  In this paper, we propose FedChain, a novel framework for
federated-blockchain systems, to enable effective transferring of tokens
between different blockchain networks. Particularly, we first introduce a
federated-blockchain system together with a cross-chain transfer protocol to
facilitate the secure and decentralized transfer of tokens between chains. We
then develop a novel PoS-based consensus mechanism for FedChain, which can
satisfy strict security requirements, prevent various blockchain-specific
attacks, and achieve a more desirable performance compared to those of other
existing consensus mechanisms. Moreover, a Stackelberg game model is developed
to examine and address the problem of centralization in the FedChain system.
Furthermore, the game model can enhance the security and performance of
FedChain. By analyzing interactions between the stakeholders and chain
operators, we can prove the uniqueness of the Stackelberg equilibrium and find
the exact formula for this equilibrium. These results are especially important
for the stakeholders to determine their best investment strategies and for the
chain operators to design the optimal policy to maximize their benefits and
security protection for FedChain. Simulations results then clearly show that
the FedChain framework can help stakeholders to maximize their profits and the
chain operators to design appropriate parameters to enhance FedChain's security
and performance.
