https://neonetwirelessng.blogspot.com/2020/01/neonetwireless-practical-telecomspower.html

1. FTTH PON TRAINING GUIDE
PART IV
BY EMMANUEL N ONUZURIKE
(CFOT/CFOS/H/I/O/D/S/T)

2. DESIGNING AND IMPLEMENTATION OF
A TYPICAL FTTH NETWORK
How to Design Your FTTH Network
Splitting Level and Ratio

3. HOW TO DESIGN A SIMPLE FTTH
SPLITTING LEVEL RATIO
In Passive Optical Network (PON), optical splitters play an
important role in Fiber to the Home (FTTH) networks by allowing a
single PON interface to be shared among many subscribers.
Optical Splitters are installed in each optical network between the
PON Optical Line Terminal (OLT) and the Optical Network
Terminals (ONTs) that the OLT serves. During the deployment of
fiber to the home passive optical network, usually, we will face
some physical access network design problems. This article may
help you solve FTTH splitting lever and ratio design problems

4. HOW TO DESIGN A SIMPLE FTTH
SPLITTING LEVEL RATIO

5. CHOOSE PLC SPLITTER OR FBT
SPLITTER
Before we start to discuss the splitting lever and ration design, it’s
necessary to choose the right optical splitter type for your FTTH
network. There are two types of splitters in our current FTTH
application—PLC splitter and FBT splitter. Here we have a
comparison between these two splitter types:
Parameters PLC Splitter FBT Splitter
Wavelength Range 1260-1650 nm Single/dual/triple window
Splitting Ratio Equal division Equal or non-equal division
Dimensions Small Large size for multi-channel
Wavelength Sensitivity Low High
Cost
Low splitting channel, high
price
Price is lower for small
channel splliter

6. CHOOSE PLC SPLITTER OR FBT
SPLITTER
As we can see in the table above, with the rapid growth of FTTH
worldwide, the requirement for larger split configurations (1×32,
1×64, etc) in these networks has also grown in order to serve
mass subscribers, since PLC splitters offer very accurate and even
splits with minimal loss in an efficient package, they are offer a
better solution for today’s FTTH applications than FBT splitters.

7. FTTH SPLITTING LEVEL DESIGN
The PON is the optical fiber infrastructure of an FTTH
network. The first crucial architectural decision for the PON
network is that of optical splitter placement. The PON
splitting may be achieved by centralized splitting (one-level)
or by cascaded splittings (two-level or more). A centralized
approach typically uses a 1×32 splitter located in a fiber
distribution hub (FDH). The splitter is directly connected via
a single fiber to a OLT in the central office. On the other side
of the splitter, 32 fibers are routed to 32 customers’ homes,
where it is connected to an ONT. Thus, the PON network
connects one OLT port to 32 ONTs.

8. CENTRALIZED SPLITTING:USUALLY
DEPLOYED IN A CROWDED CITY

9. CASCADED SPLITTING: USUALLY
DEPLOYED IN CURB OR VILLAGES

10. CASCADED VS CENTRALIZED
A cascaded approach may use a 1×4 splitter residing in an
outside plant enclosure. This is directly connected to an OLT
port in the central office. Each of the four fibers leaving this
lever 1 splitter is routed to an access terminal that houses a 1×8
level 2 splitter. In this scenario, there would be a also total of 32
fibers (4×8) reaching 32 homes. It is possible to have more than
two splitting levels in a cascaded system, and the overall split
ratio may vary (1×16 = 4×4, 1×32 = 4×8, 1×64 = 4x4x4). A
centralized architecture typically offers greater flexibility, lower
operational costs and easier access for technicians. A cascaded
approach may yield a faster return-on-investment with lower
first-in and fiber costs. Usually, the centralized splitting solution
is used in crowded city center or town areas, in order to reduce
cost and easy to maintain the optical distributed network (ODN)
nodes. In the other hand, two-level and multi-level cascaded
splitting solution is used in curb or village places, to cover widely
ODN nodes, conserve resources and save the money.

11. FTTH NETWORK SPLITTING RATIO DESIGN
The most common splitters deployed in a PON system is a
uniform power splitter with a 1:N or 2:N splitting ratio
(N=2~64), where N is the number of output ports. The optical
input power is distributed uniformly across all output ports.
Different ratio splitters may perform differently in your
network. Then, how to design your splitting ratio? According to
the passage mentioned above, if you choose the centralized
splitting solution, you may need to use 1×32 or 1×64 splitter.
However, if you choose the cascaded splitting solution, 1×4 and
1×8 splitter may be used more often. Besides, based on our
EPON/GPON project experience, when the splitting ratio is
1:32, your current network can receive qualified fiber optic
signal in 20 km. If your distance between OLT and ONU is small,
like in 5 km, you can also consider about 1:64.

12. FTTH NETWORK SPLITTING RATIO
DESIGN

13. FTTH NETWORK SPLITTING RATIO
DESIGN
When to design your FTTH network splitting level, in fact,
centralized splitting and cascaded splitting both has its advantages
and disadvantages. We had to weight these factors and select an
appropriate splitting level for our network. As for splitting ratio
design, to ensure a reliable signal transmission, the longer the
transmission distance, the lower splitting ratio should be used.
There are series of 1xN or 2xN PLC splitters which can divide a
single/dual optical input(s) into multiple optical outputs uniformly,
and offer superior optical performance, high stability and high
reliability to meet various application requirements.

14.  Power attenuation calculation of Optical
splitter
 Input attenuation of optical splitter(<1dB):
OPTICAL POWER ATTENUATION
Input Output1:2 optical
splitter
2:N optical
splitter
∵ 10 log(0.5) = - 3.01
∴
Attenuation of 1:2 splitter: 3.01 dB
Attenuation of 1:16 splitter: 12.04 dB
Attenuation of 1:64 splitter :18.06 dB
Input
Output

15. FIBER ATTENUATION & POWER
BUDGET
 Fibre attenuation relates to the fibre length
 The attenuation of fibre splicing point is
generally less than 0.2dB
 Other factors may cause attenuation, such
as fibre bending
About 0.35 dB per km
for 1310,1490nm
Table G.984.2 – Classes for optical path loss
Class A Class B Class B＋ Class C
Minimum loss 5 dB 10 dB 13 dB 15 dB
Maximum loss 20 dB 25 dB 28 dB 30 dB
NOTE – The requirements of a particular class may be more stringent for one
system type than for another, e.g. the class C attenuation range is inherently
more stringent for TCM systems due to the use of a 1:2 splitter/combiner at
each side of the ODN, each having a loss of about 3 dB.
Huawei’s OLT and ONU
28 dB (Class B+)

16. Items Unit Single fibre
OLT: OLT
•Mean launched power MIN dBm +1.5
•Mean launched power MAX dBm 5
•Minimum sensitivity dBm -28
•Minimum overload dBm -8
•Downstream optical penalty dB 0.5
ONU: ONU
•Mean launched power MIN dBm 0.5
•Mean launched power MAX dBm 5
•Minimum sensitivity dBm -27
•Minimum overload dBm -8
•Upstream optical penalty dB 0.5
PARAMETERS OF GPON INTERFACES (CLASS B+)

17. GPON LINK BUDGET (CLASS B+)EXAMPLE
+5.
0
P
(dBm)
+1.
5
+5.
0
P
(dBm)
+0.
5
-
8.0
P
(dBm)
-
27.0
-
8.0
P
(dBm)
-
28.0
1490
nm
1310
nm
path penalty: 0.5
dB
path penalty: 0.5
dB
Downstream
budget:
+1.5 – (-27) – (0.5) = 28
dB
Upstream
budget:
+0.5 – (-28) – (0.5) = 28
dB
Tx
level
Tx
level
Rx
level
Rx
level
0.30
dB/km
0.42
dB/km

18. 18
EXAMPLE:
• budget: 28 dB
• 16 way splitter loss: 13.8 dB (theoretical. 12dB)
• connector+splicing loss: 3 dB (24*0.1 dB + 2*0.3 dB)
• aging: 1 dB
• attenuation:
o 0.30 dB/km – downstream
o 0.42 dB/km – upstream
Distance:
• (28 – 13.8 – 3 – 1) / 0.42 = 10.2 / 0.42 = 24.28 km
Interpretation:
• for a 1:16 split, the max distance of an ONT is 24
km

19. CLASS C+ EXAMPLE
+7.
0
P
(dBm)
+3.
0
+5.
0
P
(dBm)
+0.
5
-
8.0
P
(dBm)
-
30.0
(**)
-
12.0
P
(dBm)
1490
nm
1310
nm
path penalty: 1 dB
(*)
path penalty: 0.5
dB
Downstream
budget:
+3 – (-30) – (1) = 32
dB
Upstream
budget:
+0.5 – (-32) – (0.5) = 32
dB
Tx
level
Tx
level
Rx
level
Rx
level
0.30
dB/km
0.42
dB/km
-32.0
(*) Accounts for DS dispersion
effects up to 60km reach
(**) ONT sensitivity in C+ mode with
FEC

20. VIDEO TRANSCEIVER
SPECIFICATIONS
EXAMPLE
+18.
5
P
(dBm)
P
(dBm)
-
4.9
1550
nm
Downstream
budget:
+18.5 – (-4.9) = 23.4
dB
Tx
level
Rx
level

21. ic
MAXIMUM RANGE FOR
SPLITTERS - CONFIGURATION
1:6
4
1:
8
1:1
6
Er
1:3
2
30 km
38 km
21 km
14 km
1:
2
1:
4
splitting be
st
cas
e
wor
st
cas
e
1 : 64 14 km 10 km
1 : 32 21 km 15 km
1 : 16 30 km 23 km
1 : 8 38 km 30 km
ITU-T G.984
Standar
d B+
Laser

22. Total Link Loss Budget
Based on the type of the deployed PON network, check each
component in an ODN before a test. The total link loss budget in an
ODN covers the following aspects:
(1)Insertion loss of the optical splitter
(2)Loss from fuse splicing and mechanical splicing
(3)Insertion loss of the connector and adapter
(4)Loss from optical transmission
(5)Extra link loss (generally about 3 dB)
If the CATV service is also provisioned, include the following aspects in
the total link lossbudget:
(6)WDM loss (loss of each WDM coupler: 0.7 dB to 1.0 dB)
(7)When the 1550 nm wavelength is used for CATV transmission, the
link power budget also needs to cover the following aspects:
attenuation of 1550 nm wavelength (about 0.2 dB/km) and minimum
optical power of the CATV receiver (-8 dBm).

23. ATTENUATION BUDGET FOR THE
ODN LINK
Item Unit Single-Mode Optical Fiber
GPON Class B+ EPON PX10 EPON PX20
Optical power
Optical link loss (max.) dB 28 21 26
Optical link loss (min.) dB 13 5 10
GPON optical transceiver: Class B+, 1:64/20km.
EPON optical transceiver: PX10/PX20, 1:32/10 km or 1:16/20 km.
The ODN link is recommended to have a certain attenuation redundancy when an
ODN is planned.

24. Example 2 of Calculating the Total Link Loss Budget
Item Type Average loss(dB)
Connection
point
Quickconnector <0.5
Mechanical
splicing
≤0.2
Fusesplicing ≤0.1
Adapter ≤0.3
Optical
splitter
1:64（PLC） ≤20.5
1:32（PLC） ≤17
1:16（PLC） ≤13.8
1:8（PLC） ≤10.6
1:4（PLC） ≤7.5
1:2（FBT） ≤3.8
Opticalfiber
(G.652D)
1310 nm (1 km) ≤0.35
1550 nm (1km) ≤0.21
Opticalfiber
(G.657A)
1310nm (1 km) ≤0.38
1550 nm (1 km) ≤0.25
Attenuation Calculation
(ODN Equipment Except Optical Cable)
FDT Indoor SplitterLegend:
OLT
1:2 Splitter
& ODF
ODF &
Splicing OCCB
FDT &
1:32 Splitter FAT TB ATB ONT
OLT
1:2 Splitter
& ODF
ODF &
Splicing OCCB FDT FAT TB ATB ONT
1:32 Indoor
Splitter
0.3+0.1 0.1 0.1+0.3+17+
0.3+0.1
0.1 0.1 0.5+0.3 0.30.3 0.3+3.8+0.3
Total Loss = 24.3db
0.3+0.1 0.1 0.1 0.1 0.1+0.3+17
+0.3+0.1
0.3 0.3+3.8+0.3
Total Loss = 24.4db
0.1 0.5+0.3 0.3
OLT
Connector
ODF OCCB
Fusesplicing
FAT TB
Mechanicalsplicing

25. Total Link Loss Budget
Dynamic range of the OLT optical receiver
MA5680T
HG850e
1:2 optical
splitter
1:16 optical
splitter
HG850e
The strength of the optical signal received
on this ONT is budgeted to be -7 dB.
The strength of the optical
signal received on this ONT
is budgeted to be -23 dB.
？Can services be provisioned
concurrently on these two
ONTs if their receive optical
powers are within the budget?
1.As specified in the protocol, the dynamic range of the OLT optical
receiver is within 15 dB. That is, the difference between the maximum
optical attenuation and the minimum optical attenuation must be within 15
dB. If a range exceeds the dynamic range of the OLT optical receiver, the
bit error rate (BER) increases, or even certain ONUs go offline.
2.The preceding problems will not occur if you plan an ODN in strict
compliance with the protocol.

26. (Optional) Step 2: Test of the Transmit Optical Power
of a PON Port
Purpose: to test the transmit optical power of an OLT PON port to ensure that the
transmit optical power is within the normal range
Item Unit Single-Mode OpticalFiber
GPON ClassB+ EPON PX10 EPON PX20
OLT
Average transmit optical power (min.) dBm 1.5 -3 2
Average transmit optical power (max.) dBm 5 2 7
Receiver sensitivity dBm -28 -24 -27
Overload optical power dBm -8 -1 -6
1:32 optical
splitter
MA5680T
HG850e
The PON
ports that
pass the
acceptance
test need not
be tested
again!

27. (Optional) Step 2: Test of the Transmit Optical
Power of a PON Port (Continued)
• Required tool: optical power meter
• Precautions:
1. Prepare a suitable patch cord because the connector type of the PON port is
SC/PC,
• but the connector type of the optical power meter is usually FC/PC(round).
2. Do use the single-mode patch cord rather than the multi-mode patch cord in a
PON network. (The single-mode patch cord is yellow and the multi-mode
patch cord is orange.)
3.After the test, use the anhydrous alcohol or the professional cleaner to clean
the
• connectors of the patch cord.

28. Step 3: Link Test at the Feeder Optical Cable Section(1)
Purpose: to test the linkstatus from the PON port on the OLT to the IN port of the
optical splitter (using the OTDR)
1:32 optical
splitter
MA5680T HG850e

29. Step 3: Link Test at the Feeder Optical Cable Section(1)
Required tool: OTDR
Precautions:
1.Most of OTDRs available to the field engineers cannot penetrate the
optical splitter; therefore, when you perform a test in the downstream
direction from the OLT, the distance displayed on the OTDR is the distance
between the OLT and the optical splitter.
2.When using the OTDR to perform a test, ensure that the optical fiber is in
the “black” state (that is, no light source exists in the optical fiber link).
Otherwise, the test results are not convincing. In addition, when performing
a test in the upstream direction from the optical splitter, remove the optical
fiber connected to the PON port on the OLT， record the test results, and
ensure that there is no rogue ONT or no ONT that is in the always active
state.
3.Try to perform bidirectional tests.
4.(Mandatory) After the test, use the anhydrous alcohol or the professional
cleanerto clean the connectors of the patchcord.

30. Step 3: Link Test at the Feeder Optical Cable Section(2)
Purpose: to test the link status from the PON port on the OLT to the IN port on the
optical splitter (using the optical power meter instead of the OTDR)
1:32 optical splitterMA5680T HG850e
Light
source
Optical
power
meter
Optical
power
meter
Page30HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

31. THANK YOU