Chapter 7: Air-Based Cooperative Transmission System

With the continuous development of network services, the defects of traditional ground cellular communication systems on coverage and transmission rate are more obvious. The new air-based transmission system, as an important supplement to the ground-based transmission system, has gradually attracted widespread attention. High-altitude platform station (HAPS) is considered to be an air-based broadband wireless access method with good potential application value, and it may become the third wireless communication system after the ground-based wireless communication system and the satellite-based communication system. It can achieve high mobility and high data rate of users and can complete wide-area coverage with less base stations and faster deployment. From the perspective of the air-based system and employing the cooperative transmission method, this chapter first introduces the background of the high-altitude platform communication system, including Google’s Project Loon. Considering that the flexible beamforming of the antenna array is the core means of high-altitude platform implementation and cell coverage optimization, this chapter then introduces the array-based air-based transmission system and discusses the air-based beamforming technology based on two-dimensional filtering. Furthermore, the high-altitude platform cell planning method is given, and the efficient transmission mechanism between high-altitude platforms is introduced finally.