PON principle

With the popularization of Ethernet technology in the metropolitan area network and the development of broadband access technology, people have proposed broadband PON technologies with a rate of 1 Gbit/s or more, including EPON and GPON technologies: "E" refers to Ethernet, " G" refers to gigabit level.

The relevant standards of EPON and GPON are formulated by different standards organizations. Among them, EPON is proposed by IEEE 802.3ah, which combines Ethernet technology with PON technology. Its goal is to achieve a point-to-multipoint structure Bit Ethernet optical fiber access system in the simplest way. GPON technology is standardized by ITU, the main goal is to achieve Gbit/s rate, and can support multiple services, and optimize all services.

PON is composed of optical line terminal (OLT), photosynthesis/splitter (Spliter) and optical network unit (ONU), and adopts a tree topology. The OLT is placed at the central office to allocate and control the channel connection, and has real-time monitoring, management and maintenance functions. The ONU is placed on the user side, and the OLT and ONU are connected through a passive photosynthesis/splitter.

PON uses Wavelength Division Multiplexing (WDM) technology to process two-way signal transmission at the same time. Upstream and downstream signals use different wavelengths, but are transmitted in the same optical fiber. The direction from the OLT to the ONU/ONT is the downstream direction, and vice versa is the upstream direction. The downstream direction uses 1490nm, and the upstream direction uses 1310nm.