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The capacity of mobile networks will soon become wholly insufficient for smart cities due to the growing number of users and new digital services being built and planned. The problem can be solved by using small cell radio frequency (RF) technologies and higher frequencies. This requires dense networks of antennas, setting new requirements for the network infrastructure.

Aalto University, together with the companies of the LuxTurrim5G ecosystem, has developed the materials and structures required for smart light poles, 5G radio technology and network architecture and new business models.

Lightpole thermal management

'We have developed a compact liquid cooling concept for the high-power electronics of 5G radios,' says Professor Ville Vuorinen from the Aalto University Energy Conversion research group.

'There is a strong societal demand for compact cooling solutions due to electrification, for example. Optimally, generated waste heat can be harvested and further utilised for saving energy,' he adds.

In LuxTurrim5G, the thermal management design process was driven by 3D fluid dynamics simulations. Understanding the details of liquid flow inside coolant channels enables compact design and hence material savings.

'Importantly, during the project, 3D simulations allowed us to eliminate several non-optimal heat exchangers. Now the thermal design of our prototype is highly optimised and scalable,' Vuorinen continues.

'The final design is a modular cooling plate which is fully 3D printed out of aluminium. This technology is currently available to us,' says Professor Jouni Partanen from the Advanced Manufacturing and Materials research group.

Managing the network

The project has also conducted analyses to discover what the best practices are for building the network; what cost items there are in planning, building and managing the network; who the key players are and how the costs of the network will be shared.

The alternative value network configurations and a cost model for the 5G smart light pole system were developed in the team of Professor Heikki Hämmäinen in the Aalto University Department of Communications and Networking. This work enables a structured planning approach in different city environments for the business actors looking for their product opportunities and business roles.

'Cities differ from each other in many ways and the same value network set-up for metropolitan 5G does not suit all cities', says Professor Hämmäinen.

The communications network based on 5G smart light pole concept creates a platform for a variety of digital services for a smart city, bringing new business opportunities to many actors. The pilot environment created by the LuxTurrim5G ecosystem already makes it possible to test them in practice now, which will significantly speed up the development of a 5G smart city.

Is 5G radio service possible indoors?

The LuxTurrim5G ecosystem has also identified potential in the smart light poles to provide 5G cellular service coverage for indoor users.

Indoor cellular coverage is more challenging for 5G because it uses higher carrier frequencies to transfer data than legacy cellular networks, e.g., long-term evolution (LTE). Higher frequency signals tend to attenuate more severely when penetrating walls of buildings, making indoor coverage a serious concern.

A tool for analysing outdoor-to-indoor 5G cellular coverage has been developed for this purpose in collaboration with companies in the LuxTurrim5G ecosystem, notably with Nokia Bell Labs. The tool shows that indoor cellular coverage at 4 and 14 GHz carrier frequency is indeed feasible, but also shed light on further challenges present at higher frequencies to ensure indoor coverage.

'5G will use the 26 GHz and maybe the 70 GHz band in the future. For the initial deployment of 5G at around 3.5 GHz, indoor coverage looks promising, similar to LTE. 26 GHz looks much more challenging, and I am sceptical about 70 GHz. New technical solutions would be necessary for those frequencies so that indoor 5G users will receive the right services', says Professor Katsuyuki Haneda from the Department of Electronics and Nanoengineering at Aalto University.

From Espoo smart city pilots to global markets

The next step is to expand the LuxTurrim5G pilot environment around the Nokia Campus and build a basis for commercialising the concept. The goal is to implement these new solutions into practice soon, in both Espoo and other Finnish cities.

'The LuxTurrim5G project has created real smart city elements that will enable Espoo to develop the modern Kera district next to the Nokia Campus. Espoo is already committed to expanding the 5G smart pole network to the Kera railway station, which allows for e.g. a self-driving bus service”, says Jukka Mäkelä, Mayor of Espoo.

'Follow-up plans include strong business development, including new business models and ways to exploit these large amounts of data to create new business. Another interesting topic is to study the feasibility of the so-called Neutral Host Operator Model in practice,' says Project Manager Pekka Wainio from Nokia Bell Labs.

Naturally, the development work is not being done for Finland alone. There is significant global demand for the solutions being developed within the LuxTurrim5G ecosystem, and companies in the ecosystem are aiming to respond to the demand by developing new products and services for the global market. The LuxTurrim5G pilot environment in Espoo, which is still being developed further, is a very important springboard for enabling Finnish companies to get a good grip on the massive business opportunities of 5G and smart cities.

For more information:

Aalto University

Professor Ville Vuorinen, ville.vuorinen@aalto.fi

Professor Jouni Partanen, jouni.partenen@aalto.fi

Professor Heikki Hämmäinen, heikki.hammainen@aalto.fi

Professor Katsuyuki Haneda, katsuyuki.haneda@aalto.fi