This blog post is part of a series called “CommScope Definitions,” in which we
will explain common terms in communications network infrastructure.
For next-generation wireless networks such as 5G, beamforming
will be an important feature of base station antennas. Beamforming has been used for decades, predominately
in military radar, jammer and satellite applications to achieve a highly
directive antenna beam that is electrically steerable. A steered beam was often achieved using a
rotatable reflector antenna as is commonly seen in airport and marine radars or
radio astronomy antennas. Yet,
mechanically steered antennas have several disadvantages, such as mechanical
joints that have limited life due to wear, fragile rotating RF joints to guide
the transmitted/received energy to the radio, relatively slow re-steering
times, and non-random access to specific pointing angles.
Electronic scanning arrays circumvent these limitations by
providing an antenna array that is fixed in its position with no moving parts.
Its antenna pattern is steered electrically rather than mechanically. In previous mobile wireless generations,
mechanically steered arrays were not viable due to the limitations mentioned,
and electrically steered arrays were considered impractical due to the intense
signal processing capability required.
As silicon densities and speeds have increased at an
exponential rate over the past decades, it is now feasible to implement electrically
steered beamforming in mobile networks—and even user equipment— at a viable
price point. For next-generation mobile communication networks, electrical
beamforming is now considered a vital feature in order to meet the required
data rates and network capacity, to achieve sufficient coverage using higher
frequency band with higher path losses, and to better manage interference.
CLICK TO TWEET: CommScope's Mike Brobston explains 5G beamforming.
Use of beamforming in mobile networks offers several
advantages over the sectorized antenna patterns used in previous and current mobile
wireless generations. In these networks, base stations broadcast the channel resources
designated for a specific user over the full sector, so only a very small
percentage of the power is radiated in the direction of the intended user. With
beamforming, the use of a directive beam focuses the transmitted signal
strength and receiver sensitivity in the direction of the intended wireless
link, increasing the range of the link and the available throughput to a given
The other significant benefit is that use of a directive
antenna beam reduces interference to other mobile users by minimizing radiation
in directions other than the intended mobile user. This allows the same wireless spectral
resources to be used for multiple, simultaneous links within a sector with manageable
A beamforming antenna array is generally comprised of many
individual antenna elements or sub-arrays.
Each element or sub-array of elements is connected to an individual
transmitter/receiver channel. The more
elements that are arrayed generally results in a narrower beam and higher gain
at the peak of the beam. Since each
antenna element is transmitting or receiving the signal, the signal transmitted
or received from some angles will add in-phase as the channels are combined, whereas
signals from other angles will subtract and thereby cancel each other.
The carrier frequency radiated by each element of the array combines
either constructively or destructively across various angles to form peaks and
nulls in the antenna beam. If the delay through each channel is equal, then the
peak of the antenna beam will point directly perpendicular to the array,
otherwise known as the boresight angle. By progressively increasing the
electrical delay across the elements of the array, the peak of the antenna beam
is positioned at an angle that is offset from boresight. Therefore, by
carefully controlling the relative electrical delay through each
transmitter/receiver path to each of the antenna elements, the antenna beam can
effectively be electrically steered across a wide angular range. Using advanced
acquisition and tracking algorithms, the angle for each mobile user is
determined and tracked to ensure the user receives the strongest signal with
Advances in semiconductor process technology
have enabled the implementation of dozens of transmitter/receiver channels and
many megaflops of processing capability within relatively small and low power
electrical components. This has in turn
brought the use of advantageous techniques such as beamforming within reach of
mobile wireless networks and low cost mobile devices to greatly enhance the
mobile experience of future network users and address the ever-increasing
demands for wireless throughput and capacity.