With 80% of mobile data already consumed indoors and customers expecting a seamless experience as they move between indoor and outdoor environments, operators and system integrators are under pressure to deliver ubiquitous connectivity.
The traditional approach is to rely on macrocells to penetrate into buildings but it is clear that this does not meet coverage and capacity requirements, particularly for large and complex buildings. The problem has been compounded by the move to higher frequency bands with 4G/LTE and now 5G. As a result, mobile operators are supplementing the ‘one size fits all’ outdoor macro model with in-building systems based on small cells, DAS and Wi-Fi to improve indoor coverage and quality of service (QoS).
The small cell market is expected to continue to rise rapidly over the next few years because of the commercial benefits in providing improved in-building and outdoor network services. Small cells are increasingly replacing macrocell sites due to their ability to boost cellular network capacity and revenue opportunities for network operators, offering enhanced quality and reliability for the end user.
But planning and designing wireless networks with small cells, DAS and Wi-Fi for indoor and outdoor environments together requires a new approach and new set of tools. Small cells require more granularity in predictions compared with macrocells. A macrocell may cover a 20 kilometer radius and therefore require a prediction resolution of 20-100 meters; whereas small cells are scaled down by a factor of 10, give or take, increasing the prediction resolution (20 meters down to 1-5 meters). This means that it is now important for software tools to take into account extra features in the model that were previously not required, such as accurate building data, higher resolution terrain data and, in some cases even foliage.
Accuracy is now the single biggest challenge and going from design phase to deployment often exposes the inaccuracy of current planning tool kits, especially when it comes to hybrid indoor/outdoor designs. This is usually because of the deployment of separate indoor and outdoor modeling tools, which have to guess how the two networks interact with one another, leading to inaccurate predictions.
This is driving the need for a more coordinated, holistic approach to indoor/outdoor network planning and design, especially in the U.S., where developing urban networks with small cells are on the rise. The communications airspace is strictly regulated by the FCC and since the sale of spectrum is monetized by the U.S. government, they are incentivized to test regularly, making sure that everyone stays within their bands. Because of this, many operators are getting very creative with their RF usage in certain markets where they are capped, which is making for some interesting and complicated designs. The only way to accomplish this level of creativity within regulatory guidelines is through intelligent design using planning tools that bridge the indoor/outdoor gap and remove the guesswork.
The challenge becomes even more acute with large complex building structures – such as skyscrapers, stadiums, college campuses, and underground environments. As the number of variables goes up, the complexity increases. With skyscrapers, the macrocells may ‘paint’ one side of the building up to the 20th floor with RF signal, but do nothing for the opposite side of the building or anything above the 21st floor. This creates an environment where the designer must take into account the macro signals while still designing the small cells, DAS and Wi-Fi for everything else. Stadiums, campuses and underground transport all have their own unique challenges that are unlike anything found in designing simple rural macro coverage.
Furthermore, the arrival of 5G, internet of things (IoT) and the drive to deliver smart city initiatives – such as the free public Wi-Fi in New York City – introduces an entirely new set of complexities. For example, the distances shorten with millimeter wavelengths and the signals can be disrupted much more easily by structures and different materials than low band signals. It is almost impossible to support 5G or IoT without some careful pre-planning and forethought to avoid wasting time and money during roll-outs over the next few years.
Why is designing for small cells key?
There are different types of small cells and their radio footprint ranges from a few meters to several kilometers depending on location requirements. The type of tool chosen for designing an RF network depends on the nature of the project such as the size, value, complexity, number of stakeholders, region, and budget. For 5G and the IoT, clients will need to simulate how wireless networks can handle growing coverage and capacity complexities driven by increased mobile broadband use, a need for faster download speeds and increased reliability and enhanced device-to-device support for multimedia applications. It will be important for these 3D modeling tools to be able to accurately optimize the most effective and efficient planned network design and realistically simulate real-world conditions, including network performance across multiple technologies.
Operators and system integrators can no longer avoid the indoor/outdoor issue and with offerings of seamless collection and transfer of data for improved prediction accuracy, increased design productivity, reduced design timescales and overall cost, this new generation of modeling tools will play a valuable role to deliver ubiquitous connectivity.
