Header error detection for wireless data cells

• US 6,628,641 B1
• Filed: 12/24/1997
• Issued: 09/30/2003
• Est. Priority Date: 12/24/1997
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Strawczynski, Leo, Gage, Bill W. A.
• Primary Examiner(s): Yao, Kwang Bin
• Application Number:
  US08/997,982
• Time in Patent Office: 2,106 Days
• Field of Search: 370/345, 370/347, 370/350, 370/389, 370/392, 370/395, 370/465, 370/471, 370/474, 370/476, 370/395.1, 714/746, 714/752, 714/758, 714/774, 714/776, 714/798, 714/799
• US Class Current: 370/349
• CPC Class Codes: H04L 2012/5607 Radio
• CPC Class Codes: H04L 2012/5627 Fault tolerance and recovery
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/555 Error detection

Abstract

An improved method and transceiver for using the method for detecting header errors includes a header processor for reconfiguring an ATM cell header by extracting the 8 bit header error check (HEC) and replacing it with an enhanced 16 or 24 bit HEC (EHEC). On the receive path, the received header is compared to the EHEC and if errors are indicated, the cell is discarded. Enhancements include FEC encoding on the entire cell during transmission, and if during reception uncorrectable errors exist using said EHEC to determine whether the error is in the header or is in the payload. If a cell with an error in its payload belongs to a group of related cells, for example an AAL5 frame, the system discontinues the transmission of the remaining cells of the frame.

Claims

1. A transceiver for receiving and transmitting data cells over a wireless interface, said transceiver comprising:

a block processor having a transmit path for reconfiguring cells for transmission over the wireless interface and a receive path for receiving transmitted signals and processing received reconfigured cells;

wherein said block processor includes;

a transmit header processor for assembling a new header for a cell to be transmitted, including;

means for extracting a Header Error Check (HEC) from said cell, and

means for calculating and inserting an Exended Header Error Check (EHEC) into said cell header;

a receive header processor, including;

means for extracting EHEC from a received cell,

means for replacing said EHEC with an HEC, and

means for detecting errors in said received cell header; and

means for discarding a received cell if an error in the header is detected.

2. A transceiver as claimed in claim 1, further comprising means for forwarding a received cell if no error in header is detected.

3. A transceiver as claimed in claim 1, wherein said block processor includes a transmit block processing stage and a receive block processing stage, wherein said transmit block processing stage includes means for adding additional bits for the purpose of allowing a receiver of the cell to determine whether there are uncorrectable errors, and wherein said receive block processing stage includes means for determining whether there are uncorrectable errors.

4. A transceiver as claimed in claim 3, wherein said means for adding additional bits adds said bits on a per cell basis.

5. A transceiver as claimed in claim 3, wherein said means for adding additional bits adds said bits on a per block basis.

6. A transceiver as claimed in claim 3, wherein said means for adding additional bits performs forward error correction encoding.

7. A transceiver as claimed in claim 3, wherein said means for adding additional bits adds additional error detection bits.

8. A transceiver as claimed in claim 3, wherein said receive header processor further includes means for determining an error is present in said payload if the receiver determines there were uncorrectable errors and no error is detected in said header.

9. A transceiver as claimed in claim 8, wherein said receive header processor further includes:

means for determining the nature of the payload by evaluating the header information; and

means for selecting from a number of payload treatment processes to execute if an error is present in said payload;

wherein the payload treatment process is selected based on the nature of the payload from the group of processes comprising;

forwarding the cell,

forwarding the cell with a flag,

discarding the cell, and

producing an error indication to a higher layer protocol.

10. A transceiver as claimed in claim 9, wherein said transmit header processor further comprises means for compressing header information from a conventional header format into a compressed header format;

and

wherein said receive header processor further comprises means for uncompressing header information from said compressed format into said conventional format if no errors in header are detected.

11. A transceiver as claimed in claim 8, wherein said header includes a payload type identifier which identifies whether a cell is the final cell of said message, and wherein said transmit header processor further comprises:

means for evaluating the header to determine whether said cell belongs to a message and whether said cell is the final cell of said message,

means for adding a message sequence identifier to said header identifying to which message the cell belongs,

means for discontinuing the transmission of non-final cells of a particular message if a discontinue indication is received; and

wherein said receive header processor comprises;

means for interpreting said message sequence identifier, and

means for sending an indication to the transmitter of a cell with an error in its payload to discontinue transmitting the remaining non-final cells of said message.

12. A transceiver as claimed in claim 11, wherein said transmit header processor further comprises means for compressing header information from a conventional header format into a compressed header format;

and

wherein said receive header processor further comprises means for uncompressing header information from said compressed format into said conventional format if no errors in header are detected.

13. A transceiver as claimed in claim 8, wherein said transmit header processor further comprises:

means for evaluating the header to determine whether said cell belongs to a message,

means for adding a message sequence identifier to said header identifying to which message the cell belongs, and

means for discontinuing the transmission of cells of a particular message if a discontinue indication is received; and

wherein said receive header processor comprises;

means for interpreting said message sequence identifier, and

means for sending an indication to the transmitter of a cell with an error in its payload to discontinue transmitting the remaining cells of said message.

14. A transceiver as claimed in claim 8, wherein said transmit header processor further comprises:

means for adding a payload type identifier which identifies whether a cell forms part of a message and if so, whether said cell is the last cell of said message, and

means for adding a message sequence identifier to said header identifying to which message the cell belongs, and

means for discontinuing the transmission of non-final cells of a particular message if an indication to do so is received; and

wherein said receive header processor comprises;

means for interpreting said message sequence identifier, and

means for sending an indication to the transmitter of a cell with an error in its payload to discontinue transmitting the remaining non-final cells of said message.

15. A transceiver as claimed in claim 1, wherein said transmit header processor further comprises means for compressing header information from a conventional header format into a compressed header format;

and

wherein said receive header processor further comprises means for uncompressing header information from said compressed format into said conventional format if no errors in header are detected.

16. A method for treating transmission errors in data cells which include a first data field, a check on said first data field, and at least one additional data field, wherein each cell is transmitted with additional bits for the purpose of allowing a receiver of the cell to determine whether there are uncorrectable errors, wherein said first data field comprises the cell header, and wherein said at least one additional data field comprises the payload,

said method comprising:

detecting errors on said first data field;

detecting uncorrected errors on said cell;

determining an error is present in said at least one additional data field if an uncorrected error is detected in said cell and no error is detected in said first data field;

determining the nature of the payload by evaluating the header information; and

executing a treatment process depending on the type of cell and the field in error;

wherein said executing an appropriate treatment step comprises;

discarding said cell if said detecting errors on said first data field detects an error in said first data field; and

selecting from a number of payload treatment processes to execute if no error is detected in said first data field and an error is detected in said at least one additional data field;

wherein the payload treatment process is selected based on the nature of the payload as determined in said determining the nature of the payload step.

17. The method as claimed in claim 16, wherein determining the nature of the payload step comprises evaluating the address, payload type identifier, and message sequence fields of said header, and wherein said selecting step comprises selecting a message treatment process from the number of payload treatment processes if said header indicates said cell is a non-final cell of a message, said message treatment process comprises the steps of:

a) discarding said cell; and

b) sending a discontinue message to the transmitter of said cell.

18. A radio unit adapted to carry out the method of claim 17.

19. A wireless network adapted to carry out the method of claim 17.

20. A radio unit adapted to carry out the method of claim 16.

21. A wireless network adapted to carry out the method of claim 16.

22. A method for receiving and transmitting data cells over a wireless interface, wherein said data cells include a header, a header error check (HEC) computed on said header and payload, said method comprising:

at a transmitter;

calculating an extended HEC (EHEC) on a cell header of cell to be transmitted;

reconfiguring said cell to be transmitted by replacing the HEC with said calculated EHEC to form a reconfigured cell;

transmitting said reconfigured cell; and

at a receiver;

receiving said reconfigured cell;

detecting errors in the header of the received cell by calculating the expected value of the EHEC on the received header and comparing said calculated EHEC with the received EHEC;

discarding the received cell if an error in the header is detected; and

replacing said EHEC with an HEC, and then forwarding the cell if no error in the header is detected.

23. The method as claimed in claim 22 further comprising:

adding additional bits for the purpose of allowing a receiver of the cell to determine whether there are uncorrectable errors during transmission; and

determining whether there are uncorrectable errors during reception.

24. The method as claimed in claim 23 wherein said step of adding additional bits comprises performing forward error correction encoding on each cell prior to transmission.

25. A wireless network adapted to carry out the method of claim 24.

26. The method as claimed in claim 23 further comprising the step of determining an error is present in the payload of a received cell if the determining whether there are uncorrectable errors during reception step determines there were uncorrectable errors and no error is detected in said header.

27. The method as claimed in claim 26 further comprising the steps of:

determining the nature of the payload by evaluating the header information; and

selecting from a number of payload treatment processes to execute if an error is present in said payload;

wherein the payload treatment process is selected based on the nature of the payload from the group of processes comprising;

forwarding the cell,

forwarding the cell with a flag,

discarding the cell, and

producing an error indication to a higher layer protocol.

28. The method as claimed in claim 26 wherein said header includes a payload type identifier which identifies whether a cell is the final cell of a message, and wherein said method further comprising the steps of:

during transmission;

evaluating the header to determine whether said cell belongs to a message and whether said cell is the final cell of said message,

adding a message sequence identifier to said header identifying to which message the cell belongs, and

discontinuing the transmission of non-final cells of a particular message if a discontinue indication is received; and

during reception;

interpreting said message sequence identifier, and

sending an indication to the transmitter of a cell with an error in its payload to discontinue transmitting the remaining non-final cells of said message.

29. The method as claimed in claim 26 wherein said header includes a payload type identifier which identifies whether a cell is the final cell of a message, and wherein said method further comprising the steps of:

during transmission;

evaluating the header to determine whether said cell belongs to a message and whether said cell is the final cell of said message, and

discontinuing the transmission of non-final cells of said message if a discontinue indication is received; and

during reception;

determining whether a cell with an error in its payload belongs to a message, and if so, discarding said cell and sending an indication to the transmitter of a cell with an error in its payload to discontinue transmitting the remaining non-final cells of said message.

30. The method as claimed in claim 26 wherein said identifies whether a cell is the final cell of a message, and wherein said method further comprising the steps of, during reception:

determining whether a cell with an error in its payload belongs to a message, and if so, discarding said cell and all subsequently received non-final cells of said message.

31. The method as claimed in claim 30 further comprising during transmission:

evaluating the header to determine whether said cell belongs to a message and whether said cell is the final cell of said message, and

discontinuing the transmission of non-final cells of said message if a discontinue indication is received; and

during reception;

determining whether a cell with an error in its payload belongs to a message, and if so, discarding said cell and sending an indication to the transmitter of a cell with an error in its payload to discontinue transmitting the remaining non-final cells of said message.

32. A radio unit adapted to carry out the method of claim 23.

33. A radio unit adapted to carry out the method of claim 22.

34. A wireless network adapted to carry out the method of claim 22.