Development challenges of millimetre-wave 5G beamformers

Beamforming is the central concept that can make millimeter‐wave (mmWave) a viable solution by solving challenges of link‐budget, cost, power, form factor, complexity, regulatory constraint, and so on. Before deployment of mmWave beamforming solution for 5G, and possibly beyond, several fundamental questions need to be answered. Some of them include hardware constraints, performance matrices, realistic propagation channel models including impairments due to obstacles such as body, blockages due to casings, phase noise, a model for spatial‐temporal variations in channels, and advanced MIMO techniques for multi‐carrier and multiuser communications. The site constraints and massive non‐line‐of‐sight transmission within the urban environment are severely questioning the conventional terrestrial low power node deployments that used to work well at low operational frequencies (sub‐6 GHz). In addition to this, in beamforming technology using massive antenna arrays, the coordination of the users and beams at the transmitter and receiver end within a large network are very challenging. In this article, we comprehensively investigate some of the most prominent and best practice solutions that attempted to answer these challenging questions