Do we need xPON and how does it work?

It seems to us that many operators have not studied the xPON topic sufficiently deeply, despite the presence of a large amount of advertising and educational information on the Internet. However, this does not apply to those who have chosen high-rise buildings as their area. In this case, the propensity for Ethernet is fully justified and xPON is simply not required.
However, for operators who are forced to delve into the unknown expanses of world, strewn with cottage villages and villages in which there is no 3G / 4G network coverage, the question "to build or not to build" is not worth it. Moreover, most users in any situation want to see something like:



Well, how would they provide something like that?


The development of the material and technical base and the reduction in the cost of materials (optical fiber, of course) for Ethernet installation removed most of the problems of this system. And the presence of a huge layer of information in the public domain allows you not to dwell on the features of the assembly. It's hard to imagine an operator who has never used something like this, but few have encountered xPON.


In the legendary, but not very distant, past, xPON was invented for the operators of America. His idea is simple, like tree-like optical lines onto which the transmitted data is superimposed. They didn’t do anything more complicated at a more or less acceptable cost and used TDM.

The wavelength at which the OLT signal emits is 1490 nm, while ONTs operate at 1310 nm. Due to the design features (we have TDM here), all ONUs include learning only at certain points in time. As a result, they are more complicated and more expensive than constantly emitting Ethernet media converters. Transceivers for OLT - WDM 1490/1310 nm, and for ONT - on the contrary, with Tx / Rx 1310/1490 nm. The wavelength of 1550 nm is allocated specifically for KTB, which can be superimposed on the optical network using 2xN dividers or WDM filters with the corresponding characteristics.


One OLT can easily support an entire customer community. A typical unit, in which you can put a huge bush of opportunities, looks something like this:



The subscriber gets a device called ONU / ONT. This switch typically has Ethernet and an optical PON port. Complement the set of Wi-Fi, RF overlay and something else.



GPON and GEPON. Is there any difference?

Standard answer: Gigabit PON is ITU G.984, and Gigabit Ethernet PON is IEE 802.3ah. What would that mean?

Pros:

Easy settings.

Low price.


The absence of a standard and the linear code assigned to redundancy, in which the “clean” band is less by twenty percent (8B / 10B), are considered negative properties.