• UFRJ Nautilus

Beamforming and it's performance in 5G

Updated: May 7

Let’s suppose that you have to go from point A to point B, and in this way there is no point of light. There are two options to take on this trip: a candle or a flashlight. Which one would you choose? The most logical answer is the flashlight, and this happens because, the candle is able to accidentally burn out and the lantern can be directed in a specific direction, and this can be very useful when you are situated in a complete dark place. From that example, we can understand how the Beamforming technique is useful within signal processing and reasons why it is so required for 5G be a reality.

Like the candle the antennas that we have in routers, for example, emit an omnidirectional signal (in all directions). This technique, however, is a digital direction of a signal, functioning as a flashlight. Thanks to this, the signal has greater power, stability and reliability.

A demand for obtain specific signals is not recent. The oldest form of directing a signal from an antenna is mechanical, like satellite dish, for example, widely used in radio astronomy which this mechanical direction It's not a problem. Basically, these antennas have a plate around them and thus a certain opening, as the device moves on one direction, the signals from that region are intensified.

However, there are several actions that this model can be a great impediment. Whether needing very high rates or for localization purposes. Based on that an electric direction called Beamforming that was created in 1940s, to be placed on WWII submarines. Until we get to the digital shape that we know. But how does it work?

This technique works by using antenna convergence to direct the energy - be it acoustic or electromagnetic - for a given direction, or also reject it. This is due to the overlap of the signals, which can obtain constructive or destructive interference of the waves and thus locate in a specific angle. Due to the principle of reciprocity it can be reception or streaming, generating something like the image below.

Thanks to this model, which has been gaining popularity in recent years due to the technical advances and cheapness of this factors, today we can have in our houses newer routers and cell phones. At Nautilus, for example, we use this technique to obtain an accurate position of the robot to the emission of a pinger in the environment. This theme is further explored in the text on echolocation, if you want to understand more.

Devices with 802.11n wifi technology onwards already start using this and MIMO (multiple input / multiple output) for greater stability of network information.

MIMO in turn use multiple antennas coupled to a processor which arranges for everyone to transmit and receive information, being able to chat with different devices at the same time, unlike old routers that communicate only one signal at time, even if imperceptible. This two technologies forms one of the bases for 5G turn into a reality today. The reason why this mechanism is so different and sophisticated it is the capacity of working in a extremely high frequency (EHF), above 30 GHz. And although it can transmit data on absurd speeds like 2Gbit / s - reaching 40x higher than provided by 4G that works on frequencies close to 3GHz - these frequencies have ranges very low, in addition to suffering a lot with obstacles along the way. Transform a region, as a city, in a 5G environment it would be the same as installing a quantity of antennas vastly larger than the one we currently have. That's where Beamforming and MIMO can become great facilitators, and sorely needed, for the realization of this technology. Being able to direct the signals to the necessary points and in the best way, the reach of the 5G becomes more viable and accurate. In addition, huge amount of data, will significantly reduce the amount of transmission and of wasted energy.

Despite that, this is a bit distant reality, it is still very difficult - and expensive - to transform 5G something ordinary. However, Beamforming is shown as one of the key parts to make this possible because reaching and positioning are its crucial problems at the time. With the cheapness of these technologies and their advances, who knows we may start to see 5G antennas appear in cities in the near future.

Written by Ronaldo Koppe


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