Low-Complexity Universal Filtered Multi-Carrier Receiver and Pilot-Aided Channel Estimation for 6G OFDM Waveforms

Waveform design is a key enabler for 6G and beyond wireless systems, where low-latency, high-reliability, and energy-efficient communication are essential. Universal filtered multi-carrier (UFMC), as an orthogonal frequency division multiplexing (OFDM)-variantwaveform, enhances spectral containment through subband filtering while remaining compatible with OFDM-based architectures. However, conventional UFMC receivers incur high computational complexity due to extended 2<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>-point FFT processing. Motivated by our prior work on reducing FFT operations in multiuser (MU) OFDM systems, this paper proposes a low-complexity UFMC receiver architecture that replaces the conventional 2<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>-point FFT with an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>-point FFT, thereby reducing computational requirements while ensuring accurate signal recovery. A pilot-assisted channel estimation framework based on least squares (LS) estimation and interpolation is further developed. To the best of our knowledge, this is the first study to jointly address low-complexity receiver design and channel estimation performance in UFMC. Complexity analysis demonstrates substantial reductions in arithmetic operations, while simulation results confirm comparable bit error rate (BER) and channel estimation accuracy under multipath fading. These findings highlight UFMC as an OFDM-compatible waveform suitable for scalable, low-power, and future wireless systems.