  As an emerging concept, the Metaverse has the potential to revolutionize the
social interaction in the post-pandemic era by establishing a digital world for
online education, remote healthcare, immersive business, intelligent
transportation, and advanced manufacturing. The goal is ambitious, yet the
methodologies and technologies to achieve the full vision of the Metaverse
remain unclear. In this paper, we first introduce the three infrastructure
pillars that lay the foundation of the Metaverse, i.e., human-computer
interfaces, sensing and communication systems, and network architectures. Then,
we depict the roadmap towards the Metaverse that consists of four stages with
different applications. To support diverse applications in the Metaverse, we
put forward a novel design methodology: task-oriented design, and further
review the challenges and the potential solutions. In the case study, we
develop a prototype to illustrate how to synchronize a real-world device and
its digital model in the Metaverse by task-oriented design, where a deep
reinforcement learning algorithm is adopted to minimize the required
communication throughput by optimizing the sampling and prediction systems
subject to a synchronization error constraint.
