6G • Spectrum
AFDM
Affine Frequency Division Multiplexing
A chirped multi-carrier waveform based on the Discrete Fractional Fourier Transform designed for high-Doppler doubly selective 6G channels.
Technical Explanation
Affine Frequency Division Multiplexing (AFDM) is an emerging 6G physical layer waveform that modulates data onto orthogonal chirps rather than static sinusoids. By tuning chirp parameters to the maximum Doppler shift of the physical environment, AFDM achieves full time-frequency diversity in doubly dispersive (delay-Doppler) channels. It matches the Doppler resilience of OTFS while retaining a lower implementation complexity comparable to standard FFT-based OFDM architectures.
Key Functions
- Orthogonal chirp-based modulation optimized for doubly selective, high-Doppler fading channels
- Optimal performance for high-speed LEO satellite and high-speed rail communications
- Lower signal processing complexity compared to delay-Doppler domain equalizers
- High spectral efficiency through fractional Fourier transform domain symbol packing
- Integrated parameter estimation directly outputting radar velocity and range measurements
Specifications
IEEE Transactions on Signal Processing, 3GPP Rel-20 Waveform Studies
Interfaces
AFDM-PHYDAFT-Core
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