Current wireless systems combat inter-symbol interference (ISI) by diagonalizing or sparsifying the channel matrix, yet they remain vulnerable to selective fading. To address this, we propose a universal random precoding (RP) transmission framework based on the universality class. RP leverages random transforms to statistically exploit all subchannels and construct an equivalent channel belonging to the universality class, thereby enhancing diversity gain while maintaining backward compatibility with existing waveforms. Low-complexity implementations include the randomly permuted fast transform (FT-RP) and the interleaved block-sparse fast transform (IBSFT-RP). A cross-domain OAMP/MAMP (CD-OAMP/MAMP) detector is designed for RP systems, which is replica maximum \textit{a posteriori} (MAP)-optimal according to state evolution (SE). Simulation results on MIMO systems demonstrate that RP with CD-OAMP/MAMP achieves near-RM performance with much lower complexity, with additional benefits of flexible compression ratios for spectral efficiency.
Jiazhen Dong, Lei Liu, Xiaojun Yuan et al.· 0 citations
The heterogeneous nature has been regarded as a predominant challenge during the deployment of federated learning (FL) systems, wherein model heterogeneity—where clients train models of fundamentally different architectures—remains underexplored. Existing methods tolerate it poorly: they enforce interdependent model families, extract sub-models of one shared model, or rely on auxiliary public datasets and proxy models, which constrain model selection or demand storage that resource-limited clients cannot afford. We posit that an effective bridge across heterogeneous models should be both model-agnostic—decoupling knowledge transfer from incompatible parameter spaces—and storage-free, staying practical for clients with sharply different resources. On this basis we propose FedGPA, a hierarchical framework in which clients with comparable resources and identical architectures form a group and a server mediates knowledge transfer across groups of diverse models; at its core, the lightweight, model-agnostic Aligned Co-decision (Alco) Unit aligns class-level prototypical information across groups to bridge heterogeneous architectures, and a prototypical fusion step interpolates prototypes to regularize local training and refine cross-group knowledge. Experiments on CIFAR-10/100, EMNIST, and Tiny-ImageNet across heterogeneous architectures show that FedGPA consistently outperforms strong baselines from four method families, with the largest gains on resource-poor clients, at a cost of only ~100 KB of additional cross-group communication per round. A limitation of this study is that we provide no formal differential-privacy guarantee for the exchanged prototypes and do not address adversarial or data-quality attacks, leaving both to future work.
Liyinglan Liu, Zikai Xiao, Zihan Chen et al.· Journal of Machine Learning...· 0 citations
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