TY - GEN
T1 - FFT-domain signal processing for spectrally-enhanced CP-OFDM waveforms in 5G new radio
AU - Yli-Kaakinen, Juha
AU - Levanen, Toni
AU - Renfors, Markku
AU - Valkama, Mikko
AU - Pajukoski, Kari
PY - 2018/10
Y1 - 2018/10
N2 - Fast Fourier transform (FFT)-domain signal processing has been considered recently as an effective tool for spectrum enhancement of orthogonal frequency-division multiplexing (OFDM)-based waveforms, which is a central element in the fifth generation new radio (5G-NR) developments. Fast-convolution (FC) filtering approximates linear convolution by effective FFT-based block-wise circular convolutions using partly overlapping processing blocks. In earlier work, we have shown that FC processing is a very flexible and efficient tool for filtered OFDM signal generation and receiver-side subband filtering, e.g., for the mixed numerology scenarios of the 5G-NR. However, with the continuous overlap-save and overlap-add processing models with fixed block-size and overlap, the FC-processing blocks are not synchronized to all OFDM symbols of a transmission frame. Furthermore, 5G-NR numerology does not allow to use transform lengths smaller than 128 because this would lead to non-integer cyclic prefix (CP) lengths. Here we present a modified FC processing scheme which avoids these limitations. The scheme is based on extrapolating the CP samples which, as an example, makes it possible to use 16-point transforms in case of a 12-subcarrier-wide subband allocation, greatly reducing the implementation complexity. Also the FC-processing blocks can be aligned with each OFDM symbol, reducing complexity and latency, e.g., in mini-slot transmissions.
AB - Fast Fourier transform (FFT)-domain signal processing has been considered recently as an effective tool for spectrum enhancement of orthogonal frequency-division multiplexing (OFDM)-based waveforms, which is a central element in the fifth generation new radio (5G-NR) developments. Fast-convolution (FC) filtering approximates linear convolution by effective FFT-based block-wise circular convolutions using partly overlapping processing blocks. In earlier work, we have shown that FC processing is a very flexible and efficient tool for filtered OFDM signal generation and receiver-side subband filtering, e.g., for the mixed numerology scenarios of the 5G-NR. However, with the continuous overlap-save and overlap-add processing models with fixed block-size and overlap, the FC-processing blocks are not synchronized to all OFDM symbols of a transmission frame. Furthermore, 5G-NR numerology does not allow to use transform lengths smaller than 128 because this would lead to non-integer cyclic prefix (CP) lengths. Here we present a modified FC processing scheme which avoids these limitations. The scheme is based on extrapolating the CP samples which, as an example, makes it possible to use 16-point transforms in case of a 12-subcarrier-wide subband allocation, greatly reducing the implementation complexity. Also the FC-processing blocks can be aligned with each OFDM symbol, reducing complexity and latency, e.g., in mini-slot transmissions.
U2 - 10.1109/ACSSC.2018.8645100
DO - 10.1109/ACSSC.2018.8645100
M3 - Conference contribution
SN - 978-1-5386-9219-6
SP - 1049
EP - 1056
BT - 2018 52nd Asilomar Conference on Signals, Systems, and Computers
PB - IEEE
T2 - Asilomar Conference on Signals, Systems and Computers
Y2 - 1 January 1900
ER -