FedFiTS: Fitness-Selected, Slotted Client Scheduling for Trustworthy Federated Learning in Healthcare AI

Abstract--Federated Learning (FL) has emerged as a powerful paradigm for privacy-preserving model training, yet deployments in sensitive domains such as healthcare face persistent challenges from non-IID data, client unreliability, and adversarial manipulation. This paper introduces F edFiTS, a trust-and fairness-aware selective FL framework that advances the FedFaSt line by combining fitness-based client election with slotted aggregation. FedFiTS implements a three-phase participation strategy--free-for-all training, natural selection, and slotted team participation--augmented with dynamic client scoring, adaptive thresh-olding, and cohort-based scheduling to balance convergence efficiency with robustness. A theoretical convergence analysis establishes bounds for both convex and non-convex objectives under standard assumptions, while a communication-complexity analysis shows reductions relative to FedA vg and other baselines. Experiments on diverse datasets--medical imaging (X-ray pneumonia), vision benchmarks (MNIST, FMNIST), and tabular agricultural data (Crop Recommendation)--demonstrate that FedFiTS consistently outperforms FedA vg, FedRand, and FedPow in accuracy, time-to-target, and resilience to poisoning attacks. By integrating trust-aware aggregation with fairness-oriented client selection, FedFiTS advances scalable and secure FL, making it well suited for real-world healthcare and cross-domain deployments. The digitisation of healthcare and advances in artificial intelligence (AI) have reshaped medical data usage, enabling improved decision-making. Federated Learning (FL) represents a pivotal development, allowing collaborative model training across institutions without compromising data privacy, making it a crucial aspect in medical contexts. However, FL in healthcare must address challenges related to trust, transparency, security, and fairness.