Signal point interleaving technique
DC CAFCFirst Claim
1. Apparatus for forming a stream of trellis encoded signal points in response to input information, said apparatus comprisingmeans for generating a plurality of streams of trellis encoded channel symbols in response to respective portions of said input information, each of said channel symbols being comprised of a plurality of signal points, andmeans for interleaving the signal points of said generated channel symbols to form said stream of trellis encoded signal points, said interleaving being carried out in such a way that the signal points of each channel symbol are non-adjacent in said stream of trellis encoded signal points and such that the signal points of adjacent symbols in any one of said channel symbol streams are non-adjacent in said stream of trellis encoded signal points.
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Abstract
Viterbi decoder performance in a data communication system using 2N-dimensional channel symbols N>1 can be further enhanced by an interleaving technique which uses a distributed trellis encoder in combination with a signal point interleaver.
60 Citations
24 Claims
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1. Apparatus for forming a stream of trellis encoded signal points in response to input information, said apparatus comprising
means for generating a plurality of streams of trellis encoded channel symbols in response to respective portions of said input information, each of said channel symbols being comprised of a plurality of signal points, and means for interleaving the signal points of said generated channel symbols to form said stream of trellis encoded signal points, said interleaving being carried out in such a way that the signal points of each channel symbol are non-adjacent in said stream of trellis encoded signal points and such that the signal points of adjacent symbols in any one of said channel symbol streams are non-adjacent in said stream of trellis encoded signal points.
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5. A modem comprising
means for receiving a stream of input bits, means for dividing said stream of input bits into a stream of uncoded bits and a plurality of streams of trellis bits, means for independently trellis encoding each of said plurality of streams of trellis bits to generate respective streams of data words each identifying one of a plurality of predetermined subsets of the channel symbols of a predetermined 2N-dimensional constellation, N being an integer greater than unity, each of said channel symbols being comprised of a plurality of signal points, means for selecting an individual channel symbol from each identified subset in response to said stream of uncoded bits to form a stream of channel symbols, and means for generating a stream of output signal points, said signal point stream being comprised of the signal points of the selected channel symbols, the signal points of said signal point stream being sequenced in such a way that signal points that are either a) part of the same channel symbol, or b) part of channel symbols that are adjacent to one another in said channel symbol stream, are separated in said output stream by at least one other signal point.
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9. Receiver apparatus for recovering information from a received stream of trellis encoded signal points, said signal points having been transmitted to said receiver apparatus by transmitter apparatus which generates said signal points by generating a plurality of streams of trellis encoded channel symbols in response to respective portions of said information, each of said channel symbols being comprised of a plurality of signal points, and by interleaving the signal points of said generated channel symbols to form said stream of trellis encoded signal points, said interleaving being carried out in such a way that the signal points of each channel symbol are non-adjacent in said stream of trellis encoded signal points and such that the signal points of adjacent symbols in any one of said channel symbol streams are non-adjacent in said stream of trellis encoded signal points,
said receiver apparatus comprising means for deinterleaving the interleaved signal points to recover said plurality of streams of trellis encoded channel symbols, and a distributed Viterbi decoder for recovering said information from the deinterleaved signal points.
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11. A method for forming a stream of trellis encoded signal points in response to input information, said method comprising the steps of
generating a plurality of streams of trellis encoded channel symbols in response to respective portions of said input information, each of said channel symbols being comprised of a plurality of signal points, and interleaving the signal points of said generated channel symbols to form said stream of trellis encoded signal points, said interleaving being carried out in such a way that the signal points of each channel symbol are non-adjacent in said stream of trellis encoded signal points and such that the signal points of adjacent symbols in any one of said channel symbol streams are non-adjacent in said stream of trellis encoded signal points.
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15. A method for use in a modem, said method comprising the steps of
receiving a stream of input bits, dividing said stream of input bits into a stream of uncoded bits and a plurality of streams of trellis bits, independently trellis encoding each of said plurality of streams of trellis bits to generate respective streams of data words each identifying one of a plurality of predetermined subsets of the channel symbols of a predetermined 2N-dimensional constellation, N being an integer greater than unity, each of said channel symbols being comprised of a plurality of signal points, selecting an individual channel symbol from each identified subset in response to said stream of uncoded bits to form a stream of channel symbols, and generating a stream of output signal points, said signal point stream being comprised of the signal points of the selected channel symbols, the signal points of said signal point stream being sequenced in such a way that signal points that are either a) part of the same channel symbol, or b) part of channel symbols that are adjacent to one another in said channel symbol stream, are separated in said output stream by at least one other signal point.
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19. A method for use in a receiver to recover information from a received stream of trellis encoded signal points, said signal points having been transmitted to said receiver apparatus by a method which includes the steps of
generating a plurality of streams of trellis encoded channel symbols in response to respective portions of said information, each of said channel symbols being comprised of a plurality of signal points, and interleaving the signal points of said generated channel symbols to form said stream of trellis encoded signal points, said interleaving being carried out in such a way that the signal points of each channel symbol are non-adjacent in said stream of trellis encoded signal points and such that the signal points of adjacent symbols in any one of said channel symbol streams are non-adjacent in said stream of trellis encoded signal points, said method comprising the steps of deinterleaving the interleaved signal points to recover said plurality of streams of trellis encoded channel symbols, and using a distributed Viterbi decoder to recover said information from the deinterleaved signal points.
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21. Data communication apparatus comprising
means for receiving input information, means for generating a plurality of streams of trellis encoded channel symbols in response to respective portions of said input information, each of said channel symbols being comprised of a plurality of signal points, means for interleaving the signal points of said generated channel symbols to form a stream of trellis encoded signal points, said interleaving being carried out in such a way that the signal points of each channel symbol are non-adjacent in said stream of trellis encoded signal points and such that the signal points of adjacent symbols in any one of said channel symbol streams are non-adjacent in said stream of trellis encoded signal points, means for applying the stream of trellis encoded signal points to a transmission channel, means for receiving the stream of trellis encoded signal points from the channel, means for deinterleaving the interleaved signal points to recover said plurality of streams of trellis encoded channel symbols, and a distributed Viterbi decoder for recovering said information from the deinterleaved signal points.
Specification