Beamforming, from cell-centric to user-centric
Beamforming is a signal processing technique used in sensor arrays for directional signal transmission or reception. This is achieved by combining elements in a phased array in such a way that signals at particular angles experience constructive interference while others experience destructive interference. Beamforming can be used at both the transmitting and receiving ends in order to achieve spatial selectivity. The improvement compared with omnidirectional reception/transmission is known as the directivity of the element.
Beamforming / beamshaping will also improve the overall radio environment of a cell by limiting interference to small fractions of the entire space around a transmitter and likewise limiting the impact of interference on a receiver to infrequent stochastic events. The use of beamforming will also be an important technology for lower frequencies; for example, to extend coverage and to provide higher data rates in sparse deployments. In addition, the transmitter and receiver can use beamforming to track one another and to improve energy transfer over an instantaneously configured link.
Beamforming is typically accompanied with Beam steering / Beam tracking. With Beam steering, a transmission is dynamically adapted (i.e. steered) both vertically and horizontally by utilizing a steerable two-dimensional antenna array. By beam steering a highly-focused beam, a stronger radio signal with higher data throughput is delivered over a greater distance using using less energy. The result is spectral efficiency enhancement, capacity gain, cell edge throughput gain and mean user throughput gain.