Patent ID: 11936432
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 5:
6. An optical line terminal (OLT) system of a passive optical communication network, the OLT system comprising:
a first OLT configured to output a first optical signal;
a second OLT configured to output a second optical signal; and
an OLT control device configured to control the first OLT and the second OLT,
wherein the first OLT and the second OLT are connected with a plurality of splitters and a plurality of optical network units (ONUs) via an optical communication path, and both ends of the optical communication path are connected to the first OLT and the second OLT, respectively,
a first splitter of the plurality of splitters distributes and outputs the first optical signal transmitted from the first OLT to a first ONU of the plurality of ONUs connected to the first splitter and a first succeeding splitter of the plurality of splitters,
a second splitter of the plurality of splitters distributes and outputs the second optical signal transmitted from the second OLT to a second ONU of the plurality of ONUs connected to the second splitter and a second succeeding splitter of the plurality of splitters,
the OLT control device determines a distribution ratio at each of the first splitter and the second splitter, the OLT control device controls the distribution ratio at each of the first splitter and second splitter, the distribution ratio indicating a ratio between an intensity of one of the first and second optical signals distributed to a corresponding one of the first succeeding splitter and the second succeeding splitter and an intensity of one of the first and second optical signals distributed to a corresponding one of the first ONU and the second ONU,
during normal communication where no failure is detected in the passive optical communication network, each of the plurality of ONUs is configured to receive the first and second optical signals and select one of the first and second optical signals, and the selected one has a higher light intensity than the other of the first and second optical signals, and
during failed communication where a failure is detected in the passive optical communication network, each of the plurality of ONUs is configured to receive one of the first and second optical signals, and
wherein the OLT control device determines and controls the distribution ratio at each of the first splitter and second splitter according to the first OLT being an assigned OLT, and determines and controls the distribution ratio at each of the first splitter and second splitter according to the second OLT being the assigned OLT.