PoWaP: Proof of Work at Proximity for a crowdsensing system for collaborative traffic information gathering

Abstract Blockchain technologies has become popular since the appearance of the first electric value exchange system on the Internet: Bitcoin. This technologies enable reliable data structure against tampering even in the absence of any authority to rely on, instead to check consistency with everyone who joins in the system. At present, however, the practical application of the blockchain technologies is to issue currency mainly traded for market speculation or money game. On the other hand, many researchers and software developers believe its applicability not only to improving today’s bank systems but also to creating a new solution to nonbank areas without relying on any centralized control system. In the field of transportation technologies for smart city, the combination of self-driving connected cars and IoT have been recently studied to achieve more efficient and safer transportation. To encourage a reduction of traffic jams by controlling mobility efficiently, it is necessary to automatically gather high-definition traffic information about traffic counts and road closures on urban roads. In this paper, a distributed crowdsensing system for collaborative gathering of traffic information is proposed. In the system, special beacon devices are asumed to be deployed along road segments by many unspecified individuals like today’s Wi-Fi routers. These devices at geographical proximity collaboratively and automatically record which vehicles passed in the road segment into the blockchain using Proof of Work (PoW). This process is incentivized by issuing its own digital currency. The system also enhances anti-tampering performance by cross-referencing blockchains of multiple road segments with each other. By chronologically saving traffic data into blocks in the blockchain, each beacon can refer traffic count and abnormal traffic, such as traffic jam and accidents. To evaluate the proposed system, we demonstrate some simple numerical simulations to show how the system makes localized PoW based consensus, and also the blockchain responds to quasi-real-time traffic status in the road segment.