In this blog post, we’ll explore why a separate communication network is necessary for stable cell phone use inside buildings, as well as the setup process and cost-sharing options.

The Rise of Mobile Data and Smartphone Use

The mobile phone market has grown significantly worldwide over the past few decades. Penetration rates have risen to the point where the majority of the global population now uses mobile phones, and in many countries, 5G mobile networks have been commercialized, moving beyond 4G. In the past, mobile data usage was limited to email and text messages, but with the widespread adoption of high-speed mobile networks enabling the transmission of large amounts of data, mobile data usage has increased dramatically. Consequently, the role of mobile phones in daily life has expanded significantly, and our lifestyles have undergone major changes.
Among these changes, a particularly notable one is the decline in landline use and the significant increase in mobile phone usage inside buildings. Furthermore, as smartphones have become more versatile, a substantial portion of mobile phone usage now takes place indoors. As a result, mobile network operators have been continuously exploring ways to provide stable communication services even inside buildings. In this article, we will examine why a separate communication network is needed for mobile phone users inside buildings and explore the factors that must be considered when establishing such a network.

Why Are Indoor Communication Networks Important?

Mobile communication typically originates from “macrocell” base stations installed on tall towers or buildings. A macro cell is a base station that provides wireless signals to mobile subscribers within a range of several kilometers. However, problems arise when mobile phone users are inside buildings. This is because the signal strength decreases significantly as the signal transmitted from the base station passes through the exterior walls of buildings made of concrete or steel frames. Consequently, it can be difficult to reliably receive signals from macro cells inside buildings, which may hinder smooth mobile phone usage.
Furthermore, even in environments where signal reception is sufficient, communication quality can degrade if many users connect simultaneously within a single building. To resolve these issues, an indoor communication network suitable for each building must be established by comprehensively considering the building’s structure, the number of occupants, and the usage environment.

Site Survey for Building-Interior Network Deployment

Signals transmitted from macro cells gradually weaken as they pass through a building. Therefore, the most critical aspect of deploying an indoor network is ensuring consistent and stable signal coverage throughout the entire building. To achieve this, several key factors must be examined.
First, it is essential to accurately identify which areas experience signal weakening based on the building’s structure. This survey can be conducted through on-site measurements or by utilizing radio wave simulation software. Simulations allow us to predict signal strength inside the building based on the number and placement of antennas, enabling efficient design by identifying areas with weak signals in advance.
Additionally, signal interference must be taken into account. Signals transmitted inside a building can bounce off walls or ceilings, causing interference with other signals. This interference hinders mobile phones from maintaining stable communication quality. Therefore, interference must also be analyzed in advance through simulation, and the impact must be minimized by adjusting the location and number of antennas.
Through this simulation process, it is possible to identify in advance areas with insufficient signal coverage inside the building and locations where signal interference occurs. This information serves as crucial data for determining the types and quantities of equipment needed to provide sufficient communication quality throughout the entire building.
The equipment used to build an in-building communication network varies widely, ranging from small devices that provide signals to specific areas to equipment that covers large spaces. However, more important than the selection of individual devices is the choice of the communication network system itself. Systems differ in terms of how flexibly they can adapt to new mobile communication technologies in the future. While some systems can support new communication services simply by replacing core equipment, others may require the replacement of the entire infrastructure.
These differences in scalability also have a significant impact on both initial deployment costs and future maintenance and repair costs. So, who should bear these installation costs?

Cost-Sharing Models for In-Building Communication Network Deployment

Another critical issue in deploying in-building communication networks is determining who will bear the deployment costs. In practice, the cost-sharing method can vary depending on the building’s characteristics and contract terms. The following are representative business models.

Cost Burden by the Telecommunications Carrier

Under this model, the mobile carrier bears the full cost of deploying the in-building network in exchange for the building’s commitment to use that carrier’s services and equipment for a specified period. This is a representative model that is currently utilized in various forms.

Cost-Sharing Model 1

This is a model in which the mobile carrier and the building owner or management entity share the installation costs. The building side provides some infrastructure, such as cables and wiring, while the mobile carrier installs the main telecommunications equipment.

Cost-Sharing Model 2

This model applies when the building side does not wish to be bound by a specific mobile carrier’s service terms or finds it difficult to comply with them; in such cases, the building owner or management entity bears a portion of the installation costs.

Cost Burden by User Group

This model applies when building occupants require more diverse features or higher performance than what is provided by the mobile carrier’s basic system; in such cases, the building management or a user group bears the full deployment cost.

Conclusion

Deploying an in-building communication network is necessary to address the issue of mobile signals transmitted from outside the building becoming significantly weakened as they pass through the exterior walls. To achieve this, on-site surveys and simulations must be conducted to thoroughly analyze signal strength and interference between signals, and systems and equipment suitable for the building environment must be selected. Furthermore, a reasonable decision must be made regarding who will bear the deployment costs. Today’s mobile phone services, which can be used reliably inside buildings, are provided through these various design and deployment processes.