Designing Trustworthy Decentralized Cross-Chain Marketplaces: A 6G Network of Networks Perspective

6G promises an evolution to network of networks, where sophisticated end-to-end (E2E) services will be able to be composed across multiple heterogeneous networks in the resulting 6G marketplaces. Due to the number and heterogeneity of constituent stakeholders, the centralized architectures of today, as well as current static approaches to trust (e.g. service-level agreements (SLAs), will not scale, and decentralization with dynamic trust will be needed. A promising emerging technology in this regard is interoperable blockchains, with cross-chain transactions being a potential underlying framework for 6G decentralized network of network marketplaces for services. However, in order to support dynamic trust, a unified treatment of cross-chain transactions and cross-chain reputation sharing will be needed. To this end, we present a set of design objectives, and describe three classes of designs aligned with these objectives. We then present a comparison of these designs vis-à-visnonfunctional requirements for E2E services including security, data privacy, and accountability, as well as key aspects from a 6G network of networks marketplace perspective.