Despite the exponential growth in mobile usage, indoor coverage continues to be a challenge. It’s not uncommon for an organization’s conference room to get a consistent, strong cell phone signal while the connection in the CEO’s office on the other side of the building is clear one moment and inaudible the next. At the same time, employees in another part of the building know to stay in their offices during a call, since the cell phone signal will instantly drop in the hallway. There are countless instances in existing and new buildings where cellular dead zones cause tremendous frustration for businesses of all sizes.
According to Cisco research, 80 percent of mobile traffic is consumed indoors. Others have put that number as high as 90 percent. Analysys Mason has estimated that indoor mobile traffic volume increased 70 percent to 90 percent between 2010 and 2015. As reliance on mobile grows, it’s not surprising to see that businesses are becoming increasingly impatient with weak or inconsistent coverage. Yet, depending on the cause, switching mobile operators does little to solve the problem.
We also know that there are a wide range of variables that cause poor indoor cellular coverage, from concrete construction materials and environmental conditions to remoteness and geographical terrain. So what are the options for achieving that last mile of signal coverage?
Overall, cellular solutions fall into two categories: “outside-in” and “inside-in.” With outside-in solutions, the user receives a mobile signal from an existing outdoor cellular network or macrocell (i.e., base station) outside the building. Since deploying macrocells is extremely costly and complex, carriers will only invest in this technology where there are large numbers of users.
There is one variant in the outside-in category known as metrocells or microcells. These are small cellular base stations that can be placed on the outside of buildings or on a street fixture, and are typically used in urban areas to improve existing cellular service coverage. However, their range is limited and, depending on the construction materials used within a building, they may not solve indoor service problems.
A more efficient and flexible option for solving the indoor coverage issue is inside-in or in-building solutions, in which mobile signals are delivered from an access point within the building. These can be deployed either in a standalone configuration or as part of an integrated or hybrid design.
The range and capabilities of in-building solutions have improved dramatically in recent years, and the product selection has expanded significantly. There are now numerous options for strengthening or relaying cellular signals to achieve a seamless indoor coverage experience, from femtocells (small cells) and Wi-Fi calling to Smart Signal Boosters® and DAS (distributed antenna systems).
As with any technology choice, not all indoor solutions will fit all scenarios. Factors that come into play include budget, coverage area, cellular tower placement, building construction, ambient conditions (e.g., in-building electrical interference), broadband availability, and in-house expertise among others. Some are suited for areas where broadband is available; others are designed for regions where broadband is not an option. Some require extensive configuration and cabling; others are plug-and-play.
Following is a synopsis of the available broadband and/or cellular-based options, how they work, and where they make the most sense in addressing indoor coverage issues.
- Small Cells – In simple terms, small cells act as miniature cell towers or cellular base stations within a facility. A small cell generates its own signal, so it doesn’t have to rely on the existing macro network to provide indoor wireless capacity for a large number of building occupants.
A small cell network requires a broadband connection to function. In most cases, small cells in a commercial environment require some configuration work and cabling to the access points. RF audits and designs are usually needed to ensure optimum coverage and minimal interference. Users also need to log in to a database to register individual devices, all of which require technical expertise. However, an indoor small cell network is a relatively inexpensive option. According to exactventures, installation of an enterprise indoor small cell network costs between $.20 to $.50 per square feet.
- Wi-Fi Calling – Wi-Fi Calling enables users to make and receive calls, as well as texts, over a Wi-Fi network (instead of a cellular network). Wi-Fi Calling requires a broadband connection to function, and only works with devices that support Wi-Fi Calling and carrier networks capable of handling it. While often associated with popular VoIP-based apps like WhatsApp and Skype, Wi-Fi Calling works differently in that it sends cellular packets to the carrier’s network using the Internet instead of cell towers; it also uses the subscriber’s regular cell phone number.
Like small cells, Wi-Fi Calling needs to be configured, and coverage footprints may not be as large as other options since users have to be within range of the Wi-Fi access point inside for it to work. Where broadband is readily available, however, it has become an increasingly popular option for homeowners and small office users. One downside with Wi-Fi Calling is the inability to hand over calls from the Wi-Fi network to the cellular network when moving from an indoor setting to the outdoors, leading to dropped calls.
- Smart Signal Boosters – FCC-approved Smart Signal Boosters are wireless devices that do not require access to a broadband network as they amplify an existing signal coming from the macro network or a small cell. Unlike analog signal boosters (which are not approved by mobile operators for use on their networks because of the interference they cause), all-digital Smart Signal Boosters are designed to be carrier specific and eliminate any interference issues while delivering more gain and coverage.
As these signal boosters are also wireless and smart, they greatly enhance coverage without the need for cabling, registration of devices or configuration. Users simply plug the units into a power outlet in a location indoors where there is at least one bar of 3G, 4G or LTE signal to boost signal coverage in areas of up to 13,000 square feet. Multiple units can be used for larger coverage areas, still at a significant cost savings from other alternatives. A Smart Signal Booster can be installed for $.10 per square foot.
While originally targeted for the residential and small business market, Smart Signal Boosters have become an increasingly popular complementary solution for larger-scale implementations because of their compatibility with small cell networks, flexibility, ease of installation and lower costs. Small cell networks can add wireless bandwidth capacity to a commercial building to allow for a higher volume of users at the venue but may still leave areas of the building with poor cellular coverage. Rather than adding expensive small cell units to extend the coverage area, connecting one or more Smart Signal Boosters to a small cell installation can cost-effectively extend signal coverage into areas of the building that are still experiencing poor coverage.
- Distributed Antenna System (DAS) – A DAS is a system of connected indoor antennas that is backhauled to a centralized hub in the building which, in turn, connects to the service provider’s core network. A DAS can also receive signals from the macro network, a small cell or Smart Signal Boosters rather than the base station. However, a DAS is relatively costly (depending on a number of variables including the size of the area that requires coverage) and complex to install as it requires the installation of cables, amplifiers and antennas. As a result, distributed antenna systems tend to be used in larger buildings that require support for multiple operators or as part of a hybrid design.
There is no question that seamless indoor mobile coverage will remain an ongoing challenge for operators in the years to come. As reliance on mobile continues to grow, the need for strong and consistent indoor signal coverage is more crucial than ever. The good news is there is no shortage of cellular and broadband-based in-building solutions available. The only question that remains is which solution (or combination of solutions) works best for the needs and budget of the venue.
George Lamb is VP Operations and Support at Nextivity and has more than 30 years of telecommunications experience, most recently at T-Mobile USA. Before T-Mobile, he worked with mobile operators in the USA, Canada, Mexico, Guatemala, Venezuela, Chile, Brazil, Australia, Denmark, the U.K., Nicaragua and New Zealand, often directing a business segment as it opened its doors. He holds multiple patents in the wireless area and is the author of two books on mobile. Contact firstname.lastname@example.org.