Method and apparatus for providing error protection for over the air file transfer
First Claim
1. An apparatus for encoding data files for over-the-air transfer while maintaining conformance to IS-99 standard comprising:
- a first encoder for encoding the data file to produce a first encoded data file;
a CRC block encoder connected to receive said first encoded data file and constructed to produce a second encoded data file; and
a convolutional encoder connected to receive said second encoded data file;
wherein said CRC block encoder and said convolutional encoder are defined by IS-99 standard.
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Abstract
In a communication system which conforms to the IS-99 standard, a concatenated code is used to provide for error free file transfer over the air. The concatenated code comprises Reed-Solomon coding, CRC block coding, and convolutional coding. The file is partitioned into data frames and Reed-Solomon encoding is performed on the data frames. CRC block encoding is then performed on the Reed-Solomon encoded data. The CRC encoded data is convolutionally encoded. The CRC block encoding and convolutional encoding are performed in accordance with the IS-99 standard. The additional Reed-Solomon encoding step provides improved error correction capability while maintaining compatibility with the IS-99 standard. At the receiver, Reed-Solomon decoding is performed if the number of erasures in a code word is less than or equal to (n−k) or the symbol errors in a code word is less than or equal to (n−k)/2. Otherwise, a request for retransmission is sent.
187 Citations
25 Claims
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1. An apparatus for encoding data files for over-the-air transfer while maintaining conformance to IS-99 standard comprising:
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a first encoder for encoding the data file to produce a first encoded data file;
a CRC block encoder connected to receive said first encoded data file and constructed to produce a second encoded data file; and
a convolutional encoder connected to receive said second encoded data file;
wherein said CRC block encoder and said convolutional encoder are defined by IS-99 standard. - View Dependent Claims (2, 3, 4)
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5. An apparatus for encoding data files for over-the-air transfer while maintaining conformance to IS-99 standard comprising:
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a first encoder for encoding the data file to produce a first encoded data file;
a CRC block encoder connected to receive said first encoded data file and constructed to produce a second encoded data file;
a convolutional encoder connected to receive said second encoded data file and constructed to produce a third encoded data file; and
a buffer for storing said third encoded data file;
wherein said CRC block encoder and said convolutional encoder are defined by IS-99 standard and said third encoded data is written to said buffer and read from said buffer in a predetermined order defined by IS-99 standard. - View Dependent Claims (6, 7, 8)
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9. An apparatus for receiving a data file encoded in conformance with IS-99 standard and transferred over-the-air comprising:
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a convolutional decoder for decoding said encoded data file to produce a first decoded data file;
a CRC check element connected to receive said first decoded data file, and constructed to perform a CRC check of said first decoded data file, said CRC checked data comprising CRC decoded data frames; and
a second decoder connected to receive said CRC checked data and constructed to produce a second decoded data file. - View Dependent Claims (10, 11, 12, 13)
a transmitter for transmitting a message indicative of CRC checked data frames which are indicated as error frames by said CRC check element.
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14. A method for encoding a data file, comprising the steps of:
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partitioning the data file into a plurality of data frames;
encoding each data frame to produce first encoded data frames;
appending Cyclic Redundancy Check (CRC) bits to said first encoded data frames to produce second encoded data frames; and
convolutionally encoding said second encoded data frames to produce third encoded data frames;
wherein said appending step and said convolutionally encoding step are in compliance with an IS-99 standard. - View Dependent Claims (15, 16, 17)
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18. A method for encoding a data file, comprising the steps of:
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partitioning the data file into a plurality of data frames;
using a IS-99 compliant encoder to encode each data frame to produce a first encoded data frame;
using a CRC encoder to append CRC bits to said first encoded data frames to produce second encoded data frames; and
using a convolutional encoder to encode said second encoded data frames to produce third encoded data frames;
wherein said CRC encoder and said convolutional encoder are compliant to an IS-99 standard. - View Dependent Claims (19, 20, 21)
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22. A method for decoding data frames, said decoding method comprising the steps of:
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using an IS-99 demodulator to demodulate said data frames; and
using a Reed-Solomon decoder to decode said demodulated data frames;
wherein said decoding method further uses a controller, said controller performing the steps of;
receiving a frame error indicator from said IS-99 demodulator; and
using said frame error indicator to decide whether to omit said Reed-Solomon decoding step. - View Dependent Claims (23, 24)
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25. A method of decoding data files, said decoding method comprising the steps of:
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demodulating data files using an IS-99 compliant demodulator; and
selectively implementing a Reed-Solomon decoder upon the IS-99 demodulated data files;
wherein the implementation of the Reed-Solomon decoder is determined by a controlling step, the controlling step comprising the steps of;
using a controller to receive frame error information from the IS-99 demodulator; and
using said controller to select and then implement exactly one of the following steps;
a. Omit the decoding step using the Reed-Solomon decoder if the frame error information indicates no errors;
b. Implement the decoding step using the Reed-Solomon decoder if the frame error information indicates errors;
c. Replace errors with erasures and then implement the decoding step using the Reed-Solomon decoder if the frame error information indicates errors;
ord. Send a retransmission request over-the-air and omit implementing the decoding step using the Reed-Solomon decoder.
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Specification