In the 5G era, indoor experience quality is as important as outdoor

In previous generations of mobile networks, outdoor deployments were prioritized over indoor deployments. This often resulted in users receiving a stable and reliable signal when moving outdoors, but inconsistent performance inside buildings. This led to black spots and dropped calls in large buildings, which undermined the efforts of many businesses to implement a mobile-first strategy in their digital plans. This, in turn, limited the ability of operators to monetize their networks.

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It is more important than ever for users to have a consistent, seamless and high-quality 5G experience, whether they are outdoors or deep inside a building. 5G is able to support a very wide range of applications and use cases due to its support for high bandwidth, low latency and high device density. It is at the heart of digital transformation initiatives in many industries and supports new ways of communicating, working and behaving, from extended reality to sensor-based automation.

Indoor 5G experience needs to be fully integrated with outdoor experience

Enterprise buildings must support 5G capabilities both inside and outside, and users must have an uninterrupted experience when entering and exiting buildings. This means that for the first time, operators and enterprises have a strong incentive to invest in in-building wireless networks to the same extent as indoor networks. The innovations emerging in the 5G era will not only enhance the business case, but also use advanced technologies to provide a superior indoor mobile experience.

For the first time, networks will be deployed where indoor quality of service is of equal importance to outdoor quality of service, rather than an afterthought. As a result, indoor and outdoor coverage must be planned and optimized as a single network to support a holistic experience and a common set of applications.

At the same time, this has challenges. Indoor cellular systems need to operate differently than outdoor ones. They have different power limitations and backhaul requirements. They often need to support more people and devices per square meter, and may need to integrate with other IT systems, such as LANs or edge computing.

To meet these indoor needs, technology has evolved, but each solution had its shortcomings in the early networking era and had very limited integration with outdoor networks.

From Massive MIMO to Small Business Units, a Range of Solutions is Needed

Initially, the dominant indoor solution was the Distributed Antenna System (DAS) for large venues and small cells. In recent years, we have seen the emergence of Digital Indoor Systems (DIS), which address the shortcomings of the first generation approach by using powerful centralized baseband units along with Ethernet and fiber cabling to maximize scalability and ease of deployment.

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DIS has made great progress in the 5G era and now incorporates technologies such as massive MIMO to achieve higher performance and scalability. Most importantly, DIS allows indoor networks to be planned and deployed in parallel with outdoor networks. Massive MIMO is usually associated with outdoor macro cells, but in solutions such as Huawei's LampSite, massive MIMO can now be extended indoors as well.

In this case, the outdoor base station has 64T64R antennas, while the indoor system (LampSite with massive MIMO) incorporates a virtual 64T64R architecture within a single cell to support multi-user MIMO and distributed beamforming. This improves the quality of experience for each user, even in hard-to-reach parts of buildings, and makes it more practical to use high-frequency bands that have high capacity but very short distances.

About 20% of indoor sites have higher traffic and will need capacity expansion in the next 2-3 years, but other sites have lower traffic and may be more difficult for operators to make a profit. This is why indoor solutions must come in multiple form factors that can be combined to achieve the best balance of cost, capacity and coverage for operators and users.

For example, Huawei’s DIS product line ranges from high-end MIMO, metro and campus models to LightSite (for smaller venues) and LampSite Spartan (a low-cost, small-form-factor design for small businesses), and also includes LampSite Sharing, a multi-operator solution for locations where multiple MNO customers use the network, such as shopping malls.

Operators in Europe and China are leading early, large-scale indoor 5G deployments

Early demand for indoor 5G networks is high. More than 30 operators in more than 20 countries have deployed 5G DIS in indoor/outdoor environments such as stadiums, campuses, large hotels and transportation hubs.

For example, in Europe, there are already projects replacing DAS with 4G and 5G DIS, such as the Zurich Exhibition Center and hotels in Switzerland. Shopping malls and event venues have been the main focus in the Middle East so far, while the top five environments for 5G DIS adoption in China are transportation hubs, commercial offices, operators’ own stores, large event venues and government buildings.

Cities and governments require wide indoor coverage to provide a wide range of services to their citizens. For example, the Shanghai government released a report that rated the mobile user experience in different areas of the city. In the 4G era, the rating was mainly for outdoor environments, but in the 5G era, the rating also applies to hospitals, shopping malls, transportation hubs, university campuses and other indoor/outdoor areas, which shows how the government is now pushing operators to improve the quality of service for mobile experiences no matter where users are.

As more businesses and consumers adopt 5G and use it to support new applications and ways of working and playing, there will be a wider range of environments where an excellent indoor/outdoor 5G experience is critical. That's why it's so important to provide a flexible, scalable solution that can be deployed now to support current usage patterns and then expanded or adjusted in an elastic way to enable future locations and use cases.

This way, there will be no difference in quality of service whether a 5G user is indoors or outdoors, which in turn will provide operators with many new ways to leverage their 5G networks.