The indoor coverage hardware challenge – hype vs. reality

There are many reasons why in-building cellular coverage can be challenging. The placement of cell towers, geographical terrain, or building materials can all play a role in poor in-building coverage. Even where there is a proliferation of cellular towers, there can be topographic or interference issues that can make cellular service a challenge. Phones hop from one tower to another, which can cause jitter, warble, or even disruptions in service.

There are plenty of options for tackling the in-building cellular coverage challenges enterprises continue to face today. As with any technology, there is also plenty of hype around what solutions can do, versus their actual capabilities.

So here’s a quick rundown of the hype and the reality around the available options.

Wi-Fi calling

The Hype: Wi-Fi Calling can be used everywhere.

The Reality: No, it can’t.

Wi-Fi Calling is only available in some contexts. An underlying problem is that many enterprises experience poor Quality of Service (QoS). Wi-Fi is a “best effort” service, not a managed service like cellular. In a business context Wi-Fi is great as a data layer. Wi-Fi Calling only works with certain cellular devices, and carriers, and those devices need to be attached to the WLAN. Enterprise networks are becoming less accessible than ever as security concerns escalate. There can also be issues relating to the handover of cellular calls when a caller is on the move. Managed Wi-Fi services are evolving, and they can help, but Wi-Fi calling may not be good enough for many enterprise business processes.

 Small cell

The Hype: Call your carrier, order a small cell or two. Simply drop them into your building, and connect them to the internet. Problem solved!

The Reality: It’s not quite that simple.

Small cells continue to improve each year with advanced technologies such as interference cancellation and SON (self-organizing network) capabilities. Unlike Wi-Fi, which can be quite inexpensive, small cells (i.e. femtocells and picocells) are typically $3K to $5K each for the hardware. Not all small cells are created equal in terms of ease of setup and performance.

There are a few significant issues related to small cells. First, similar to Wi-Fi, the coverage footprint is highly dependent on the interior layout of the indoor space, specific alignments, and other factors that may inhibit the spread of the signal.
Second is backhaul. In addition to a dedicated bandwidth requirement, some small cells actually require specific and detailed IP settings that may require professional-grade IT skills to install, setup, and maintain.

Third is performance. Although small cells have improved greatly, users can still experience dead or low-performance spots within a facility as a result of interference.

Active DAS (aDAS)

The Hype: aDAS is expensive, but high performance. In all but the largest installations (500,000 square feet and above), DAS is not a viable solution.

The Reality: There’s some truth to that, with exceptions.

In some areas the hype and the reality are fairly well-aligned. aDAS is expensive and it is high performance. Some aDAS providers are working on smaller footprint solutions for the middleprise (mid-sized enterprise) space. While capex costs are coming down, aDAS still requires an infrastructure ecosystem, which adds to the cost and time to deploy:

nextivity DAS in-building

One of the biggest challenges with any DAS installation is establishing the signal source(s). Typically, multiple network operators need to be included to support a maximum number of users, so it is not uncommon for a DAS project to require 12 to 18 months before it even gets off the ground.

Passive DAS (pDAS)

The Hype: Passive DAS is the most cost-effective way to improve medium or large in-building cellular coverage.

The Reality: It has its limits and can cost you more than you think.

Passive DAS differs from active DAS in that it pulls its donor signal (the signal source) off-air or “over-the-air” (OTA) from the macro network. It requires less equipment, setup, and maintenance than aDAS, but does require many of the same skills, and personnel. These costs can drive pDAS beyond an acceptable ROI for the enterprise. What’s often not mentioned is that pDAS doesn’t add capacity to the macro network – a problem in environments with a large number of active users, and one reason network operators are not enthusiastic about pDAS.

One additional note: pDAS is an analog system in which cellular signals are distributed over coax cable, and transmitted through regular antennas, adding to installation costs.

Active DAS Hybrid

The Hype: It’s disrupting in-building cellular coverage for enterprise.

The Reality: It’s disrupting in-building cellular coverage for enterprise.

Newer active DAS hybrid systems are increasingly being deployed to address the in-building cellular coverage demands of the middleprise market, where venues range in size from 25,000 to 500,000 sq. ft.

These systems can be used in off-air mode or tethered to a small cell to achieve uniform coverage and capacity distribution for venues up to 500,000 sq. ft., both at a far lower price than traditional DAS.

Using a lossless digital distribution method, Cat5 (LAN) cable, both simplifies the installation process and assures performance when complete. Active DAS hybrid systems eliminate issues relating to interference and macro network dominance, solving QoS issues that can remain with other technology solutions.

The small cell/active DAS hybrid configuration creates a “Supercell” (i.e. a large single cell versus multiple small cells) that provides uniform access to the capacity introduced by the small cell. Supercells are inherently uncomplicated from a planning and deployment point of view and are far more resilient to the potential of interference or performance degradation considerations.

For more information, download the Nextivity white paper: Simplifying Cellular Coverage for the Middleprise with Cel-Fi QUATRA.

About the Author

Joe Schmelzer has 20 years’ experience driving the creation of products and solutions for chipset vendors, device OEMs, and service providers, including Sony, Qualcomm, Google, Verizon Wireless, AT&T, Dell, and HP. Mr. Schmelzer has previously held positions with Wavecom, Sierra Wireless, and Novatel Wireless. He was also a founding member of CTIA’s Wireless Internet Caucus. For more information, contact hello@cel-fi.com or visit www.cel-fi.com

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