Like all PON systems, GPON consists of ONU, OLT, and passive optical distribution networks. OLT provides the interface between the network side and the core network for the access network, and connects with each ONU through ODN. As the core function equipment of PON system, OLT has the functions of centralized bandwidth allocation, control of ONU, real-time monitoring, operation and maintenance management PON system. The ONU provides the user side interface for the access network, and provides the ODN access to the voice, the data, the video and so on, which is controlled by the Olt centralized control. The system supports a branch ratio of 1:16/32/64, with the development of Optical transceiver module, the Support branch ratio will reach 1:128. Gpon transmission mechanism and epon are identical, using single fiber bidirectional transmission mechanism, on the same fiber, using WDM technology, transmission up and down data at different wavelengths. In the same optical fiber, the GPON can be used to realize the bidirectional transmission of the signal using Wavelength division multiplexing (WDM) technology. According to the actual needs, we can also improve the survivability of the network by adopting the corresponding PON protection structure on the basis of the traditional tree topology.
The GPON technical features are mainly embodied in the transmission aggregation layer. The GPON protocol reference model is shown in the graph, in which the transport aggregation layer is divided into the PON frame and the suitable gamete layer. GTC (GPON transmission convergence) of the frame to complete the GTC frame of the encapsulation, the end of the required ODN transmission function, the specific functions of pon (such as ranging, bandwidth allocation, etc.) also in the Pon's frame of the end of the layer, in the appropriate gametes layer can not be seen. The GTC's suitable gametes layer provides the interface between the PDU and the high-level entity. ATM and Gem Information completes the conversion of the Business Data Unit (SDU) and the PDU of the Protocol Data unit in its respective adaptive gametes layer. OMCI is higher than ATM and gem-suitable gametes layer, it recognizes/and Port-id, and completes OMCI channel data exchange with high-level entities.
Application of GPON in Access network GPON can be applied to the fiber in the access network to the household, fiber to the floor/roadside and fiber to junction box.
1. FTTB for Business
Symmetric broadband services (such as group Software, Content broadcast, e-mail, file interaction, etc.) POTS and ISDN dedicated lines (GPON must be able to flexibly provide dedicated line services at different rates).
2. FTTC and Fttcab
Asymmetric broadband services (such as digital broadcasting services, VOD, IPTV, file downloads, online games, etc.) symmetric broadband services (such as content broadcast, e-mail, file interaction, distance education, remote diagnostics, etc.) POTS and ISDNXDSL extension.
Asymmetric broadband services (such as digital broadcasting services, VOD, IP TV, file downloads, etc.)
Symmetric broadband services (such as content broadcast, e-mail, file interaction, distance education, remote diagnostics, online games, etc.).