GPON Technology Introduction

- Jul 15, 2019-


GPON(Gigabit passive active network) is called Gigabit-capable PON Gigabit / Gigabit passive fiber network and is also an passive passive fiber network. The GPON service is an extension of BPON. Compared with other PON standards, the GPON standard provides unprecedented high bandwidth(down rate of nearly 2.5 Gbps), and its asymmetric characteristics can be more suitable for the broadband data service market; It provides QoS full-service security, while carrying ATM letter elements and/or GEM frames, with a good service level, QoS guarantee and full-service access capabilities; When hosting GEM frames, the TDM business can be mapped to GEM frames, and the standard 8kHz(125μs) frame can directly support the TDM business. As a technical standard at the telecommunications level, GPON also stipulates protection mechanisms and complete OAM functions at the access level. The maximum downlink transmission rate can be as high as 2.488 Gps, the maximum uplink transmission rate can reach 1.244 Gbps, and the transmission distance can reach 20 to 37 kilometers. Therefore, it has many characteristics such as high bandwidth, high speed, efficient transmission, large-scale coverage, and rich user interface. Therefore, It has been regarded by most operators as an ideal technology to realize the broadband and integrated transformation of the access service.
As a flexible broadband fiber access technology proposed by ITU-T, in the GPON standard, the types of services that GPON needs to support include data services(Ethernet services, including IP services and MPEG video streams), and PSTN services(POTS, ISDN services), dedicated lines(T1, E1, DS3, E3 and ATM services) and video services(digital video), Can meet multi-user VoIP, multi-video streams using MPEG-2 or -4 specifications(such as IPTV) and standard resolution television(SDTV) or high-definition television(HDTV) and multi-user high-speed Internet access and other "three-network integration" requirements. The multi-service mapping in GPON is transmitted to ATM cells or GEM frames to provide QoS guarantees for various business types. GPON generally adopts a tree(or tree) topology. If business protection and channel protection are required, a protection ring can be added to provide protection for some optical network terminals ONT.
It is composed of the Optical Line Terminal OLT(Operation Line Terminal), the Optical Network Terminal ONT(Operation Network Terminal) / ONU(Operation Network Unit) and the circular(or tree-shaped) topology of the passive light network PON. OLT is located in the central computer room and provides wide area network interfaces up, including GbE, OC-3 / STM-1, DS-3, etc.. Downward to PON, it can provide 2.488 Gbps optical interfaces. ONT/ONU is placed on the user terminal and provides users with 10/100 BaseT, T1/E1, DS-3 application interfaces. The optical interface rate for PON is 155Mbps, 622Mbps, and 1.244 Gbps.
And 2.488 Gbps and other options. The direction from OLT to ONT/ONU is in the downward direction, using the data flow transmission method transmitted by broadcast; In the uplink direction, time division multiple access technology based on statistical multiplexing is adopted. PON can cover the full duplex transmission of data flows by using CWDM(Coase Wavelength Division Ltiplexing) through rough wave division multiplexing.

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