Orthogonal frequency division multiplexing using subsymbol processing

Apparatus comprising a transmitter for modulating a set of data symbols into a combined modulated symbol, the transmitter comprising:

• a data symbol grouper adapted to divide the set of data symbols into M groups of data symbols, M>1;
• one or more transforms adapted to transform each group of data symbols into a time-domain subsymbol, wherein:
• the transformation of each group of data symbols is based on a set of subcarriers, of which only a subset of the set of subcarriers is modulated by the group of data symbols;
• each data symbol in each group modulates a different subcarrier in a corresponding subset of the set of subcarriers;
• no two subsets of the set of subcarriers have a subcarrier in common;
• and
• each transformation transforms the set of subcarriers;
• and
• a subsymbol combiner adapted to combine the M time-domain subsymbols to form the combined modulated symbol.

A method for demodulating a combined modulated symbol into a set of demodulated data symbols, the method comprising:

• (a) separating the combined modulated symbol into M time-domain subsymbols, M>1;
• (b) transforming each time-domain subsymbol into a group of demodulated data symbols, wherein:
• the transformation of each time-domain subsymbol is based on a set of subcarriers, of which only a subset of the set of subcarriers is modulated by the group of demodulated data symbols;
• each demodulated data symbol in each group modulates a different subcarrier in a corresponding subset of the set of subcarriers;
• no two subsets of the set of subcarriers have a subcarrier in common;
• and
• each transformation transforms the set of subcarriers;
• and
• (c) de-grouping the M groups of demodulated data symbols to generate the set of demodulated data symbols, wherein at least one step of the method is performed by at least one apparatus.

Apparatus comprising a receiver for demodulating a combined modulated symbol into a set of demodulated data symbols, the receiver comprising:

• a subsymbol separator adapted to separate the combined modulated symbol into M time-domain subsymbols, M>1;
• one or more transforms adapted to transform each time-domain subsymbol into a group of demodulated data symbols, wherein:
• the transformation of each time-domain subsymbol is based on a set of subcarriers, of which only a subset of the set of subcarriers is modulated by the group of demodulated data symbols;
• each demodulated data symbol in each group modulates a different subcarrier in a corresponding subset of the set of subcarriers;
• no two subsets of the set of subcarriers have a subcarrier in common;
• and
• each transformation transforms the set of subcarriers;
• and
• a data symbol de-grouper adapted to de-group the M groups of demodulated data symbols to generate the set of demodulated data symbols.

A method for modulating a set of data symbols into a combined modulated symbol, the method comprising:

• (a) dividing the set of data symbols into M groups of data symbols, M>1;
• (b) transforming each group of data symbols into a time-domain subsymbol to produce M time-domain subsymbols, wherein:
• the transformation of each group of data symbols is based on a set of subcarriers, of which only a subset of the subcarriers is modulated by the group of data symbols;
• each data symbol in each group modulates a different subcarrier in a corresponding subset of the subcarriers;
• no two subsets of subcarriers have a subcarrier in common;
• step (b) comprises, for each subset of modulated subcarriers, transforming both the subset of modulated subcarriers and one or more unmodulated subcarriers to form the corresponding time-domain subsymbol;
• and
• for each group of data symbols, the sum of (1) the number of the modulated subcarriers and (2) the number of the one or more unmodulated subcarriers is equal to the total number of subcarriers in the set;
• and
• (c) combining the M time-domain subsymbols to form the combined modulated symbol, wherein at least one step of the method is performed by at least one apparatus.