Apparatus and method for communicating digital data using trellis coded QAM with punctured convolutional codes
First Claim
Patent Images
1. A method for communicating digital data using trellis coded QAM comprising the steps of:
- coding symbols for transmission using a rate 1/2 convolutional encoder punctured to rate 2/3;
transmitting the coded symbols;
receiving the transmitted coded symbols at a receiver;
computing two sets of branch metrics for each received symbol; and
decoding the received symbols by using said branch metrics to effect two passes through a rate 1/2 Viterbi decoder for each symbol.
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Abstract
Digital data is communicated using trellis coded QAM. Symbols are coded for transmission using a rate 1/2 convolutional encoder punctured to rate 2/3. The coded symbols are transmitted for receipt at a receiver. At the receiver, two sets of branch metrics are computed for each received symbol. The received symbols are decoded by using the branch metrics to effect two passes through a modified rate 1/2 Viterbi decoder for each symbol.
74 Citations
21 Claims
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1. A method for communicating digital data using trellis coded QAM comprising the steps of:
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coding symbols for transmission using a rate 1/2 convolutional encoder punctured to rate 2/3; transmitting the coded symbols; receiving the transmitted coded symbols at a receiver; computing two sets of branch metrics for each received symbol; and decoding the received symbols by using said branch metrics to effect two passes through a rate 1/2 Viterbi decoder for each symbol. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for decoding received convolutionally encoded symbols comprising the steps of:
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computing two sets of branch metrics for each received symbol; and decoding the received symbols by using said branch metrics to effect two passes through a rate 1/2 Viterbi decoder for each symbol. - View Dependent Claims (8, 9, 10, 11)
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12. Apparatus for encoding digital QAM data for communication to a receiver comprising:
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means for coding symbols representative of QAM constellation points for transmission using a rate 2/3 code provided by a rate 1/2 convolutional encoder having a trellis with alternating branches punctured to form said rate 2/3 code; and means for transmitting the coded symbols provided by said coding means; wherein said symbols are coded on the basis of groups forming an 8-way partition of a QAM constellation and each require the computation of two sets of branch metrics and two passes through said trellis for decoding. - View Dependent Claims (13, 14, 15, 16)
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17. Apparatus for decoding received convolutionally encoded symbols comprising:
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means for computing two sets of branch metrics for each received symbol; and means responsive to said branch metrics for decoding the received symbols by effecting a first pass through a rate 1/2 Viterbi decoder for each symbol in accordance with the first set of branch metrics for the symbol and a second pass through said decoder for each symbol in accordance with the second set of branch metrics for the symbol. - View Dependent Claims (18, 19, 20, 21)
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Specification