Communication-Efficient Federated Learning via Robust Distributed Mean Estimation

Federated learning commonly relies on algorithms such as distributed (mini-batch) SGD, where multiple clients compute their gradients and send them to a central coordinator for averaging and updating the model. To optimize the transmission time and the scalability of the training process, clients often use lossy compression to reduce the message sizes. DRIVE is a recent state of the art algorithm that compresses gradients using one bit per coordinate (with some lower-order overhead). In this technical report, we generalize DRIVE to support any bandwidth constraint as well as extend it to support heterogeneous client resources and make it robust to packet loss.

DRIVE: One-bit Distributed Mean Estimation

We consider the problem where $n$ clients transmit $d$-dimensional real-valued vectors using $d(1+o(1))$ bits each, in a manner that allows the receiver to approximately reconstruct their mean. Such compression problems naturally arise in distributed and federated learning. We provide novel mathematical results and derive computationally efficient algorithms that are more accurate than previous compression techniques. We evaluate our methods on a collection of distributed and federated learning tasks, using a variety of datasets, and show a consistent improvement over the state of the art.