Note that there exist many other different generalizations/forms of OFDM, to see their essential differences, it is critical to see their corresponding received signal equations to demodulate. The above VOFDM is the earliest and the only one that achieves the received signal equation (1) and/or its equivalent form, although it may have different implementations at transmitter vs. different IFFT algorithms. It has been shown (Yabo Li et. al., "IEEE Trans. on Signal Processing", Oct. 2012) that applying the MMSE linear receiver to each vector subchannel (1), it achieves multipath diversity.     