Enforcing Cooperation in IoT-Based VDTNs

In IoT-based Vehicular Delay-Tolerant Networks (VDTNs), intermittent connectivity and node mobility often lead to selfish behavior, where nodes drop packets to conserve resources, resulting in lower delivery rates and higher delays. Existing incentive mechanisms, including reputation-based, credit-based, and hybrid approaches, frequently depend on centralized entities or remain vulnerable to collusion and manipulation. Blockchain-enabled schemes in VANETs and DTNs have been proposed, but their adaptation to fully opportunistic VDTNs with prolonged disconnects remains limited. This paper presents Blockchain-Based Hybrid Reputation-Credit (BCHRC), a blockchain-enhanced hybrid reputation-credit mechanism designed to promote cooperative packet forwarding in VDTNs. Reputation scores are derived from direct and indirect observations using weighted aggregation, while credits are issued and redeemed through smart contracts on a lightweight consortium blockchain secured by Practical Byzantine Fault Tolerance (PBFT). Off-chain computation and batch processing minimize overhead in disconnected environments. The mechanism mitigates bad-mouthing, ballot-stuffing, collusion, and Sybil attacks via threshold validation and cryptographic commitments. BCHRC's key novelty is a tunable decision-making utility function that formally integrates reputation and credit scores, enabling adaptive forwarding decisions distinct from monitoring-oriented schemes like EMS and congestion-aware incentives like CAPPS. Simulations in the Opportunistic Network Environment (ONE) simulator show BCHRC achieves up to ۲۳% higher packet delivery probability than EMS and CAPPS under high selfishness (۵۰% selfish nodes), with ۱۸% lower average delay and comparable control overhead. Quantitative analysis of blockchain latency, message costs, and parameter sensitivity confirms robustness across network conditions. BCHRC provides a practical framework for decentralized trust in opportunistic vehicular networks, balancing security and efficiency under resource constraints.

کلیدواژه ها:

Vehicular Delay-Tolerant Networks (VDTNs) ، Internet of Things (IoT) ، blockchain ، hybrid incentive mechanism ، reputation system ، credit-based incentive ، selfish behavior