Advanced antenna technologies in the beyond IMT-advanced systems [Editorial]

Both the fourth generation (4G) and fifth generation (5G) mobile systems will use multiple-input multiple-output (MIMO) technologies with multiantenna capabilities at both the base station and user equipment. To improve the capacity, extend the coverage, and decrease the antenna deployment complexity, many advanced antenna technologies have been proposed recently, such as the large-scale array antenna and the small-scale smart antenna.