It is obligatory for many venues - large and small - to ready all infrastructure and systems needed for the first responders to communicate seamlessly over their radio equipments. Building owners and managers want to ensure that they can communicate clearly within their jurisdictions. Most often, this requires the deployment of DAS (Distributed Antenna System) that expand the outdoor public safety coverage to the interiors of the buildings in a way that no internal section of the building or facility is out of coverage.
Most building owners would already have the commercial cellular wireless network within their buildings. So, what is the right approach of going about the Public Safety DAS? Implement it as a separate overlay? Or integrate it into the cellular wireless network? What do you need to consider to decide which approach tackles the problem best? Well, there are a few DAS integration issues that need to be deliberated.
NFPA (National Fire Protection Association) and IFC (International Fire Code) standards apply to Public Safety, but they do not apply to Commercial/Cellular DAS equipment. The former is the trade association that "creates and maintains private, copyrighted, standards and codes for usage and adoption by local governments". From model building codes to equipment utilized by Firefighters while engaging in hazmat response, rescue response, and firefighting. The latter is a model code that regulates minimum fire safety requirements for "new and existing buildings, facilities, storage and processes".
These bodies and standards drive the new installations of Public Safety DAS. And they have established the framework for regulations nationwide dealing with required in-building safety communications coverage. We cover some of these codes in detail in this article, but some of the key points they cover are, coverage areas, signal strengths, amplification components, enclosures, general building areas, system design, power requirements, acceptance test procedures, and many more.
Cellular DAS systems, on the other hand, do not need to meet these extensive code requirements. Which means that a converged DAS system would amplify the cost of the DAS system installation and maintenance.
As the Public Safety DAS system is there to ensure stable, consistent and flawless communication for the first responders, the Public Safety DAS equipment is undoubtedly a mission-critical equipment. While the converged DAS system is an option, what also needs to be considered is that it must not be easily accessible to other general technicians and maintenance personnel. Separation of the two systems, equipment, and maintenance protocols ensures that the two DAS systems are accessed, handled, and controlled by the authorized personnel only. It is required by the NFPA that the public safety equipment are kept in specific enclosures and accessed only by authorized crew. Converged DAS systems would mean that personnel with access to the complete co-located system could accidentally cause interruption to public-safety equipment.
Technical and economic
There are many standards that Public Safety DAS system is required to meet. For example, redundant equipment and fiber paths, and overlapping coverage. Redundancy for cellular DAS is merely a preference rather than a requirement. The convergence of the two systems with a redundant and non-redundant infrastructure in one configuration is not a good engineering practice.
Similarly, Public Safety network is required to have antennas installed in places where it's not typically required for commercial purposes, and instead only adds to an unnecessary cost. Power control and coverage standards is another component that Public Safety DAS mandates, where Public Safety handset transmits full power all the time, and a commercial handset doesn't. This leads to the differences in various technical design and hardware requirements, thereby making the convergent DAS a difficult ordeal to manage and optimize.
Not only these, but there are also many concerns about the lack of 'safe operations', unnecessary risk of interference, cost optimization, unnecessary complications, and greater long-term maintenance cost outlays.