EPON Network

Design Considerations

By Sun Telecom

Summarization

1. Bandwidth Requirements

2. Splitting Architecture

3. Distance

4. Optical power budget to make sure the optical loss in

proper range

5. Services to provide

6. Update the existing network

7. Network Nodes

8. Cables

1.Bandwidth Requirements

1. The number of subscribers.

2. Bandwidth for each subscriber.

3. Bandwidth Calculation:

4. Actual Average Bandwidth = Bandwidth for each User x

Network Concurrent Rate x Online Rate or Actual Total

Bandwidth = Bandwidth for each Subscriber x The

Number of Subscribers x Network Concurrent Rate x

Online Rate

5. According to the effective bandwidth of each PON

port(about 900M) calculate the number of PON cards.

6. Distribute different bandwidth for different users according

to the situation.

7. Reserve bandwidth for update if needed.

2.Splitting Architecture

1. The splitting architecture is depend on the distribution of

the users, and the need of service providing.

2. Decide 1-stage splitting or 2-stage splitting.

3. Consider average splitting or not. Generally in EPON

system PLC splitter will be used for equal optical power

division and FBT splitter for unequal optical power division.

The comparison as follows:

Parameters PLC Splitter FBT Splitter

Wavelength Range (nm) 1260 ~ 1650nmSingle/dual/triple

window

Splitting Ratio Equal divisionEqual or non-equal

division

Dimensions SmallLarge size for multi

channel

Wavelength Sensitivity Low High

CostLow splitting channel,

high price

Price is lower for small

channel splitter

Splitting Architecture

Splitting Architecture

4. For PLC splitter we have following splitting architectures:

Distribution Splitting Aggregation Splitting Centralized Splitting

Cascading Splitting (1 x 8 / 1x 4 or 1x 4 / 1x 8)

Placement

POS Located in LCP and NAP

Features

Multi-point testing and maintenance

High optical loss

Low OLT PON port utilization rate

Complicated network structure, hard to maintain

Application

Aerial access method

Network reform

Single Splitting (1 : 32)

Placement LCP

Features Integrated link testing and user management

Low Optical loss

High OLT PON port utilization rate

Low cost for splitter

Simple network topology, easy to maintain

Application Duct access method

New Project

Placement CO

Features Single point link testing and maintain

Low Optical loss

High OLT PON port utilization rate

Low cost for splitter

Dedicated cable for each house

Flexible topology

Huge infrastructure cost

Application Duct access, new project, user close to CO

1. EPON can support a transmitting distance for about 20 km under 1:32 splitting ratio, and about 10 km under 1:64 splitting ratio.

2. The distance mainly depends on the optical loss. The higher the optical loss is, the shorter the transmitting distance will be.

3. If the transmitting distance of cable is more than 2 km, fiber splicing should be taken into account.

4. For nodes in different distances we may use FBT splitter to distribute more optical power for the further node and less optical power for the nearer node thus make sure all the nodes can get enough optical power.

5.Optical power budget

1. EPON System

2. CATV System

Light Budget Calculation

Items Unit Single Fiber (PX20)

OLT

Mean Output Power MIN dBm 2

Mean Output Power MAX dBm 7

Min Sensitivity dBm -29

Min Overload dBm -10

ONU

Mean Output Power MIN dBm -1

Mean Output Power MAX dBm 4

Min Sensitivity dBm -25

Min Overload dBm -3

Optical Power

Max. Optical Power Consume dB 27

Min Optical Power Consume dB 14

Name Avg. Loss (dB)

Connection

Adapter 0.2

Quick Connection Connector 0.4

Fusion Splicing 0.1

Splitter

1:32 16.5

1:16 13.5

1:8 10.5

1:4 7.2

1:2 3.2

Cable (G. 652)1310nm 0.36 /km

1490nm 0.25 /km

Power Loss Point Analysis

Length of Fiber Cable

Wavelength of the Light

Quantity of Adapter

Number of Quick Connection Connector

Splitter

ODN Light Budgeting (Example)

Loss Type Qty

Avg.

Loss

(dB)

Total Avg. Loss (dB)

1:64 1:32 1:16 1:8 1:4 1:2

Cable (G.652) (km) 20 0.36 7.2 7.2 7.2 7.2 7.2 7.2

Adapter (pc) 7 0.2 1.4 1.4 1.4 1.4 1.4 1.4

Quick Connection

Connector (pc)1 0.4 0.4 0.4 0.4 0.4 0.4 0.4

Extra Loss 1 1 1 1 1 1 1 1

Passive

Optical

Splitter

(pc)

1;64 1 19.7 19.7

1:32 1 16.5 16.5

1:16 1 13.5 13.5

1:8 1 10.5 10.5

1:4 1 7.2 7.2

1:2 1 3.2 3.2

Total Loss (dB) 29.7 26.5 23.5 20.5 17.2 13.2

20km Optical Loss (1 Splitter)

10km Optical Loss (2 Splitters)

Loss Type Qty

Avg.

Loss

(dB)

Total Avg. Loss (dB)

1:64 1:32 1:16 1:8 1:4 1:2

Cable (G.652) (km) 10 0.36 3.6 3.6 3.6 3.6 3.6 3.6

Adapter (pc) 8* 0.2 1.6 1.6 1.6 1.6 1.6 1.6

Quick Connection

Connector (pc)1 0.4 0.4 0.4 0.4 0.4 0.4 0.4

Extra Loss 1 1 1 1 1 1 1 1

Passive

Optical

Splitter

(pc)

1;64 1 19.7

1:32 1 16.5 16.5

1:16 1 13.5 13.5

1:8 1 10.5 10.5

1:4 1 7.2 7.2

1:2 1 3.2 3.2 3.2 3.2 3.2 6.4* 3.2

Total Loss (dB) 26.3 23.3 20.3 16.9 12.9 9.7

1:64, 1:32 Optical Budgeting

20km 15km 10km 5km

1:64 1:32 1:64 1:32 1:64 1:32 1:64 1:32

1:64 29.5 27.75 26 24.25

1:32 26.3 24.55 22.8 21.05

Preserve 3 3 3 3 3 3 3 3

Total Loss 32.5 29.3 30.75 27.55 29 25.8 27.25 24.05

1550nm

Transmitter: 17.5dBm

Receiver: -6 ~ 2dBm (-10 ~ 2dBm)

17.5dBm 23.3dBm = - 5.8dBm

5.Services to provide

1. EPON provides services such as data, IPTV/CATV and VoIP,

widely used in various applications like FTTH, FTTB, FTTC,

triple play, security system, video surveillance system,

intelligent community, city hotspot (airport, station, etc.), Wi-

Fi access, and even TDM over EPON.

2. FTTH topology.

3. FTTB/C topology.

4. FTTO topology.

5. EPON surveillance topology.

FTTH topology

FTTB/C Topology

FTTO Topology

EPON surveillance topology

1. Update the existing network by adding cables and devices

to provide new services.

2. CATV coaxial network can be upgraded to HFC network to

provide triple play service by adding EOC devices.

3. Pure data EPON network can be upgraded to provide CATV

service by adding WDM devices.

4. CATV fiber optical network can be upgraded to provide triple

play service.

5. Former fiber optical network can also be upgraded to

provide services for a wider area and more users.

1.Deployment and design requirement

OLT central office should be easy to handling large equipment

Enough space for device installation and storage

Good working environment (Temperature & Humidity)

Central Office construction standard

CO with fire safety equipment

The CO should be far away from high-intensity vibration source, noise source, electromagnetic interference, and flammable and explosive materials

2.Power supply requirement

Provide -48V power supply

Highest power load requirement that the area can have

Individual power line access, dedicated power

distribution box

UPS power supply

3.Grounding requirement

AC/DC Power supply grounding

Section size of grounding wire should greater than

25mm2

Ground resistance should be less than 5 ohm

User aggregation point

Located in place that is easy to manage and

maintain

Building distributor, weak current vertical shaft,

outdoor optical cross-connection cabinet, man

hole, pole etc

Active connection, easy to inspect and

maintain

Close to subscriber

The terminal device can not too big

Floor vertical shaft, staircase, electrical pole

Distribution cable spliced with drop cable

For FTTH application, dedicated box for install

ONU, embedded on the wall

Local power supply

Feeder Fiber Cable

Feeder Cable for connection Cable from ODF in central

office and splitter distribution cabinet in LCP.

Direct burial, duct, or aerial installation.

Distribution Fiber Cable

For connection Splitter distribution point to fiber distribution point,

Indoor or outdoor application.

Drop Cable

The last-mile of the ODN, from fiber distribution point to user

terminal.

Direct burial, duct, or aerial installation.

Thanks!

http://www.suntelecom-cn.com