Continuous byte-stream encoder/decoder using frequency increase and cyclic redundancy check

• US 5,907,566 A
• Filed: 05/29/1997
• Issued: 05/25/1999
• Est. Priority Date: 05/29/1997
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Benson, Miles, Kimmitt, Myles, Ater, Dan
• Primary Examiner(s): MOISE, EMMANUEL LIONEL
• Application Number:
  US08/865,246
• Time in Patent Office: 726 Days
• Field of Search: 371/37.01, 371/5.1, 371/20.1, 371/47.1, 341/59, 360/40, 360/49, 370/395, 370/513, 395/200.57, 395/200.66, 395/200.72, 395/200.81, 395/872, 395/888, 395/891
• US Class Current: 714/798
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 2012/5647 Cell loss
• CPC Class Codes: H04L 2012/5673 Coding or scrambling
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A continuous byte stream encoder/decoder process where a continuous stream of ATM data cells is received with a plurality of words, where each word has a plurality of bits in parallel. The ATM data cell is analyzed and new control words are created to convey information such as Start-of-Cell, parity and synchronization signals for the serializer and deserializer chip set. These control words are combined with the data words of the ATM data cell to form a combined word stream. This word stream having a higher word transfer rate than the original ATM data cell. This combined word stream is fed to a known 8B/10B encoder which further modifies the data for proper transmission over an AC coupled serial path. Data from the 8B/10B decoder is then serialized through known serialization/deserialization chip sets passed over the serial path and then deserialized back into an recombined word stream. This word stream is decoded both with a 8B/10B decoder and with a frequency decreasing decoder to restore the data to its original data cell format.

Claims

1. A continuous byte stream encoder/decoder process in an ATM (Asynchronous Transfer Mode) network, the process comprising:

providing a network concentrator with a plurality of ATM cards and a backplane with a serial line;

receiving a continuous stream of ATM data cells on one of said ATM cards, each of said data cells including a plurality of data words received at a first rate, each of said plurality of data words including a number of bits in parallel;

creating a plurality of control words each representing characteristics of one of said data cells, each of said plurality of control words including a plurality of bits in parallel;

combining said control words and data words into a combined word stream at a second rate higher than said first rate;

converting said plurality of parallel bits of said combined word stream into a serial stream of bits;

transmitting said serial stream of bits at a serial rate over said serial line;

receiving said serial stream of bits from said serial line by another of said ATM cards;

converting said serial stream of bits back into respective said control and data words using said control words to identify boundaries of said data words;

recombining said data words from said serial stream of bits back into respective said data cells using a location of said control words.

2. A process in accordance with claim 1, further comprising:

transmitting out said recombined data words in a respective cell at said first rate;

said serial rate transmitting more bits per unit time than said first rate.

3. A process in accordance with claim 1, further comprising:

encoding said data words prior to said converting into said serial stream by using an 8-bit to 10 bit encoding scheme.

4. A process in accordance with claim 1, wherein:

said data cells and said data words are received immediately one after the other;

an out-of-band signal is received in addition to said stream of data cells;

said creating of said control words uses information from said out-of-band signal.

5. A process in accordance with claim 4, wherein:

said out-of-band signal includes information regarding boundaries and parity of each of said data cells.

6. A process in accordance with claim 5, further comprising:

determining an error correction code for one of said data cells;

reading said parity of said one data cell and corrupting said error correction code if said parity indicates an error;

inserting said error correction code in said combined word stream at said one ATM card;

retrieving said error correction code from said serial stream at said another ATM card;

determining from said retrieved error correction code if said one data cell has been corrupted.

7. A process in accordance with claim 4, wherein:

said out-of-band signal indicates parity error for a respective data cell;

an error detection code is merged with said combined data and control words to determine data integrity, said error detection code indicating an error when said out-of-band signal indicates a parity error.

8. A process in accordance with claim 1, wherein:

said combining of said control words and data words includes placing a first type control word only at periodic locations in said combined word stream;

said converting of said serial stream of bits includes a deserial process which only uses said first type control word to determine boundaries of said data words.

9. A process in accordance with claim 8, further comprising:

encoding said data and control words prior to said converting into said serial stream, said encoding having a first and second version of said first type control word, said encoding using said first and second versions of said first type control word to maintain an even balance of high and low bits transmitted over said serial line;

said combining of said control and data words placing a second type control word in said combine word stream to cause said encoding to sufficiently use said first version of said first control word for said converting of said serial stream to determine said boundaries.

10. A process in accordance with claim 9, wherein:

said encoding places said second type control word halfway between said periodic locations.

11. A process in accordance with claim 8, wherein:

said combining places an error detection code in said combined word stream to determine data integrity;

said error detection code is placed in said periodic locations.

12. A process in accordance with claim 11, wherein:

said error detection code is placed between said data cells in said combined word stream.

13. A process in accordance with claim 8, wherein:

boundaries of said data cells correspond to said periodic locations in said combined word stream.

14. A process in accordance with claim 8, wherein:

said control words are placed in said combined word stream at control locations, said control locations include said periodic locations.

15. A process in accordance with claim 14, wherein:

boundaries of said data cells correspond to said control locations in said combined word stream.

16. A process in accordance with claim 15, wherein:

said encoding places an error detection code in said combined word stream to determine data integrity, said error detection code is placed in said control locations between said data cells in said combined word stream.

17. A process in accordance with claim 15, wherein:

said recombining of said data words back into respective said data cells detects when a control word is not in one of said control locations.

18. A process in accordance with claim 14, wherein:

said data words of one of said data cells and said control words of said one of said cells form a frame in said combined word stream;

said combining of data and control words forms a first type of frame and a second type of frame, said first type of frame having said periodic locations in different locations than said second type of frame, said combining placing said first and second types of frames in said combined word stream to properly align said periodic locations.

19. A process in accordance with claim 18, wherein:

each of said frames having a last location of a last word in said frame, said first type of frame has said last location as one of said periodic locations, said second type of frame has said last location as not being one of said periodic locations.

20. A process in accordance with claim 1, wherein:

said creating, said combining, said converting of said parallel bits, and said transmitting being performed by said one ATM card;

said converting of said serial stream of bits and said recombining is performed by said another ATM card.

21. A process in accordance with claim 1, wherein:

said continuous stream of data is received in an Atlanta chip set interface format.

22. A process in accordance with claim 1, wherein:

said Atlanta chip set interface format includes 8 bits of data, one bit of parity and one Start-of-Cell indication.

23. A process in accordance with claim 1, wherein:

said converting of said plurality of parallel bits and said converting of said serial stream of bits is performed according to an operation of serializer-deserializer chip sets manufactured by AMC as part #S2052.