Turbo decoding techniques
First Claim
1. A turbo decoding method for decoding a stream of a plurality orthogonal frequency division multiplexing (OFDM) symbols in which a plurality of constellations are generated by block coding and trellis coding a first number of least significant bits and only block coding a second number of most significant bits, comprising:
- receiving the plurality of orthogonal frequency division multiplexing (OFDM) symbols;
demodulating the plurality of OFDM symbols to obtain a plurality of signal constellations having variable sizes inputting, to a soft input soft output (SISO) constellation demapper, the plurality of signal constellations, along with information about a number of bits represented by each constellation from the plurality of signal constellations;
operating a soft input soft output (SISO) constellation demapper on constellations of variable sizes to generate an output for subsequent soft decoding, andperforming convolutional interleaving of a decoded output of the convolutional deinterleaving.
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Abstract
Techniques are disclosed for turbo decoding orthogonal frequency division multiplexing (OFDM) symbols. Techniques for combined turbo decoding and equalization are disclosed. The disclosed techniques can be implemented in receivers that receive wired or wireless OFDM signals and produce data and control bits by decoding the received signals. The techniques may be incorporated within an ADSL or a VDSL receiver.
36 Citations
19 Claims
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1. A turbo decoding method for decoding a stream of a plurality orthogonal frequency division multiplexing (OFDM) symbols in which a plurality of constellations are generated by block coding and trellis coding a first number of least significant bits and only block coding a second number of most significant bits, comprising:
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receiving the plurality of orthogonal frequency division multiplexing (OFDM) symbols; demodulating the plurality of OFDM symbols to obtain a plurality of signal constellations having variable sizes inputting, to a soft input soft output (SISO) constellation demapper, the plurality of signal constellations, along with information about a number of bits represented by each constellation from the plurality of signal constellations; operating a soft input soft output (SISO) constellation demapper on constellations of variable sizes to generate an output for subsequent soft decoding, and performing convolutional interleaving of a decoded output of the convolutional deinterleaving. - View Dependent Claims (2, 3, 4, 5)
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6. A turbo decoding apparatus, at least partially implemented in hardware, with a feedback or pipelined architecture, and one or more high level modules, for decoding a stream of a plurality orthogonal frequency division multiplexing (OFDM) symbols in which a plurality of constellations are generated by block coding and trellis coding a first number of least significant bits and only block coding a second number of most significant bits, comprising:
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a module that demodulates a plurality of OFDM symbols to obtain a plurality of signal constellations having variable sizes; a module that provides, to a soft input soft output (SISO) constellation demapper, the plurality of signal constellations, along with information about a number of bits represented by each constellation from the plurality of signal constellations; and a module with either soft inputs soft outputs (SISO) or soft inputs and hard outputs (SIHO) that demaps the constellations of variable sizes to encoded bits; a module with SISO or SIHO that decodes a trellis code; a module with SISO, or hard inputs hard outputs (HIHO), that synchronizes inputs from the module that decodes the trellis code and inputs from the module that demaps the constellations, assembles the bits into a plurality of bytes, and outputs the plurality of bytes; a module with SISO or HIHO that convolutionally deinterleaves the plurality of bytes; a module with SISO or hard inputs soft outputs (HISO) that decodes the deinterleaved plurality of bytes and generates soft or hard decoded bytes; and a module with SISO that convolutionally interleaves the decoded bytes and provides a priori information to the module that decodes the trellis code. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A turbo decoding method, at least partially implemented in hardware, with a feedback or pipelined architecture, for decoding a stream of a plurality orthogonal frequency division multiplexing (OFDM) symbols in which a plurality of constellations are generated by block coding and trellis coding a first number of least significant bits and only block coding a second number of most significant bits, comprising:
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an operation that demodulates a plurality of OFDM symbols to obtain a plurality of signal constellations having variable sizes; an operation that provides, to a soft input soft output (SISO) constellation demapper, the plurality of signal constellations, along with information about a number of bits represented by each constellation from the plurality of signal constellations; and an operation that, with either soft inputs soft outputs (SISO) or soft inputs and hard outputs (SIHO), demaps the constellations of variable sizes to encoded bits; an operation that, with SISO or SIHO, decodes a trellis code; an operation that, with SISO, or hard inputs hard outputs (HIHO), synchronizes inputs from the module that decodes the trellis code and inputs from the module that demaps the constellations, assembles the bits into a plurality of bytes, and outputs the plurality of bytes; an operation that, with SISO or HIHO, convolutionally deinterleaves the plurality of bytes; an operation that, with SISO or hard inputs soft outputs (HISO), decodes the deinterleaved plurality of bytes and generates soft or hard decoded bytes; and an operation that, with SISO, convolutionally interleaves the decoded bytes and provides a priori information to the module that decodes the trellis code. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification