  With the development of communication technologies in 5G networks and the
Internet of things (IoT), a massive amount of generated data can improve
machine learning (ML) inference through data sharing. However, security and
privacy concerns are major obstacles in distributed and wireless networks. In
addition, IoT has a limitation on system resources depending on the purpose of
services. In addition, a blockchain technology enables secure transactions
among participants through consensus algorithms and encryption without a
centralized coordinator. In this paper, we first review the federated leaning
(FL) and blockchain mechanisms, and then, present a survey on the integration
of blockchain and FL for data sharing in industrial, vehicle, and healthcare
applications.
