Follow us on LinkedIn Phone icon Contact Us Optical News Become a Customer

5 Key Facts about PON and the evolution of GPON technology to 10G PON & XGS PON

In our first article on Passive Optical Networking we looked at some of the key foundations of PON, to get an understanding of what Passive Optical Networking (PON) is, how PON works, along with the core key benefits and some definitions of some of the key terms you will come across. We also took a look at the history of PON and where it is headed in the future.

In this article we’ll take a more in-depth look at GPON technology, including the latest 10G PON standards (XG-PON and XGS PON) and NG-PON2. We’ll also look at GPON transceivers, the criteria you need to consider for selection and PLC splitters that do the hard work of splitting fiber connections.

But, first of all a quick reminder of what GPON is…

What is GPON?

Just to recap a little, GPON is used predominantly in FTTH (Fiber to the Home), FTTB (Fiber to the Building) and FTTP (Fiber to Premises) networks. GPON is the standard that enables a single fiber connection, sent from the central office, to be split using fiber optical splitters into multiple fiber connects to serve the needs of multiple end customers. GPON makes more efficient use of the physical fiber network being deployed than point-to-point fiber. Gigabit Passive Optical Networking (GPON) was the first ITU standard enabling 1Gbps communications.

1) ITU PON Transmission Standards – GPON, XG-PON, XGS-PON and NG-PON2

In our first blog we covered the evolution of the ITU PON standards. Here we take a closer look at the specifications for each of the latest standards.

ITU Standard
GPON
XG-PON
XGS-PON
NG-PON2

Transmission

Asynchronous
Transfer Mode
(ATM)

Wavelength
Division
Multiplexing
(WDM)

Asymmetric

Wavelength
Division
Multiplexing
(WDM)

Symmetric

Time and
Wavelength
Division
Multiplexing
(TWDM)

Symmetric

TWDM + multiple
channels and
wavelength tuning
which can increase
bandwidth to
40Gbps down and
10Gbps up using 4
wavelengths at
10/2.5 Gbps rates

Downstream Speed

2.5Gbps

10Gbps

10Gbps

10Gbps

Upstream Speed

1.25Gbps

2.5Gbps

2.5Gbps or 10Gbps

2.5Gbps or 10Gbps

Reach

20km

20km

20km

20km

Transceiver Form Factors

SFP
Class B+ and Class
C+

XFP

XFP

SFP+/XFP

GPON

GPON (Gigabit-capable PON)–  The first GPON standard increased the speed of downstream data to 2.5Gbps and upstream data to 1.25Gbps.  In 2014 the GPON standard was updated to cover wavelength division multiplexing (WDM) which enabled the transmission of video, data and voice over the same fiber.

XG-PON

XG-PON / 10G PON – Developed by ITU in 2010, XG-PON (also known as 10G-PON) enables downstream speeds of 10 Gbps and 2.5 Gbps upstream using asynchronous transmission.  XG-PON also uses wavelength division multiplexing, but at different wavelengths from the GPON standard, thus enabling the simultaneous use of GPON and XG-PON over the same fiber.

XGS-PON

XGS-PON – XGS-PON is an evolution of the PON standard released in 2016. Providing both symmetrical transmission of up to 10Gbps.  XGS-PON uses Time and Wavelength Division Multiplexing for transmission and like XG-PON, the wavelengths have been changed from the original GPON standard to enable simultaneous transmission of GPON, XGS-PON and NG-PON2.

NG-PON2

NG-PON2 / TWDM-PON –  The NG-PON2 (Next Generation PON) standard was developed in 2015 by the ITU, a year before the XGS-PON Standard.  The architecture of NG-PON2 uses Time Wavelength Division Multiplexing (TWDM).  It enables 4 or more wavelengths to each deliver symmetrical bitrates of 2.5 Gbps or 10Gbps.  Thus, it is enables communications over the 4 channels of up to 40 Gbps.  The NG-PON2 standard describes several possible subscriber deployment rates for downstream and upstream, including 10Gbps/10Gbps for each subscriber, as well as 10Gbps/2.5Gbps and 2.5Gbps/2.5Gbps.

2) GPON vs XG-PON vs XGS-PON vs NG-PON2 – What is the difference?

GPON technology has been the most widely used PON standard in FTTH networks.  The ITU standard has been updated to handle higher transmission speeds, which resulted in the development of XG-PON (in 2010) and XGS-PON (in 2017), which can handle bitrates of up to 10Gbps.

NG-PON2 – In between the development of XG-PON and XGS-PON, NG-PON2 was standardized in 2013.  NG-PON2 uses TWDM (Time and Wavelength Division Multiplexing) to handle both asymmetrical (10Gbps/2.5Gbps) and symmetrical transmission  (10Gbps/10Gbps) over multiple channels and across tunable wavelengths.

XG-PON vs XGS-PON– As mentioned earlier, XG-PON was standardized in 2010 and provides asymmetric bandwidths of 10Gbps downstream and 2.5Gbps upstream. However, XGS-PON is not a development of XG-PON, as its name might suggest, but is an adaptation of TWDM-PON used in NG-PON2 without multi-channels and tunable wavelengths.  Therefore, XGS-PON can provide both asymmetrical transmission at 10G/2.5G or symmetrical transmission at 10G/10G versus XG-PON which is only able to provide asymmetrical 10G/2.5G. 

XGS-PON and NG-PON2 – With enhanced speeds over GPON, both offer the opportunity of advanced services for FTTH, support mission-critical business applications and underpin 5G mobile.  The key difference between XGS-PON and NG-PON2 is the multiple  tunable wavelengths supported by NG-PON2, versus the fixed wavelengths supported by XGS-PON.

3) GPON, XGS-PON and NG-PON2 Wavelengths for Service Flexibility

Because XGS-PON and NG-PON2 were designed to co-exist with GPON, the standards use different wavelengths on the same fiber, which enable different portions of the optical distribution network (ODN) to be used to provide different levels of service for different purposes and applications. For example, service providers are able to increase the bandwidth capacities of existing FTTH GPON networks, reduce deployment costs, enable more customers to share the same fiber and even enable multiple operators to share the same network.

GPON technology diagram

The diagram above shows each Transmission Standard and the wavelength range used, along with the potential upload and download speeds.

4) Selecting the Right PON Transceiver

Transceivers are an essential part of any Passive Optical Network and are needed at both the central optical line terminal (OLT) and subscriber optical network unit (ONU). PON transceivers are specifically designed for use in passive optical networking and use different wavelengths to transmit and receive signals between the OLT and ONU.

When selecting the right PON transceiver there are several selection criteria to consider:

  • OLT or ONU – to determine where the transceiver will be used
  • Form Factor – different form factors are available depending on the PON standard being used. For example, SFP (Single Form Factor Pluggable), SFP+ (Enhanced Small Form-Factor Pluggable), XFP (10 Gigabit Small Form Factor Pluggable).  The table below shows the form factors for each of the PON standards.
  • GPON SFP transceivers are available in two classes – Class B+ and C+. The main differences between the classes being:
    • the amount of power transmission (Tx) and reception (Rx) they can support, along with
    • the number of connections they can support. Class B+ support up to 32 ONUs and Class C+ supports up to 64 end-user ONU connections.
 
GPON
XG-PON
XGS-PON
NG-PON2

Transceiver Form Factors

SFP Bi-directional transceiver with SC connector over simplex single-mode fiber.

Available in Class B+ and Class C+

XFP

XFP

SFP+ / XFP

5) Selecting PLC Splitters used in Passive Optical Networks

A PLC splitter (PLC stands for Planar Lightwave Circuit) is the device at the heart of the PON used to split light beams received from the OLT into multiple light beams to be transmitted to ONUs.  The PLC splitter also receives light beams back from multiple ONUs and combines them back into one light beam.  Usually positioned at a central office or at distribution points within the passive optical network. 

Split ratios – GPON technology can typically handle up to a 1:128 split ratio. Newer 10G GPON technologies can handle up to a split ratio of 1:256 (or 2:128). 

Find out more about Pro Optix PLC Splitters >

PLC Splitters
PLC Splitters

GPON, XGS-PON and NG-PON2 – Offering flexible, reliable networks of the future

The latest 10G-PON standards, XGS-PON and NG-PON2, enable service providers to increase their FTTH networks’ bandwidth capacities and reduce costs by sharing the same fiber with more connected customers. PON networks are generally more cost-effective to build and maintain compared to active point-to-point networks. Because PON uses passive components and shares a fiber cable between multiple users, the need for active equipment is reduced, leading to lower costs for installation and operation. In addition, it provides the flexibility to offer different service levels for FTTH, but also for businesses needing much higher bandwidth for critical applications, and for the networks needed to support smart cities, smart infrastructure 5G mobile networks.

Find out more about Pro Optix GPON, XGS-PON and NG-PON2 >

GPON Technology Facts

 

What to read next...

 
Nordiskt TV-Bolag
Pro Optix Products

The Pro Optix Product Porftolio

Our comprehensive portfolio of fiber optical networking solutions enables us to offer our customers a solution tailored to their specific network demands.

+ View Products
Channel Partner Services
Maximising Opportunities and Driving Business

Channel Partner Services

Pro Optix have offered a suite of value-added services to enable our channel partners maximise opportunities and drive their business. Our specialist value-added services include network design, testing lab facilities, logistics and delivery, marketing support and more.

+ Learn More
 

Newsletter Subscribe