Guest Editorial Special Issue on When Blockchain Meets 5G/6G—Enabling Endogenously Secure IoT

The standardization of the fifth-generation (5G) communications has been completed, and the visioning and planning of the sixth-generation (6G) communications have begun, with an objective of casting the high technical standard of new spectrum, high time and phase synchronization accuracy, and 100% geographical coverage to flexibly and efficiently connect upper trillion-level devices in the future. The transition from 5G to 6G is expected to integrate all operational networks, especially the Internet of Things (IoT), which involves massive heterogeneous devices to interact with our physical world.