True-Time-Delay Wideband Dbf System: Performance Analysis in Multipath Environments

Wideband digital beamforming (DBF) in large-scale antenna arrays (LSAAs) is emerging as a dominant technology for next-generation wireless systems, yet their performance is severely constrained by beam squint and array inter-symbol interference (ISI). Digital True-Time-Delay (TTD) beamforming is highly favored because of its flexibility and effectiveness in eliminating these two effects. However, when it comes to multipath environments, channel-induced ISI further complicates accurate signal reception for antenna arrays. Since both types of ISI share similar distortion mechanisms, we analyze them jointly and introduce a hybrid phase shifter-TTD (PS-TTD) beamforming architecture integrated with a Recursive Least Squares-Decision Feedback Equalizer (RLS-DFE) to eliminate these distortions. We evaluated the performance under both additive white Gaussian noise (AWGN) and multipath fading. Through comparative simulations under 8-PSK and 16-QAM modulations with interference, we demonstrate that the joint PS-TTD-DFE system achieves good error vector magnitude (EVM) value in multipath environments, while maintaining beam pointing accuracy within 0.1° across 600 MHz bandwidth. These results validate TTD as a critical enabler for practical wideband and LSAAs deployments.