Patent ID: 7116726

Claim:
A method for transferring a data sequence through a narrowband channel comprising the steps of: (a) transmitting a narrowband signal, including the steps of (a.1) distributing the data sequence over a plurality of concurrent sub-sequences, (a.2) modulating each of a plurality of subchannel carriers with a corresponding sub-sequence, (a.3) producing a complex orthogonal frequency-division multiplexed (OFDM) signal representing the inverse Fourier transform (IFT) of a combination of the modulated subchannel carriers, (a.4) modulating a channel carrier signal with the complex OFDM signal, (a.5) amplifying the modulated channel carrier signal to produce an output signal representing the narrowband signal, (a.6) producing two vector baseband feedback signals corresponding to the output signal, in part, by demodulating the output signal using a delayed channel carrier signal, and (a.7) adjusting the modulated channel carrier signal to maintain output signal linearity responsive to the two vector baseband feedback signals in a feedback loop, and (b) receiving the narrowband signal, including the steps of (b.1) detecting the narrowband signal, (b.2) producing an input signal representing the Fourier transform (FT) of the narrowband signal, and (b.3) demodulating the input signal to recover a corresponding plurality of sub-sequence waveforms, and the corresponding data sequence.