Duplicate message detection and mending of garbled messages

• US 6,381,241 B1
• Filed: 09/30/1997
• Issued: 04/30/2002
• Est. Priority Date: 09/30/1997
• Status: Expired due to Term

• Current Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Original Assignee: Wireless Access Incorporated (EDCI Holdings Incorporated)
• Inventors: Ghirnikar, Avinash L., Lima, Paul J., Pinter, Gregory J.
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): CONTEE, JOY KIMBERLY
• Application Number:
  US08/941,791
• Time in Patent Office: 1,673 Days
• Field of Search: 340/825.44, 455/63, 455/38.1, 455/38.2, 455/573, 455/228, 455/466, 379/67.1, 714/822, 714/797, 714/746, 714/748, 714/751, 714/758, 714/747, 714/749, 370/312, 370/313, 370/394, 370/473, 370/474
• US Class Current: 370/394
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 51/23 Reliability checks, e.g. acknowledgments or fault reporting
• CPC Class Codes: H04L 51/58 Message adaptation for wireless communication
• CPC Class Codes: H04W 4/12 Messaging; Mailboxes; Announcements
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

A method and apparatus for detecting duplicate messages and correcting garbled messages in a wireless communication device are provided. According to one aspect of the present invention, erred messages received by a wireless communication device are corrected. A first message fragment is received by the wireless communication device. The first message fragment is corrected based upon a second message fragment after it has been determined that the first message fragment contains one or more errors. According to another aspect of the present invention, a wireless communication device includes a receiver configured to receive messages transmitted over a forward channel from a messaging system; a transmitter configured to transmit responses over a reverse channel to the messaging system; and a processor. The processor is coupled to the receiver to receive messages from the messaging system. The processor is further coupled to the transmitter to transmit acknowledgments to the messaging system. Additionally, the processor is configured to correct garbled messages by determining whether or not a second message is a duplicate of the garbled message. If the second message is a duplicate of the garbled message, then the garbled message is corrected based upon the second message.

Claims

1. A method of correcting erred messages in a wireless communication device, the method comprising:

receiving a first message fragment at the wireless communication device, the first message fragment including an embedded message identifier and an embedded fragment number generated by a messaging system for the purpose of interleaving transmission of message fragments;

receiving a second message fragment at the wireless communication device, the second message fragment including an embedded message identifier and an embedded fragment number generated by a messaging system for the purpose of interleaving transmission of message fragments;

determining the second message is a duplicate of the first message fragment based upon a plurality of parameters including the embedded message identifier and embedded fragment number; and

correcting the first message fragment based upon the second message fragment sent from the messaging system in response to a communication protocol between the messaging system and the wireless communication device after determining the first message fragment contains one or more errors.

2. The method of claim 1, further including determining whether any errors are present in the second message fragment.

3. The method of claim 2, further including:

determining a first error pattern based upon error correction information contained in the first message fragment, the first error pattern identifying one or more portions of the first message fragment that are in error; and

determining a second error pattern based upon error correction information contained in the second message fragment; and

wherein correcting the first message fragment based upon a second message fragment includes combining zero or more portions of the first message fragment and one or more portions of the second message fragment based upon the first and second error patterns.

4. The method of claim 2, wherein said correcting the first message fragment based upon a second message fragment occurs only if no errors are determined to be present in the second message fragment.

5. The method of claim 1, wherein the method further includes determining the second message fragment is a duplicate of the first message fragment based upon the message identifier and fragment number embedded in the first message, the message identifier and fragment number embedded in the second message, and contents of the first and second message fragments.

6. The method of claim 5, wherein said determining the second message fragment is a duplicate of the first message fragment further includes:

comparing the first message identifier to the second message identifier;

comparing the first fragment number to the second fragment number; and

determining if the contents of the first and second message fragments have at least a predetermined percentage of matching content.

7. The method of claim 6, wherein the predetermined percentage of content is 100%.

8. The method of claim 6, wherein the predetermined percentage of content is a codeplug parameter.

9. The method of claim 5, wherein the first message fragment is associated with a first address, the second message fragment is associated with a second address, and said determining the second message fragment is a duplicate of the first message fragment further includes determining the first address is equal to the second address.

10. The method of claim 5, wherein said determining the second message fragment is a duplicate of the first message fragment is further based upon the relative lengths of the first and second message fragments.

11. The method of claim 5, wherein said determining the second message fragment is a duplicate of the first message fragment is further based upon the presence of one or more embedded system prefixes or suffixes in either the first or second message fragments.

24. The method of claim 3, wherein the size of said portion is one bit.

12. A wireless communication device comprising:

a receiver configured to receive message fragments transmitted over a forward channel from a messaging system, the message fragments each including an embedded message identifier and an embedded fragment number generated by the messaging system for the purpose of interleaving transmission of message fragments to individual wireless communication devices;

a transmitter configured to transmit responses over a reverse channel to the messaging system; and

a processor coupled to the receiver to receive message fragments from the messaging system, the processor further coupled to the transmitter to transmit acknowledgments to the messaging system, the processor configured to correct a garbled message fragment by

determining whether or not a second message fragment is a duplicate of the garbled message fragment based upon the embedded message identifiers and fragment numbers of the garbled message fragment and the second message fragment, and

if the second message fragment is a duplicate of the garbled message fragment, then correcting the garbled message fragment based upon the second message fragment.

13. The wireless communication device of claim 12, further comprising an error correction decoder coupled to the receiver and the processor, the error correction decoder configured to determine whether any errors are present in the second message fragment by performing error correction decoding.

14. The wireless communication device of claim 13, wherein the error correction decoder produces a first error pattern and a second error pattern, the first error pattern is based upon parity information contained in the garbled message fragment, the first error pattern identifying one or more portions of the garbled message fragment that are in error, the second error pattern is based upon parity information contained in the second message fragment, and wherein the processor is further configured to combine zero or more portions of the garbled message fragment and one or more portions of the second message fragment based upon the first error pattern and the second error pattern.

15. The wireless communication device of claim 13, wherein the processor is configured to correct the garbled message fragment based upon the second message fragment only if the second message fragment is determined to have no errors by the error correction decoder.

16. The wireless communication device of claim 12, further comprising a display to present messages to the user, the processor configured to update the display if the garbled message fragment is being presented to the user when the garbled message fragment is corrected based upon the second message fragment.

25. The method of claim 14, wherein the size of said portion is one bit.

17. A method of correcting garbled messages in a wireless communication device operated by a user, the method comprising:

receiving a first message fragment at the wireless communication device containing an embedded message identifier and an embedded fragment number generated by a messaging system for the purpose of interleaving transmission of message fragments, the first message fragment including one or more errors;

receiving a second message fragment at the wireless communication device;

determining whether or not the second message fragment is a duplicate of the first message fragment; and

if the second message fragment is a duplicate of the first message fragment, then correcting the one or more errors in the first message fragment based upon the second message fragment.

18. The method of claim 17, wherein the second message fragment includes an embedded message identifier and an embedded fragment number generated by the messaging system, and said determining whether or not the second message fragment is a duplicate of the first message fragment is based upon the embedded message identifier and fragment number of the first message fragment, the embedded message identifier and fragment number of the second message fragment, and contents of the first and second message fragments.

19. The method of claim 17, wherein the wireless communication device includes a display for presenting messages to the user, the method further including updating the display to reflect corrected information if the first message fragment is currently being presented to the user.

20. The method of claim 17, wherein the wireless communication device is participating in a communication network supporting a forward channel from the messaging system to the wireless communication device and a reverse channel from the wireless communication device to the messaging system.

21. The method of claim 20, wherein the wireless communication device is a pager and the messaging system is a paging system.

22. The method of claim 20, further including:

performing error correction on the first message fragment;

if there are residual errors in the first message fragment, then transmitting a first response to the messaging system over the reverse channel signaling the messaging system to transmit a duplicate of the first message fragment; and

if there are no residual errors in the first message fragment, then transmitting a second response to the messaging system over the reverse channel signaling the messaging system to refrain from transmitting a duplicate of the first message fragment.

23. The method of claim 22, wherein the first response comprises a negative acknowledgment (NAK) and the second response comprises an acknowledgment (ACK).

26. A wireless communication device, comprising:

means for receiving a first message fragment at the wireless communication device, the first message fragment including an embedded message identifier and an embedded fragment number generated by a messaging system for the purpose of interleaving transmission of message fragments; and

means for receiving a second message fragment at the wireless communication device, the second message fragment including an embedded message identifier and an embedded fragment number generated by a messaging system for the purpose of interleaving transmission of message fragments;

means for determining the second message is a duplicate of the first mess age fragment based upon a plurality of parameters including the embedded message identifier and embedded fragment number; and

means for correcting the first message fragment based upon the second message fragment sent from the messaging system in response to a communication protocol between the messaging system and the wireless communication device after determining the first message fragment contains one or more errors.

27. The wireless communication device of claim 26, further including means for determining whether any errors are present in the second message fragment.

28. The wireless communication device of claim 27, wherein said determining includes:

determining a first error pattern based upon error correction information contained in the first message fragment, the first error pattern identifying one or more portions of the first message fragment that are in error;

determining a second error pattern based upon error correction information contained in the second message fragment; and

wherein

said correcting the first message fragment based upon a second message fragment includes combining zero or more portions of the first message fragment and one or more portions of the second message fragment based upon the first and second error patterns.

29. The wireless communication device of claim 26, further including means for determining the second message fragment is a duplicate of the first message fragment based upon the message identifier and fragment number embedded in the first message, the message identifier and fragment number embedded in the second message, and contents of the first and second message fragments.

30. The wireless communication device of claim 29, wherein said determining the second message fragment is a duplicate of the first message fragment includes:

comparing the first message identifier to the second message identifier;

comparing the first fragment number to the second fragment number; and

determining if the contents of the first and second message fragments have at least a predetermined percentage of matching content.

31. The wireless communication device of claim 29, wherein said determining the second message fragment is a duplicate of the first message fragment is further based upon the relative lengths of the first and second message fragments.