I. Introduction
In recent years, the rapid development of mobile communication technologies, including 5G and mobile edge computing, has fueled the widespread adoption of next-generation Internet of Things (IoT). This has facilitated extensive interconnections among a large number of devices, such as sensors, portable devices, wearable devices, VR devices and smart devices. The surge in the number of next-generation IoT devices has led to a deluge of service requests and a variety of diverse applications, encompassing face recognition and interactive online games [1]. The service requests of IoT applications are often computationally extensive or latency sensitive. However, traditional service provisioning methods struggle to efficiently guarantee service performance and meet the diversified service requirements of IoT applications, since middleboxes are heavily dependent on specific hardware devices. Network Function Virtualization (NFV), a technology enabler for next-generation IoT networks, has garnered significant attention from academics and industries [2]. The crux of NFV lies in decoupling network functions and hardware devices, allowing network functions to be replaced by software based Virtual Network Functions (VNFs). In NFV-enabled next-generation IoT networks, each IoT service can be perceived as a Service Function Chain (SFC), which comprises an ordered sequence of VNFs [3]. By leveraging SFC technology, IoT users can define a sequence of heterogeneous VNF instances (such as IDS, NAT and FW) in a specified order to flexibly process the massive data flows generated by IoT applications. NFV empowers next-generation IoT networks to provide flexible and scalable services to a diverse range of IoT users.