The document discusses key concepts and technologies of GPON (Gigabit-capable Passive Optical Networks), including:
1) The basic architecture of PON networks consisting of an OLT, ONUs, and a passive optical splitter.
2) Reasons for adopting the GPON standard such as supporting high-bandwidth transmission and long reach.
3) Key GPON technologies including ranging, equalization delay, dynamic bandwidth assignment (DBA), and wavelength division multiplexing (WDM) for upstream/downstream transmission.