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Jiasong Han

Publications and source records attributed to Jiasong Han.

3 recordsLinked to original sources

Channel Estimation with Hierarchical Sparse Bayesian Learning for ODDM Systems

Orthogonal delay-Doppler division multiplexing (ODDM) is a promising modulation technique for reliable communications in high-mobility scenarios. However, the existing channel estimation frameworks for ODDM systems cannot achieve both high accuracy and low complexity simultaneously, due to the inherent coupling of delay and Doppler parameters. To address this problem, a two-dimensional (2D) hierarchical sparse Bayesian learning (HSBL) based channel estimation framework is proposed in this paper. Specifically, we address the inherent coupling between delay and Doppler dimensions in ODDM by developing a partially-decoupled 2D sparse signal recovery (SSR) formulation on a virtual sampling grid defined in the delay-Doppler (DD) domain. With the help of the partially-decoupled formulation, the proposed 2D HSBL framework first performs low-complexity coarse on-grid 2D sparse Bayesian learning (SBL) estimation to identify potential channel paths. Then, high-resolution fine grids are constructed around these regions, where an off-grid 2D SBL estimation is applied to achieve accurate channel estimation. Simulation results demonstrate that the proposed framework achieves performance superior to conventional off-grid 2D SBL with significantly reduced computational complexity.

econ.EM

FilterLoss: A Transfer Learning Approach for Communication Scene Recognition

Communication scene recognition has been widely applied in practice, but using deep learning to address this problem faces challenges such as insufficient data and imbalanced data distribution. To address this, we designed a weighted loss function structure, named FilterLoss, which assigns different loss function weights to different sample points. This allows the deep learning model to focus primarily on high-value samples while appropriately accounting for noisy, boundary-level data points. Additionally, we developed a matching weight filtering algorithm that evaluates the quality of sample points in the input dataset and assigns different weight values to samples based on their quality. By applying this method, when using transfer learning on a highly imbalanced new dataset, the accuracy of the transferred model was restored to 92.34% of the original model's performance. Our experiments also revealed that using this loss function structure allowed the model to maintain good stability despite insufficient and imbalanced data.

econ.EM

Dynamic SINR-Guided Iterative Interference Cancellation for ODDM Systems in Doubly Dispersive Channels

Orthogonal delay-Doppler division multiplexing (ODDM) modulation has recently gained significant attention as a promising candidate to promote the communication reliability in high-mobility environments. Low complexity signal detection is one of the most significant challenges for ODDM over general physical channels, due to the large channel spreading caused by the fractional delay and Doppler shifts. In this paper, we investigate the low-complexity data detection for ODDM system by utilizing iterative interference cancellation. Based on the theoretical analysis of signal to interference plus noise ratio (SINR) during the iteration, a dynamic SINR-guided approach is proposed to provide a better initialization result. Specifically, we analyze the SINR of each time domain sample before initial estimate with consideration of off-grid delay and Doppler shifts. The iteration is then started from the multi-carrier symbol index which has the best SINR. The corresponding interference is then eliminated for other time domain samples while the SINR for symbol awaiting detection is also updated. Based on the updated SINR, the next multi-carrier symbol index is selected for the same processing until all data symbols have been initialized. Finally, we update the SINR synchronously until the end of the initialization. Simulation experiments indicate that our proposed algorithms demonstrate satisfying convergence and error performance while avoiding the huge complexity introduced by full linear minimum mean squared error (LMMSE) initialization.

econ.TH