While all development phases of the 4G mobile network are yet to be implemented, the fifth generation (5G) mobile networks are already becoming an increasingly hot topic. VTT is building the first 5G test network in Finland in Oulu in cooperation with industrial partners and the local university.
“Our aim is to make Finland a pioneer in 5G development and specification, as well as the best global development location for 5G technology and applications,” says Research Team Leader Kyösti Rautiola from VTT’s Radio Systems Team.
In terms of network evolution, the 4G networks currently used have significantly higher data transfer speeds and capacity than 3G networks. According to the leader of the 5GTN project and Senior Scientist Atso Hekkala from VTT, 5G will be rolled out in 2020 and will introduce even more profound changes. The projects has many objectives – and challenges.
“This makes it much more interesting for the researchers. Based on expectations, it is safe to say that digitalisation will encompass all areas of the society, and we see 5G as the enabler of this development,” Hekkala explains.
Speeds will become hundredfold on average
On average, users will be offered speeds hundreds of times faster than those available in current 4G networks. To develop more advanced network applications, it is no longer enough to transfer bits as fast as possible. Eliminating latency will change the way mobile networks are used by industry, for example. According to Rautiola, once latencies are measured in milliseconds, it is possible to communicate in real time with robots on the other side of the world.
“The autonomously moving vehicles of the future also require highly reliable, real-time data transfer.”
With increasing data transfer speeds, energy-efficiency also needs to be considered. This has previously been tackled by improved battery technologies. Hekkala says that while the CMOS microprocessor technology has been an effective solution up to this point, it is reaching the limits of reducing power consumption further.
Setting sights on the future
“Going forward, it is critical to make devices smarter so that they do not stay connected to the network unnecessarily. Mobile phones are connected continuously, which consumes a lot of power,” Hekkala explains.
Smartphone batteries go flat quickly because, as Hekkala points out, the 4G network is primarily designed to offer the highest possible data transfer speeds to support entertainment use, such as watching videos on smartphones. At the same time, the network is less capable of supporting large numbers of devices, which has a negative impact on data transfer quality during large public events or at venues such as sports stadiums. The 5G network will also do away with this problem.
Exponential growth of connected devices
At the moment, network device capacity is preventing the Internet of Things (IoT) from gaining ground.
IoT applications are already in use on a small scale, and Rautiola predicts that the number of connected devices will grow exponentially in the coming years as devices such as smart fridges that can order groceries automatically or smart clothes that monitor body functions become more common.
“Smart clothes and other devices that contain sensors do not send a lot of data; for them, it is enough to access the network. However, vast numbers of such devices will create a new challenge,” Hekkala says.
The 5G mobile network must have greater speed, less latency and more reliability while being able to support vast numbers of connected devices. How can this be achieved? The solution lies in many areas: Hekkala explains that firstly, radio frequencies will be used more efficiently. While the mobile networks currently operate around the 2 GHz frequency band, 5G can utilise free bandwidth in the 60 GHz frequency band, for example.
“Technologies are more advanced now, and it is possible to use higher frequency bands without making the devices too expensive,” Rautiola explains.
However, finding new bandwidth is not unproblematic. Many older users think fondly of the NMT450 network, the first generation of mobile networks, that could reach even the most remote areas. It used the relatively low frequency band of 450 MHz. More capacity was needed once mobile phones became more common, leading to the introduction of NMT900 – and larger areas with no coverage. The same applies today.
“High frequency signals have shorter range. It was previously unthinkable to use them for mobile communications,” Hekkala says.
5G can use several frequency bands
The test network currently uses the 2.6 GHz band. The 3.5 GHz band may also be taken into use in 2016. Hekkala points out that the frequencies of bands are not that essential to the 5G network.
“5G is a collection of many technologies. While older generations of phones used a specific band, 5G is capable of using several of them and do it seamlessly.”
VTT is building an open test network for 5G developers
VTT’S OULU FACILITIES now have a macro cell base station on the roof, and a network of numerous small cells is under construction to serve as the first 5G test environment in Finland. Similar cells pay a significant role in the future of 5G.
“We are currently carrying out initial measurements, to specify, for example, the best locations for base stations. We are also testing the performance of different antennas,” Atso Hekkala says.
The 5G Test Network (5GTN) in Oulu will be an open test environment for all 5G developers. The network is built in cooperation with academic and industry partners that have the expertise and device base required. IoT and 5G will be available for real-life testing after the turn of the year.
VTT is coordinating four 5G test network projects in Finland.
For more information, please see www.5gtnf.fi