GPON consists of three main elements

 

OLT (Optical Line Terminal), ONU (Optical Network Unit) devices, and passive splitters. Passive optical splitters typically split the signal up to 64, allowing the use of only one fiber optic cable connecting the Internet service provider with multiple end users.

So how does the whole process work? In simple terms, it goes like this:

• First, the optical line terminal transmits data in the form of optical signals through a process called optical wavelength division multiplexing (WDM). The OLT is usually an ISP and can be thought of as the starting point of GPON.

• The signal propagates on a single optical fiber through the Optical Distribution Network (ODN) and finally reaches a passive splitter. GPON fiber optic networks can reach distances of up to 20 km.

• The passive GPON splitter receives the optical signal and splits it into up to 64 multiple signals. This allows point-to-multipoint access and up to 64 fiber optic connections.

• Finally, the last mile split optical signal reaches individual GPON ONT/ONU devices installed on the premises of a residential or commercial building. This is the endpoint of GPON, which can convert optical data signals to electrical signals. Conversely, data is transmitted upstream from GPON ONT/GPON ONU to OLT.

 

GPON has another great feature: it integrates voice and data traffic on the same network using Asynchronous Transfer Mode (ATM) coding. After all, GPON is very useful today to securely deliver triple play services (data, IPTV, VoIP) at higher data rates, higher bandwidth, and longer distances. GPON also supports all types of Ethernet protocols.

 

How does GPON work?

Now that we have a good understanding of GPON, it is natural to try to understand how it works. The key to GPON's operation is its point-to-multipoint access fiber network topology.