FBMC/OQAM equalization: Exploiting the imaginary interference

Filter bank based multicarrier (FBMC) modulations have recently gained a great interest. Indeed, when coupled with an Offset QAM (OQAM) coding on each sub-carrier, FBMC/OQAM can reach the maximum Nyquist rate and provide a compact spectrum. However, as with this modulation scheme no cyclic prefix is used, equalizers more efficient than a simple 1-tap Zero Forcing may be sometimes required. In this paper, we investigate a new type of equalizers for FBMC/OQAM systems. Instead of discarding the imaginary interference component at the receiver side, as usually done in relation with the real orthogonality property of FBMC/OQAM, we exploit it. We, first, show that a strong correlation exists between the real and the appropriately shifted imaginary interference components. This correlation is used afterwards to provide a new equalizer structure which complexity is evaluated. Finally, simulation results of the FBMC/OQAM transmission over a multipath channel are provided which illustrate the improvements, in terms of bit error rate, brought by our equalizer.