Wireless Systems- Differences and Intended uses

May 24, 2024

As Low Voltage systems designers, we are often asked about the various wireless systems and  how each of them works.  Let's begin with the three types of wireless systems: WiFi, Cellular DAS and ERRCS.  Each system’s objective is to provide an adequate (preferably strong)  signal for wireless communication.  Each can be affected by a number of factors, such as distance from the device attempting to connect, and the density of the walls, doors and glass in the building that degrade signal strength.  Let’s look at each of the three types of systems.

Wi-Fi System

Most people  know that the WiFi system serves to deliver internet connection to portable and stationary electronic devices such as laptops, tablets, and cell phones.  These devices access the wireless signal via a WiFi node (a.k.a. WAP).  Implementation of these systems is not mandated by law. However,  WiFi today is ubiquitous, and people expect it to be available in any place they visit.  The signal is expected to have ample bandwidth to provide excellent speed in every space throughout the building, as well as the adjacent outside on occasion.  Not having adequate WiFi is perceived as unacceptable.  

Common components of the WiFi system include:

  • The router/controller
  • Wireless access points (WAPs)
  • Data cable between the router and the WAP
  • Distance extenders where needed (extenders can be wired or wireless)

Cellular Distributed Antenna System (DAS)

A cellular DAS serves to deliver enhanced cellular signals inside of a building.  In the United States in 2020, it was estimated that 80% of all wireless voice calls originated inside a building.   In 2024, that percentage may well be higher.  
The implementation of the system that make those calls possible can come with substantial cost.  For example, it is not unusual for the cost to be up to $2/SF.  

The major components of a DAS include: 

  • The signal source, such as donor antenna
  • Distribution antennae throughout the structure
  • Cables which connect these elements

While not required by law, a DAS is functionally mandatory for buildings in places where the native coverage from nearby towers is not sufficient to support the anticipated demand from the new facility. Whatever the building type, cell coverage for residents, employees, guests and students is not an optional amenity.

DAS Antenna
cellular enhancement das system

First Responders System

The Emergency Responders Radio Communication System (ERRCS) is the only one of the three systems which can be legally mandated, at the cost of the building owner if deemed to be necessary.  

  • The Emergency Responders Radio Communication System (ERRCS) is the only one of the three systems described here that can be legally mandated, at the cost of the building owner if deemed to be necessary.  For clarity:
  • ERRC systems are also known as BDAs (Bi-Directional Amplifiers).  
  • The governing body for an ERRCS system is the Authorities Having Jurisdiction (AHJ).
  • An AHJ authorizes only a qualified ERRCS contractor, who must be licensed by the state or otherwise be considered qualified by the AHJ. 
  •  These systems provide E-911 workers with reliable radio communication including such areas as stairwells, basements, and other places where native signal is weak.

Important Aspects of Cellular DAS and ERRCS:

  • Native Signal - The native (cellular) signal is the signal that is in place without any attempts to augment or extend it.  This signal can be adequate for a small coffee shop, for example.   However, a new 23 story apartment or office building, will likely require one or both systems.
  • E-glass - seriously degrades propagation of the outside signal into the building and increases the necessity of the systems implementation.
  • Elevation & height -  Native cell signals will be affected in below grade areas, and are often  weaker in higher floors of a building as they get farther from cell towers.    

Another common question we hear - Can these systems be combined?

From a practical standpoint, these systems are typically not combined.     

In conclusion: Wi-Fi, Cellular DAS and ERRCA are typically installed as (3) distinct and independent systems, each for their specific purpose. WiFi and Cellular DAS at the owner’s discretion.  However, the expectations of guests, visitors, companies and students make these systems functionally mandatory.   ERRCS, on the other hand, is exclusively for first responders and is mandated by the AHJ for the safety of us all.

About the author 

Ilya Rapoport, PMP, RCDD/NTS

Ilya serves as an Associate Principal at NTI working out of our Kennesaw office and has been with the company since 2005.  He has an M.S. in Electrical Engineering  and an M.S. in Computer Science. Before joining NTI, Ilya had 20 years of experience in low voltage and fiber optic research.

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