Effective bypass of error control decoder in a digital radio system
First Claim
1. A method of bypassing a decoder that, in use, decodes a received digital signal, said method comprising:
- (1) decoding a received digital signal to produce at least one codeword;
(2) generating information including error patterns and an error estimate based on decoding step (1); and
(3) feeding, to said decoder, said error patterns to force the decoder to produce (a) a codeword corresponding to the codeword produced by step (1), and (b) an error estimate corresponding to the error estimate generated by step (2), thereby effectively bypassing said decoder.
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Abstract
A digital radio communications system including a suboptimal soft decision (e.g., errors and erasures) channel decoder and a speech decoder can be upgraded to effectively bypass the hard decision channel decoder and allow a higher performance soft decision (e.g., maximum likelihood sequence estimate (MLSE)) decoder to be used--without requiring physical removal or disconnection of the hard decision channel decoder. The new decoder can feed the existing decoder the right choice of received vector r'"'"' to force the existing decoder to produce a certain codeword y'"'"' and a certain bit error estimate b'"'"'. This technique is useful to test new MLSE decoders on existing radios, or to add an MLSE decoder as an upgrade on existing receivers.
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Citations
24 Claims
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1. A method of bypassing a decoder that, in use, decodes a received digital signal, said method comprising:
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(1) decoding a received digital signal to produce at least one codeword; (2) generating information including error patterns and an error estimate based on decoding step (1); and (3) feeding, to said decoder, said error patterns to force the decoder to produce (a) a codeword corresponding to the codeword produced by step (1), and (b) an error estimate corresponding to the error estimate generated by step (2), thereby effectively bypassing said decoder. - View Dependent Claims (2, 3, 4)
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5. A method of decoding a received digital signal comprising:
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(1) decoding a received digital signal to produce at least one codeword; (2) generating an error estimate based on decoding step (1); and (3) feeding information including said error estimate and said codeword to a further decoding process that forces the further decoding process to produce (a) a codeword corresponding to the codeword produced by step (1), and (b) an error estimate corresponding to the error estimate produced by step (2), wherein step (3) includes the step of feeding artificial errors to the further decoding process. - View Dependent Claims (6)
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7. A method of decoding a received digital signal comprising:
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(1) decoding a received digital signal to produce at least one codeword; (2) generating an error estimate based on decoding step (1); and (3) feeding information to a further decoding process that forces the further decoding process to produce (a) a codeword corresponding to the codeword produced by step (1), and (b) an error estimate corresponding to the error estimate produced by step (2), wherein step (2) includes the step of determining the number of bit errors, and step (3) includes the step of determining whether the further decoding process can correct the determined number of bit errors.
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8. A digital signal decoding arrangement for bypassing a decoder that, in use, decodes a received digital signal, said arrangement comprising:
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a first decoder for decoding the received digital signal to produce at least one codeword and for generating an error estimate based on said decoding; and output means coupled to the first decoder for feeding, to a further decoder to be bypassed, information including error patterns that forces the further decoder to produce (a) a codeword corresponding to the codeword produced by the first decoder, and (b) an error estimate corresponding to the error estimate produced by the first decoder, thereby effectively bypassing said further decoder. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A digital signal decoding arrangement comprising:
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a first decoder for decoding the received digital signal to produce at least one codeword and for generating an error estimate; and output means coupled to the first decoder for feeding, to a further decoder, information that forces the further decoder to produce (a) a codeword corresponding to the codeword produced by the first decoder, and (b) an error estimate corresponding to the error estimate produced by the first decoder, wherein the decoding arrangement further includes the further decoder, and wherein the further decoder produces, in response to the information fed to it by the outputting means, an error estimate that is the minimum of;
(i) the error estimate produced by the first decoder, and (ii) the largest corresponding coset leader weight of the further decoder.
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16. A digital signal decoding arrangement comprising:
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a first decoder for decoding the received digital signal to produce at least one codeword and for generating an error estimate; and output means coupled to the first decoder for feeding, to a further decoder, information including said error estimate and said code word that forces the further decoder to produce (a) a codeword corresponding to the codeword produced by the first decoder, and (b) an error estimate corresponding to the error estimate produced by the first decoder, wherein the outputting means includes means for feeding artificial errors to the further decoder. - View Dependent Claims (17)
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18. A digital signal decoding arrangement comprising:
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a first decoder for decoding the received digital signal to produce at least one codeword and for generating an error estimate; and output means coupled to the first decoder for feeding, to a further decoder, information that forces the further decoder to produce (a) a codeword corresponding to the codeword produced by the first decoder, and (b) an error estimate corresponding to the error estimate produced by the first decoder, wherein the first decoder includes means for detecting errors, and the output means includes means for determining whether the further decoder can correct the detected errors.
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19. In a radio communications system having a demodulator, an existing channel decoder that produces a decoded received signal output and an error estimate, and a speech decoder that expands the received signal output to recover a digitized voice data stream based at least in part on the error estimate, a method for upgrading the radio communications system by supplying a further channel decoder and effectively bypassing the existing channel decoder without removing the existing channel decoder from the system, said method comprising the step of inserting, between the demodulator and the channel decoder, a further channel decoder that:
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(a) detects and corrects errors in the demodulator'"'"'s output, and (b) provides information including error patterns to the existing detector that forces the existing channel decoder to provide the speech decoder with an error estimate that corresponds to the errors corrected by the further channel decoder, thereby effectively bypassing said further channel decoder. - View Dependent Claims (20)
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21. A radio communications system comprising:
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a demodulator, a first channel decoder that produces a decoded received signal output and an error estimate, a speech decoder, connected to receive the decoded received signal output and the error estimate, that expands the decoded received signal output to recover a digitized voice data stream based at least in part on the error estimate, and a further channel decoder connected between the demodulator and the first channel decoder, the further channel decoder including; a channel decoder arrangement that detects and corrects at least some errors in the demodulator'"'"'s output that the first channel decoder cannot correct, and an output circuit connected to the channel decoder arrangement that provides information including error patterns to the first channel decoder forcing the first channel decoder'"'"'s error estimate to reflect the errors corrected by the further channel decoder, thereby effectively bypassing said first channel decoder.
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22. A radio communications system comprising:
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a demodulator, a first channel decoder that produces a decoded received signal output and an error estimate, a speech decoder, connected to receive the decoded received signal output and the error estimate, that expands the decoded received signal output to recover a digitized voice data stream based at least in part on the error estimate, and a further channel decoder connected between the demodulator and the first channel decoder, the further channel decoder including; a channel decoder arrangement that detects and corrects at least some errors in the demodulator'"'"'s output that the first channel decoder cannot correct, and an output circuit connected to the channel decoder arrangement that provides information to the first detector forcing the first channel decoder'"'"'s error estimate to reflect the errors corrected by the further channel decoder, wherein the output circuit includes means for routing the demodulator'"'"'s output to the first decoder if the first decoder can correct all errors contained in the demodulator'"'"'s output.
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23. A digital receiver method comprising:
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(a) receiving an RF signal; (b) demodulating the received RF signal to provide a received digital signal; (c) performing maximum likelihood sequence estimate channel decoding on the received digital signal to produce at least one error-corrected codeword; (d) generating an error correction estimate based on step (c); (e) producing an artificial received digital signal, based on the error correction estimate, that contains error information that will force a further decoding step (f) to produce the error-corrected codeword and a further error correction estimate that corresponds to the error correction estimate generated by step (d); and (f) channel decoding and speech decoding the artificial received digital signal. - View Dependent Claims (24)
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Specification