  Efficient Vehicle-to-Everything enabling cooperation and enhanced
decision-making for autonomous vehicles is essential for optimized and safe
traffic. Real-time decision-making based on vehicle sensor data, other traffic
data, and environmental and contextual data becomes imperative. As a part of
such Intelligent Traffic Systems, cooperation between different stakeholders
needs to be facilitated rapidly, reliably, and securely. The Internet of Things
provides the fabric to connect these stakeholders who share their data, refined
information, and provided services with each other. However, these cloud-based
systems struggle to meet the real-time requirements for smart traffic due to
long distances across networks. Here, edge computing systems bring the data and
services into the close proximity of fast-moving vehicles, reducing information
delivery latencies and improving privacy as sensitive data is processed
locally. To solve the issues of trust and latency in data sharing between these
stakeholders, we propose a decentralized framework that enables smart contracts
between traffic data producers and consumers based on blockchain. Autonomous
vehicles connect to a local edge server, share their data, or use services
based on agreements, for which the cooperating edge servers across the system
provide a platform. We set up proof-of-concept experiments with Hyperledger
Fabric and virtual cars to analyze the system throughput with secure unicast
and multicast data transmissions. Our results show that multicast transmissions
in such a scenario boost the throughput up to 2.5 times where the data packets
of different sizes can be transmitted in less than one second.
