A true-time-delay array architecture for wideband multi-beam tracking

The true-time delay (TTD) units are critical for solving beam squint and frequency selective fading in Wideband Large-Scale Antenna Systems (LSASs). In this work, we propose a TTD array architecture for wideband multi-beam tracking that eliminates the beam squint phenomenon and filters out interference signals by applying a spatial filter and time delay estimations (TDEs). The paper presents a novel approach to spatial filter design by introducing a transformation matrix that can optimize the beam response in a specific direction and at a specific frequency. Using the variable fractional delay (VFD) filters, we propose a TDE algorithm with a Newton-Raphson iteration update process that corrects the arrival time delay difference between sensors. Simulations and examples have demonstrated that the proposed architecture can achieve beam tracking within 10 ms at the low signal-to-noise ratio (SNR) and demodulation loss is less than 0.5 dB in wideband multi-beam scenarios.