Method for soft modulation in a wireless telecommunication network
AssigneeQUALCOMM Incorporated
InventorsMaxim Gotman, Avner Dor, Eran Richardson, Assaf Touboul
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Abstract
A method for soft remodulation in a receiver of transmissions over a wireless telecommunication system, the method including obtaining from a FEC decoder a-posteriori LLR values, converting the a-posteriori LLR values into bit probabilities and computing improved soft symbols estimates as expected values using the bit probabilities in a recursive algorithm. Preferably, the step of converting is implemented using a pre-computed Look Up Table (LUT). Preferably, the step of computing is implemented in a Multiplier-Accumulator having a SIMD structure.
Claims20
A method for soft remodulation, in a receiver, of transmissions over a wireless telecommunication system, the method comprising:
- obtaining from a Forward Error Correction (FEC) decoder a-posteriori log likelihood ratio (LLR) values in a processor;
- converting, in said processor, said a-posteriori LLR values into bit probabilities;
- and
- computing, in said processor, a soft symbol estimate as an expected value of a received half-symbol based on said bit probabilities according to a calculation comprising a number of recursive stages defined by a dimension (q) of said half-symbol, wherein computing said soft symbol estimate includes computing a first stage expected value as E1=1−2P1, where E1 comprises said first stage expected value and P1 comprises a first one of said bit probabilities.
A modulator, in a receiver, for soft remodulation of transmissions over a wireless telecommunication system, the modulator comprising:
- a processor configured to obtain from a FEC decoder a-posteriori LLR values;
- a Look Up Table (LUT) stored in memory, said LUT comprising a plurality of pre-computed bit probabilities associated with said a-posteriori LLR values;
- and
- a soft symbol calculator configured to compute a soft symbol estimate as an expected value of a received half-symbol based on said bit probabilities according to a calculation comprising a number of recursive stages defined by a dimension (q) of said half-symbol, wherein computing said soft symbol estimate includes computing a first stage expected value as E1=1−2P1, where E1 comprises said first stage expected value and P1 comprises a first one of said bit probabilities.
A computer program product comprising:
- a non-transitory computer-readable medium comprising instructions which, when carried out by a processor, cause the processor to:
- obtain from a Forward Error Correction (FEC) decoder a-posteriori log likelihood ratio (LLR) values;
- convert the a-posteriori LLR values into bit probabilities;
- and
- compute a soft symbol estimate as an expected value of a received half-symbol based on the bit probabilities according to a calculation comprising a number of recursive stages defined by a dimension (q) of said half-symbol, wherein computing said soft symbol estimate includes computing a first stage expected value as E1=1−2P1, where E1 comprises said first stage expected value and P1 comprises a first one of said bit probabilities.
A receiver apparatus for soft remodulation of transmissions over a wireless telecommunication system, comprising:
- means for obtaining from a Forward Error Correction (FEC) decoder a-posteriori log likelihood ratio (LLR) values;
- means for converting said a-posteriori LLR values into bit probabilities;
- and
- means for computing a soft symbol estimate as an expected value of a received half symbol based on said bit probabilities according to a calculation comprising a number of recursive stages defined by a dimension (q) of said half-symbol, wherein computing said soft symbol estimate includes computing a first stage expected value as E1=1−2P1, where E1 comprises said first stage expected value and P1 comprises a first one of said bit probabilities.
Dependencies are inferred from the claim text.