ResearchUniversity of Melbourne

Evidential Trust-Aware Decentralized Federated Learning

A modular framework for Byzantine-resilient decentralized FL with uncertainty-driven peer evaluation and personalized model aggregation for Wearable IoT.

Rangwala, Sinnott, Buyya - University of Melbourne

Trust

What is Murmura?

Murmura is a comprehensive framework for Evidential Trust-Aware Decentralized Federated Learning. It leverages Dirichlet-based uncertainty decomposition to evaluate peer trustworthiness and enable Byzantine-resilient model aggregation for wearable IoT applications.

Evidential Deep Learning

Dirichlet-based models for uncertainty quantification

Byzantine Resilient

Robust against malicious nodes using trust-aware filtering

Wearable IoT

Designed for activity recognition on resource-constrained devices

The Key Insight

Epistemic-aleatoric uncertainty decomposition from Dirichlet-based evidential models directly indicates peer reliability:

High Epistemic Uncertainty (Vacuity)

Indicates insufficient learning or evidence - possibly Byzantine behavior. These peers should be filtered.

High Aleatoric Uncertainty (Entropy)

Reflects inherent data ambiguity - the peer is still trustworthy and should be included in aggregation.

This distinction allows intelligent peer filtering that traditional distance-based methods cannot achieve.

Key Contributions

Murmura introduces novel techniques for trust-aware decentralized federated learning.

Evidential Trust-Aware Aggregation

Novel algorithm leveraging Dirichlet-based uncertainty to identify and filter Byzantine peers via cross-evaluation.

Uncertainty-Driven Personalization

Adaptive self-weighting based on local model confidence, balancing knowledge transfer with personalized learning.

BALANCE-Style Threshold Dynamics

Progressive trust threshold tightening as models converge - starting lenient, becoming stricter over training.

Byzantine Attack Resilience

Robust against Gaussian noise and directed deviation attacks with up to 30% compromised nodes.

Flexible Topologies

Support for ring, fully-connected, Erdos-Renyi, and k-regular network topologies.

Config-Driven Experiments

YAML/JSON configuration for reproducible experiments with CLI and Python API support.

Wearable IoT Datasets

Evaluated on three real-world wearable sensor datasets with natural user heterogeneity.

UCI HAR

Source
Smartphone sensors
Nodes
10 subjects
Activities
6 classes
Features
561

PAMAP2

Source
Body-worn IMUs
Nodes
9 subjects
Activities
12 classes
Features
4000

PPG-DaLiA

Source
Wrist-worn PPG/EDA
Nodes
15 subjects
Activities
7 classes
Features
192

Aggregation Algorithms

Compare against state-of-the-art Byzantine-resilient aggregation methods.

Evidential Trust

Uncertainty-aware

FedAvg

Baseline averaging

Krum

Distance-based

BALANCE

Adaptive threshold

Sketchguard

Sketch compression

UBAR

Two-stage robust

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