Efficient collaboration between collaborative machine learning and wireless
communication technology, forming a Federated Edge Learning (FEEL), has spawned
a series of next-generation intelligent applications. However, due to the
openness of network connections, the FEEL framework generally involves hundreds
of remote devices (or clients), resulting in expensive communication costs,
which is not friendly to resource-constrained FEEL. To address this issue, we
propose a distributed approximate Newton-type algorithm with fast convergence
speed to alleviate the problem of FEEL resource (in terms of communication
resources) constraints. Specifically, the proposed algorithm is improved based
on distributed L-BFGS algorithm and allows each client to approximate the
high-cost Hessian matrix by computing the low-cost Fisher matrix in a
distributed manner to find a "better" descent direction, thereby speeding up
convergence. Second, we prove that the proposed algorithm has linear
convergence in strongly convex and non-convex cases and analyze its
computational and communication complexity. Similarly, due to the heterogeneity
of the connected remote devices, FEEL faces the challenge of heterogeneous data
and non-IID (Independent and Identically Distributed) data. To this end, we
design a simple but elegant training scheme, namely FedOVA, to solve the
heterogeneous statistical challenge brought by heterogeneous data. In this way,
FedOVA first decomposes a multi-class classification problem into more
straightforward binary classification problems and then combines their
respective outputs using ensemble learning. In particular, the scheme can be
well integrated with our communication efficient algorithm to serve FEEL.
Numerical results verify the effectiveness and superiority of the proposed
algorithm.