Smart Building

What to Expect in Terms of Connectivity with a DAS System

Ron Tellas

When you stop to think about how much workplaces have changed in the last decade, you realize how dependent we have become on mobile connectivity for nearly everything: communication, information transfer, media consumption, building control, etc.

Encouraging this change is the fact that our current workforce is made up of 56 million Millennials: digital natives who grew up with wireless connectivity and, as a result, are altering expectations for response times, communication and collaboration. This generation is made up of content creators who record and broadcast live videos, capture and share high-res photos, and post original content on social media channels and blogs. Case in point: At the 2012 Super Bowl in Indianapolis, for the first time in history, there were more data uploads than downloads (more people creating and pushing out content vs. downloading content). In fact, fans uploaded 40% more data than they downloaded at that game, posting videos and photos and sending messages.


More than 80% of today's cellular minutes are consumed inside a building, according to JMA Wireless, one of Belden’s strategic alliance partners. And approximately 92% of Millennials consider the smartphone their device of choice for business communications. Wireless networks are not only connecting more people, but also connecting growing numbers of devices with unlimited data. In addition, as devices that aren’t directly controlled or managed by people – like lighting systems, security systems and even parking systems – all connect to the network, this number will continue to increase.


Because of how we use our devices, mobile and wireless coverage have become as vital as a utility. In fact, wireless connectivity has been dubbed the “fourth utility,” meaning that it’s just as expected – and as needed – as other utilities like water, electricity and gas. Buildings of all types and sizes are expected to make connectivity reliable and effortless – regardless of the number of people and devices trying to connect at once.


As our networks are expected to connect us without wires, and maintain our mobility, how can they keep up? How can we continue to support increasing numbers of devices and mobile users without interrupting the speed of the content being created and shared? A distributed antenna system (DAS) can make it happen.


There are several options for providing service to mobile-network subscribers. These radio access nodes offer network densification based on application size: femto cells, small cells, enterprise radio access networks (RAN), distributed antenna systems (DAS) and Cloud RAN (CRAN).


For the purposes of this white paper, we will use the term "distributed antenna system" (or "DAS") throughout to refer to these types of radio access nodes.


What is a DAS System?

Distributed antenna systems are used today in almost any type of indoor or outdoor environment: hotels, high-rise offices, sports stadiums, hospitals, manufacturing facilities, entertainment venues, parking garages, college campuses and even across cities and metropolitan areas – anywhere mobile connectivity is needed.


The reason for deploying a DAS system varies based on the building. For example, some buildings are constructed of metal, reflective glass and concrete, which block cellular signals. Even if the signals are strong outside, once you step inside, your device may lose the signal and drop the connection. In other cases, the venue experiences significant cellular data usage (think an arena or music venue), making reliable connection difficult. Cell towers can also be difficult to connect to when they're too far away. In high-rise towers, buildings in close proximity make signals more difficult to propagate due to reflections or objects in the line of sight. This can lead to a rise in RF noise levels.


When there is no DAS system in place in these situations, cellular signals are sent out from the carrier’s tower (like AT&T or Verizon). Then they must permeate and travel through the building, where they're then shared with everyone else utilizing those signals from that same tower. Lowered data throughput or dropped calls and poor cellular coverage often result because of signal degradation.


Distributed antenna systems can fix this problem by redistributing the signals being sent from cellular carriers either through the air or via direct line and bringing them inside a building and/or dispersing them across a vast area. Without these systems, carriers struggle to get their signals inside any building.


Upon first glance, distributed antenna systems may seem similar to Wi-Fi technology, but these two systems operate at different signal frequencies.


Wi-Fi works in an unlicensed band, meaning that devices connected to a network must coexist with other unlicensed, non-networked devices. Advances in Wi-Fi technology have improved connections to devices that are essentially static at an acceptable throughput level. When there are many people connected via Wi-Fi, or if a Wi-Fi connection is moved among a vast area, a connection to a carrier using DAS is needed. Today, venues need Wi-Fi (for DAS offloading) and DAS for maximum wireless/mobile coverage and capacity.


How DAS Systems Work

DAS hardware consists of a centralized head-end connected through fiber to the building. This head-end receives the carrier signals and distributes the signals to remote units (also called repeaters) deployed throughout a building in places like IT closets, server rooms or concourse areas. The remote units boost indoor signals and push the cellular signal out to antennas strategically placed throughout the venue – sometimes up to hundreds of feet from the remote units. Supporting this system is a mix of fiber, copper and/or coax cables and connectivity.


As with a traditional wireless system design, each DAS system and design is unique to its venue. Through engineering, locations offering the highest signal propagation and realistic spots for antenna installation are identified – and the antennas are placed there.


When a DAS system is designed and deployed correctly, cellular coverage is even extended to hard-to-reach areas like tunnels, basements, stairwells and inner rooms. DAS can support signals and bands from many carriers, as well as support two-way radio coverage for public safety initiatives.


Providing Power in a DAS System

In an upcoming blog, we’ll cover the different options for powering in DAS systems: PoE, DC power or digital electricity. Until then, if you have questions about distributed antenna systems or the cabling required to support them, contact us!


And be sure to watch our free archived webinar (link below) about DAS systems to learn how they can complement existing Wi-Fi networks, what kind of cabling and connectivity infrastructure is required to make DAS a reality and how it supports the people and devices that are constantly creating, streaming and sharing content.