Does Your Building Need a Passive or Active DAS?

Posted on October 29, 2021October 29, 2021 by rfsolutions

Does Your Building Need a Passive or Active DAS?

At RF Solutions, we design public safety and cellular enhancement distributed antenna systems (DAS) for high-rise buildings and other large venues. Cell DAS installations are almost always active solutions, but public safety systems can be passive, active, or hybrid. Before we begin to design a system, there are many factors to be considered. The optimal system design will depend on the unique characteristics of the building in which it will live and the communications requirements of local first responders. These factors include the coverage area, the design of the building, the building materials, signal source(s), and the project timeline. Once we’ve gathered the building particulars, we can determine whether the system should be passive, active, or a hybrid of the two.

A passive system uses “passive” components like coaxial cable and splitters to distribute RF signals. Using coax to distribute the signal will produce a higher signal loss than an active solution. The further the antennas are located from the head end, the higher the signal loss, which results in lower downlink output power. These restrictions are the reasons why a passive system may not be appropriate for a specific building.

An active system uses fiber optic cable to distribute signal between a centralized signal source (head end) and remote nodes placed strategically throughout the building. A hybrid solution is built upon an active system using fiber to distribute signal but relies on a passive DAS design for most signal distribution. Buildings with unique challenges might benefit from a hybrid solution.

When determining if a building needs an active system, there is no magic size (square footage) number per se, but it usually falls around the 1million sq. ft. mark. However, there are many sub-1mm sq ft buildings where we’d choose an active system. You could easily have a 750,000 sq ft legacy hospital facility with dense walls and floors that will need to use an active system to meet the required coverage because RF signals will have poor penetration. Many older (pre-war) buildings present these same issues. A new, smaller building might require an active system if it’s steel reinforced. A warehouse with heavy shelving and dense stored materials may need one as well. Conversely, a +1mm sq. ft football stadium might not require an active system due to the open architecture. That’s why it’s so important to understand the propagation characteristics, like wall density, building composition, and building age, before starting the design.

You might ask why not always use an active solution? The simple answer is cost. Active systems are expensive, but an added benefit of using a fiber DAS is that it’s future-proofed. Using fiber provides the unique ability to upgrade when new technologies or frequencies must be added to a system. Converting the radio signals to light over fiber allows the use of multiple distribution points (nodes) with little or no loss in the transport system.

So, you see, there isn’t a hard and fast rule you can use to determine which way to go with your public safety DAS but knowing all the building’s characteristics and technology requirements beforehand will steer you in the right direction.

‘First Do No Harm’ Applies to Installing Public Safety Systems in Hospitals Too

Posted on December 30, 2019July 21, 2021 by rfsolutions

‘First Do No Harm’ Applies to Installing Public Safety Systems in Hospitals Too

Installing in-building wireless communication systems inside existing hospitals adds several layers of complexity and comprises some of the most challenging construction environments. The factors involved include uninterrupted patient care, significant infection risk control measures, and high levels of hygiene, which are considerably more critical in a medical facility than a commercial or residential building. These public safety installation projects require extra steps to be taken to minimize the interaction between construction activity and caregiving operations. To ensure a safe environment for their patients, nurses, doctors, and staff, hospitals have developed industry-standard project management tools such as life safety plans and physical requirements like tenting to ensure patients’ safety during construction.

Every Project Begins With ICRA
Construction projects in occupied hospitals require specialized procedures and equipment as they can negatively affect patients and possibly spread infection. Before any work begins, hospitals use a system called Infection Control Risk Assessment (ICRA). It’s a roadmap a project manager follows, which delineates proactive environmental undertakings such as protective barriers, negative air pressure, dust control, and protective apparel. An Interim Life Safety Plan (ILS) is put in place to protect the safety of patients, staff, and visitors during construction activity. Every aspect of a cable installation must be reviewed in advance to identify hazards and specify preventative measures. In many cases, the setup time may take longer than the actual work itself.

The Infection Control Cube aka the Popemobile
Work takes place within an infection control cube; a four-sided Plexiglas workspace often referred to as a Popemobile, which connects to ceiling tiles and contains the work and debris inside. It minimizes the possibility of patient contamination. The work takes longer to complete and is significantly more complicated than installing a system in a residential building. It takes an incredible amount of coordination, but it’s the cost of doing business in an occupied hospital.

Challenges Are Not Limited to Installation
Hospitals have unique design challenges, too, as they are often constructed using concrete, steel, and low-E glass. Radiology labs use lead lining in walls, and many hospitals have subfloors, up to 60 feet below ground level. These hospital-specific characteristics can all degrade hospital communications. The age of the building and the presence of lead-lined rooms and walls result in obstructions to RF signal propagation. These factors need to be considered when designing a new system for a hospital. The reliability of in-building public safety systems is even more critical in healthcare facilities due to the confinement of its residents.

DAS to the Rescue of the IoMT
The Internet of Medical Things (IoMT) involves connected devices used within a medical facility that allows doctors and nurses the ability to check on and monitor patients without physically being in the same room, allowing for significant increases in productivity. About 70 percent of health care organizations now utilize technology for monitoring practices. The influx of monitoring devices can put a strain on a hospital’s network, which is where the installation of a distributed antenna system (DAS) comes into play. A DAS draws in signals from a macro network and evenly distributes it using multiple antennas placed throughout a medical complex, ensuring uninterrupted service. A DAS can support various wireless carriers, making it the obvious choice for hospitals today. DAS are flexible, robust, cost-effective solutions for private enterprises.