GPON Knowledge Sorting
An access network (AN) is a series of transmission entities (such as line and transmission facilities) between service node interface (SNI) and user network interface (UNI), which is an implementation system providing bearer capabilities for telecom services.
Classification by transmission mode:
- Wired mode
Twisted pair copper cable access, coaxial cable access, and optical fiber access
Fixed wireless access and mobile wireless access
The use the advanced digital signal processing technology to provide broadband digital access on twisted-pair copper lines. In this way, the supports digital signal line coding and two-wire duplex digital transmission on non-inductive subscriber lines, improving the transmission capacity and transmission rate. This is the so-called copper line access technology.
The following figure shows the limitations of copper line access.
Access Network Trend – Fiber-in Copper-out
Considering many broadband applications in the future, more and more countries realize that the bottleneck of access must be broken as soon as possible. Optical fibers are the best transmission media by far.
What is GPON?
A passive optical network (PON) is a point-to-multipoint (P2MP) passive optical network. The mainstream PON technologies include broadband passive optical network (BPON), Ethernet passive optical network (EPON), and gigabit-capable passive optical network (GPON). BPON uses the ATM encapsulation mode and is mainly used to carry ATM services. However, with the obsolescence of ATM technology, BPON technology also disappears. EPON is an Ethernet passive optical network technology.
GPON is a gigabit passive optical network (GPON) technology, which is the most widely used mainstream optical access technology. It is a gigabit PON defined by ITU-T G.984.x series standards.
The following figure shows the GPON network structure.
IFgpon: GPON Interface SNI: Service Node Interface
UNI: User to Network Interface CPE: Customer Premises Equipment
With the popularization of broadband services and the trend of replacing copper cables with optical cables, carriers have higher requirements on the transmission distance, bandwidth, reliability, and low operating expense (OPEX) of services. The following features of GPON meet these requirements:
- Longer transmission distance: Optical fibers are used for transmission. The maximum coverage radius of the access layer is 60 km. This resolves the conflict between the distance and bandwidth of twisted pairs.
- Higher bandwidth: Each port supports a maximum downstream rate of 2.5 Gbit/s and a maximum upstream rate of 1.25 Gbit/s. This feature meets users’ requirements for high-bandwidth services, such as high-definition television (HDTV) and live broadcast.
- The flexible full-service experience offered by Quality of Service (QoS): QoS controls traffic for different users and user services, ensures multi-service bandwidth for multiple users, and provides differentiated services based on different user services.
- Optical splitting: A single fiber in the central office is divided into multiple drop fibers with the help of an optical splitter. The optical split ratio of 1:128 is supported. In this way, GPON saves backbone fiber resources and reduces O&M costs.
I hope that today’s content will help you understand the basic contents of GPON. If you have any questions, please feel free to contact: [email protected]