Millimeter-Wave Digital Beamforming Receiver Using RFSoC FPGA for MIMO Communications

The paper presents a first-of-its-kind digital beamformer using single-ADC for multiple-input-multiple-output (MIMO) applications. The efficacy of this low power ultra-wideband (UWB) beamformer is demonstrated by evaluating inter-channel interference (ICI), a major challenge in MIMO. Central to the approach is a code multiplexing method using orthogonal Walsh-Hadamard (WH) codes generated via a radio-frequency system-on-chip (RFSoC) field programmable gate array (FPGA). This is done at a maximum of 400 MHz clock frequency. The multiplexed signals are passed through a single channel for digitization. Experimental validation is performed using UWB tightly-coupled dipole array (TCDA) and a direct-conversion receiver architecture. Measurements results showed beamforming capabilities and ICI cancellation of 36 dB with little or no signal-to-noise ratio (SNR) degradation. To the best of our knowledge, this is the highest clock frequency and ICI value achieved to date.