A 23-37GHz Autonomous Two-Dimensional MIMO Receiver Array with Rapid Full-FoV Spatial Filtering for Unknown Interference Suppression

Abstract

Due to the rapid growth in wireless mobile devices use (e.g., autonomous vehicles and unmanned aircraft systems), there is a rising demand for high-speed/Multiple-Input-Multiple-Output (MIMO) wireless links to navigate the increasingly dynamic environments. Current mm-Wave links rely on large transmitting/receiving (Tx/Rx) digital arrays to support the required mm-Wave link budget at the cost of narrower communication beamwidth, which demands fine beam alignment over the entire field-of-view (FoV), increases the number of iterations required to establish a reliable link, and worsens the overall array's response time. Agile and rapid spectral-spatial front-end filtering/beamforming is required to facilitate wideband mm-Wave digital arrays to handle varying strong blocker signals with unknown frequency/angle-of-arrival (AoA) in practical EM scenarios. Most existing front-end spatial filtering methods in digital arrays use open-loop analog beamformers [1]–[3], which have limited FoV, require previous knowledge (frequency/AoA) of the signals/blockers or perform on-the-fly beam-space computations using digital backends which is not suitable for mobile applications. An alternative to FoV-limited analog front-end beamforming is utilizing the digital backend to identify the blockers'/signals' AoA and applying the optimum spatial filtering and beamforming in response [4]. The presence of multiple strong signals/blockers imposes high linearity and high dynamic range requirements on the receiver front-end and ADC; otherwise, strong signals/blockers may saturate the front-end, and exceed the ADC dynamic range. A DLL-like autonomous beamformers using phase-domain negative feedback is reported in [5] which rapidly suppresses multiple unknown strong signals or blockers and support wideband Gbit/s signals/blockers [5]. However, its array architecture only demonstrates 1–D array operation and cannot handle practical applications in a planar 2-D array.