Researchers at Aalborg University Working on Massive MIMO Base Stations

As we move towards a world that is interconnected with billions of devices, the need for a well-functioning mobile network with ample room for more connected devices as well as increased data traffic becomes increasingly important. Researchers at Aalborg University are at the forefront of developing a new antenna technology to enable faster transmission, improved energy efficiency, better security and wider coverage.

Elisabeth De Carvalho, Associate Professor in the Department of Electronic Systems at Aalborg University, along with her colleagues, is working on a massive MIMO base station that caters to the seemingly endless increased need for data transmission. MIMO (Multiple-Input Multiple-Output) is a wireless technology used to transmit and receive data between a large crowd of connected devices and users at the same time.

The team in Aalborg is working on a base station unit that holds several hundred small antennas, making it possible to connect much more precisely to each mobile unit. Adding hundreds of antennas to a base station basically increases the data transmission rate many times because the energy can become much more focused. And because focused energy is also able to travel farther, the mobile coverage is likely to improve.

At the same time, base station energy consumption is expected to drop in comparison to present day systems. Its like having thin, concentrated water hoses that are aimed directly where you want them - rather than a huge, leaky fire hose that just splashes water all over the place.

With this technology they are not simply sending out data in all directions like a radio transmitter; they hope to be able to create a sort of virtual cable that is focused and narrow between the base station and the connected unit. They confine the space that we use for the transmission. This provides a faster and better connection.

Confining the transmission space is not only a capacity issue. One of the added benefits of having a massive amount of antennas is that it improves the security of the data transmission.

The more you can confine space, the harder it gets for others to listen in. When you have a broadcast you can always put up an antenna and pick up the signal if you are CIA or KGB or whatever, if you have equipment that is strong enough to decode the signal. But if you can’t get the signal in the first place it becomes really difficult to tap in to. The more you control space, the harder it gets for intruders to get in.

So far, the team has built a scaled-up model of a part of a massive MIMO array in the lab in order to do channel measurement and to figure out how to build a base station later on. They are looking at which types of performances you can get out of a massive MIMO. The performances depend very much of what is happening in the air between your device and the base station. They want to build channel models from those measurements. The models are necessary for engineers to test their algorithms. There is a lot of research that they still need to do before they build their proto type.