What is UF-OFDM?
UF-OFDM (Universal Filtered OFDM) is a multicarrier modulation technique that improves the out-of-band characteristics of OFDM by applying filtering to groups of subcarriers (sub-bands) rather than to individual subcarriers (as in FBMC) or to the entire band (as in standard windowed OFDM). UF-OFDM offers a practical compromise — better spectral confinement than CP-OFDM with lower complexity than FBMC. It was studied as a candidate waveform during 5G NR standardization.
How Does UF-OFDM Work?
In UF-OFDM, the available bandwidth is divided into sub-bands of multiple contiguous subcarriers. Each sub-band is independently filtered using a bandpass filter (typically a Chebyshev or Dolph-Chebyshev window-based FIR filter) to suppress sidelobes. The filtered sub-band signals are then summed for transmission. Because the filter operates on groups of subcarriers rather than individually, the filter length is shorter than in FBMC, reducing latency and complexity. UF-OFDM does not require a cyclic prefix (the filter’s inherent guard interval provides protection against ISI), further improving spectral efficiency. However, the receiver requires modified processing to handle the filtered signal.
Use Cases
Fragmented spectrum aggregation without guard bands, asynchronous multi-user access, mixed-numerology operation, cognitive radio and dynamic spectrum sharing, and 6G waveform research.
3GPP / Standards Reference
3GPP TR 38.802 (NR waveform study), 5G PPP research projects (5GNOW, METIS-II)
Related Terms
OFDM | FBMC | P-OFDM | W-OFDM | CP-OFDM
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