While 5G is at the early deployment state around the globe, the research and industrial communities have already started concentrating their efforts on formulating the overall 6G vision comprising requirements, key enabling technologies, performance indicators, and applications. Following the trend, it is evident that 6G will emerge as highly softwarized and open networks allowing the participation of multiple stakeholders. This undoubtedly will make 6G more flexible, agile, autonomous, intelligent, and cost-efficient networks. However, the programmability and openness will make 6G networks more prone to issues like security, privacy, traceability, interoperability, auditability, resource manageability, spectrum efficiency, and 3D mobility. To address these issues, a deep integration of blockchain technology with 6G networks is foreseen. Thus, we aim to put together blockchain and 6G under a magnifying lens to gain a comprehensive understanding of the role of blockchain in the 6G ecosystem. We begin by providing an overview of the envisioned 6G networks and blockchain technology. Next, we present a high-level view of the role of blockchain for 6G trends and requirements. Following that, we conduct an in-depth study on how the blockchain can provide a secure, transparent, and decentralized underpinning to various technical aspects and use cases of 6G. Thereafter, we discuss the deployment challenges to be faced while integrating blockchain in 6G and the possible solutions. Finally, future research directions are expounded to set the floor for further advancements in the blockchainized 6G.

虽然 5G 在全球处于早期部署状态，但研究和工业界已经开始集中精力制定包括需求、关键使能技术、性能指标和应用在内的 6G 总体愿景。顺应这一趋势，很明显 6G 将成为高度软件化和开放的网络，允许多个利益相关者参与。这无疑将使6G网络更加灵活、敏捷、自主、智能和经济高效。然而，可编程性和开放性将使 6G 网络更容易出现安全、隐私、可追溯性、互操作性、可审计性、资源可管理性、频谱效率和 3D 移动性等问题。为了解决这些问题，深度整合可以预见具有 6G 网络的区块链技术。因此，我们旨在将区块链和 6G 放在一个放大镜下，以全面了解区块链在 6G 生态系统中的作用。我们首先概述设想的 6G 网络和区块链技术。接下来，我们对区块链在 6G 趋势和需求方面的作用提出了一个高层次的看法。之后，我们对区块链如何为 6G 的各个技术方面和用例提供安全、透明和去中心化的基础进行了深入研究。此后，我们讨论了在 6G 中集成区块链时面临的部署挑战以及可能的解决方案。最后，阐述了未来的研究方向，为区块链化 6G 的进一步发展奠定了基础。