ABSTRACT
In September 2019, the world's first 6G white paper was published as an outcome of the first 6G wireless summit, which was held in Levi, Finland, earlier in March 2019 with almost 300 participants from 29 countries, including major infrastructure manufacturers, operators, regulators as well as academia. The radical potential of blockchain technology has long spread outside the world of crypto into the hand of the general public. Blockchain technology is being successfully applied in both financial and non-financial applications. Blockchain oracles can be classified depending on a number of different qualities: source, i.e., the origin of data, direction of information, i.e., inbound or outbound from the viewpoint of the blockchain, the initiator of the data flow, whether it is push- or pull-based communication, trust, i.e., centralized or decentralized, and design pattern. The chapter also presents an overview on the key concepts discussed in this book.
