Enhanced fiber nodes with CMTS capability

• US 20020136203A1
• Filed: 10/24/2001
• Published: 09/26/2002
• Est. Priority Date: 03/06/2000
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Yee, James, Sharma, Alok, Smith, Lance, Liva, Valentino
• Granted Patent: US 7,149,223 B2
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04B 10/272 Star-type networks or tree-type networks
• CPC Class Codes: H04J 1/05 using digital techniques
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 12/2856 Access arrangements, e.g. Internet access asynchronous transfer mode networks H04L12/5601; broadband local area networks H04L12/2801; optical access or distribution networks H04Q11/0067; access to open networks H04L12/5691; digital subscriber line end-user equipment and bit-level processing of data on a PSTN-based network H04M11/00; home network gateways H04L12/2834; wireless access networks H04W
• CPC Class Codes: H04L 12/287 Remote access server, e.g. BRAS
• CPC Class Codes: H04L 12/2898 Subscriber equipments DSL modems H04M11/062; cable modems H04L12/2801
• CPC Class Codes: H04L 27/3416 in which the information is carried by both the individual signal points and the subset to which the individual points belong, e.g. using coset coding, lattice coding, or related schemes
• CPC Class Codes: H04N 21/2221 being a cable television head-end CATV in broadcast systems H04H20/78
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6168 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/10 Adaptations for transmission by electrical cable H04N7/12 takes precedence
• CPC Class Codes: H04N 7/173 with two-way working, e.g. subscriber sending a programme selection signal
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications
• CPC Class Codes: H04N 7/22 Adaptations for optical transmission

Abstract

Enhanced Cable Modem Termination System (CMTS) functionality, including programmable digital domain modulators and demodulators for dynamic channel assignment, is incorporated into Fiber Nodes (FNs) or mini Fiber Nodes (mFNs), yielding enhanced Fiber Nodes (eFNs). These eFns distribute CMTS functionality deep into Hybrid-Fiber-Coax Networks (HFCN) rather than centralizing the CMTS functions within a single location. Moving the cable modem terminations closer to the subscribers shortens the analog RF paths required to support cable modems. Communication of both subscriber data and CMTS control data is performed over Ethernet-compatible packet networks between the field-based CMTSs and an upstream facility (e.g., the Head End), which includes an Internet gateway. Packet data for multiple subscriber cable modems is easily compressed and merged over common network paths, reducing cabling plant complexity and increasing bandwidth utilization. This approach dramatically reduces the infrastructure cost per cable modem. Distributing CMTS functionality among multiple eFNs also reduces demands on already stretched resources at the Head End for space, power, and HVAC. For HFCN channels containing signals with modulation or encoding schemes that are unknown or best processed upstream, the invention also provides for tunneling their spectrum over the same packet network as used for the cable modem data. The channels to be tunneled are isolated using digital receivers, translated to baseband, their data framed, merged with cable modem subscriber data, and transmitted over the packet network. Upstream, the framed channel data is parsed and the original channel spectrum reconstructed to permit information recovery.

Claims

1. A fiber node for deployment in a hybrid fiber-coax network (HFCN) at an intermediate point between an upstream HFCN facility and a plurality of subscriber cable modems, the fiber node comprising:

a) a packet protocol block having a packet data interface, a transmitter data interface, and a receiver data interface, said packet protocol block communicating subscriber cable modem data with said upstream HFCN facility via said packet data interface;

b) a plurality of modulators transmitting data to said subscriber cable modems via a downstream analog RF interface, said transmitted data being provided by said packet protocol block via said transmitter data interface; and

c) a plurality of demodulators for extracting data from subscriber cable modems received via an upstream analog RF interface, said extracted data being provided to said packet protocol block via said receiver data interface.

2. The fiber node of claim 1, wherein the cable modems are compatible with the DOCSIS standard.

3. The fiber node of claim 1, wherein the upstream facility is a head end.

4. The fiber node of claim 1, wherein the upstream facility is a secondary head end.

5. The fiber node of claim 1, wherein the upstream facility is a hub.

6. The fiber node of claim 1, wherein channel separation is performed prior to the demodulators such that multiple channels are extracted from each physical transmission path of the upstream analog RF interface.

7. The fiber node of claim 1, further including at least one digitizing framer for digitizing modulated signals as received via an upstream analog RF interface, said digitized modulated signal data being provided to said packet protocol block via said receiver data interface.

8. The fiber node of claim 7, wherein the cable modems are compatible with the DOCSIS standard and the modulated signals are legacy telephone signals.

9. The fiber node of claim 7, wherein the extracted data and the digitized modulated signal data are merged in said packet protocol block for communication over a common packet transmission path with the upstream facility.

10. The fiber node of claim 8, wherein the extracted DOCSIS cable modem data and the digitized legacy telephone data are communicated with said upstream facility via a common Ethernet-compatible transmission path.

11. The fiber node of claim 7, wherein channel separation is performed prior to the digitizing framer, such that at least one selected channel and only selected channels are communicated with said upstream facility.

12. The fiber node of claim 11, wherein the channel separation is performed in the digital domain after analog-to-digital conversion.

13. The fiber node of claim 12, wherein the digitized modulated signal data is compressed prior to being communicated to said upstream facility.

14. The fiber node of claim 9, wherein reconstruction of the digitized modulated signals is performed at the upstream facility.

15. The fiber node of claim 12, wherein a plurality of selected non-contiguous channels having respective modulated signals are concurrently separated and framed, merged together for communication over a common Ethernet-compatible transmission path, and subsequently separated and concurrently reconstructed at the upstream facility.

16. The fiber node of claim 15, wherein the upstream facility is a head end.

17. The fiber node of claim 16, wherein the cable modems are compatible with the DOCSIS standard and the modulated signals are legacy telephone signals.

18. The fiber node of claim 15, wherein the upstream facility is a secondary head end.

19. The fiber node of claim 18, wherein the cable modems are compatible with the DOCSIS standard and the modulated signals are legacy telephone signals.

20. The fiber node of claim 15, wherein the upstream facility is a hub.

21. The fiber node of claim 20, wherein the cable modems are compatible with the DOCSIS standard and the modulated signals are legacy telephone signals.

22. The fiber node of claim 6, wherein the channel separation is performed in the digital domain after analog-to-digital conversion.

23. The fiber node of claim 22, wherein the channel separation is performed by digital receivers with programmable center frequency and bandwidth.

24. The fiber node of claim 23, wherein the receivers are programmed by sending commands to the fiber node via the packet data interface.

25. The fiber node of claim 24, wherein the fiber node is an mFN.

26. The fiber node of claim 1, further including analog combine and split circuitry coupled to the upstream analog RF interface, the downstream analog RF interface, and to the subscriber cable modems.

27. The fiber node of claim 26, wherein the analog combine and split circuitry is coupled to the subscriber cable modems via a coaxial-cable distribution.

29. The HFCN system of claim 28, wherein the CMTS comprises:

a) a packet protocol block having a packet data interface, a transmitter data interface, and a receiver data interface, said packet protocol block communicating subscriber cable modem data with said upstream HFCN facility via said packet data interface;

b) a plurality of modulators transmitting data to said subscriber cable modems via a downstream analog RF interface, said transmitted data being provided by said packet protocol block via said transmitter data interface; and

c) a plurality of demodulators for extracting data from subscriber cable modems received via an upstream analog RF interface, said extracted data being provided to said packet protocol block via said receiver data interface.

30. The HFCN system of claim 29, wherein the cable modems are compatible with the DOCSIS standard.

31. The HFCN system of claim 29, wherein the upstream facility is a head end.

32. The HFCN system of claim 29, wherein the upstream facility is a secondary head end.

33. The HFCN system of claim 29, wherein the upstream facility is a hub.

34. The HFCN system of claim 29, wherein channel separation is performed prior to the demodulators such that multiple channels are extracted from each physical transmission path of the upstream analog RF interface.

35. The HFCN system of claim 29, wherein the CMTS further includes at least one digitizing framer for digitizing modulated signals as received via an upstream analog RF interface, said digitized modulated signal data being provided to said packet protocol block via said receiver data interface.

36. The HFCN system of claim 35, wherein the cable modems are compatible with the DOCSIS standard and the modulated signals are legacy telephone signals.

37. The HFCN system of claim 35, wherein the extracted data and the digitized modulated signal data are merged in said packet protocol block for communication over a common packet transmission path with the upstream facility.

38. The HFCN system of claim 36, wherein the extracted DOCSIS cable modem data and the digitized legacy telephone data are communicated with said upstream facility via a common Ethernet-compatible transmission path.

39. The HFCN system of claim 35, wherein channel separation is performed prior to the digitizing framer, such that at least one selected channel and only selected channels are communicated with said upstream facility.

40. The HFCN system of claim 39, wherein the channel separation is performed in the digital domain after analog-to-digital conversion.

41. The HFCN system of claim 40, wherein the digitized modulated signal data is compressed prior to being communicated to said upstream facility.

42. The HFCN system of claim 37, wherein reconstruction of the digitized modulated signals is performed at the upstream facility.

43. The HFCN system of claim 40, wherein a plurality of selected non-contiguous channels having respective modulated signals are concurrently separated and framed, merged together for communication over a common Ethernet-compatible transmission path, and subsequently separated and concurrently reconstructed at the upstream facility.

44. The HFCN system of claim 43, wherein the upstream facility is a head end.

45. The HFCN system of claim 44, wherein the cable modems are compatible with the DOCSIS standard and the modulated signals are legacy telephone signals.

46. The HFCN system of claim 43, wherein the upstream facility is a secondary head end.

47. The HFCN system of claim 46, wherein the cable modems are compatible with the DOCSIS standard and the modulated signals are legacy telephone signals.

48. The HFCN system of claim 43, wherein the upstream facility is a hub.

49. The HFCN system of claim 48, wherein the cable modems are compatible with the DOCSIS standard and the modulated signals are legacy telephone signals.

50. The HFCN system of claim 34, wherein the channel separation is performed in the digital domain after analog-to-digital conversion.

51. The HFCN system of claim 50, wherein the channel separation is performed by digital receivers with programmable center frequency and bandwidth.

52. The HFCN system of claim 51, wherein the receivers of each CMTS are programmed by sending commands to the respective packet data interface of each CMTS.

53. The HFCN system of claim 52, wherein at least one of fiber nodes having a CMTS is an mFN.

54. The HFCN system of claim 29, further including analog combine and split circuitry coupled to the upstream analog RF interface, the downstream analog RF interface, and to the subscriber cable modems.

55. The HFCN system of claim 54, wherein the analog combine and split circuitry is coupled to the subscriber cable modems via a coaxial-cable distribution.

28. A hybrid fiber-coax network (HFCN) system, comprising:

a) an upstream HFCN facility;

b) a plurality of subscriber cable modems;

c) a first plurality of fiber nodes at intermediate points between said upstream HFCN facility and said plurality of subscriber cable modems, at least a second plurality of said first plurality of fiber nodes have an integral Cable Modem Termination System (CMTS), each CMTS communicating with at least some of said plurality of cable modems via analog RF, each CMTS communicating subscriber cable modem data with said upstream HFCN facility via packet data.