Preprint: Federated NEXUS-MI Cuts Motor-Imagery BCI Backbone Traffic by About 42%
Motor-imagery brain-computer interfaces vary widely between users and have little calibration data, and federated learning lets them share a model without uploading raw EEG. NEXUS-MI treats gateway synchronization as a joint learning-and-communication control problem: raw EEG and classifier heads stay local, while an edge coordinator maintains the shared backbone network. On the BCICIV-2a and OpenBMI datasets, communication-aware coordination cut server-to-client backbone traffic by about 42%, with small, implementation-dependent differences in cohort-average accuracy. Those averages masked individual vulnerability: on BCICIV-2a, losses relative to an ideal-link reference reached about 12 percentage points.
Why it matters
Federated learning is usually pitched as a privacy fix, but this preprint treats it as a communication-scheduling problem in which gateway synchronization, stale-update admission and backbone download timing all shape individual accuracy; the 42% saving comes from backbone traffic rather than local EEG, and the more telling result is that cohort averages barely moved while some individuals lost up to 12 percentage points, so federated BCI evaluations that report only averages fall short and reliability must be judged per user.