FBMC

FBMC, or Filter Bank Multicarrier, is a multicarrier modulation technique that uses a bank of filters to split the available bandwidth into many subcarriers. Each subcarrier is shaped by a carefully designed prototype filter to confine its spectrum, achieving lower out-of-band emissions and better spectral localization than conventional multicarrier schemes.

Its common form, FBMC-OQAM, maps data onto real-valued symbols that are offset in time by half a symbol (OQAM). The subcarriers are generated by a polyphase synthesis filter bank at the transmitter and a matched analysis filter bank at the receiver, with per-subcarrier equalization to cope with channel effects.

FBMC can operate without a cyclic prefix, reducing overhead and increasing spectral efficiency in tightly packed spectra and multi-user environments. It offers strong adjacent-channel leakage suppression, which is advantageous for spectrum sharing. Drawbacks include higher receiver complexity, longer filter lengths introducing latency, and more challenging channel estimation and equalization compared with CP-OFDM.

Developed in the 1990s and 2000s as an alternative waveform to OFDM, FBMC has been studied extensively in academia and standardization fora. While CP-OFDM remains dominant in many systems, FBMC and its variants are considered for future wireless research and specialized deployments where spectral containment and asynchronous operation are critical.