Patent Application
20120134663
Existing optical communication systems sometimes include a primary optical communication path and a protection path (also referred to as a backup path) for use in the event of fault or failure on the primary optical path. When only optical data is being transferred within a system, the existing protection path mechanism may be adequate to enable communication to continue despite the existence of a disruption in the primary path.
However, more modern communication systems may include one or more data streams that converge with data on the optical data paths at a downstream location. Such other data streams may include optical or other forms of data. In the event of a failure on the primary optical path, the additional data streams continue to supply data intended to converge with the primary optical data path. However, with the primary optical data path in a failure mode, the additional data streams will end up going unused and be lost.
Accordingly, there is a need in the art for an improved system and method for combining data on a primary optical data path with one or more additional data streams in the event of a fault condition on a primary data path.
According to one aspect, the invention is directed to a system that may include an optical line terminal (OLT); an optical splitter; primary and backup optical paths extending from the optical line terminal to the optical splitter; a video feed system having a first and second video output paths; and a network management system in communication with the OLT and operable, in the event of a fault, to cause the video feed to switch a flow of video data from the first video output to the second video output path and to merge the video with the backup optical path extending from the OLT to the optical splitter, thereby providing a merged data stream.
According to another aspect, the invention is directed to a reflector assembly that may include a housing; a fiber stud disposed within the housing; a filter lens having an OTDR reflective layer, the filter lens located downstream from the fiber stud and receiving light energy from the fiber stud, and configured to be transparent for light within a communication wavelength band and reflective within a diagnostic wavelength band.
Other aspects, features, advantages, etc. will become apparent to one skilled in the art when the description of the preferred embodiments of the invention herein is taken in conjunction with the accompanying drawings.
For the purposes of illustrating the various aspects of the invention, there are shown in the drawings forms that are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
In the following description, for purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one having ordinary skill in the art that the invention may be practiced without these specific details. In some instances, well-known features may be omitted or simplified so as not to obscure the present invention. Furthermore, reference in the specification to phrases such as “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of phrases such as “in one embodiment” or “in an embodiment” in various places in the specification do not necessarily all refer to the same embodiment.
Video feed 300 may include video data communication paths 310 and 320 which may be configured to converge with optical data paths 112 and 122 respectively. Optical splitter 400 may include upstream (i.e. OLT side) ports 410 and 420 and downstream (i.e. ONT side) ports 430 and 440 which may be coupled to optical paths 432 and 442 respectively. ONTs 500 and reflectors 600 are discussed in greater detail in connection with
Under normal operating conditions, OLT 100 conducts optical data communication with optical splitter 400 along primary optical data path 112. Moreover, video feed 300 provides video data that is configured to merge with the optical data from OLT 100 along primary video data path 310. Data paths 310 and 112 are shown converging at node 114. Node 114 is shown at a mid-point along path 112 for the sake of convenience. The optical and video data paths preferably converge within port 410 of optical splitter 400. However, the present invention is not limited to this implementation. The combination of the video and optical data paths could be combined at any desired point.
In the event of a fault condition, OLT 100 transfers the flow of optical data from port 110 and primary data path 112 to port 120 and backup data path 122. In order to ensure that the process of combining of video data from video feed 300 and optical data through OLT 100 continues, OLT 100 notifies network management system 200 of the fault condition. Upon being notified the fault condition, network management system 200 preferably causes video feed 300 to switch the flow of video data from data path 310 to data path 320 so as to combine the video data with the data on backup optical path 122. The video data and optical data, for the sake of convenience, are shown converging at node 124. However, system 10 may be configured to cause the actual physical combination of the two data streams to occur wherever this data convergence can be most effectively accomplished.
Thus, the data streams from video data path 320 and optical data path 120 are combined once at port 420 of optical splitter 420. In the above manner, video feed 300 and/or other possible sources of data suitable for combination with data from OLT 100 may be switched to suitable alternative data paths in the event of a fault condition on the primary optical data path 112.
The path of standard PON communication signals (also referred to as communication signal energy) is indicated by solid line 102. The OTDR signal energy preferably includes signal energy with a wavelength of between about 1625 nm and 1670 nm and is indicated with dashed line 622 which includes dashes of substantially equal length. Links in system 10 carrying a combination of PON communication 102 and OTDR signals 620 are indicated using a combined signal 152 indicated with a dashed line that includes dashes of unequal length.
For the sake of convenience, the communication from OTDR device 620 is marked as a dashed line, with reference numeral 622, identifying the OTDR signal present on that link. Likewise, other signal types have identifiers, such as conventional PON communication out of OLT 100, which is designated with reference numeral 102. It is believed helpful to identify the preferred type of physical link in each section of the system shown in
Under normal operation, in the absence of a fault condition, a standard stream of optical data proceeds from OLT 100 over a fiber optic link to multiplexer 150, is then split at splitter 400, and then proceeds along paths 432 and 442 toward ONTs 502 and 504 respectively. If OLT 100 detects a communication failure between OLT 100 and any of ONTs 500, OTDR signaling device 620 is preferably activated. It is noted that, in the prior art, it would be difficult to determine whether the communication failure resides somewhere on the optical fiber links coupling the various devices or within one of the ONT 500 devices.
Upon determining that a communication breakdown exists somewhere between OLT 100 and ONT 502 (or any other ONT), the OLT 100 may notify NMS 200 of the fault condition. NMS 200 may then instruct OTDR signal generator 620 (or other suitable device) to transmit a test signal and then measure for any reflection of the test signal to determine whether the fault lies between multiplexer 150 and one of reflectors 602 or 604. The OTDR test signal 622 may have a wavelength between about 1625 nm and 1670 nm. However, the invention is not limited to the above-specified wavelength, and test signals having other wavelength values may be employed for OTDR test signal 622. Once the test signal is transmitted, the OTDR test signal is preferably reflected by reflector 602 or 604, even while reflectors 602, 604 allow non-OTDR light energy to pass therethrough mostly or completely undisturbed.
After sending the test signal, OTDR 620 preferably measures any reflected signal energy along the fiber link between OTDR 620 and multiplexer 150. If significant reflected signal energy is present, system 10 presumes that all fiber links in system 10 are operational and that the ONT to which the PON message was sent from OLT 100 is at fault. A threshold may be established above which the method disclosed herein determines that the OTDR signal is being reflected and the fault lies with the ONT 500. If reflected OTDR signal energy is below the threshold, the method disclosed herein preferably determines that there is a failure in the optical link leading upstream from the ONT 500 being tested. The pertinent threshold may be set to any desired proportion of the magnitude of the outgoing OTDR test signal, such as but not limited to 70%, 60%, 50%, 40%, 30%, 20%, 10% or other proportion of the magnitude of the outgoing OTDR test signal 622.
In one embodiment, if reflected OTDR signal energy is not detected at OTDR 620, the system 10 presumes that a fiber link between OTDR 620 and an ONT 500 has failed. In the case where multiplexer 150 is located very close to OTDR 620, the fiber link failure is presumed to have occurred between multiplexer 150 and the ONT 500 to which the PON message was sent by OLT 100.
Where needed, in order to ensure the reflected OTDR signal energy 622 is being reflected by the ONT 500 of interest, and not a different ONT, the outgoing OTDR signals may be adjusted such that wavelength of the outgoing OTDR signal has a different value for each ONT that is in communication with multiplexer 150. Alternatively, the outgoing OTDR test signal from OTDR device 620 may include an address designation to ensure that the OTDR test signal is sent only along the optical path of interest (such as, for instance, the optical path leading to ONT 502).
Various embodiments of the system shown in
The OTDR signal 622 may be configured to include clear peaks to enable easy location and identification of the various ONTs. The use of high-precision reflectors, such as for reflectors 602 and 604, makes it possible to diagnose subtle changes in the optical links within system 10. The determination of the location of the fault, using reflectors 602, 604 preferably enables a clear separation of maintenance and repair responsibilities between the service provider and a customer-owned ONT 500.
The materials for various components within reflector assembly 600 are briefly discussed here. Ball lens 618 is preferably made of glass. Fiber ferrule 612 is preferably made of ceramic. Housing 608 is preferably made of plastic. OTDR reflective layer 614 is preferably made of a multi-layer dielectric on glass.
In some embodiments, the OTDR reflector 600 can be incorporated within an ONT 500 to achieve compactness and a high degree of compatibility between the reflector 600 and the remainder of the ONT 500. Alternatively, the OTDR reflector 600 could be embedded within a bi-directional optical sub-assembly (BOSA).
In an embodiment, RAM 906 and/or ROM 908 may hold user data, system data, and/or programs. I/O adapter 910 may connect storage devices, such as hard drive 912, a CD-ROM (not shown), or other mass storage device to computing system 900. Communications adapter 922 may couple computing system 900 to a local, wide-area, or global network 924. User interface adapter 916 may couple user input devices, such as keyboard 926, scanner 928 and/or pointing device 914, to computing system 900. Moreover, display adapter 918 may be driven by CPU 902 to control the display on display device 920. CPU 902 may be any general purpose CPU.
It is noted that the methods and apparatus described thus far and/or described later in this document may be achieved utilizing any of the known technologies, such as standard digital circuitry, analog circuitry, any of the known processors that are operable to execute software and/or firmware programs, programmable digital devices or systems, programmable array logic devices, or any combination of the above. One or more embodiments of the invention may also be embodied in a software program for storage in a suitable storage medium and execution by a processing unit.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
