A new system of multi carrier modulation is described, which takes advantage of the biorthogonality property, to generalize the oversampled OFDM technique into a biorthogonal frequency division multiplex scheme named BFDM/QAM. A discrete-time analysis of this scheme leads to a discrete model of modulated transmultiplexer. Using a polyphase decomposition of this transmultiplexer, and assuming a distortion free channel, we determine the mathematical conditions on the prototype filters, allowing an exact cancellation of intersymbol and interchannel interference. Then, computationally efficient realizations of the modulators and demodulators are given. Lastly, some design examples are provided, illustrating the respective advantages of BFDM/QAM and OFDM/QAM.