Single fiber passive optical network wavelength division multiplex overlay

• US 7,254,330 B2
• Filed: 07/19/2002
• Issued: 08/07/2007
• Est. Priority Date: 07/20/2001
• Status: Active Grant

• Current Assignee: Tellabs Bedford, Inc. (Infinera Corp.)
• Original Assignee: Tellabs Bedford, Inc. (Infinera Corp.)
• Inventors: Zuhdi, Muneer, BuAbbud, George H., Pratt, Michael K., Wawro, Debra
• Primary Examiner(s): Li; Shi K.
• Application Number:
  US10/199,566
• Publication Number:
  US 20030076560A1
• Time in Patent Office: 1,845 Days
• Field of Search: 398/63, 398 66- 67, 398/72, 398/76
• US Class Current: 398/67
• CPC Class Codes: H04B 10/27 Arrangements for networking
• CPC Class Codes: H04B 10/272 Star-type networks or tree-type networks
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• CPC Class Codes: H04J 14/0232 for downstream transmission
• CPC Class Codes: H04J 14/0245 for downstream transmission, e.g. optical line terminal [OLT] to ONU
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/0247 Sharing one wavelength for at least a group of ONUs
• CPC Class Codes: H04J 14/0249 for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0252 Sharing one wavelength for at least a group of ONUs, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0291 Shared protection at the optical multiplex section (1:1, n:m)
• CPC Class Codes: H04J 14/0298 with sub-carrier multiplexing [SCM]

Abstract

A single fiber passive optical network (PON) wavelength division multiplex (WDM) overlay includes a central office, a fiber optic network, and a plurality of optical network termination (ONT) units. The central office has a baseline optical link that receives a baseline communication signal and converts the baseline communication signal into a downstream baseline optical signal within a first optical bandwidth, and has an additional optical link that receives a second type of communication signal and converts the second type of communication signal into a second downstream optical signal within a second optical bandwidth. The downstream baseline optical signal generated by the baseline optical link is combined with the second optical signal generated by the additional optical link to generate a broadband optical signal. The fiber optic network is coupled to the central office and receives the broadband optical signal on at least one optic fiber. The fiber optic network splits the broadband optical signal to a plurality of fiber drops. The optical network termination (ONT) units are each coupled to a fiber drop. At least one of the ONT units is a baseline ONT unit that receives the broadband optical signal from the fiber drop and splits the downstream baseline optical signal from the broadband optical signal, and at least one other of the ONT units is an upgraded ONT unit that receives the broadband optical signal from the fiber drop and splits the downstream baseline optical signal and the second downstream optical signals from the broadband optical signal. In addition, the installation of the upgraded ONT unit to the PON does not effect baseline optical service to any other ONT unit.

Claims

1. A system for upgrading a baseline passive optical network (PON), comprising:

a central office having a baseline optical link that receives a baseline communication signal from one or more service provider and converts the baseline communication signal into a downstream baseline optical signal within a first optical bandwidth, and having an additional optical link that receives a second type of communication signal and converts the second type of communication signal into a second downstream optical signal within a second optical bandwidth, wherein the downstream baseline optical signal is combined with the second downstream optical signal to generate a broadband optical signal;

a fiber optic network coupled to the central office that receives the broadband optical signal on at least one optic fiber and splits the broadband optical signal to a plurality of fiber drops; and

a plurality of optical network termination (ONT) units with each ONT unit coupled to a fiber drop, wherein at least one of the ONT units is a baseline ONT unit that receives the broadband optical signal from the fiber drop and splits the downstream baseline optical signal from the broadband optical signal, and wherein at least one other of the ONT units is an upgraded ONT unit that includes a first filter operable to receive the broadband optical signal from the fiber drop and isolate the second downstream optical signal from the broadband optical signal, the upgraded ONT unit including a second filter operable to isolate the downstream baseline optical signal from a remaining portion of the broadband optical signal after the second downstream optical signal has been isolated from the broadband optical signal, the first and second filters operable to pass an upstream optical signal to the fiber drop;

wherein the installation of the upgraded ONT unit to the PON does not effect baseline optical service to any other ONT unit.

2. The system of claim 1, wherein the central office includes a wavelength division multiplexer (WDM) that combines the downstream baseline optical signal with the second downstream optical signal.

3. The system of claim 1, wherein the baseline optical link is a baseline optical line termination (OLT) unit.

4. The system of claim 1, wherein the baseline communication signal includes a telephony signal.

5. The system of claim 1, wherein the baseline communication signal includes a data transmission signal.

6. The system of claim 1, wherein the second type of communication signal is a sub-carrier modulated (SCM) signal.

7. The system of claim 6, wherein the SCM signal includes a community antenna television (CATV) signal.

8. The system of claim 6, wherein the SCM signal includes a direct broadcast satellite (DBS) signal.

9. The system of claim 6, wherein the additional optical link is an optical video distribution sub-system.

10. The system of claim 9, wherein the optical video distribution sub-system comprises an SCM module that receives the SCM signal from one or more service providers and converts the SCM signal into the second downstream optical signal.

11. The system of claim 1, wherein the second downstream optical signal is a T-Band signal.

12. The system of claim 11, wherein the upgraded ONT unit is a T-Band upgraded ONT unit that includes a wave division multiplexer (WDM) that separates the T-Band signal from the broadband optical signal.

13. The system of claim 11, wherein the additional optical link is a course wavelength division multiplexing (CWDM) optical line termination (OLT) unit.

14. The system of claim 13, wherein the upgraded ONT unit is a T-Band upgraded ONT unit that includes a wave division multiplexer (WDM) that separates the T-Band signal from the broadband optical signal, and wherein the T-Band upgraded ONT unit includes a CWDM ONT unit that receives the T-Band signal from the WDM and demultiplexes the T-Band signal.

15. The system of claim 1, wherein the second downstream optical signal is an L-Band signal.

16. The system of claim 15, wherein the upgraded ONT unit is an L-Band upgraded ONT unit that includes a wave division multiplexer (WDM) that separates the L-Band signal from the broadband optical signal.

17. The system of claim 15, wherein the additional optical link is a dense wavelength division multiplexing (DWDM) optical line termination (OLT) unit.

18. The system of claim 17, wherein the upgraded ONT unit is an L-Band upgraded ONT unit that includes a wave division multiplexer (WDM) that separates the L-Band signal from the broadband optical signal, and wherein the L-Band upgraded ONT unit includes a DWDM ONT unit that receives the L-Band signal from the WDM and demultiplexes the L-Band signal.

19. The system of claim 1, wherein the fiber optic network is a point-to-multipoint network.

20. The system of claim 1, wherein the central office includes a cross-connection unit that couples the broadband optical signal to the fiber optic network.

21. The system of claim 20, wherein the cross-connection unit includes a wavelength division multiplexer (WDM) that combines the downstream baseline optical signal with the second downstream optical signal.

22. The system of claim 20, wherein the fiber optic network includes at least two optic paths between the central office each ONT unit, and wherein the cross-connection unit includes an optical route protection switch that switchably connects the broadband optical signal to one of the optic paths.

23. The system of claim 22, wherein the central office includes a route protection control circuit that monitors the continuity of the optic paths in the fiber optic network and causes the optical route protection switch to switch the broadband optical signal from a first optic path to a second optic path if a discontinuity is detected in the first optic path.

24. The system of claim 1, wherein the ONT units receive an upstream baseline signal and convert the upstream baseline signal into an upstream baseline optical signal, wherein the upstream baseline optical signal is transmitted to the central office through the fiber optic network and is received by the baseline optical link.

25. The system of claim 24, wherein the baseline optical link is a baseline optical line termination (OLT) unit that includes a baseline optical filter that splits the upstream baseline optical signal and passes the downstream baseline optical signal.

26. The system of claim 24, wherein the upstream baseline optical signal is within a third optic bandwidth, and wherein the upstream baseline optical signal, the downstream baseline optical signal and the second downstream optical signal are transmitted through the fiber optic network on a single optic fiber.

27. The system of claim 24, wherein the upgraded ONT unit receives a second upstream signal and converts the second upstream signal into a second upstream optical signal, wherein the second upstream optical signal is transmitted to the central office through the fiber optic network and is received by the additional optical link.

28. The system of claim 1, wherein upgraded ONT includes a course wavelength division multiplexing (CWDM) ONT unit, and wherein the CWDM ONT unit generates an upstream T-Band optical signal that is transmitted to the central office through the fiber optic network and is received by the additional optical link.

29. The system of claim 28, wherein the upgraded ONT unit also includes a baseline ONT unit and a wavelength division multiplexer (WDM), wherein the baseline ONT unit generates an upstream baseline optical signal that is combined with the upstream T-Band optical signal by the WDM to generate a broadband upstream signal that is transmitted to the central office through the fiber optic network and is demultiplexed at the central office by an additional WDM.

30. The system of claim 1, wherein upgraded ONT includes a dense wavelength division multiplexing (DWDM) ONT unit, and wherein the DWDM ONT unit generates an upstream L-Band optical signal that is transmitted to the central office through the fiber optic network and is received by the additional optical link.

31. The system of claim 30, wherein the upgraded ONT unit also includes a baseline ONT unit and a wavelength division multiplexer (WDM), wherein the baseline ONT unit generates an upstream baseline optical signal that is combined with the upstream L-Band optical signal by the WDM to generate a broadband upstream signal that is transmitted to the central office through the fiber optic network and is demultiplexed at the central office by an additional WDM.

32. A method for upgrading a baseline passive optical network (PON), comprising the steps of:

providing a baseline optical link in a central office that receives downstream baseline communication signals from one or more service provider and converts the downstream baseline communication signals into a downstream baseline optical signal;

installing an additional optical link in the central office that receives an additional type of communication signals from one or more service provider and converts the additional type of communication signals into an additional downstream optical signal;

multiplexing the downstream baseline optical signal and the additional downstream optical signal to generate a broadband optical signal;

transmitting the broadband optical signal over a fiber optic network;

providing a baseline optical network termination (ONT) unit at a location in the PON;

receiving the broadband optical signal from the fiber optic network with the baseline ONT unit and splitting the downstream baseline optical signal from the broadband optical signal;

installing an upgraded ONT unit at a location in the PON;

receiving the broadband optical signal from the fiber optic network with the upgraded ONT unit;

filtering at a first filter the broadband optical signal to isolate the additional downstream optical signal from the broadband optical signal;

forwarding a remaining portion of the broadband optical signal to a second filter;

filtering at the second filter the remaining potion of the broadband signal to isolate the downstream baseline optical signal from the remaining portion of the broadband optical signal after the second downstream optical signal has been extracted from the broadband optical signal;

passing an upstream signal through the first and second filters to the fiber optic network.