Although significant efforts have been made into tackling statistical data heterogeneity,the diversity in the processing capabilities andnetworkbandwidth ofclients,termedassystemheterogeneity,hasremained largelyunexplored.

While this could be done using thesynthesis formulation, we demonstrate that this leads to slower performances. The main difficulty inapplying suchmethods intheanalysisformulation liesinproposing a way to compute the derivatives through the proximal operator.