A Joint Filter and Spectrum Shifting Architecture for Low Complexity Flexible UFMC in 5G

Abstract

The hardware realization of Universal Filtered Multi Carrier (UFMC) architecture has attracted significant attention in fifth generation (5G) and beyond. In addition to the flexibility in fast Fourier transform (FFT)-length, a flexible prototype filter in combination with multiplicative complex spectrum shifting co-efficients is required for realizing flexible UFMC architecture. The existing architectures of UFMC transmitter commonly adopted fixed-size FFT-length, number of subbands, subband size, and filter-length. Moreover, the lack of flexible prototype filter and spectrum localization of filter co-efficients to individual subbands limits the flexible UFMC system design. In this paper, we propose VLSI architecture for a flexible length prototype filter that can generate spectrally shifted filter co-efficients to individual subbands in tune with the changing value of FFTlength, number of subbands, subband size, and filter-length. For 16-bit word size architecture, our proposed design produces filter co-efficients and spectrum shifting co-efficients upto length, 2 15 . Thus, any desired combination of FFT-length, number of subbands, subband size and filter-length is selected to generate the filter co-efficients for the individual subbands. Moreover, complex multiplication and addition operations are reduced in proposed architecture, quantitatively, about 58.81% reduction in filtering unit is achieved over the state-of-the-art architecture. Finally, hardware implementation output and XILINX post route simulation result matches perfectly with MATLAB simulations.

Reconfigurable Logic Design of CORDIC Based FFT Architecture for 5G Communications

“…Because of end-device power and resource constraints, computational complexity in hardware implementation becomes important in UFMC systems. In reality, the most resource-intensive components in UFMC systems are the Inverse Discrete Fourier Transform/Inverse Fast Fourier Transform (IDFT/IFFT) and pulse-shaping filters [10,11]. For this reason, proposed a 64-point IFFT instead of the more common 1024-point IFFT.…”