Non-orthogonal frequency-division multiplexing

The history of N-OFDM signals theory was started in 1992 from the Patent of Russian Federation No.

[1] In this patent, Vadym Slyusar proposed the 1st method of optimal processing for N-OFDM signals after Fast Fourier transform (FFT).

that "it is not possible to recover the information from the received signal, even in the case of an ideal channel.

"[4] In 2001, V. Slyusar proposed non-orthogonal frequency digital modulation (N-OFDM) as an alternative of OFDM for communications systems.

[5] The next publication about this method has priority in July 2002[2] before the conference paper regarding SEFDM of I. Darwazeh and M.R.D.

[6] Despite the increased complexity of demodulating N-OFDM signals compared to OFDM, the transition to non-orthogonal subcarrier frequency arrangement provides several advantages: This section describes a simple idealized N-OFDM system model suitable for a time-invariant AWGN channel.

[8] An N-OFDM carrier signal is the sum of a number of not-orthogonal subcarriers, with baseband data on each subcarrier being independently modulated commonly using some type of quadrature amplitude modulation (QAM) or phase-shift keying (PSK).

This composite baseband signal is typically used to modulate a main RF carrier.

The real and imaginary components are first converted to the analogue domain using digital-to-analogue converters (DACs); the analogue signals are then used to modulate cosine and sine waves at the carrier frequency,

, which is then quadrature-mixed down to baseband using cosine and sine waves at the carrier frequency.

[1] The method of optimal processing for N-OFDM signals without FFT was proposed in October 2003.

To the building of MIMO system can be used digital antenna array as transmitter and receiver of N-OFDM signals.

In this area of research, a wavelet transform is introduced to replace the DFT as the method of creating non-orthogonal frequencies.

This is due to the advantages wavelets offer, which are particularly useful on noisy power lines.

[17] To create the sender signal the wavelet N-OFDM uses a synthesis bank consisting of a

-band transmultiplexer followed by the transform function On the receiver side, an analysis bank is used to demodulate the signal again.