GPON Technology

C

CPE customer premises equipment

D

DBA dynamic bandwidth allocation

E

EPON Ethernet passive optical network

F

FTTB fiber to the building

FTTC fiber to the curb

FTTD fiber to the door

FTTH fiber to the home

FTTO fiber to the office

FTTW fiber to the Wi-Fi

G

GEM GPON encapsulation mode

GPON gigabit-capable passive optical

network

I

ISP Internet service provider

N

NSP network service provider

O

ODN optical distribution network

ONU optical network unit

OLT optical line terminal

P

PON passive optical network

P2P Point-to-point

P2MP Point-to-multipoint

S

SNI service node interface

T

T-CONT transmission container

TDMA time division multiple access

U

UNI user network interface

W

WDM wavelength division multiplexing

Principles

The GPON technology uses the P2MP architecture of a standard PON network. A GPON network consists

of an OLT, ONUs, and optical splitters. The following figure shows the GPON network architecture.

The GPON technology uses different upstream and downstream wavelengths to transmit data bidirectionally over a single optical fiber.

Wavelength/Center

Wavelength (nm)

US 12901360/1310

DS 14801500/1490

Bandwidth (Gbit/s) US 1.244

DS 2.488

Protocol Line NRZ/FSS

Link ATM/GEM

Maximum Logical Reach (km) 60

Maximum Physical Reach (km) 20

Nominal Reach (km) 20

Split Ratio 1:641:128

DS center wavelength: 1490 nm

US center wavelength: 1310 nm

GEM port

T-CONT

T-CONT

Optical splitter

OLT

Data is broadcast in downstream direction. ONUs receive the

desired data according to GEM port IDs.

1

3

2 1 2 3

1

3

2

1

2

3

Data is transmitted in TDMA mode in upstream direction. In this mode,

multiple timeslots are allocated to an uplink. ONUs transmit data based

on allocated timeslots. This prevents data conflict.

A GEM frame is a GPON service transmission unit with a length of 125 s. All data is encapsulated into

GEM frames for transmission.

DA

SFD

Preamble

Inter-packet gap

SA

Length/Type

MAC client data

FEC

EOF

5 b

yte

s

TDM data

Ingress buffer

Mapping Ethernet frames to GEM frames Mapping TDM data to GEM frames

TDM packets enter a buffer queue and are encapsulated

to GEM frames in a fixed number of bytes for transmission.

The GPON system transparently transmits the TDM

packets.

Ethernet frames are mapped to GEM frame payloads.

Each Ethernet frame is mapped to one or multiple GEM

frames.

A GEM frame supports only an Ethernet frame.

A GEM port is the minimize unit for

carrying data.

A T-CONT is an upstream service flow

control unit.

A GPON port on an ONU contains

multiple T-CONTs.

A T-CONT contains multiple GEM

ports.

Item XGPON1

Wavelength (nm) DS: 15751580

US: 12601280

Center wavelength(nm) DS: 1577

US: 1270

Rate (Gbit/s) DS: 9.953

US: 2.488

Power budget (dB)

Class N1: 1429

Class N2: 1631

Class E1: 1833

Class E2: 2035

Maximum fiber distance (km) 60

Maximum differential fiber distance(km) 40

Split ratio 1:64

Frame structure XGEM

The PON technology is being evolved at NG PON1 and NG PON2 phases.

NG PON1 provides higher rates based on the TDMA PON technology. The NG PON1 phase involves XGPON1 and XGPON2.

XGPON1: provides asymmetric 10G PON transmission with a downstream rate of 9.953 Gbit/s and an upstream rate of 2.488 Gbit/s.

XGPON2: provides symmetric 10G PON transmission with a downstream rate of 9.953 Gbit/s and an upstream rate of 9.953 Gbit/s.

NG PON2: ITU-T has already used TWDM PON as the NG PON2 standard.

GPON

XGPON1

NGA1

NGA2

2010 2011

ODN reuse

ODN reuse is not obligation

XGPON2

TWDM-PON, stacked, 40G,

GPON Standards and Protocols

US

1. ONU data is mapped to GEM ports.

2. ONUs transmit data to the OLT based on T-CONT requirements.

3. The OLT restores GEM port data and transmits the data to its service

processing units.

IFgpon

IFgpon

IFgpon T-CONT GEM port

GEM port

ONU 1

ONU N

T-CONT GEM port

OLT

IFgpon

IFgpon GEM port

ONU 1

ONU N

GEM port

GEM port

IFgpon

Filt

er

Filt

er

GEM port filter

OLT

DS

1. OLT data is mapped to GEM ports.

2. The OLT broadcasts GEM port data to all ONUs.

3. ONUs receive the desired data according to GEM port IDs.

DBA report

BW map

Timeslot

T-CONT

T-CONT

T-CONT Scheduler

ONU OLT

Control plane

Data plane

DBA

The DBA module in the OLT continuously

collects DBA reports from the ONU and uses

the DBA algorithm to calculate the bandwidth to

be allocated to the ONU.

The OLT issues the calculated bandwidth to the

ONU through a BW map.

The ONU uses the allowed timeslot to transmit

data upstream based on the BW map data.

OLT

ONU in ranging

state

Start of D/S Frame

Reception of D/S Frame

Transmission of

S/N Response

Actual

reception of

S/N response

Desired

start of the

U/S frame

Assigned EqD

Pre-assigned EqD

Zero-distance EqD

Desired

reception of

SN response

Sstart

U/S BW map containing

a ranging request

ONU

response

time

Pre-assigned

EqD

Start of the U/S

frame for the pre-

ranged ONU

Sstart

Ranging

During the ranging process, the OLT obtains ONU's

RTD.

The OLT specifies proper EqD values for ONUs

based on the RTD to ensure the same logical reach

from all ONUs to the OLT.

Continuous transmit module Burst transmit module

OLT

Data conflict

Burst Transmission

The ONU optical transmit module uses only a preset

timeslot to transmit data upstream in burst mode.

Burst receive module

OLT

Signal recovery

Continuous receive module

Burst Reception

The OLT optical receive module dynamically and

promptly adjusts power threshold based on received

signals. This prevents signal discarding or signal

recovery faults caused by large attenuation.

The DBA technology uses the dynamic upstream bandwidth adjustment mechanism to effectively improve upstream bandwidth usage.

The ranging technology ensures that all ONU upstream data does not conflict.

ONU 1

ONU 2

ONU 3

OLT

Threshold

The burst optical and electrical technology prevents upstream data conflict and ensures correct data reception.

Service node

Optical splitter

R/S S/R ODN

UNI SNI

IFgpon IFgpon

OLT

ONU

ONU

CPE

Type C full backup Type B OLT port backup

IFgpon GPON port Protection scope IFgpon Single GPON uplink port on an ONU IFgpon

IFgpon Dual GPON uplink ports on an ONU

An OLT uses two GPON ports as active and standby ones.

If the active feeder fiber is faulty, the OLT automatically switches data to the

standby feeder fiber.

Feeder fibers and GPON ports are protected in this mode. Drop fibers are not

protected.

Both OLT and ONU use two GPON ports as active and standby ones.

Feeder and drop fibers as well as GPON ports are protected in this mode.

All standby ports are idle, resulting in a low bandwidth usage.

GPON lines are protected in type B or type C mode.

IFgpon

2:N optical splitter OLT

IFgpon

ONU 1

IFgpon

ONU N

IFgpon

1:N optical splitter OLT

1:N optical splitter

ONU 1

ONU N

IFgpon

IFgpon

IFgpon

IFgpon

IFgpon

IFgpon

The GPON technology applies on FTTB, FTTC, FTTD, and FTTH networks based on access nodes.

Service Transmission Principles

Service Multiplexing Principles

Physical Control Block Downstream (PCBd)

Payload

AllocID Start End AllocID Start End

1 100 200 2 300 500

T-CONT 1

(ONU 1)

T-CONT 2

(ONU 2)

Slot

100

Slot

200

Slot

300

Slot

500

PLOu PLOAMu PLSu DBRu Payload x DBRu Y Payload y

Upstream

Bandwidth Map

125 s

DS Frame

US Frame

OLT

ONU N

ONU 1

OLT OLT

ONU 1

ONU 2

ONU 3

ONU 1

ONU 2

ONU 3

ONU N

ONU 1

DBA module

PLI

PTI

Port ID

CRC

GEM payload

PLI

PTI

Port ID

HEC

Payload

TDM fragment

ITU-T G.984.3

GTC layer specifications

GTC multiplexing architecture and protocol stack

GTC layer frame structure

ONU registration and activation flows

DBA specifications

Alarms and performance

ITU-T G-984.1/2/3/4

ITU-T G.984.1

GPON network parameters

Networking requirements for a protection

switchover

ITU-T G.984.4

OMCI message structure

OMCI device management architecture

OMCI principles

ITU-T G.984.2

ODN parameter specifications

2.488 Gbit/s downlink optical port parameter specifications

1.244 Gbit/s uplink optical port parameter specifications

Physical layer overhead allocation

Service Supporting

Data GFP

Voice TDM/VoIP

Video GEM-IPTV

TDM GEM

Format of DBA packets Standard

Ranging Equidistant EqD mode

Bandwidth Efficiency 92%

ONT Management-compliant Protocol OMCI

Data Encapsulation Protocol GEM

Optical Power Budget Class A/B/C

GPON Parameters

Distribution point

FTTH/FTTD

FTTC

FTTB

Distribution point

Macro ONU

Micro ONU

Pico ONU OLT

Multi-Scenario

@Home

@Move

@Work

Multi-Mode

FTTH, FTTC, FTTB, and

FTTDp

FTTW and FTTO

Multi-Medium

Copper, optical fiber, coaxial

cable, and electric power cable

Wi-Fi and small cell

CO

Residential

Residential

Small cell Wi-Fi

Business

FTTC

FTTH/FTTD FTTW

FTTO

FTTDp

FTTB

The GPON technology applies on FTTB, FTTC, FTTD, FTTH, FTTO, and FTTW networks based on service scenarios.

Networking Protection

Technology Evolution

Working Principles

Key Technologies

Networking Applications

Overview

Frame Structure

Acronyms