Hello, everyone!
Today, I want to start to explain the XG(S)-PON technology. This is a very important topic because the migration from GPON to XGS-PON has started in the last few years.
The first phase of the XG-PON standard was published in October 2009. ITU-T defined XGS-PON in June 2016. Figure 1. shows the evolution of GPON to XG-PON and XGS-PON.
10G-PON or XG(S)-PON was created with the development of GPON technology. “X” is the Roman number 10. There are two versions of this standard: asymmetric – XG-PON and symmetric – XGS-PON. The XG-PON has 10 Gbps for downstream and 2.5 Gbps for upstream. The XGS-PON has 10 Gbps for downstream and 10 Gbps for upstream. The new standard works at 1578 nm for downstream and 1270 nm for upstream.
Figure 1. Evolution from GPON to XG(S)-PON
There are many reasons why it is necessary to implement XG(S)-PON. An increasing number of services require larger bandwidth and a large number of business users. XG(S)-PON allows more sharing and more distance between OLT and ONU devices. This allows us to build larger ODN networks. GPON can't do it.
GPON and XG(S)-PON standards use different wavelengths, because of that, both standards can use the same optical fiber (figure 2). And, this is used for migration from GPON to XG(S)-PON.
Figure 2. Wavelengths of GPON and XG(S)-PON
The main features of GPON, XG-PON and XGS-PON are shown in the next figure.
Figure 3. The difference between GPON and XG(S)-PON
XG(S)-PON architecture consists of:
OLT (Optical Line Terminal) - the main element of the system, which allows ONUs to connect to it and enable services over the ODN network. It is usually located in the headend or CO (Central Office).
ODN (Optical Distribution Network) is the largest part of the system. They allow the connection of OLT and ONUs. It consists only of passive elements - optical cables, optical closures, optical splitters, etc. There are three segments: feeder, distribution, and drop segment.
ONU is a subscriber's device in a house, building, or outdoor cabinet. It performs signals conversion and enables services. There are a number of different types.
In the next figure, we can see this architecture.
Figure 4. The architecture of XG(S)-PON
This is the end of this article. I will continue to write about this topic in the next article >> XG(S)-PON (2): Basic concepts.
Thank you!
