Beaming the New Wireless Connectivity Experience with Beamforming

As consumers continue to increase their use of mobile data, mobile network operators (MNOs) are actively looking for ways to increase network capacity and data throughput while at the same time finding ways to expand coverage deeper into rural communities and sparsely populated areas. Traditional options like buying more spectrum or densifying the challenged areas with more base stations can take care of these needs - but those approaches are not always technically feasible or financially viable, and they can take a long time. Spectrum is a scarce resource that is not easily come by, so operators must use it as wisely as possible. Likewise, increasing base station density in already dense locations can lead to signal interference, which causes the user experience to deteriorate.

So how does an operator make the best use of available spectrum and enhance capacity and coverage without increasing the base station density? Beamforming is one solution that is one of the key technologies available in advanced 4G and 5G networks. It has many advantages, including the potential to bridge the digital divide in rural areas by helping expand the network coverage as well as increasing data speeds. 

What exactly is beamforming? Technically, radio resources operate in two dimensions - time and frequency, and beamforming adds a third - spatial filtering. With beamforming, a base station is now aiming what it is transmitting in a particular direction instead of broadcasting the signal across a much larger area. Simply put, beamforming is an intelligent antenna technology that focuses radio signal or transmission energy in the direction of the mobile user. 

With traditional antennas, once a signal leaves the antenna it gets wider and wider, and as the signal travels away from the source, it loses its strength. We call this signal degradation through space and over distance "path loss." This loss occurs at different rates and is dependent on many factors, but a key aspect is the distance between the transmitting and receiving antennas. Path loss especially impacts users at the cell edge - they might get a radio signal, but the signal may not be sufficient to provide the service. Also, traditional sectored antennas transmit signals across the entirety of the area the sector covers, which is an improvement over omni-antennas that have minimal directional control. The benefit of sectored antennas is that the antenna sends the signal to the general area where the user is. A challenge comes when the target is in a highly loaded sector with many users; the signal sent from the cell to the user is being made available to all of the users in the sector. If the cell can focus the beam even more to the correct area of the target, other users are not "hearing" that unnecessary signal. 

Beamforming provides that targeting function - it narrows the horizontal and vertical planes of the radio signal to point at a specific user. This directional focus of the radio signal improves the reach of the signal while it also reduces interference to surrounding devices. This ability to focus the signal means base stations can be more efficient in delivering downlink data streams to users and in receiving uplink data streams from users.

Why do operators need beamforming? Operators are always looking for ways to improve their cell coverage. Beamforming concentrates energy into smaller areas, and by concentrating the signal, it helps operators achieve the goal of improving coverage while minimizing interference.

Beamforming offers three key benefits for mobile operators - 

• It ensures efficient utilization of the radio resources. By concentrating signals and pointing them in a particular direction, beamforming reduces interference at the receiving antennas of devices not near the target device. The directional "steering" improves session completions and reduces dropped calls for the intended device, and reduces interference for those who are not in the target area;
  
  
• It provides a focused, directed signal that results in an improvement of signal-to-noise ratio, which means that users receive stronger signals, resulting in a better experience at the cell edge. Mobile operators can also use beamforming to more efficiently deliver coverage to rural communities by focusing signals toward different large areas with fewer base stations ¹;
  
  
• It can enable a better customer experience. The increased network capacity and coverage from the efficient utilization of radio frequency that beamforming offers can lead to this better customer experience.

Beamforming improves the effectiveness of Massive MIMO, as it allows the base station to control the antennas sending a signal, so the base station is not simply broadcasting from the larger amount of antenna elements. The control allows the focused signal to target the coverage area with the established number of signals from a portion of the 32, 64, or 128 antenna elements. By controlling the number of transmitting signals to a portion of the antenna array, beamforming addresses one of the key challenges that users have with multiple signals - it reduces interference. Beamforming ensures that radio signals emitted by these antennas do not introduce unnecessary interference, which is critical in large antenna systems.

In addition to the benefits that beamforming is providing in today’s 4G LTE networks, it will have a critical role in 5G networks that operators are now beginning to roll out. It is a key technology for making 5G successful in the higher spectrum bands. As millimeter wave spectrum is expected to play a key role in 5G networks, beamforming is helping millimeter wave frequencies support user mobility via reflection and steering signals to end devices. With beamforming, operators can deliver the high speed, low latency, and high-reliability network that applications like AR / VR, gaming, autonomous cars, and 5G connected drones will need.