A device for bit-demultiplexing in a multicarrier MIMO communication system (e.g. precoded spatial multiplexing MIMO communication systems using adaptive OFDM), including a multicarrier MIMO transmitter and a multicarrier MIMO receiver. The multicarrier MIMO transmitter includes a demultiplexer and symbol mapper unit receiving an input bit stream and generating a plurality of symbol streams, each symbol stream being associated with a different transmission channel and including a plurality of data symbols, each data symbol being attributed to a different carrier; one or more multicarrier modulators generating at least two multicarrier modulated signals based on the symbol streams; and at least two transmit ports respectively transmitting the at least two multicarrier modulated signals, wherein a data throughput rate of each transmission channel is separately variable.