APPARATUS, AND ASSOCIATED METHOD, FOR DECODING CONVOLUTIONALLY ENCODED DATA

• US 20090193320A1
• Filed: 10/22/2008
• Published: 07/30/2009
• Est. Priority Date: 10/23/2007
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Furbeck, David
• Granted Patent: US 8,381,084 B2
• Time in Patent Office: Days
• US Class Current: 714/786
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 76/50 for emergency connections

Abstract

An apparatus, and an associated method, for correcting errors in decoded data, decoded by a convolutional decoder, such as an SOVA (Soft Output Viterbi Algorithm). A CRC check is performed upon the decoded data. If the CRC check fails, a conclusion is made that the decoded data contains errors. Portions of the decoded data indicated to exhibit low levels of reliability are toggled with values of most-likely error events. A corrected sequence of the decoded data is formed that corrects for the errors in the decoded data.

Claims

1. An apparatus for facilitating recovery of transmitted data, said apparatus comprising:

a decoded data recovery checker configured to check whether the transmitted data, once decoded, is successfully decoded; and

a bit changer configured to change part of the transmitted data once decoded associated with reliability levels less than a threshold if said decoded data recovery checker determines the transmitted data to be successfully decoded.

2. The apparatus of claim 1 wherein said decoded data recovery checker is further configured to check whether the transmitted data, once decoded, and with the part changed by said bit changer is successfully decoded.

3. The apparatus of claim 2 wherein said decoded data recovery checker and said bit changer are configured to operate iteratively.

4. The apparatus of claim 1 wherein said bit changer is configured to toggle selected bits of the part of the transmitted data, once decoded, that is associated with the reliability levels less than the threshold.

5. The apparatus of claim 1 further comprising a decoder configured to decode the transmitted data.

6. The apparatus of claim 5 wherein said decoder comprises a convolutional decoder.

7. The apparatus of claim 1 wherein said decoded data recovery checker comprises a CRC, cyclic redundancy code, checker.

8. The apparatus of claim 1 further comprising a storage element configured to store a value used by said bit change when changing the part of the transmitted data, once decoded.

9. The apparatus of claim 8 wherein said storage element is further configured to store a plurality of values.

10. The apparatus of claim 8 wherein the value corresponds to a coded data part whose decoding is associated with a likely error event.

11. The apparatus of claim 1 wherein the transmitted data checked by said decoded data recovery checker comprises voice-band modem data.

12. The apparatus of claim 1 wherein said decoded data recovery checker is embodied at a PSAP, Public Safety Access Point.

13. A method for facilitating recovery of transmitted data, said method comprising:

checking whether the transmitted data, once decoded, is successfully decoded; and

changing part of the transmitted data, once decoded, associated with reliability levels less than a threshold if the transmitted data is unsuccessfully decoded.

14. The method of claim 13 wherein said checking comprises performing a CRC, Cyclic Redundancy Code, check upon a CRC contained in the transmitted data.

15. The method of claim 13 wherein said checking and said changing are performed iteratively.

16. The method of claim 13 wherein said checking further comprises checking whether the transmitted data, once decoded, and with the part changed responsive to said changing the part of the transmitted data is successfully decoded.

17. The method of claim 13 wherein said changing comprises toggling selected bits of the part of the transmitted data, once decoded, that is associated with the reliability levels less than the threshold.

18. The method of claim 13 further comprising storing a value used when changing the part of the transmitted data, once decoded.

19. The method of claim 18 wherein said storing comprises storing a plurality of values.

20. The method of claim 18 wherein the value corresponds to a coded data part whose decoding is associated with a likely error event.

21. An apparatus for facilitating initiation of communication of emergency data pursuant to a vehicular emergency, said apparatus comprising:

a paired transceiver detection initiation detector adapted to detect occurrence of a vehicular trip start event, said paired transceiver detection initiation detector configured to generate a paired transceiver search command responsive to the occurrence of the vehicular trip start event; and

a local transceiver adapted to receive indicia associated with the vehicle at which the local transceiver is positioned and to receive indication of occurrence of the vehicular emergency, said local transceiver configured to perform a paired transceiver search responsive to the paired transceiver search command and to generate a vehicular emergency report responsive to the indication of the occurrence of the vehicular emergency.

22. The apparatus of claim 21 wherein said local transceiver comprises a Bluetooth™

transceiver.

23. A method for facilitating initiation of communication of emergency data pursuant to a vehicular emergency of a vehicle, said method comprising:

detecting occurrence of a vehicular trip start event;

generating a paired transceiver search command responsive to detection of the occurrence of the vehicular trip start event;

detecting indicia associated with the vehicle and indication of occurrence of the vehicular emergency; and

generating a vehicular emergency report responsive to the indication of the occurrence of the vehicular emergency.