PON equipment

PON passive optical network technology. Passive optical network technology is a rather popular and rapidly developing technology for multi-service broadband multiple access over a single optical fiber, supporting the time division multiplexing protocol (TDMA).

The main features of the Passive optical network technology are quite effective use of the optical fiber bandwidth and its dynamic distribution. At the same time, it is possible to reserve both all and individual subscribers. And thanks to the use of passive optical splitters, PON’s tree-like fiber-cable architecture helps to effectively increase network nodes and its bandwidth, focusing on real and future user needs.

One fiber-optic PON network segment can include a different number of subscriber nodes, depending on the type of technology:

for GEPON technology – up to 64 nodes within a range of up to 20 km;
for GPON technology – up to 128 nodes within a radius of 60 km.
The essence of the technology lies in the fact that between the headend or the transmitting module of the central OLT (Optical line terminal) and remote subscriber nodes (optical network devices) ONT (Optical network terminal) in ITU-T terminology, or ONU (optical network unit) in IEEE terminology, a passive optical network is created. This tree topology in their intermediate nodes has a so-called splitters ( the PLC Splitters ) – planar dividers (passive optical couplers) or couplers ( Couplers ) – welded dividers (splitters), which need no power, no maintenance. Such a network design allows solving the problem of optical-electrical signal conversion.

Operating principle. To transfer data from the OLT module to the ONT subscriber terminals, infrared radiation with a wavelength of 1490 nm is used. For the return flow of information from subscriber nodes to the central node, a wavelength of 1310 nm is used. For video signals, it is 1550 nm.

Network structure and principle of operation. It should be noted that the TDMA (Time Division Multiple Access) protocol is used for the transmission of upstream streams from subscribers. It regulates the broadcasting of information from various ONTs in accordance with the individual schedule, taking into account the correction for the delay caused by the distance of subscribers from the headend.

PON advantages. Despite the increasing complexity of PON technology, which requires rather thorough training and education of personnel, it has a number of important advantages.

Among the most important, it should be noted that there are significant savings in both fibers (with a network length of up to 60 km, up to 128 subscriber terminals are connected per optical fiber), and optical transceivers at the main node. This network design significantly reduces its cost. And the use of passive equipment in the PON infrastructure reduces the cost of maintaining and operating the distribution network.

The tree-like structure of the network assumes its gradual build-up, i.e. connecting new users in a profitable way that does not require additional costs.

PON technology is characterized by high bandwidth of optical fiber, flexibility, allowing it to be used in various network configurations of the FTTx family, and high reliability.