Department Publications

The optimal selection of approximate computing units towards low-complexity FPGA-based hardware architectures for approximate discrete cosine transform (ADCT) and approximate discrete Fourier transform (ADFT) are explored. The proposed methodology employs an existing library of FPGA based approximate adders to select Pareto-optimal 1 approximate adders for cascaded signal flow architectures found in ADCT and ADFT operations. Benefits are presented with examples from 8-point ADCT based image compression and 16-point ADFT based digital multi-beamforming applications. Examples demonstrate a nearly 25% LUT reduction in FPGA utilization compared to error-free computing, with a corresponding degradation of nearly 1 dB in terms of PSNR in image compression and 0.3 dB loss in SNR improvement in beamforming.

The 6-24 GHz upper midband - FR3 range - is the next generation spectrum for mobile wireless applications. Traditionally allocated for defense and scientific use cases, the possible adoption of FR3 frequencies for commercial applications opens the possibility for severe interference between different commercial and scientific/defense systems. We demonstrate lowcomplexity adaptive array processing in the FR3 range using realtime implementation in the 10.7-10.8 GHz band, with 100 MHz of bandwidth using Xilinx Virtex-6 Sx475T FPGA technology. The demonstration supports a uniform linear array with 8 Vivaldi antennas (6-24 GHz) and can provide up to 6 nulls in the aperture pattern in addition to the desired RF beam. The FPGA back-end utilizes sampling at 200 MS/s and exploits digital signal processing to furnish up to 100 MHz of bandwidth at IF.