What are the processing requirements for implementing a 5G NR base station on an SDR platform?

Implementing a 5G NR (New Radio) base station (gNB) on an SDR platform requires massive processing capability due to 5G's wide bandwidth (up to 100 MHz per carrier below 6 GHz, up to 400 MHz per carrier in mmW bands), OFDM processing with large FFT sizes (up to 4096 points), MIMO spatial multiplexing (2x2 to 64x64 antenna configurations), low-latency requirements (slot duration as short as 0.125 ms for 120 kHz subcarrier spacing), and complex channel coding (LDPC for data, Polar codes for control). The processing chain for the downlink includes: channel coding and rate matching, modulation mapping (up to 256-QAM), layer mapping and precoding for MIMO, OFDM modulation (IFFT, cyclic prefix insertion), digital predistortion for the power amplifier, and digital upconversion for the RF output. The uplink chain includes the inverse operations plus equalization. Approximate processing requirements for a single-carrier, 100 MHz bandwidth, 4x4 MIMO 5G NR cell: 50-100 GOPS for the physical layer (FFT, equalization, channel estimation), 10-30 GOPS for channel coding/decoding (LDPC), 5-10 GOPS for higher-layer processing (MAC, scheduling). Total: approximately 100-200 GFLOPS sustained. This exceeds what a general-purpose CPU can handle in real time and requires FPGA acceleration (Xilinx Zynq UltraScale+, Intel Stratix 10) or GPU acceleration for the computationally intensive blocks.