Highly-Spectrally-Efficient OFDM Receiver

Abstract

A transmitter may comprise a symbol mapper circuit and operate in at least two modes. In a first mode, the number of symbols output by the mapper circuit per orthogonal frequency division multiplexing (OFDM) symbol transmitted by said transmitter may be greater than the number of data-carrying subcarriers used to transmit the OFDM symbol. In a second mode, the number of symbols output by said mapper circuit per orthogonal frequency division multiplexing (OFDM) symbol transmitted by said transmitter is less than or equal to the number of data-carrying subcarriers used to transmit said OFDM symbol. The symbols output by the symbol mapper circuit may be N-QAM symbols. While the circuitry operates in the first mode, the symbols output by the mapper may be converted to physical subcarrier values via filtering and decimation prior to being input to an IFFT circuit.

1 - 20 . (canceled) 
     
     
         21 . A receiver comprising:
 front-end circuitry operable to receive a signal resulting from a plurality of transmitted subcarrier values;   nonlinearity modeling circuitry operable to generate a model of nonlinear distortion experienced by said signal en route to said receiver;   decoding circuitry operable to:   generate a candidate corresponding to a plurality of candidate subcarrier values;   distort said candidate using said model of nonlinearity;   compare a result of said distortion to said received signal; and   determine a likelihood that said plurality of candidate subcarrier values is equal to said plurality transmitted subcarrier values based on a result of said comparison.   
     
     
         22 . The receiver of  claim 21 , wherein said nonlinearity modeling circuitry is configured based on a parameter received from a transmitter of said signal. 
     
     
         23 . The receiver of  claim 22 , wherein said parameter comprises a power back-off setting of a power amplifier of said transmitter. 
     
     
         24 . The receiver of  claim 22 , wherein said parameter comprises a mode of operation of said transmitter. 
     
     
         25 . The receiver of  claim 21 , comprising circuitry for measuring a performance indicator for said received signal. 
     
     
         26 . The receiver of  claim 25 , wherein said nonlinearity modeling circuitry is configured based on said measured performance indicator. 
     
     
         27 . The receiver of  claim 21 , wherein said decoding circuitry is a sequence estimation circuit operable to perform iterative maximum likelihood-based decoding. 
     
     
         28 . The receiver of  claim 21 , wherein said decoding circuitry is a sequence estimation circuit operable to perform iterative maximum a priori-based decoding. 
     
     
         29 . The receiver of  claim 21 , wherein said comparison comprises calculation of a Euclidean distance. 
     
     
         30 . The receiver of  claim 21 , wherein said decoding circuitry is operable to generate per-bit log-likelihood ratios based on said plurality of candidate subcarrier values. 
     
     
         31 . A method comprising:
 in an electronic receiver:
 receiving, by front-end circuitry of said electronic receiver, a signal resulting from a plurality of transmitted subcarrier values; 
 generating, by nonlinearity modeling circuitry of said electronic receiver, a model of nonlinear distortion experienced by said signal en route to said electronic receiver; 
 generating, by decoding circuitry of said electronic receiver, a candidate corresponding to a plurality of candidate subcarrier values; 
 distorting, by said decoding circuitry, said candidate using said model of nonlinearity; 
 comparing, by said decoding circuitry, a result of said distortion to said received signal; and 
 determining, by said decoding circuitry, a likelihood that said plurality of candidate subcarrier values is equal to said plurality transmitted subcarrier values based on a result of said comparison. 
   
     
     
         32 . The method of  claim 31 , comprising configuring, by control circuitry of said electronic receiver, said nonlinearity modeling circuitry based on a parameter received from a transmitter of said signal. 
     
     
         33 . The method of  claim 32 , wherein said parameter comprises a power back-off setting of a power amplifier of said transmitter. 
     
     
         34 . The method of  claim 32 , wherein said parameter comprises a mode of operation of said transmitter. 
     
     
         35 . The method of  claim 31 , comprising measuring, by circuitry of said electronic receiver, a performance indicator for said received signal. 
     
     
         36 . The method of  claim 35 , comprising configuring, by control circuitry of said electronic receiver, said nonlinearity modeling circuitry based on said measured performance indicator. 
     
     
         37 . The method of  claim 31 , comprising performing, by said decoding circuitry, iterative maximum likelihood-based sequence estimation. 
     
     
         38 . The method of  claim 31 , comprising performing, by said decoding circuitry, iterative maximum a priori-based sequence estimation. 
     
     
         39 . The method of  claim 31 , comprising calculating, by said decoding circuitry as part of said comparing, a Euclidean distance. 
     
     
         40 . The method of  claim 31 , comprising generating, by said decoding circuitry, per-bit log-likelihood ratios based on said plurality of candidate subcarrier values.