# Reputation-Based Blockchain for Spatial Crowdsourcing in Vehicular Networks
###### Abstract  
The sharing of high-quality traffic information plays a crucial role in enhancing the driving experience and safety performance for vehicular networks, especially in the development of electric vehicles (EVs). The crowdsourcing-based real-time navigation of charging piles is characterized by low delay and high accuracy. However, due to the lack of an effective incentive mechanism and the resource-consuming bottleneck of sharing real-time road conditions, methods to recruit or motivate more EVs to provide high-quality information gathering has attracted considerable interest. In this paper, we first introduce a blockchain platform, where EVs act as the blockchain nodes, and a reputation-based incentive mechanism for vehicular networks. The reputations of blockchain nodes are calculated according to their historical behavior and interactions. Further, we design and implement algorithms for updating honest-behavior-based reputation as well as for screening low-reputation miners, to optimize the profits of miners and address spatial crowdsourcing tasks for sharing information on road conditions. The experimental results show that the proposed reputation-based incentive method can improve the reputation and profits of vehicle users and ensure data timeliness and reliability. blockchain; reputation; crowdsourcing; incentive mechanism; vehicular networks +
Footnote †: journal: Applied Sciences  
Meanwhile, traditional crowdsourcing platforms are notorious for being untrustworthy and unfair. The distributed blockchain can also be a decentralized crowdsourcing platform. The crowdsourcing task centers on solving a task request submitted by the user, by submitting it to the blockchain and publishing it in the form of a Proof of work (PoW) problem. Blockchain facilitates the transfer and exchange of information and data in the absence of a third-party [7]. In vehicular networks, the distributed ledger mainly monitors the legitimacy of transactions by recording the index of transactions jointly by the geographical distributed vehicles; the consensus mainly achieves the consensus, to complete the validity verification; the encryption algorithm is utilized to encrypt and decrypt keys and signatures, which renders it unbreakable. The essence, solutions and required computational resources of crowdsourcing tasks and blockchain PoW puzzles are equivalent. Different from traditional crowdsourcing platforms, since there is no third-party participation in the blockchain-crowdsourcing system, the security and efficiency are determined by computational capability or the degree of participation of vehicle nodes. As mentioned, crowdsourcing tasks are divided according to attributes, and according to attribute task assignment miners can choose sub-tasks that are suited to their abilities. The execution of the task is different from that in the traditional methodology. It is processed and executed in the blockchain network in the form of a blockchain transaction. Therefore, we can see that when the PoW problem is solved, the crowdsourcing task is completed. Taking the EV charging task as an example, customers will receive solutions by sending their task requirements (such as charging piles, road condition information, usage of the piles, traffic congestion, etc.) to the blockchain. When miners generate unresolved blocks, verification nodes are required to verify. In short, EV charging tasks are solved efficiently and safely through the blockchain. Based on distributed ledger technology, blockchain adoption can ensure that transactions cannot be tampered or forged, an especially important consideration behind its successful application in digital economics. Blockchain provides a feasible solution for distributed edge computing deployment scenarios, e.g., Vehicular Networks [8], Drone Networks [9], Non-Fungible Tokens (NFTs) [10]. Blockchain technology can realize the distributed deployment of application services without intermediaries, so that individuals who lack trust can interact in a safe and credible manner.