In-band framing method and apparatus

• US 5,003,599 A
• Filed: 02/07/1989
• Issued: 03/26/1991
• Est. Priority Date: 02/07/1989
• Status: Expired due to Fees

• Current Assignee: Simulation Laboratories Incorporated
• Original Assignee: Simulation Laboratories Incorporated
• Inventors: Landry, James
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): GREGORY, BERNARR E
• Application Number:
  US07/306,959
• Time in Patent Office: 777 Days
• Field of Search: 370/105, 370/100.1, 371/47.1, 371/49.1, 364/200, 364/900, 380/48, 380/9, 380/50
• US Class Current: 380/261
• CPC Class Codes: H04J 3/0602 Systems characterised by the synchronising information used

Abstract

An in-band framing encoder, for continuously operating on bit stream having external-framing data and payload data. The bit stream includes a plurality of time-division-multiplexed frames of payload data achieving channel integrity with external-framing data. The encoder comprises a framing-bit detector and a framing-bit remover for detecting the external-framing data of the bit stream, and removing the external-framing data from the bit stream. A unique-bit-pattern generator generates a unique-bit-pattern sequence. A multiplexer multiplexes the unique-bit-pattern sequence with payload data over the plurality of time-division-multiplexed frames of payload data, thereby generating internally-reframed data having the unique-bit-pattern sequence multiplexed with the payload data. The in-band framing decoder continuously operates on internally-reframed data having a unique-bit-pattern sequence multiplexed with payload data, wherein the internally-reframed data includes a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence. The decoder further comprises a synchronizer for detecting the unique-bit-pattern sequence in the internally-reframed data. In response to detecting the unique-bit-pattern sequence the synchronizer generates a synchronization signal. A unique-bit-pattern-sequence masker responsive to the synchronization signal for masks the unique-bit-pattern sequence in the internally-reframed data, thereby generating second-payload data. A channelizer means is responsive to the synchronization signal, inserts external-framing data into the second-payload data.

Claims

1. An in-band framing encoder having a data input and a data output, for use with an in-band framing decoder through an encrypted communications channel, for continuously operating on a bit stream having external-framing data and payload data, wherein the bit stream, transmitted at a bit rate, includes a plurality of time-division-multiplexed frames or payload data having channel integrity maintained with external-framing data, said in-band framing encoder comprising:

means coupled to said data input for detecting the external-framing data of the bit stream;

means coupled and responsive to said detecting means for removing the external-framing data from the bit stream wherein the data rate of the bit stream is at a second bit rate, with the second bit rate being less than the first bit rate, thereby reducing the bit rate of the bit stream to payload data having a data rate slower than the bit stream;

pattern means for generating a unique-bit-pattern sequence;

multiplexer means coupled to said pattern means, said removing means and said data output, for multiplexing the unique-bit-pattern sequence with payload data over the plurality of time-division-multiplexed frames of payload data, thereby generating internally-reframed data having the unique-bit-pattern sequence multiplexed with the payload data; and

wherein said in-band framing decoder reestablishes channel integrity by restoring external-framing data from detecting the unique-bit-pattern sequence in the internally-reframed data.

2. The in-band framing encoder as set forth in claim 1 wherein said detecting means includes a framing-bit detector for detecting external-framing data of the bit stream.

3. The in-band framing encoder as set forth in claim 1 wherein said removing means includes a framing bit remover.

4. The in-band framing encoder as set forth in claim 1 wherein said pattern generating means includes a unique-bit-pattern-sequence generator.

5. The in-band framing encoder as set forth in claim 1 wherein said pattern multiplexing means includes a multiplexer.

6. An in-band framing encoder having a data input and a data output, for use with an in-band framing decoder through an encrypted communications channel, for operating on a bit stream having external-framing data and payload data, wherein the bit stream includes a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with external-framing data, said in-band framing encoder comprising:

deletion means coupled to said data input for detecting the external-framing data of the bit stream, and removing the external-framing data from the bit stream;

pattern means for generating a unique-bit-pattern sequence;

multiplexer means coupled to said pattern means, said deletion means and said data output, for multiplexing the unique-bit-pattern sequence with payload data over the plurality of time-division-multiplexed frames of payload data, thereby generating internally-reframed data having the unique-bit-pattern sequence multiplexed with the payload data; and

wherein said in-band framing decoder reestablishes channel integrity by restoring external-framing data from detecting the unique-bit-pattern sequence in the internally-reframed data.

7. The in-band framing encoder as set forth in claim 6 wherein said deletion means includes a framing-bit detector for detecting external-framing data of the bit stream.

8. The in-band framing encoder as set forth in claim 6 wherein said deletion means includes a framing bit remover.

9. The in-band framing encoder as set froth in claim 6 wherein said pattern generating means includes a unique-bit-pattern-sequence generator.

10. The in-band framing encoder as set forth in claim 6 wherein said pattern multiplexing means includes a multiplexer.

11. An in-band framing decoder having a data input and a data output, for use with an in-band framing encoder through an encrypted communications channel, for operating on internally-reframed data having unique-bit-pattern sequence multiplexed with payload data, wherein said internally-reframed data include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence, said in-band framing decoder comprising:

synchronization means coupled to said data input for detecting the unique-bit-pattern sequence in the internally-reframed data, and in response to detecting the unique-bit-pattern sequence generating a synchronization signal;

masking means coupled to said synchronization means and responsive to the synchronization signal for masking the unique-bit-pattern sequence in the internally-reframed data, thereby generating second-payload data; and

channelization means coupled to said synchronization means and to said data output, for use with an in-band framing encoder through an encrypted communication channel, and responsive to the synchronization signal, for inserting external-framing data into the second-payload data.

12. The in-band framing decoder as set for in claim 11 wherein said synchronization means includes a shift-register chain.

13. The in-band framing decoder as set forth in claim 11 wherein said masking means includes a unique-bit-pattern-sequence masker.

14. The in-band framing decoder as set forth in claim 11 wherein said channelization means includes a framing-bit inserter.

15. An in-band framing decoder having a data input and a data output, for use with an in-band framing encoder through an encrypted communications channel, for continuously operating on internally-reframed data having a unique-bit-pattern sequence multiplexed with payload data, wherein the internally-reframed data, transmitted at a internally-reframed-data rate, include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence, said in-band framing decoder comprising:

synchronization means coupled to said data input for detecting the unique-bit-pattern sequence in the plurality of frames of payload data in the internally-reframed data, and in response to detecting the unique-bit-pattern sequence generating a synchronization signal;

masking means coupled to said synchronization means and responsive to the synchorinzation signal for masking the unique-bit-pattern sequence in the internally-reframed data, thereby generating second-payload data; and

channelization means coupled to said synchronization means and to said data output, and responsive to the synchorinzation signal, for generating a reframed-bit stream by inserting external-framing data into the second-payload data and outputting the reframed-bit stream at a bit rate.

16. The in-band framing decoder as set for in claim 15 wherein said synchronization means includes a shift-register chain.

17. The in-band framing decoder as set forth in claim 15 wherein said masking means includes a unique-bit-pattern-sequence masker.

18. The in-band framing decoder as set forth in claim 15 wherein said channelization means includes a framing-bit inserter.

19. The in-band framing decoder as set forth in claim 15 further including means for detecting an in-lock and out-of-lock status of a unique-bit-pattern sequence.

20. A method using an in-band framing encoder with an in-band framing decoder through an encrypted communications channel, for operating on a bit stream having external-framing data and payload data, wherein the bit stream includes a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with external-framing data, comprising the steps, performed by said in-band framing encoder and said in-band framing decoder, of:

detecting, with said in-band framing encoder, the external-framing data of the bit stream;

removing, with said in-band framing encoder, the external-framing data from the bit stream;

generating, with said in-band framing encoder, an unique-bit-pattern sequence; and

multiplexing, with said in-band framing encoder, the unique-bit-pattern sequence with payload data over the plurality of time-division-multiplexed frames of payload data, and thereby generating internally-reframed data having the unique-bit-pattern sequence multiplexed with the payload data; and

reestablishing, with said in-band framing decoder, channel integrity by restoring external framing data from detecting the unique-bit-pattern sequence in the internally-reframed data.

21. A method using an in-band framing encoder having a data input and a data output, for operating on a bit stream having external-framing data and payload data, wherein the bit stream, transmitted at a bit rate, include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with external-framing data, and using an in-band framing decoder coupled to said in-band framing encoder through an encrypted communications channel, comprising the steps, performed by said in-band framing encoder and said in-band framing decoder, of:

detecting, with said in-band framing encoder, the external-framing data of the bit stream;

removing, with said in-band framing encoder, the external-framing data from the bit stream;

generating, with said in-band framing encoder, an unique-bit-pattern sequence;

multiplexing, with said in-band framing encoder, the unique-bit-pattern sequence with payload data, and thereby generating internally-reframed data having the unique-bit-pattern sequence multiplexed with the payload data;

outputting, from said data output, the internally-reframed data at a internally-reframed-data rate; and

reestablishing, with said in-band framing decoder, channel integrity by restoring external framing data from detecting the unique-bit-pattern sequence in the internally-reframed data.

22. A method using an in-band framing decoder having a data input and a data output, for operating on internally-reframed data having a unique-bit-pattern sequence multiplexed with payload data, wherein said internally-reframed data include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence, said in-band framing decoder coupled to an in-band framing encoder through an encrypted communications channel, comprising the steps, performed by said in-band framing decoder, of:

detecting a unique-bit-pattern sequence in the internally-reframed data;

generating a synchronization signal in response to detecting the unique-bit-pattern sequence;

masking, in response to the synchronization signal, the unique-bit-pattern sequence in the internally-reframed data; and

inserting, in response to the synchronization signal, external-framing data into second-payload data.

23. A method using an in-band framing decoder having a data input and a data output, for operating on internally-reframed data having a unique-bit-pattern sequence multiplexed with payload data, wherein said internally-reframed data, transmitted at a internally-reframed-data rate, include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence, said in-band framing decoder coupled to an in-band framing encoder through an encrypted communications channel, comprising the steps, performed by said in-band framing decoder, of:

detecting a unique-bit pattern sequence in the internally-reframed data;

generating a synchronization signal in response to detecting the unique-bit-pattern sequence;

masking, in response to the synchronization signal, the unique-bit-pattern sequence in the internally-reframed data, thereby generating second-payload data;

inserting, in response to the synchronization signal, external-framing data into the second-payload data for generating a bit stream; and

outputting from said data output the bit stream at a bit rate.

24. The method as set forth in claim 23 further including the step of detecting an in-lock and out-of-lock status of a unique-bit-pattern sequence.

25. An in-band framing decoder having a data input and a data output, for operating on internally-reframed data having a unique-bit-pattern sequence multiplexed with payload data, wherein said internally-reframed data include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence, said in-band framing decoder coupled to an in-band framing encoder through an encrypted communications channel, said in-band framing decoder comprising:

synchronization means coupled to said data input for detecting the unique-bit-pattern sequence in the internally-reframed data, and in response to detecting the unique-bit-pattern sequence generating a synchronization signal; and

restoring means coupled to said synchronization means and responsive to the synchronization signal for masking the unique-bit-pattern sequence in the internally-reframed data, thereby generating second-payload data, and inserting external-framing data into the second-payload data.

26. An in-band framing decoder having a data input and a data output, for use with an in-band framing encoder through an encrypted communications channel, for operating on internally-reframed data having a unique-bit-pattern sequence multiplexed with payload data, wherein said internally-reframed data include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence, said in-band framing decoder comprising:

synchronization means coupled to said data input for detecting the unique-bit-pattern sequence in the internally-reframed data, and in response to detecting the unique-bit-pattern sequence generating a synchronization signal; and

restoring means coupled to said synchronization means and responsive to the synchronization signal for inserting external-framing data into the internally-reframed data for reestablishing channel integrity in the internally-reframed data.

27. A method using an in-band framing decoder having a data input and a data output, for operating on internally-reframed data having a unique-bit-pattern sequence multiplexed with payload data, wherein said internally-reframed data, transmitted at a internally-reframed-data rate, include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence, said in-band framing decoder coupled to an in-band framing encoder through an encrypted communications channel, comprising the steps, performed by said in-band framing decoder, of:

detecting a unique-bit-pattern sequence in the internally-reframed data;

generating a synchronization signal in response to detecting the unique-bit-pattern sequence;

inserting, in response to the synchronization signal, external-framing data into the internally-reframed data for reestablishing channel integrity in a bit stream; and

outputting from said data output the bit stream at a bit rate.

28. An in-band framing encoder for use with an in-band framing decoder through an encrypted communications channel, for continuously operating on a bit stream having external-framing data and payload data, wherein the bit stream, transmitted at a bit rate, includes a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with external-framing data, said in-band framing encoder comprising:

means for detecting the external-framing data of the bit stream;

means for removing the external-framing data from the bit stream;

pattern means for generating a unique-bit-pattern sequence;

multiplexer means for multiplexing the unique-bit-pattern sequence with payload data over the plurality of time-division-multiplexed frames of payload data, thereby generating internally-reframed data having the unique-bit-pattern sequence multiplexed with the payload data; and

wherein said in-band framing decoder reestablishes channel integrity by restoring external-framing data from detecting the unique-bit-pattern sequence in the internally-reframed data.

29. The in-band framing encoder as set forth in claim 28 wherein said detecting means includes a framing-bit detector for detecting external-framing data of the bit stream.

30. The in-band framing encoder as set forth in claim 28 wherein said removing means includes a framing bit remover.

31. The in-band framing encoder as set forth in claim 28 wherein said pattern generating means includes a unique-bit-pattern-sequence generator.

32. The in-band framing encoder as set forth in claim 28 wherein said pattern multiplexing means includes a multiplexer.

33. An in-band framing decoder for operating on internally-reframed data having a unique-bit-pattern sequence multiplexed with payload data, wherein said internally-reframed data include a plurality of time-division-multiplexed frames of payload data having channel integrity maintained with the unique-bit-pattern sequence, said in-band framing decoder used with an in-band framing encoder through an encrypted communications channel, said in-band framing decoder comprising:

synchronization means for detecting the unique-bit-pattern sequence in the internally-reframed data, and in response to detecting the unique-bit-pattern sequence, generating a synchronization signal; and

channelization means responsive to the synchronization signal, for inserting external-framing data into the internally-reframed data.

34. The in-band framing decoder as set for in claim 33 wherein said synchronization means includes a shift-register chain.

35. The in-band framing decoder as set forth in claim 33 wherein said channelization means includes a framing-bit inserter.