second splitters to the Bth stage splitters , L6.f is the length of

the fiber which connects different ONUs (F) to the sixth stage splitter, αcon is

the loss from connectors and splices and is to be assumed to be 2dB, A to F

are the number of branches of the first, second and up to sixth stages of the

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splitter respectively and Ms is the system margin which is assumed to be 7 dB

which counts output power variations from components flexibility.

(iv) maximum link length La (max) can be calculated from

expression (4.4)

n m 3

t r si fd mn 1 m 1 i 1

aff 0

L maxP P 11dB L L P

L / L

(4.4)

In this chapter first, n, m and six stages of splitters are taken as

4, 64 and six stage splitters (1/2, 1/4, 1/8, 1/16, 1/32, 1/64). In the basic

research of simulation study, GPON has been considered the standard method

and the parameters are listed in Table 4.2 and the calculated values are given

in Table 4.3.

(v) Bandwidth-distance product has been calculated for the

dispersion measurement as in (4.5)

d 2 2nL b

cL (max) 2D f

(4.5)

where, fb is bit frequency, nL =1.55 m , n=1 to 4 and fiber dispersion

parameter D is 17ps/nm/.km)

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Table 4.2 Parameters for proposed 10Gbps GPON model using

1550.92 nm

Speed Mode Range of

Wavelength(nm) Channel

spacing (nm)

Minimum transmitted

Power(TXpmin) in dB

Minimum received Power

(RXpmin) in dB

10 Gbps Single Mode Fiber

1550.92 – 1552.52(nm)

0.8 nm 100GHz

- 7.5dBm - 30dB

Table 4.3 Estimated values for attenuation with distance transmission

for various power margin and span loss level for proposed

10Gbps GPON architecture

Attenuation

Amplifiers or Repeaters Required for distance transmission (km)

Pm =2 dB ; SL = 20.5 dB

Pm =4 dB ; SL = 18.5 dB

Pm =6 dB ; SL = 16.5 dB

Pm =8 dB; SL = 14.5 dB

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

53.6 38.2 29.7 24.3 20.6 17.8 15.7 14.1 12.7 11.6 10.7

49.6 35.4 27.5 22.5 19.1 16.6 14.5 13.1 11.8 10.7 9.90

45.6 32.5 25.3 20.7 17.5 15.2 13.4 12.0 10.8 9.90 9.10

41.6 29.7 23.1 18.9 16.0 13.8 12.2 10.9 9.90 9.00 8.30

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The simulated result with respect to equations (4.3) to (4.5)

describes the bandwidth distance product of mathematical analysis in the

access 10 Gbps GPON with the varying parameter of attenuation 0-2dBm.

The obtained result for maximum distance of 50 – 55 km with a power margin

(Pm) range of 2-8 and is shown in Figure 4.3.

Figure 4.3 Variation of attenuation with distance between repeaters for

different power margin level

From the simulation analysis, the variation of loss in attenuation

with distance between repeaters is studied for different values of power

margins. It shows that the maximum values of distance between repeaters are

42 km for a power margin of 8 when no loss condition exists. If the value of

attenuation is 2, the distance between the repeaters are nearly 10 km. This is

clearly seen from the Figure 4.3 where the attenuation in dB increases and the

distance between the repeaters is decreasing. In order to get the optimum

performance, choose the power margin and distance between repeaters which

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should be an optimum one. Similarly dispersion performance in the range of

15 – 20 ps/nm/km is obtained and the results are depicted in Figure 4.4. It is

seen that various dispersion values of 5, 17 and 40 ps/nm/km, to determining

the dispersion limit which has been found out 10.5, 3.7 and 1.7 km

respectively for the bit rate 10 Gbps. The maximum dispersion limit occurs at

the high dispersion which is also another performance parameter for link

power budget analysis of GPON architecture. The values used for 6 stage

1x2 splitter at RN design have been given in the Table 4.4.

0 1 2 3 4 5 6 7 8 9 10

x 109

0

2

4

6

8

10

12x 105 Bit rate (R) vs Dispersion limit (Lmax)[17 in ps/(nm km)]

Bit rate (R) in bits/sec-->

Dis

pers

ion

limit

(Lm

ax) i

n km

-->

D=5psD=17psD=40ps

Figure 4.4 Variation of bit rate with dispersion limit

Disp

ersio

n lim

it (L

max

) in

km

Bit rate (R) in bits/sec

Bit rate (R) vs Dispersion limit (Lmax) [17 in ps/nm/ km]

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Table 4.4 Performance parameter and its value chosen for 6 stage

1x 2 splitter for 10Gbps GPON architecture

Parameters Value

Data format and Bit rate NRZ ; 10 Gbps Pulse Shape Super Gaussian Pulse Laser Source Optical power ranges and modulator

DFB CW ; -7.5 to 15 dBm MZ modulator

Wavelength 1550.92 nm SMF Maximum step size Phase difference

1000 30km/50km/80km 0.1

Amplifier – Gain block EDFA Noise figure

15 dB 4 dB

Splitting ratio 0.5 Insertion ratio 0 dB Avalanche photo detector Current Multiplication factor Impact Ionization factor

Ic = 17 pA / Hz^0.5 Ia = 0 nA 10(hole )116.4 1/cm (electron) 26.39 1/cm

Frequency response Butterworth filter 3dB Bandwidth filter

Order : 4 10 GHz

Figure 4.5 shows the simulation results using Photonics CAD 1.6,

the EOP for various values of dispersion parameters for various values of

distance. Distance increases between the repeaters, the EOP is decreased and

it is closed when the distance reaches to 80 km. This is due to the various

noise components and the weak signals which are due to various loss

mechanisms encountered in the transmission process. The simulated result for

CW signals at 1550.92 nm for dispersion at 15ps/nm/km is depicted in Figure 4.6. Figure 4.6 (a) and (b) show the input signal with optical power for

a distance of 10 km and 80 km respectively. The corresponding NRZ coded signal is shown in Figure 4.6 (c). The output signals at 10 km and 80 km have

been depicted in Figure 4.6 (d) and (e), respectively. The later signal is more

corrupt and weak in nature which is due to various loss occurred.

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(a) (b)

(c) (d)

(e)

Figure 4.5 Various EOP for 6 stage GPON (a) EOP 0.21dBm – dispersion 15 - 18 ps /nm/km, 10 km,

attenuation 0-2, laser power -7.5 to 15dBm (b) EOP 0.20 dBm – dispersion 19 ps /nm/km, 10 km, attenuation 0-2, laser power -7.5 to 15dBm (c) EOP 1.57 dBm – dispersion 15 ps /nm/km, 80 km, attenuation 0-2, laser power -7.5 to 15dBm (d) EOP 2.45 dBm – dispersion 17 ps /nm/km, 80 km, attenuation 0-2, laser power -7.5 to 15dBm (e) EOP – Eye may be closed – dispersion 19 ps /nm/km, 80 km, attenuation 0-2, laser power -7.5 to 15dBm

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(a) (b)

(c)

(d) (e)

Figure 4.6 1550.92 nm CW signals for dispersion at 15ps/nm/km (a) input signal for 10 km (b) input signal for 80 km (c) NRZ signal

(d) output signal for 10 km (e) output signal for 80 km

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Figure 4.7 illustrates the comparison of EOP with distance. It is

seen from the figure that the high EOP power needed at the dispersion value

of 19 ps/ nm/km at 70 km with maximum of 2.45dBm and above almost EOP

is closed in its response. At the same time EOP required for 15 ps/ nm/km is

only 1.57 dBm. Similarly at short distance transmission like 20 km the EOP

power is required only 0.21dBm.

Figure 4.7 Comparison of various ranges dispersion and Distance for

EOP analysis for needs of power budget

From the simulation results using Photonics CAD 1.6, the 6 stage

1x2 splitter at RN without optical amplifier were analyzed and studied.

It describes innovatively the performance of the link power budget estimation

of GPON architecture for handling data rate upto 10Gbps using DBA scheme.

Various loss encountered during the transmission have also been considered

to study the power budget estimation. The variation of attenuation with

transmission distance for various values of power margin was estimated. EOP

power in dBm for various values of dispersion with distance has also been

studied for 64 ONUs. Also the recent existing architecture for the GPON

consists of providing access to about 1024 users at a maximum reach from the

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OLT to the ONU is 100 km. It is capable of supporting transfer rates from 2.5

to 10 Gbps in the downstream with splitter configuration of 1x4 with 2 stage

1x16 (1024) and three stage optical amplifiers which would cause undesirable

effects in the repair of links affecting the entire network (Darren P.Shea and

John E.Mitchell 2007, Ivica Cale et al 2007). It is necessary that further

research and study has been required to carry out to providing DBA and link

power estimation for 1024 ONUs by the RN performance. In this research the

SMF distance 30 km and 2 km have been considered between OLT to RN and

RN to ONUs with following requirements.

(a) The analysis is considered with more number of splitter

stages at RN

(b) To avoid the nonlinear effects

(c) To obtain satisfied link power and guaranteed bandwidth to

all ONUs

Based on the above needs in this research work, two different novel

designs using power splitters are proposed at RN for the performance of

GPON. This has been classified as per the Figure 4.1 for following types;

(i) 10 stage 1x2 splitter – without and with splitting loss case

(ii) 2 stage 1x512 splitter – without and with splitting loss case

At RN, a loss of 1dB has been introduced in first(ONU1),

fourth(ONU 16) and eighth (ONU 256) stages of 10 stage 1x2 splitter

classification whereas first stage (ONU 1) only considered in the 2 stage

1 x 512 splitter classification as ‘with splitting loss’ case. For ‘without

splitting loss’ case has considered with 0 dB loss at RN. Both case responses

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are measured and studied with the support of optical amplifiers performance

in the following sections of this chapter.

4.3.2 Using 10 stage 1×2 Splitter at RN with Optical Amplifiers

Proposed GPON architecture provides access to about 1024 ONUs

with same bandwidth. Different splitting stages using 10 stage 1×2 optical

power splitter has been chosen as ten splitting stages at RN as shown in

logical Figure 4.8. The specific values chosen for the above two

classifications are given in common Table 4.5.

CW(OPTICALSOURCE)

AM(MOD)

10 Stage1x2

SPLITTER(With and

Without loss)

ONU 1

ONU 1024

SOA / EDFA(AMPLIFIER)

PRBS (Bit Rate 10Gbps)

NRZPG

PRBSG – Pseudo Random Bit Sequence GeneratorNRZPG – Non Return To Zero Pulse Generator

OLT

OLT – Optical Line TerminalSMF – Single Mode FiberONU – Optical Network

SMF

SMF

CW(OPTICALSOURCE)

AM(MOD)

10 Stage1x2

SPLITTER(With and

Without loss)

ONU 1

ONU 1024

SOA / EDFA(AMPLIFIER)

PRBS (Bit Rate 10Gbps)

NRZPG

PRBSG – Pseudo Random Bit Sequence GeneratorNRZPG – Non Return To Zero Pulse Generator

OLT

OLT – Optical Line TerminalSMF – Single Mode FiberONU – Optical Network

SMF

SMF

Figure 4.8 Logical block diagram of 10 Gbps GPON with 10 stage

1x2 splitter at RN

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Table 4.5 Common specifications used for 10 Gbps GPON Architecture – Proposed model of 10 stage 1x2 splitter and 2 stage 1x 512 splitter (default)

Parameters Values in Units Amplitude Modulator Modulation Index

1

PRBS Bit rate

10Gbps

NRZ pulse generator Amplitude

1 a.u.

SMF(OLT – RN) Attenuation Dispersion Reference wavelength Length

0.2 dB/km 16.75 ps/(nm.km) 1550 nm 30 km , 2 km

APD Gain Responsivity Dark current Multiplication factor

3 1A/W 10 nA 1

EDFA Noise figure Gain

4 dB 20 dB

SOA –Traveling Wave SOA Length Width Height Differential gain Loss Optical Confinement factor Line width Enhancement factor

0.0005 m 3e-006 m 8e-008 m 2.78e-020 m^2 0 1/m 0.15 5

CW Laser Frequency Power (Iterative Analysis I1 to I8)

193.1THz (1552.52 nm) -7.5 to 10dBm

Power Splitter - Splitting loss introduced in RN type of -10 stage 1 x 2 splitter - 2 stage 1x 512 splitter Splitting loss

Stage 1(ONU1), Stage 4(ONU16) and Stage 8(ONU 256) Stage 1 (ONU1) 1 dB

LPGF Cut off frequency Insertion loss Depth Order

0.75* Bit rate 0 dB 100 dB 1

The maximum distance 30 km with attenuation 0.2 dB/km considered between OLT and ONU has been kept in this novel analysis to

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transport 10Gbps downstream transmission. The OLT taken in this work is with CW laser source power -7.5 to 10 dBm and electrical 10Gbps NRZ pulse as shown in Figure 4.9. In this RN node using splitters performance model has been analyzed with eight SIA. The value of every iteration is chosen with a difference of 2.5 dBm and specifically to investigate and the link power performance of 10Gbps GPON while changing optical input pulse power range from -7.5 dBm to 10 dBm.

Figure 4.9 Input signal sourced from OLT (a) CW laser optical pulse with eight iterations

(b) Electrical 10Gbps Pulse in NRZ encoded signal format Two types of optical amplifiers have been specially linked with single stage in the feeder network of this novel GPON architectural design; the first one is Erbium Doped Fiber Amplifier (EDFA) and the second one is Semiconductor Optical Amplifier (SOA) and its type is called ‘Travelling Wave SOA’ to transport the 10Gbps for 1024 ONUs. Every ONUs consists of APD, filters and analyzers. APD recovers the transmitted optical signal back to electrical form. Suitable values of the APD characteristics are chosen to reproduce the transmitted signal without any distortion. To achieve the distortionless signal, two stages of LPGF are used. The downstream transmission of this 10 Gbps GPON architecture has been simulated by SIA analysis with the maximum of eight iterations from I1 to I8 using Optisystem 6.0 and 7.0. All eight iterations are performed well and better response is obtained in all ONUs which depend on how much CW optical pulse source

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power range -7.5 to 10 dBm is utilized effectively. A good eye opening in the EOP visualizer reveals perfect reproduction of the transmitted signal. The obtained various simulation results are shown in Figures 4.10, 4.11, 4.12 and 4.13 for eight iterative responses and almost same for ONU1 to ONU 1024. But different responses are found out for the RN performance in all cases (1a) to (1d). The obtained simulated results are easy to compare and analyze the innovations for the cases of both ‘without and with splitting loss’ responses of 10 stage 1x2 splitter RN using EDFA and SOA in the 10Gbps GPON. A comparative analysis has been investigated using EDFA and SOA for GPON performance with SIA approach. Based on the above plotted Figure 4.10 to Figure 4.13 and measured values in Tables 4.6 and 4.7,

Case (1a) EDFA - 10 stage 1x2 splitter – without splitting loss

(a) (b)

(c) (d)

Figure 4.10 SIA results using EDFA and 10 stage 1x2 splitter - without

splitting loss at RN (Continued)

89

(e) (f)

(g) (h) (i)

(j) (k)

Figure 4.10 SIA results using EDFA and 10 stage 1x2 splitter - without splitting loss at RN

(a) Q Factor (b) Min.BER (c) ER at Min.BER (d) Eye diagrams (e) 3D view of BER patterns (f) 3D - Eye opening view (g) Output optical pulse power spectrum (h) Output optical power level for Iteration 1 (i) Output optical power level for Iteration 8 (j) Output Electrical power level for Iteration 1 (k) Output Electrical power level for Iteration 8 Case (1b) EDFA -10 stage 1x2 splitter – with splitting loss

log of BER

90

(a) (b)

(c) (d)

(e) (f)

Figure 4.11 SIA results using EDFA and 10 stage 1x2 splitter - with


log of BER

91

(g)

(h) (i)

(j) (k)

Figure 4.11 SIA results using EDFA and 10 stage 1x2 splitter - with splitting loss at RN

(a) Q Factor (b) Min.BER (C) ER at Min.BER (d) Eye diagrams (e) 3D view of BER patterns (f) 3D - Eye opening view (g) Output optical pulse power spectrum (h) Output optical power level for Iteration 1 (i) Output optical power level for Iteration 8 (j) Output Electrical power level for Iteration 1 (k) Output Electrical power level for Iteration 8

92

Case (1c) SOA - 10 stage 1x2 splitter – without splitting loss

(a) (b)

(c) (d)

(e) (f)

Figure 4.12 SIA results using SOA and 10 stage 1x2 splitter - without


log of BER

93

(g)

(h) (i)

(j) (k)

Figure 4.12 SIA results using SOA and 10 stage 1x2 splitter - without splitting loss at RN

(a) Q Factor (b) Min.BER (c) ER at Min.BER (d) Eye diagrams (e) 3D view of BER patterns (f) 3D - Eye opening view (g) Output optical pulse power spectrum (h) Output optical power level for Iteration 1 (i) Output optical power level for Iteration 8 (j) Output Electrical power level for Iteration 1 (k) Output Electrical power level for Iteration 8

94

Case (1d) SOA - 10 stage 1x2 splitter – with splitting loss

(a) (b)

(c) (d)

(e) (f)

Figure 4.13 SIA results using SOA and 10 stage 1x2 splitter - with


log of BER

95

(g)

(h) (i)

(j) (k)

Figure 4.13 SIA results using SOA and 10 stage 1x2 splitter - with splitting loss at RN


96

Table 4.6 Comparative measured values of 10 Gbps GPON - 10 stage 1 x 2 splitter as RN – without and with splitting

loss analysis using EDFA

10 Gbps GPON - 10 stage 1 x 2 splitter Erbium Doped Fiber Amplifier ( EDFA )

Iterative Analysis for input power in dBm I1= -7.5 I2=-5 I3=-2.5 I4=0 I5=2.5 I6=5 I7=7.5 I8=10

Without Splitting

loss

Q - factor 5.430 9.022 13.958 19.161 23.174 25.613 26.947 27.688 BER 3.3e-008 9.7e-020 1.4e-044 3.9e-082 4.1e-119 5.3e-145 3.0e-160 4.8e-169

ER at min.BER 44.831 44.042 43.604 43.356 43.204 43.166 43.143 43.128 OSP in dBm -26.986 -24.486 -21.986 -19.486 -16.986 -14.486 -11.986 -9.486 ONP in dBm -64.079 -64.079 -64.079 -64.079 -64.079 -64.079 -64.079 -64.079 OSNR in dB 37.093 39.593 42.093 44.593 47.093 49.093 52.093 54.593 ESP in dBm -71.428 -66.438 -61.444 -56.447 -51.449 -46.45 -41.45 -36.451 ENP in dBm -88.830 -88.561 -88.125 -87.449 -86.464 -85.131 -83.463 -81.516

With splitting

loss

Q - factor 2.780 4.852 8.190 12..929 18.240 22.587 25.312 26.802 BER 0.0027 6.1e-007 1.3e-016 1.5e-038 1.8e-074 2.8e-113 1.2e-141 1.5e-158


97

Table 4.7 Comparative measured values of 10 Gbps GPON - 10 stage 1 x 2 splitter as RN – without and with splitting loss analysis using SOA

10 Gbps GPON - 10 stage 1 x 2 splitter Semiconductor Optical Amplifier ( SOA )

Iterative Analysis for input power in dBm I1=-7.5 I2=-5 I3=-2.5 I4=0 I5=2.5 I6=5 I7=7.5 I8=10

Without losses

Q - factor 6.125 5.473 5.118 4.975 4.926 4.873 4.805 4.766 BER 3.7e-010 1.8e-008 1.2e-007 2.6e-007 3.3e-007 4.4-007 6.0e-007 7.3e-007

ER at min.BER

27.38 27.887 29.102 30.262 31.84 32.487 34.223 35.493

OSP in dBm -15.844 -15.566 -15.317 -15.081 -14.863 -14.667 -14.489 -14.312 ONP in dBm -100 -100 -100 -100 -100 -100 -100 -100 OSNR in dB 84.155 84.433 84.683 84.918 85.136 85.332 85.51 85.688 ESP in dBm -49.231 -48.583 -48.012 -47.497 -47.030 -46.607 -46.215 -45.827 ENP in dBm -86.128 -85.996 -85.863 -85.730 -85.592 -85.464 -85.349 -85.239

With losses


ER at min.BER

27.676 28.244 29.504 30.704 32.3036 32.950 34.700 35.983

OSP in dBm -18.844 -18.566 -18.317 -18.081 -17.863 -17.667 -17.489 -17.312 ONP in dBm -100 -100 -100 -100 -100 -100 -100 -100 OSNR in dB 81.155 81.433 81.653 81.918 82.136 82.332 82.510 82.688 ESP in dBm -55.231 -54.583 -54.012 -53.497 -53.030 -52.607 -52.214 -51.827 ENP in dBm -87.370 -87.280 -87.197 -87.104 -87.005 -86.913 -86.830 -86.750

98

The following details were found for without and with splitting loss

cases in 10 stage 1x2 splitter as per Table 4.6 and 4.7.

(i) Using EDFA, the Q-factor arrived is in better improvements

with different values in the range of 2 to 6 at low input

optical power iterations I1 to I5 and 1 to 2 at high input

optical power iterations I6 to I8. But using SOA, the Q factor

value is almost decreasing in the range of 1 to 2 for all

iterations I1 to I8.

(ii) The BER values are 1 to 2 times decreased in linear range

10-4 to 10-169 using EDFA whereas using SOA the BER is

increased in linear range 10-10 to 10-7 for successive iterations

I1 to I8 . This shows that the input optical power is one of the

affecting parameters for BER estimation.

(iii) The extinction ratio (ER) at Minimum BER has varied its

value within the range 1 for without splitting loss, whereas

ER is severely decreased in the range value of 12 with

splitting loss using EDFA. At the same time using SOA, the

ER is higher and the value difference is 8, increased in every

iteration I1 to I8 for both without and with splitting loss case.

(iv) The OSP difference is 15 dBm and 1 dBm among all

iterations of EDFA and SOA. But 3 dBm occurs as a major

difference between without and with splitting loss case using

both EDFA and SOA.

(v) All iterations I1 to I8 are having the same ONP and its

differences have occurred within the range 1dBm for both

EDFA. But the difference -3 dBm has occurred among the

without splitting and splitting loss of EDFA. In SOA a

99

constant ONP value -100 dBm is obtained for both without

and with splitting loss.

(vi) The OSNR values have increased as 2 dB for all successive

iterations I1 to I8, but same range has obtained for both

without and with splitting loss using EDFA. But using SOA,

the OSNR values are in a maximum difference of 3dB and

obtained values for all iterations are 2 times higher than

EDFA.

(vii) The obtained ESP is 5 dBm and 1 dBm in differences for all

iterations using EDFA and SOA. The 6 dBm difference has

occurred between without and with splitting loss using both

amplifiers. The ESP value using SOA is 2 times higher than

the EDFA.

(viii) Finally, the obtained electrical noise power (ENP) is almost

the same values for without and with splitting loss, but 1 to 3

dBm differences are in every iteration using EDFA and

SOA. The ENP using EDFA is less than SOA in the range of

1dBm.

4.3.3 Using 2 stage 1×512 Splitter at RN with Optical Amplifiers

Another model has been dealt in this section to find the

comparative RN performance with reference to previous section 4.2. The RN

consists of 2 stages of 1×512 optical power splitter which is taken as a novel

approach again with the same split ting loss analysis set up. The logical block

diagram of 10Gbps GPON architecture with 2 stage of 1x512 splitter is

shown in Figure 4.14.

100

Figure 4.14 Logical block diagram of 10 Gbps GPON with 2 stage

1 X 512 splitter at RN

The analyses are made by introducing loss of 1 dB in the first stage

of RN. Similarly, the CW source optical powers have chosen for the ranges of

-7.5 to 10 dBm with 8 iterations and values used for simulations are given in

the common specifications Table 4.4. The obtained various simulation results

are shown in Figures 4.15, 4.16, 4.17 and 4.18 for eight iterative responses

and compared various performance measures for ONU1 and ONU 1024 with

following cases 2(a) to 2(d). The measured values for different performance

parameters using EDFA and SOA are given in Table 4.8 and 4.9.

101

Case (2a) EDFA - 2 stage 1x512 splitter – without splitting loss

(a) (b)

(c) (d)

(e) (f)

Figure 4.15 SIA results using EDFA and 2 stage 1x512 splitter - without


log of BER

102

(g)

(h) (i)

(j) (k)

Figure 4.15 SIA results using EDFA and 2 stage 1x512 splitter - without splitting loss at RN

(a) Q Factor (b) Min.BER (C) ER at Min.BER (d) Eye diagrams (e) 3D view of BER patterns (f) 3D - Eye opening view (g) Output optical pulse power spectrum (h) Output optical power level for Iteration 1 (i) Output optical power level for Iteration 8 (j) Output Electrical power level for Iteration 1 (k) Output Electrical power level for Iteration 8

103

Case (2b) EDFA - 2 stage 1x512 splitter – with splitting loss

(a) (b)

(b) (d)

(e) (f)

Figure 4.16 SIA results using EDFA and 2 stage 1x512 splitter - with


log of BER

104

(g)

(h) (i)

(j) (k)

Figure 4.16 SIA results using EDFA and 2 stage 1x512 splitter - with splitting loss at RN


Wavelength (m)

Po

wer

(dBm

)

105

Case (2c) SOA - 2 stage 1x512 splitter – without splitting loss

(a) (b)

(c) (d)

(e) (f)

Figure 4.17 SIA results using SOA and 2 stage 1x512 splitter – without


log of BER

106

(g)

(h) (i)

(j) (k)

Figure 4.17 SIA results using SOA and 2 stage 1x512 splitter – without splitting loss at RN


107

Case (2d) SOA - 2 stage 1x512 splitter – with splitting loss

(a) (b)

(c) (d)

(e) (f)

Figure 4.18 SIA results using SOA and 2 stage 1x512 splitter – with


log of BER

108

(g)

(h) (i)

(j) (k)

Figure 4.18 SIA results using SOA and 2 stage 1x512 splitter – with splitting loss at RN

(a) Q Factor (b) Min.BER (c) ER at Min.BER (d) Eye diagrams (e) 3D view of BER patterns (f) 3D - Eye opening view (g) Output optical pulse power spectrum (h) Output optical power level for Iteration 1 (i) Output optical power level for Iteration 8 (j) Output Electrical power level for Iteration 1 (k) Output Electrical power level for Iteration

109

Table 4.8 Comparative measured values of 10 Gbps GPON - 2 stage 1x512 splitter as RN – without and with splitting loss analysis using EDFA

10 Gbps GPON - 2 stage 1 x 512 splitter Erbium Doped Fiber Amplifier ( EDFA )

Iterative Analysis for input power in dBm I1= -7.5 I2= - 5 I3 = - 2.5 I4=0 I5=2.5 I6=5 I7=7.5 I8=10

Without losses



With losses



110

Table 4.9 Comparative measured values of 10 Gbps GPON - 2 stage 1x 512 splitter as RN – without and with splitting

loss analysis using SOA

10 Gbps GPON - 2 stage 1 x 512 splitter Semiconductor Optical Amplifier ( SOA)

Iterative Analysis for input power in dBm I1= -7.5 I2= -5 I3 = -2.5 I4 = 0 I5=2.5 I6=5 I7=7.5 I8=10

Without losses


ER at min.BER 27.38 27.887 29.102 30.262 31.842 32.487 34.223 35.493 OSP in dBm -15.844 -15.566 -15.317 -15.081 -14.863 -14.667 -14.489 -14.312

ONP in dBm -100 -100 -100 -100 -100 -100 -100 -100 OSNR in dB 84.155 84.433 84.683 84.918 85.136 85.332 85.51 85.688 ESP in dBm -49.231 -48.583 -48.012 -47.497 -47.030 -46.607 -46.215 -45.827 ENP in dBm -86.128 -85.996 -85.863 -85.730 -85.592 -85.464 -85.349 -85.239

With losses


ER at min.BER 27.456 27.979 29.206 30.377 31.961 32.607 34.347 35.62 OSP in dBm -16.844 -16.566 -16.317 -16.081 -15.863 -15.667 -15.489 -15.312

ONP in dBm -100 -100 -100 -100 -100 -100 -100 -100 OSNR in dB 83.155 83.433 83.653 83.918 84.136 84.332 84.510 84.688 ESP in dBm -51.231 -50.583 -50.012 -49.497 -49.030 -48.607 -48.214 -47.827 ENP in dBm -86.598 -86.482 -86.363 -86.244 -86.12 -86.003 -85.898 -85.798

111

In this 2 stage 1x512 splitter performance at RN of 10 Gbps GPON

has been carried out by SIA simulations. Its results are shown in Figures 4.15,

4.16, 4.17 and 4.18 and measured values are given in Tables 4.8 and 4.9

above and the performances are investigated using EDFA and SOA.

The following details are found out from the result analysis for the case of

without and with splitting loss in 10 stage 1x2 splitter.

(i) Q-factor continuously varied in difference of 4 to 6 for I1 to

I5 and 1 to 2 for I6 to I8 using EDFA whereas the value of

Q-factor is almost decreasing in the range of 1 to 1.5 for all

successive iterations I1 to I8 using SOA for both case of

without and with splitting loss.

(ii) BER values are also decreasing 2 times in the range 10-8 to

10-169 using EDFA. The BER is increased from 10-10 to 10-7 for all iterations I1 to I8 using SOA. The result of BER

estimation highlights the variations of BER while changing

the power splitter set up at RN and applying input optical

power for the case of without and with splitting loss.

(iii) The ER at Minimum BER has changed in minimum range

0.8 to 0.1 for without splitting loss, whereas ER is decreased

in the range of 3 to 1 for with splitting loss using EDFA. By

using SOA, the ER value increased for every iteration with

differences of 1 to 2 and maximum is 8 when comparing I1

and I8, for the case of without and with splitting loss.

(iv) OSP difference between I1 and I8 is 14 to 16 dBm and 2 dBm

among every iterations of EDFA. But using SOA, the

difference in OSP is 1dBm which has occurred as a major

difference for without and with splitting loss case.

112

(v) ONP difference is almost 0 dBm for all iterations I1 to I8, but

1dBm difference has occurred when comparing without and

with splitting loss case using EDFA. In the SOA analysis,

the ONP is less in value -100dBm compared with EDFA, but

the difference of ONP difference is similar to EDFA for

iterations.

(vi) OSNR values are the same for iterations of EDFA for the

case without and with splitting loss, but 2 to 3dB differences

have occurred in every iteration. In the analysis of SOA, the

OSNR values have increased 2 times when compared with

EDFA but the difference has occurred for every iteration

which is similar to EDFA for both the case of without and

with splitting loss.

(vii) The ESP value difference is 5dBm and 0.5dBm for every

iteration and 2dBm differences have occurred when

compared to the cases of without and with splitting loss

using both EDFA and SOA respectively. In the ESP

comparison, the SOA is obtained 0.25 times higher values

than the EDFA.

(viii) Finally, the values obtained ENP for without and with

splitting loss cases are in the range of 0 to 1 dBm and

maximum of 3dBm differences among EDFA and SOA in

every iteration.

The following plots shown in Figure 4.19 and 4.20 give the

detailed comparative graphical analysis from the measured values for PPRs

requirements using 10 stage 1x2 splitter and 2 stage 1x512 splitter for

10 Gbps GPON with the support of EDFA and SOA.

113

(a) (b)

(c) (d)

(e) (f)

(g) (h) Figure 4.19 Comparison of 10Gbps GPON – 10 stage 1x2 splitter at

RN - without and with splitting loss using EDFA and SOA (a) Q - Factor (b) Min.BER (c) ER at Min.BER (d) Received Optical Signal Power (e) Received Optical Noise Power (f) OSNR (g) Received Electrical Signal Power (g) Received Electrical Noise Power

114

(a) (b)

(c) (d)

(e) (f)

(g) (h)

Figure 4.20 Comparison of 10Gbps GEPON – 2 stage 1x512 splitter at RN - without and with splitting loss using EDFA and SOA (a) Q-Factor (b) Min.BER (c) ER at Min.BER (d) Received Optical Signal Power (e) Received Optical Noise Power (f) OSNR (g) Received Electrical Signal Power (h) Received Electrical Noise Power

115

4.4 COMPARATIVE ANALYSIS FOR PPR AND RN

PERFORMANCE OF PROPOSED GPON ARCHITECTURE

PPR point of view revealed a fact that the lower input optical

powers obtained lower values of power penalties and higher input optical

powers obtained higher power penalties in both splitting loss cases of EDFA.

But for SOA there is no large variation in PPRs values for both lower and

higher input optical powers. Also obtained Q-factor and BER are almost

expected values towards a better response. But eye opening with the

3D analysis and reconstruction of received electrical signal for 10Gbps

describe somewhat average response in SOA compared with EDFA

performance.

So the analysis is extended to SPO techniques to find PPR by

obtaining the gain and noise figure for all iterations. The SPO for PPR is

estimated power level from OLT to RN in the range of 30 to 100 km. At the

same time the link power estimation depends on the fiber length used in the

entire PON. In this research work the PPR of all PONs is estimated using

SPO with more than 50 passes individually done for iteration 1 and 8 are

processed. Also the feeder network fiber length and RN splitting loss are

considered as major parameters. Using Dual WDM analyzer, every iteration is

individually optimized by SPO techniques. The gain and noise figure are

measured with respect to already obtained OSNR values. Finally the optimum

pulse power analysis and optimized maximum fiber length 32.4 km for all

case of PPR values are determined for CW 1552.52 nm wavelength while

transporting 10Gbps using GPON which are given in Table 4.10.

116

Table 4.10 Measured value of PPR for 10 Gbps GPON

10 Gbps GPON – Power Penalty Requirements using SPO techniques for CW 1552.52 nm (193.1 THZ)

Fiber distance( km)

Minimum 30 km I1= -7.5 dBm to I8=10 dBm

Maximum 100 km I1= -7.5 dBm to I8=10 dBm

10 stage

1 x 2 splitter

Type of Optical amplifier and splitting considerations

Gain(dB) Noise Figure(dB) Gain(dB) Noise

Figure(dB) Optimized

maximum Fiber length (km) I1= -7.5 I8=10 I1= -7.5 I8=10 I1= -7.5 I8=10 I1= -7.5 I8=10

EDFA without splitting loss -19.48 -19.48 20.43 20.43 -33.45 -33.45 34.40 34.40 32.4

EDFA wit splitting loss -22.48 -22.48 22.98 22.98 -36.45 36.95 -36.45 36.95 32.4

SOA without splitting loss -8.34 -24.31 8.34 24.31 -12.30 -25.46 12.30 25.46 32.4

SOA with splitting loss -11.34 -27.30 11.34 27.30 -15.30 -28.46 15.30 28.46 32.4

2 stage 1 x 512 splitter

EDFA witout splitting loss -19.48 -19.48 20.43 20.48 -33.45 -33.45 34.40 34.40 32.4

EDFA with splitting loss -20.48 -20.48 21.25 21.25 -34.45 -34.45 35.22 35.22 32.4

SOA witout splitting loss -8.33 -25.45 8.33 25.45 -12.30 -23.77 12.30 23.77 32.4

SOA without splitting loss -9.34 -25.30 9.34 25.30 -13.30 -26.46 13.30 26.46 32.4

117

From the above Table 4.10, it is investigated that the major difference in requirements penalty power using EDFA and SOA for 10 stages 1x2 splitter and 2 stages 1x512 splitter which are summarized in the following points:

1. There is no difference found out in all iterations due to without and with splitting loss parameter changes at RN using EDFA. The obtained optimized gain and noise figure value are same for all iterations though varying optical input pulse power.

2. Both without and with splitting loss cases at RN using SOA the optimized mean and noise figure values are changing for all iterations which depends on the changing input optical pulse power.

3. The PPR acquires less gain and maximum noise figures both obtained by extending the fiber length from 30 km to 100 km using EDFA.

4. The PPR is controlled with the maximum gain and minimum noise figure using SOA even extending the fiber length.

4.5 SUMMARY It is summarized from the overall performance including PPR results of this chapter that the SOA is better than EDFA. It is maintaining optimum pulse power if single wavelength carries 10Gbps information in the GPON architecture. The SOA is also suitable to investigate the link power estimation for DBA scheme using GPON architecture. It supports RN performance using both type of power splitter for10 Gbps transmission using GPON architecture with respect to performance values of OSP, OSNR, Q-Factor, BER, ESP and ENP. Few samples of GPON using SPO technique are given in Appendix 2.

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