Method for modulation of a codeword

The invention relates to a method for modulation of a codeword, wherein the codeword comprises modulated symbols spanning over different chunks or chunk layer and a different modulation format can be used on each chunk or chunk layer. Within the transmission system OFDM-radio transmission techniques are used. A given data stream is partitioned into at least two sub-streams. A first sub-stream of the two sub-streams is then coded with an encoder. A fixed and equal number of coded bits from the first substream are mapped on each modulated symbol transmitted on the chunks, independently of the modulation format on each chunk. Bits from the second sub-stream of the two sub-streams are mapped on each modulated symbol of each chunk in a number depending on the modulation format.