Optical network, monitoring unit and monitoring method
An optical network having a tree-like structure with a main line and a plurality of branches, at least two of the branches comprising a monitoring unit for upstream signalling to the main line, wherein each of the monitoring units comprises a signal generation unit with a light source for generation of a pre-defined optical signal, and the monitoring units are construed to generate pre-defined optical signals which are different from each other, as well as a monitoring unit for generating a periodic upstream signal in such an optical network and a method for monitoring such an optical network.
1. A passive optical network, comprising:
a tree-like structure with a main line and a plurality of branches extending from a switch to optical network terminations of a user network, at least two of the branches including; and
monitoring units, between the switch and respective ones of the optical network terminations, for upstream signaling to the main line, each of the monitoring units including a signal generation unit with a light source, each signal generation unit configured to generate an optical signal with a period different from that of the optical signal of other monitoring units in the passive optical network;
wherein the passive optical network is configured to superimpose the optical signals of the monitoring units at the main line so that in a length of time corresponding to a longer period or a longest period of any of the optical signals with different periods, the superimposed signal includes at least one period of each of the optical signals with the different periods.
2. The passive optical network of claim 1 , wherein each signal generation unit is configured to generate binary optical signals including patterns different from the patterns of the binary optical signals of the other monitoring units in the passive optical network.
3. The passive optical network of claim 1 , wherein the signal generation unit of at least one of the monitoring units is configured to code status information about the at least one of the monitoring units into the optical signal of the at least one of the monitoring units.
4. The passive optical network of claim 1 , including a signal processing unit connected to the main line and configured to recover the optical signals from the superimposed signal.
5. The passive optical network of claim 1 , wherein at least one of the monitoring units includes an electrical power supply.
6. The passive optical network of claim 1 , wherein at least one of the monitoring units includes an optical-to-electrical (o/e)-conversion element connected to the branch corresponding to the at least one of the monitoring units,
wherein the o/e-conversion element is connected to an energy storage, and
wherein the energy storage is connected to the signal generation unit of the at least one of the monitoring units.
7. A monitoring unit configured to generate a periodic upstream signal in the passive optical network of claim 1 , comprising:
a signal generation unit including a light source and an optical-to-electrical (o/e)-conversion element, the light source and the o/e-conversion element configured to connect to a branch of the passive optical network;
an energy storage connected to the o/e-conversion element; and
a switch configured to activate an electrical connection between the energy storage and the signal generation unit when a threshold level of energy stored in the energy storage is reached.
8. A monitoring method for a passive optical network having a tree-like structure with a main line and a plurality of branches extending from a switch to optical network terminations, at least two of the branches each including a monitoring unit configured to signal upstream to the main line, the method comprising:
generating, by each of the monitoring units, an optical signal with a period different from the optical signal of other monitoring units of the passive optical network, each of the monitoring units being between the switch and a respective one of the plurality of optical network terminations;
superimposing the optical signals of the monitoring units at the main line so that in a length of time corresponding to a longer period or a longest period of any of the optical signals with different periods, the superimposed signal includes at least one period of each of the optical signals with the different periods; and
recovering the optical signals from the superimposed optical signal.
9. The monitoring method of claim 8 , including analyzing the optical signals for extracting status information about the monitoring units, the status information being coded into the optical signals by the monitoring units.