Programmable Dataflow Accelerators: A 5G Ofdm Modulation/Demodulation Case Study

Via OFDM technology, FFT and Inverse FFT (IFFT) operators enable the latest 5G radio stan- dards. In these latests standards, the behaviour of FFT and IFFT needs to be flexible, supporting sub-carrier spacings from 15kHz to 480kHz and point sizes of up to 4096 point. An FFT or IFFT accelerator for 5G can take any configuration inside this spectrum both at design time, or potentially at run-time, under the control of a system control plane. This necessitates accelerators which combine high levels of flexibility and performance. This paper describes an FFT accelerator for such a context. Specifically, a novel data-driven programmable softcore processor is presented which enables run-time variable workloads and respond to data as provided by control processors in an MPSoC operating architecture. It is the first such accelerator to enable real-time IFFT/FFT for 5G, providing up to 3.89 times greater data rate than comparable accelerators.