Passive optical network system

摘要

When an ONU accommodating range is enlarged, and ONUs shorter and ONUs longer in a communication path to an OLT are accommodated in a PON at the same time, there is a need to change a light intensity at the time of transmitting a downstream signal in order that both of the ONUs receive a downstream signal from the OLT. When a near-end ONU receives a signal having a light intensity necessary to communicate between the OLT and a far-end ONU, there arises such a problem that the light intensity is as high as an ONU receiver fails. In order to eliminate the ONU failure of the above problem, prior to transmission of the downstream signal, a downstream signal transmission schedule (downstream light intensity map) is notified to all of the ONUs. An optical transceiver of the OLT has a function of adjusting an output light intensity, and adjusts the light intensity to values receivable by the individual ONUs when the signal arrives at the respective ONUs according to route distances to the respective ONUs.

主权项

1. A communication system comprising:
a plurality of optical network units, and an optical line terminal connected to the optical network units through optical fibers, wherein the optical line terminal measures communication distances to the optical network units, holds measurement results, adjusts a light intensity of a downstream communication signal to each of the optical network units on the basis of the measurement results, and notifies the optical network units of a transmission schedule of the downstream communication signal prior to transmission of the downstream communication signal, each of the optical network units receives only an optical signal of the subject optical network unit on the basis of the received transmission schedule, and discards or blocks optical signals addressed to other optical network units, and the optical line terminal has a function of transmitting arrival timing information in a given period, in transmitting a signal having the arrival timing information, about the light intensity of the downstream communication signal addressed to the respective optical network units to the respective optical network units in advance, prior to processing of transmitting the downstream communication signal to the respective optical network units.