Over-the-Air Computing for 6G -- Turning Air into a Computer

Wireless data aggregation (WDA), referring to aggregating data distributed at devices, is a common operation in 5G-and-beyond networks for supporting applications related to distributed sensing, learning, and consensus. Conventional WDA techniques that are designed based on a separated-communication-and-computation principle encounter difficulty in meeting the stringent throughput/latency requirements imposed by emerging applications (e.g., auto-driving). To address this issue, over-the-air computation (AirComp) is being developed as a new WDA solution by integrating computation and communication. By exploiting the waveform superposition property of a multiple-access channel, AirComp turns the air into a computer for computing and communicating functions of distributed data at many devices, thereby dramatically accelerating WDA. In view of growing interests on AirComp, this article provides a timely overview of the technology by discussing basic principles, advanced techniques, applications, answering frequently asked questions, and identifying promising research opportunities.