A blockchain-empowered crowdsourcing system for 5G-enabled smart cities *

With the development of 5G(5th generation mobile networks) technology, smart cities are an inevitable trend in modern city development. Among them, smart city services are the foundation of 5G-enabled smart cities. As an emerging and informational city service model, crowdsourcing has been widely used in our daily life. However, in the existing crowdsourcing systems, the requesters and the workers are usually required to use the crowd sourcing platform as the trust center, and the payment depends on the third-party central payment institutions, which have a massive security risk. Once these centers are attacked or do evil, it will bring higher losses to the crowdsourcing parties. These problems will negatively affect the further development of 5G-enabled smart cities. To address these issues, we propose a blockchain-empowered and decentralized trusted service mechanism for the crowdsourcing system in 5G-enabled smart cities. In the proposed mechanism, the crowdsourcing service process is divided into nine stages: initialization, task submission, task publication, task reception, scheme submission, scheme arbitration, payment, task rollback, and service compensation. The smart contract controls the execution of each step in each stage, and the payment is completed by blockchain without the involvement of third-party central institutions. Finally, we develop smart contracts to conduct experiments based on Ethereum and compare it with the existing crowdsourcing system. The experimental results show the effectiveness and applicability of the crowdsourcing system service mechanism without the central institutions.