FCOM: A Federated Collaborative Online Monitoring Framework via Representation Learning
Tanapol Kosolwattana, Huazheng Wang, Raed Al Kontar, Ying Lin
TL;DR
The paper addresses online monitoring of large, heterogeneous populations under resource and privacy constraints. It introduces Federated Collaborative Online Monitoring (FCOM), which learns a shared low-rank representation $Q \in \mathbb{R}^{p\times K}$ and unit-specific coefficients $c_i \in \mathbb{R}^K$ to model per-unit rewards as $f_i(x) = x^T Q c_i$, enabling cross-unit knowledge transfer without data sharing. An alternating least squares–based online federated procedure with event-triggered communication estimates $Q$ and $c_i$; a UCB-based monitoring score guides resource allocation, yielding sublinear regret with a bound $R(T) = O(NK\sqrt{T}\ln T)$ when $K\ll p$, and a controlled communication cost. Empirical results on simulations and online cognitive monitoring in Alzheimer's disease demonstrate improved decision performance and privacy preservation relative to centralized or non-representation-based federated baselines.
Abstract
Online learning has demonstrated notable potential to dynamically allocate limited resources to monitor a large population of processes, effectively balancing the exploitation of processes yielding high rewards, and the exploration of uncertain processes. However, most online learning algorithms were designed under 1) a centralized setting that requires data sharing across processes to obtain an accurate prediction or 2) a homogeneity assumption that estimates a single global model from the decentralized data. To facilitate the online learning of heterogeneous processes from the decentralized data, we propose a federated collaborative online monitoring method, which captures the latent representative models inherent in the population through representation learning and designs a novel federated collaborative UCB algorithm to estimate the representative models from sequentially observed decentralized data. The efficiency of our method is illustrated through theoretical analysis, simulation studies, and decentralized cognitive degradation monitoring in Alzheimer's disease.
