To address the substantial measurement challenges in characterizing self-interference (SI) intensity for full-duplex (FD) large-scale arrays, we propose an innovative prediction method using Vision Transformer (ViT) and transfer learning. The proposed model integrates array multi-modal features and employs multi-head attention mechanisms to accurately predict SI intensity in FD array systems with limited measured data. The proposed transfer learning strategy is composed of a pre-training phase based on the spherical-wave model and a fine-tuning phase utilizing limited measured data, which further enhances the predictive performance of the proposed model. Our experimental evaluation in the upper 6 GHz (U6G) band (6675 ∼ 6875 MHz) shows that, compared to traditional methods, the proposed method achieves approximately 16% and 10% improvements in Structural Similarity Index Measure (SSIM) and the proportion of predictions with errors below 3 dB, respectively. These results confirm its effectiveness for SI intensity prediction in FD arrays and indicate its potential for supporting beam management and optimization in B5G/6G FD systems.

The future 6G network will enhance smart cities' data integration and analysis capabilities through Integrated Sensing and Communication (ISAC) technology. This paper proposes a millimeter wave (mmW) in-band full-duplex (IBFD) ISAC system architecture and explores three direction-finding techniques based on subarray splitting for its architecture. Firstly, the mutual interference problem in the IBFD ISAC system was analyzed. Using the Taylor synthesis method to suppress array sidelobes and reduce false alarm rate, combined with a two-dimensional fast Fourier transform (2D-FFT), the direction-finding accuracy is improved under an extremely low signal-to-noise ratio (SNR). Then, the performance of three direction-finding methods was compared through simulation. The simulation results showed that the sum difference beam direction-finding method has better mean square error (MSE) performance. In addition, a sum difference beam direction-finding experiment was conducted, and the direction-finding errors for moving and static targets were as low as 0.6° and 0.5°, respectively, demonstrating excellent direction-finding capability.