Towards a Decentralized and Privacy-Preserving Quality of Experience System for 6G Networks

The transition to 6G networks is expected to support a broader range of user-centric applications. As these applications
expand, Quality of Experience (QoE) has emerged as a key metric for evaluating user satisfaction. However, the use of
centralized systems lacks transparency and limits users’ ability to govern their data usage. It also introduces challenges in
managing QoE data while preserving privacy. At the same time, verification mechanisms are needed that allow regulators to
evaluate compliance without exposing confidential business information. To address this, we propose a decentralized, privacypreserving
QoE system that integrates blockchain with fully homomorphic encryption (FHE). This design enables transparent
evaluations between users and service providers by supporting computations directly on encrypted data, ensuring that all
information remains protected throughout the process. Users contribute QoE metrics through a decentralized infrastructure
and retain control over their data. Regulators can monitor compliance without accessing raw data, and service providers
can use encrypted QoE data to perform privacy-preserving computations via smart contracts without relying on a central
authority. We developed a proof-of-concept integrating FHE smart contracts compatible with Ethereum Virtual Machine
(EVM) blockchains and evaluated their performance using a video streaming dataset. Our results show that encryption and
FHE operations consistently occur within milliseconds when tested in a local environment. We also evaluated these operations
on a public blockchain testnet. In this setting, our system adds a millisecond-scale delay while supporting privacy-preserving
computations directly on encrypted user data.