Over-the-air Signaling in Cellular Networks: An Overview

To improve the capacity and coverage of current cellular networks, many advanced technologies such as massive MIMO, inter-cell coordination, small cells, device-to-device communications, and so on, are under studying. Many proposed techniques have been shown to offer significant performance improvement. Thus, the enabler of those techniques is of great importance. That is the necessary signaling which guarantee the operation of those techniques. The design and transmission of those signaling, especially the over-the-air (OTA) signaling, is challenging. In this article, we provide an overview of the OTA signaling in cellular networks to provide insights on the design of OTA signaling. Specifically, we first give a brief introduction of the OTA signaling in long term evolution (LTE), and then we discuss the challenges and requirements in designing the OTA signaling in cellular networks in detail. To better understand the OTA signaling, we give two important classifications of OTA signaling and address their properties and applications. Finally, we propose a signature-based signaling named (single-tone signaling, STS) which can be used for inter-cell OTA signaling and is especially useful and robust in multi-signal scenario. Simulation results are given to compare the detection performance of different OTA signaling.