1. Introduction
Air transportation is the driving force for national or regional economic development and industrial upgrading, and the aero-nautical communication system (ACS) is a core infrastructure of the air transportation system (ATS), ensuring safety and a high level of efficiency. With the fast development of global ATSs, various aviation fields including air traffic control (ATC), airline operation control (AOC), and airline passenger communi-cation (APC) have introduced higher requirements for aeronauti-cal communication capability. However, due to outdated technologies and application barriers, the current ACS has reached its theoretical limit in terms of efficiency and data rate, and thus cannot accommodate the surging demands of diversi-fied aeronautical communication services, such as large band-width, high reliability, and global coverage. According to the consensus of the global aviation community, promoting the development of the ACS from narrowband to broadband has become an inevitable choice for modern ACS construction, as well as being necessary for aviation operation safety, efficiency, and service improvement.