AoI-Guided Client Selection for Robust and Timely Federated Intrusion Detection in Cloud-Edge Security Analytics

Federated learning (FL) is attractive for cloud-edge intrusion detection because it enables collaborative training over distributed telemetry without centralizing raw logs. In production security analytics pipelines, however, only a subset of clients participates in each round, and heterogeneous bandwidth, stragglers, and dropouts can cause the server to rely on stale client information. This paper studies client participation as a timeliness-aware systems problem using Age of Information (AoI). We compare three lightweight policies for federated intrusion detection: AoI-first, utility-first, and a hybrid AoI+utility rule with a tunable trade-off parameter. Across a CIC-IDS2017 DDoS/PortScan mini subset, NSL-KDD, ToN-IoT, and a synthetic drift benchmark under clean, poisoning, and poisoning-plus-robust-aggregation settings, AoI-aware selection reduces average AoI by about 39--41% and peak AoI by about 70% relative to random sampling while keeping the per-round communication budget fixed. The hybrid policy usually preserves Macro-F1/AUC and provides an interpretable knob for balancing freshness, detection quality, and robustness, although it is not uniformly Pareto-dominant once false positive rate is included. Robustness is evaluated by combining AoI-guided selection with trimmed-mean aggregation under label-flip poisoning; the selection policy itself is not intended as a standalone Byzantine defense. The main practical message is that cloud-edge, privacy-preserving intrusion analytics can improve timeliness through a lightweight scheduling layer without changing the underlying FL participation budget.