Antenna and Array Technologies for Future Wireless Ecosystems

Chapter 9Angle‐of‐Arrival Estimation in Large‐Scale Hybrid Antenna Arrays

Kai Wu and Y. Jay Guo

Global Big Data Technologies Centre, University of Technology Sydney, Sydney, Australia

9.1 Introduction

Large‐scale antenna arrays, or massive antenna arrays, are widely regarded as a critical technology for the emerging fifth‐generation (5G) [1–3] and beyond 5G communications (B5G) systems [4]. These large‐scale antenna arrays can produce very high antenna gain and needle‐like antenna beams, thus enabling long communications range and spectrum reuse in the spatial domain. Another driver for employing large‐scale antenna arrays is the frequency increase planned for 5G and B5G systems. The scarcity of spectrum resources has already pushed 5G toward the millimeter‐wave (mmWave) frequencies [5] and 6G is expected to occupy part of the terahertz (THz) range. While using higher frequencies leads to greater propagation losses, the related shorter wavelengths fortunately allow for the integration of larger numbers, i.e. up to hundreds and even thousands, of miniaturized antennas in a limited space. The consequent array gain can partially compensate for the significant radio propagation losses associated with mmWave and THz signals [4, 6].

It should be noted that the physical sizes of radio frequency (RF) chains, which consist of analog‐to‐digital converters (ADC) and digital‐to‐analog converters (DAC), power amplifiers, and filters, etc., do not shrink as much as the antenna array when ...