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Indoor mobile signal coverage systems aim to address poor signal quality within buildings, particularly the severe signal attenuation experienced with high-frequency bands like 5G n78. With 80% of mobile communication occurring indoors, reliable indoor signals are critical for user experience. However, telecom operators have increasingly shifted the responsibility for indoor signal coverage to building owners or tenants, especially in private buildings. Consequently, indoor signal coverage systems have become essential infrastructure, comparable to electricity and water. To resolve signal deficiencies, buildings must adopt effective solutions such as DAS to ensure signal stability and coverage. This article explores the possible solutions and their challenges, including some basic information you should know about DAS.
The Necessity of Indoor Mobile Signal Coverage Systems
Mobile signals are transmitted by telecom providers through their deployed base stations, which include both equipment and antennas. These base stations are designed primarily for broad outdoor ground coverage, enabling users to access telecom services within the coverage area. However, the transmission of wireless signals is inherently limited by obstacles and penetration challenges. This is particularly problematic for high-frequency bands such as 5G n78, which experience greater signal attenuation and weaker penetration capabilities. These limitations result in poor signal reception in locations such as buildings, high-rises, basements, and tunnels.
Statistics indicate that 80% of mobile communication occurs indoors—at workplaces, homes, restaurants, hotels, and hospitals. In today’s mobile-reliant society, the absence of reliable indoor mobile signals creates significant inconveniences for users, leading them to avoid or minimize time spent in poorly covered areas. For buildings, inadequate mobile signal coverage can indirectly affect real estate sales, while for businesses, it can disrupt operations, inconvenience employees and customers, and negatively impact overall efficiency and profitability.
Who Is Responsible for Poor Indoor Signal Reception?
It is a common misconception that telecom providers are solely responsible for ensuring mobile signal coverage. During the early 2G and 3G eras, telecom operators often resolved indoor signal issues for free by installing small cells (e.g., femtocells, picocells, or microcells) or Distributed Antenna Systems (DAS). However, with the widespread adoption of mobile communication, increasing competition, and the simplified process of switching telecom providers, operators have gradually shifted the responsibility for indoor signal coverage to users.
Today, addressing indoor signal issues is often considered the responsibility of the building owner or tenant, particularly in private buildings such as small houses, shops, large apartments, enterprises, and commercial office buildings. As a result, indoor mobile signal coverage systems have become an essential infrastructure component, akin to utilities like electricity and water distribution systems inside a building.
Market Segmentation by Ownership
From a payer’s perspective, the global indoor mobile signal coverage market can be divided into two categories: privately owned systems and telecom operator-owned systems. This distinction largely depends on the building's purpose:
Privately Owned Systems: In private residences and apartments, the building constructor, owner or tenant typically bears the cost of indoor signal coverage. These systems prioritize cost-effectiveness and are often budget-sensitive.
Telecom Operator-Owned Systems: For large public venues such as airports, transportation hubs, and stadiums, telecom operators often fund the deployment of indoor coverage systems. These solutions prioritize user experience and system performance.
In addition to these categories, some venues are serviced by third-party providers known as Neutral Hosts. These providers, often system integrators, manage the deployment and operation of indoor signal systems while balancing the needs of both users and telecom operators.
Solutions for Indoor Mobile Signal Coverage
A. Wi-Fi as an Alternative
Some users may consider Wi-Fi systems, combined with Voice over Wi-Fi (VoWiFi) and Voice over LTE (VoLTE) technologies, as an alternative to mobile signal coverage. While Wi-Fi can support basic communication, it significantly differs from mobile networks in terms of bandwidth, stability, data rate, and security. Common issues with Wi-Fi-based solutions include connection failures, instability, the need for manual logins in new locations, and potential extra costs. Public Wi-Fi networks also pose substantial cybersecurity risks, making them a less appealing option for seamless mobile communication.
B. Small Cell
Small Cells are low-power, short-range base stations capable of supporting approximately 30 mobile devices. They connect to the telecom operator’s core network via Ethernet to address indoor signal coverage issues. However, installing Small Cells requires telecom operator approval and on-site setup.
The main drawbacks of Small Cells include their high cost, recurring licensing fees, making telecom operators reluctant to provide them. Furthermore, each Small Cell supports only one operator's signal. For multi-operator coverage, multiple devices must be installed at the same place, making this solution impractical for many scenarios.
C. Distributed Antenna System (DAS)
A Distributed Antenna System (DAS) is a network of antennas deployed throughout a building to provide bi-directional wireless signal services. DAS solutions are categorized based on their system architecture into passive, active, and hybrid systems. Each type has its unique components and architectures. Their challenges and advantages will be discussed in detail in a separate article. (For more information: The Passive, Active, and Hybrid DAS, and their Pros & Cons)
The core concept of a DAS is similar to a "local area network," which interconnects antennas within a physical location to share available signal power throughout its structure. As such, the system’s headend must connect to telecom service providers, requiring "sufficient signal strength" across "needed frequency bands" from "all necessary telecom operators" to serve as the DAS signal sources. This connection enables the DAS to distribute signals to indoor antennas, ensuring seamless voice and data access for mobile users. Consequently, identifying the required operators, frequency bands, and bandwidth is one of the most critical initial tasks for any DAS project.
DAS systems extend telecom signals indoors, allowing users to transition seamlessly between indoor and outdoor environments without additional operations or costs. This makes DAS the mainstream solution for indoor signal coverage.
(ZQAM offers active and hybrid systems; for more details, please refer to the ZoneDAS Series Product Page.)
Obtaining DAS Signal Sources
Since mobile signals are owned by telecom operators, there are two primary ways to obtain signal sources for DAS:
1. Receiving Wireless Signals from Base Stations:
This approach involves installing outdoor antennas to capture wireless signals from nearby base stations. The captured signal is often weak and requires amplification using repeaters (boosters) or bidirectional amplifiers (BDA) before being fed into the DAS. This process functions similarly to a water pump, boosting available signals to improve coverage and strength.
Repeaters and amplifiers vary by supplier and specifications, such as supported frequency bands, bandwidth, maximum output power, and system gain. For instance, Zyxel offers dual-band and quad-band low-power full-bandwidth repeaters featuring high gain and feedback avoidance, effectively boosting signals without causing interference to base stations (Operator-friendly). For more details, please refer to the Repeater product page.
2. Connecting Directly to Base Station Equipment:
This method involves a physical cable connection to the output port on the telecom base station devices (e.g., RRU, RRH, O-RAN RU, or Small Cell). While this ensures stable signal coverage and increases link capacity to support more users, it requires telecom operator consent and on-site equipment installation. This method is typically feasible only for operator-initiated projects and is nearly impossible for private residential or commercial buildings.
For high-traffic venues such as transportation hubs, direct connections provide irreplaceable advantages in terms of stability and capacity, making them a preferred solution.
Conclusion
The demand for reliable indoor mobile signal coverage continues to grow as mobile communication becomes integral to modern life and the 5G is prevailing. Addressing this demand requires a comprehensive understanding of user needs, building characteristics, and the available technological solutions. Distributed Antenna Systems (DAS) remain the most effective and widely adopted approach, offering seamless connectivity and robust performance for a variety of indoor environments.
Join Zyxel DAS Alliance today, and let’s build a more competitive future together! Visit our Solutions page to learn more our product’s technical details, or leave us a message via Contact Us.
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