I. Introduction
Internet of Vehicles (IoV), an essential paradigm of the Internet of Things (IoT) [1] related to intelligent transportation systems (ITS), are networks of interconnected vehicles and roadside units (RSUs) that exchange information to detect, prevent, and manage traffic problems [2]. For example, vehicles can exchange information about road conditions in order to avoid traffic jams. Due to their expansion, several commercial applications (e.g., multimedia and infotainment) have also been integrated into such networks for marketing and business purposes. Unfortunately, vehicular networks have been an appealing target for countless malicious attacks (e.g., impersonation and bogus information dissemination) due to their infrastructureless and distributed nature [3]. Such attacks are likely to result in catastrophic consequences ranging from loss of lives (in case of traffic management applications) to loss of revenue (in case of commercial applications) [4]. This demands setting up strict security measures (i.e., intrusion detection and prevention systems) to protect the vehicular network from being an easy target for attackers. This is however a difficult task in such networks that have special restrictions and needs. The main restriction is related to the massive computation load that is often needed for analyzing big intrusion detection data. For example, previous results showed that running an intrusion detection system (IDS) over a data set of 10-MB size can consume up to 212 J of energy, up to 100 MB of RAM and up to 460 s of CPU on a mobile device, with an execution time of 459 s [5]. On the other hand, with the rapid evolution in ITS and the integration of artificial intelligence (AI) capabilities into today’s smart devices (i.e., autonomous vehicles), the resources that are available on smart vehicles have to be efficiently exploited to ensure the success of such technology and avoid undesirable consequences. In other words, the resources that are available on AI-powered vehicles should be primarily dedicated to making real-time driving decisions (e.g., detecting pedestrians, cyclists, etc.), rather than to security assurance. Therefore, there should be a smart load distribution mechanism to efficiently decide where the intrusion detection tasks should be executed. Motivated by this idea, we design in this work a distributed multilayer offloading approach that takes advantage of the emerging edge computing technology to perform intrusion detection in vehicular communication systems in an efficient and resource-aware manner.