Integrated digital loop carrier system with virtual tributary mapper circuit

• US 5,784,377 A
• Filed: 06/06/1995
• Issued: 07/21/1998
• Est. Priority Date: 03/09/1993
• Status: Expired due to Term

• Current Assignee: Pulse Communications, Inc. (Enginuity Communications Corporation)
• Original Assignee: Hubbell, Inc.
• Inventors: Timbs, Jeffrey, Carter, Nicholas, Tucker, Thomas, Moran, Michael, Renucci, Peter, Chen, Chung, Boudreaux, J. Bradley, Klonsky, Steven, Baydar, Ertugrul, Wardak, Waleed
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): VU, HUY DUY
• Application Number:
  US08/471,224
• Time in Patent Office: 1,141 Days
• Field of Search: 370/58.1, 370/60, 370/60.1, 370/112, 370/99, 370/105.1, 370/105.2, 370/105.3, 370/102, 370/110.1, 370/84, 370/94.2, 370/357, 370/463, 370/466, 370/468, 370/503, 370/358, 370/359, 370/386, 370/403, 370/404, 370/405, 370/420, 370/421, 375/371, 375/372, 379/27, 379/28, 379/29, 379/30, 379/31, 379/240, 379/64, 379/65, 379/93, 379/94, 379/90.01, 379/102.01, 379/102.02, 379/219, 379/399, 379/419, 379/156, 379/224, 379/242, 359/113, 359/115, 359/117, 359/137
• US Class Current: 370/463
• CPC Class Codes: H04J 2203/0028 Local loop
• CPC Class Codes: H04J 2203/0041 Star, e.g. cross-connect, concentrator, subscriber group equipment, remote electronics
• CPC Class Codes: H04J 2203/0046 User Network Interface
• CPC Class Codes: H04J 2203/0048 Network termination, e.g. NT1, NT2, PBX
• CPC Class Codes: H04J 2203/006 Fault tolerance and recovery
• CPC Class Codes: H04J 3/1611 Synchronous digital hierarchy [SDH] or SONET H04J3/1664 takes precedence for interactions with OTN
• CPC Class Codes: H04L 41/0213 Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/0226 Mapping or translating multiple network management protocols
• CPC Class Codes: H04L 41/046 comprising network management agents or mobile agents therefor
• CPC Class Codes: H04Q 11/0407 using a stored programme control
• CPC Class Codes: H04Q 2213/13003 Constructional details of switching devices
• CPC Class Codes: H04Q 2213/1301 Optical transmission, optical switches
• CPC Class Codes: H04Q 2213/13106 Microprocessor, CPU
• CPC Class Codes: H04Q 2213/13176 Common channel signaling, CCS7
• CPC Class Codes: H04Q 2213/13209 ISDN
• CPC Class Codes: H04Q 2213/13292 Time division multiplexing, TDM
• CPC Class Codes: H04Q 2213/1332 Logic circuits
• CPC Class Codes: H04Q 2213/13367 Hierarchical multiplexing, add-drop multiplexing
• CPC Class Codes: H04Q 2213/13381 Pair-gain system, digital loop carriers
• CPC Class Codes: H04Q 3/0095 Specification, development or application of network management software, e.g. software re-use

Abstract

An integrated digital loop carrier (IDLC) system includes digital line feeders and signal processors to interface with the feeders and to ultimately provide data to subscriber instruments. The system can be employed as a central office terminal (COT) or remote digital terminal (RDT) with analog, T1 or SONET feeders and any conventional link medium. Data are put in DS1 format and multiplexed onto optical loops for delivery to banks of channel units wherein the optical signals are translated to electrical signals for delivery to the channel units and subscribers. A method and apparatus is provided for mapping and demapping signals between virtual tributaries (VT) and digital signal formats in the RDT of an integrated digital loop carrier. An application-specific circuit provides such mapping and demapping functions as Floating Byte Synchronous VT to Locked Byte Synchronous VT, Floating Asynchronous VT to Locked Byte Synchronous VT, Floating Asynchronous VT to Floating Asynchronous VT, DS1 to Locked Byte Synchronous VT, DS1 to Floating Asynchronous VT, and DS1 to Floating Byte Synchronous VT.

Claims

1. A digital terminal for a telephone system comprising the combination of:

a plurality of digital line feeders for carrying digital signals;

signal processor means connected to at least one of said digital line feeders for receiving said digital signals therefrom and for translating said digital signals into optical signals;

at least one channel unit shelf, said shelf comprising a plurality of channel units and first and second optical-electrical interface units for converting said optical signals into electrical signals;

first and second optical transmission signal conducting means connected to said signal processor means for receiving therefrom and carrying said optical signals, said first optical signal conducting means being connected in a serial loop to said first optical-electrical interface unit and said signal processor means and said second optical signal conducting means being connected in a serial loop to said second optical-electrical interface unit and said signal processor means for delivering to said optical-electrical interface units said optical signals; and

a channel shelf processor in said channel unit shelf which is coupled to said first and second optical-electrical interface units for selectively delivering to individual ones of said channel units electrical signals converted to electrical signals from at least one of said optical signals delivered by one of said first and second optical transmission signal conducting means.

2. A terminal according to claim 1, comprising a plurality of channel unit shelves, each of said shelves comprising two groups of said channel units, two of said channel shelf processors and said first and second optical-electrical interface units.

3. A digital terminal according to claim 1, further comprising an optical feeder for carrying optical signals, and said signal processor means is operable to convert data from said optical signals into electrical signals, to process said electrical signals, and to convert said electrical signals to optical signals for delivery to said channel unit shelf via said first and second optical transmission signal conducting means.

4. A digital terminal apparatus according to claim 1, wherein said signal processor means and said channel unit shelf are configured to communicate with each other via embedded signals exchanged therebetween on said first and second optical transmission signal conducting means.

5. A digital terminal apparatus according to claim 4, wherein said channel unit shelf is operable to assign time slots onto said first and second optical transmission signal conducting means on a per call basis under the control of said signal processor means.

6. A digital terminal apparatus according to claim 5, wherein said channel unit shelf is operable to assign time slots onto said first and second optical transmission signal conducting means such that no active time slots overlap.

7. A digital terminal apparatus according to claim 5, wherein said signal processor means coordinates said time slot assignments by said channel unit shelf via said embedded signals.

8. A digital terminal apparatus according to claim 7, further comprising a time slot multiplexer coupled between said signal processor means and said first and second optical transmission signal conducting means for recovering optical signals received from said channel unit shelf and for transmitting signals from said signal processor means.

9. A digital terminal for a telephone system for transmitting digital signals between a feeder and customer service equipment connected to groups of channel units, comprising:

signal processor means connected to said feeder for receiving feeder signals therefrom, and for converting said feeder signals into optical signals; and

an optical ring coupled to said signal processor means and said groups of channel units for receiving said feeder signals from said signal processor means and providing them to said groups of channel units;

wherein

said groups of channel units are operable to receive customer signals from said customer service equipment, convert said customer signals to optical signals, and provide said customer signals to said optical ring for delivery to said signal processor means.

10. A digital terminal according to claim 9, wherein:

each of said groups of channel units comprises first and second optical-electrical interface circuits for converting optical ones of said feeder signals into electrical signals and for converting electrical ones of said customer signals into optical signals; and

said optical ring comprises first and second optical transmission signal conducting means connected in series, respectively, with said first and second optical-electrical interface circuits in said groups of channel units to create two signal paths on which said optical signals are transmitted in opposite directions.

11. A digital terminal according to claim 9, wherein each of said groups of channel units comprises at least one customer service equipment interface, an optical ring interface, and a channel unit processor coupled to said equipment interface and said optical ring interface and operable to process and deliver signals between said customer service equipment and said signal processor means via said optical ring, wherein:

said customer service equipment is selected from the group consisting of plain old telephone service, integrated services digital network, extensions and optical fiber; and

said channel unit processor is configured to perform functions specific to at least one of said customer service equipment in said group, and said signal processor means is configured to perform functions that are common to each of said customer service equipment in said group.

12. A digital terminal according to claim 9, wherein said optical ring is configured to connect remotely located customer service equipment to said signal processor means.

13. A digital terminal according to claim 9, wherein said signal processor means is operable to rearrange signaling bits contained in said digital signals from said feeder on a single byte-per-channel basis.

14. A digital terminal according to claim 9, wherein said signal processor means and said groups of channel units are configured to communicate with each other via embedded signals exchanged therebetween on said optical ring.

15. An apparatus according to claim 14, wherein said groups of channel units each comprise means for assigning time slots onto said optical ring on a per call basis under the control of said signal processor means.

16. An apparatus according to claim 15, wherein said groups of channel units are operable to assign time slots onto said optical ring such that no active time slots overlap.

17. An apparatus according to claim 15, wherein said signal processor means coordinates said time slot assignments by said groups of channel units via said embedded signals.

18. An apparatus according to claim 17, further comprising a time slot multiplexer coupled between said signal processor means and said optical ring for recovering optical signals received from said group of channel units and for transmitting signals from said signal processor means.

19. An apparatus according to claim 19, wherein said signal processor means comprises:

at least one optical interface for receiving optical signals from said feeder and converting said optical signals to electrical signals and demultiplexing said electrical signals from an optical channel format to a synchronous transport signal, STS, format;

STS multiplexing means for receiving the demultiplexed STS signals and providing an output of parallel STS signals as virtual tributary, VT, signals;

a VT mapper circuit for mapping and demapping the virtual tributary signals;

a time slot multiplexer coupled between said signal processor means and said optical ring for recovering optical signals transmitted thereon by said group of channel units and for placing signals thereon for delivery from said signal processor means;

a common equipment processor; and

a synchronous local area network for communication between said common equipment processor and said optical interface, said STS multiplexing means, said VT mapper circuit, and said time slot multiplexer.

20. A digital terminal for processing digital signals transmitted between a central office and customer service equipment, comprising:

a common unit adapted to receive and process DS1 signals and optical signals from a central office; and

at least one channel unit adapted to interface with the customer service equipment and said common unit and operable to deliver said processed signals to the customer service equipment;

wherein said customer service equipment is at least one of a plurality of customer service equipment types comprising a plain old telephone, integrated services digital network equipment, special service equipment, a trunk, and optical fiber, said channel unit being adapted to operate as a portion of a channel bank for at least one of said plurality of customer service equipment types, said common unit being operable to process said DS1 signals and said optical signals by performing functions required for each of said plurality of customer service equipment types and generating output signals, and said channel unit being operable to process said output signals by performing functions particular to said at least one of said plurality of customer service equipment types to which said channel unit is connected.

21. A digital terminal according to claim 20, wherein said channel unit comprises a portion of a high-density plain old telephone service channel bank.

22. A digital terminal according to claim 20, wherein said channel unit is configured to accommodate an additional type of customer service equipment in addition to the customer service equipment in said plurality of customer service equipment types without requiring modification of said common unit.

23. A digital terminal according to claim 20, wherein a plurality of said channel units are configured in an n-channel bank for interfacing with at least one type of customer service equipment selected from said plurality of customer service equipment types, and wherein said digital terminal is expandable in n-channel increments by coupling additional ones of said n-channel banks to said common unit.

24. A digital terminal according to claim 23, wherein said digital terminal is operable to process as many as 672 channels by connecting between one and seven 96-channel channel banks to said common unit.

25. A digital terminal according to claim 24, wherein said digital terminal is operable to groom said 672 channels into any combination of 28 DS1 feeder signals.

26. A digital terminal according to claim 20, wherein said common unit is adapted to support a plurality of external signaling types associated with the central office.

27. A digital terminal for a telephone system comprising the combination of:

at least one digital line feeder for carrying digital signals;

signal processor means connected to said digital line feeder for receiving said digital signals therefrom and for translating said digital signals into optical signals;

at least one channel unit shelf, said shelf comprising a plurality of channel units and first and second optical-electrical interface units for converting said optical signals into electrical signals;

first and second optical transmission signal conducting means connected to said signal processor means for receiving therefrom and carrying said optical signals, said first optical signal conducting means being connected in a serial loop to said first optical-electrical interface unit and said signal processor means and said second optical signal conducting means being connected in a serial loop to said second optical-electrical interface unit and said signal processor means for delivering to said optical-electrical interface units said optical signals; and

a channel shelf processor in said channel unit shelf which is coupled to said first and second optical-electrical interface units for selectively delivering to individual ones of said channel units electrical signals converted to electrical signals from at least one of said optical signals delivered by one of said first and second optical transmission signal conducting means.

28. A terminal according to claim 27, comprising a plurality of channel unit shelves, each of said shelves comprising two groups of said channel units, two of said channel shelf processors and said first and second optical-electrical interface units.

29. A terminal according to claim 27, comprising a plurality of channel unit shelves, said first optical signal conducting means being connected in a serial loop to said first optical-electrical interface unit of each of said shelves and then to said signal processor means.

30. A terminal according to claim 29, said second optical signal conducting means being connected in a serial loop to said second optical-electrical interface unit of each of said shelves and then to said signal processor means.