Hello, everyone!
Today I will write about migration from GPON to XG(S)-PON. This is a very popular and important topic today.
High demands of users for internet speeds, new services, have led to the development of access networks, especially PON networks. PON networks have experienced great popularity in the last 10 years.
Low prices of optical cables and other passive and active equipment have enabled the mass use of optical cables in access networks. In addition, there has been an accelerated development of PON. Old access networks, such as HFC, xDSL, etc, slowly began to be suppressed. An increasing number of telecommunications operators have begun to introduce PON.
Two independent international organizations have developed PON standards. These are ITU and IEEE. ITU PON standards started with APON, then BPON, GPON, XG(S)-PON, 25G-PON, etc. On the other hand, the IEEE organization has developed its own standards - EPON, 10GE-PON, 25GE-PON, etc. For more information, you can read about these standards at the following link: PON Standard evolution.
The main features for actual PON standards are shown in the next table.
PON | APON | BPON | GPON | EPON | XG(S) PON | 10G EPON |
Standard | G.983 | G.983 | G.984 | 802.3 ah | G.987 | 802.3 av |
Frame | ATM | ATM | GEM | Ethernet | XGEM | Ethernet |
Downstream wavelength | 1550 nm or 1310 nm | 1490 nm | 1490 nm | 1490 nm | 1578 nm | 1578 nm |
Upstream wavelength | 1310 nm | 1310 nm | 1310 nm | 1310 nm | 1270 nm | 1310/1270 nm |
Max speed | 622/155 Mbps | 1.2Gbps/622 Mbps | 2.5/1.25 Gbps | 1/1 Gbps | 10/1.25 Gbps or 10/10 Gbps | 10/1 Gbps |
Number of fibers | 1 or 2 | 1 | 1 | 1 | 1 | 1 |
Split Ratio | 32 | 32 | 128 | 64 | 128/254 | 128 |
Max Distance | 20 km | 20 km | 20 km | 20 km | 20/40 km | 20 km |
Fiber Type | G.652 | G.652 | G.652, G.657 | G.652 | G.652, G.657 | G.652, G.657 |
Table 1. PON standards
The architecture of all PON standards is the same:
OLT (Optical Line Terminal). The main device in the PON system. OLT is a multi-service access device, which can have many functions. Generally, it allows ONU to connect to MAN/WAN network. OLT can be located in headend or central office. Sometimes, there are remote OLTs.
ODN (Optical Distribution Network). It is a total passive optical network, which is composed of feeder optical cables, distribution optical cables and drop optical cables. And,
ONU/ONT (Optical Network Unit/Optical Network Terminal). It is the user’s device, which converts signals and allows services.
Each of these PON standards has different scenarios, it depends on the location of the ONU device. So we have:
FTTC – Fiber To The Curb,
FTTB – Fiber To The Building,
FTTH – Fiber To The Home,
FTTO – Fiber To The Office,
FTTD – Fiber To The Desk, etc
Today, the most popular are FTTH GPON systems. But in recent years, migration from GPON to the next generation of PON - mostly XGS-PON - has begun.
I will continue to write about this topic in the next article >> Evolution from GPON to XG(S)-PON (2).
Thank you!
