Even with a resistant AHJ, integrators can succeed in converging the commercial cellular system with the public-safety system.
Mohammed Ali
June 10, 2024
Widespread digital transformation means the need for ubiquitous wireless connectivity is always increasing. One of the most significant modern challenges for building and venue owners is dealing with escalating indoor cellular infrastructure and cabling costs to support this need.
Fortunately, there is an emerging opportunity for systems integrators (SI) that are charged with procuring and installing these systems, to leverage converged wireless networking and significantly lower the cost for building owners.
Primarily, public safety wireless systems have their own platforms and cabling that run completely separate, often in parallel, to the commercial (cellular) solutions designed for the public. Converged wireless networking allows both to be installed using the same enclosures, significantly reducing the amount of cabling and passive components needed in a deployment. For smaller projects, the cost savings of shared systems may be considered insignificant. But for stadiums, Fortune 500s, and other large facilities it could range from the hundreds of thousands to millions of dollars. In turn, it also creates a cost-competitive advantage for installers that are aware of this opportunity.
Benefits of converged wireless
While indoor wireless for commercial use is optional, the implementation of Emergency Responder Communication Enhancement Systems (ERCES) is mandatory to receive a certificate of occupancy. This means either buildings already have an ERCES or must obtain one before opening for business. Since the network design and architecture of an ERCES and commercial distributed antenna system (DAS) are similar, there is an opportunity to lower the barrier-to-entry and initiate cost savings for installing both simultaneously. In addition, unified network infrastructure provides enhanced efficiencies such as better resource allocation, space savings, and a backup for first responder push-to-talk radio. Since first responders are now using smartphones more than their land mobile radios (LMRs), converged solutions support this transition.
Even though shared systems is not a new concept, it has historically been held back by ambiguity in the National Fire Protection Association (NFPA) and International Fire Codes (IFC) that greatly influence what is permitted in public safety wireless communication deployments. Authorities having jurisdiction (AHJs) that interpret and enforce these codes in the installation of ERCES within counties across the United States have largely disallowed converged networking simply because there was no language for or against it in the applicable code.
The publication of NFPA 1225 on September 15, 2021, marked a significant development in addressing shared systems. Section 18.6 of NFPA 1225 introduced language specifying the requirements for systems sharing infrastructure with public safety services. Section 18.6.3 states, “Systems that share infrastructure with non-public safety services shall ensure that the coverage and performance of the public safety communications channels are not degraded below the level of performance identified in Sections 18.8 and 18.9, regardless of the amount of traffic carried by the non-public safety services.” In other words, deploying these converged systems is fine as long as the commercial systems is up to the same specifications as the ERCES and neither interferes with the signal of the other.
Even still, some AHJs are reluctant to update their thinking simply because there is no requirement to adopt the most recent code year or keep up with the modern language. For example, some counties might be interpreting NFPA 2016 instea of adopting NFPA 1225, which exists in NFPA 2021. However, a stakeholder can legally petition the state under equivalency and recommend the different code version be enforced than the one under current observation. Certain counties in Florida have been successful in this process to approve converged networking in their counties. This is an important avenue for installers to consider in their counties.
Types of converged wireless systems
Generally, there are two approaches to deploy converged wireless networking systems in buildings that depend on size and location. For servicing a small to medium-sized building, integrators are likely to deploy a passive converged system. This is a less-costly model that requires a public safety bidirectional amplifier (BDA) and a type 90/20 commercial repeater connected to a signal source (whether that is a cell tower or small cell). Those individual devices would then converged and share antenna and cabling infrastructure throughout the construction.
For larger venues, a converged active DAS deployment is necessary. In this setup, a public safety DAS headend that propagates either VHF/UHF or PS700/800 radio frequencies would be used alongside a commercial DAS for LTE/5G. Instead of the convergence happening at the headend, both would need to connect to their respective mid or high-powered remote unit before sharing infrastructure. It is worth noting that AHJs generally are more reluctant to allow for active converged networking because of the complexity and scale of the deployment. This concern is unwarranted as long as the system is tested in accordance with the rigorous guidelines in the NFPA and IFC codes, as happens with any installation.
Converged wireless networking is a win-win for installers, building owners, and even first responders. As connectivity continues to become more a fourth utility than a “nice-to-have,” it’s important that each stakeholder in the wireless ecosystem makes an effort to improve the efficiency and affordability of in-building cellular connectivity. As the only true roadblock for converged wireless networking is antiquated thinking and resistance to change, integrators need to petition for the usage of the most up-to-date codes with AHJs in their counties.
About the Author
Mohammed Ali
Mohammed Ali is the Manager of DAS Engineering at Advanced RF Technologies, Inc. (ADRF), responsible for leading the DAS engineering division within the company across all global accounts. He has more than 10 years of experience in in-building DAS engineering and wireless network planning. Prior to joining ADRF, Mohammed worked as an RF Engineer at TeleworX and Huawei Technologies Sudan and a Network Management Engineer at ZAIN Sudan. Mohammed holds a Bachelor of Science in Telecommunications Engineering from the University of Khartoum in Sudan and a Master of Science degree in Telecommunications Engineering from the University of Maryland.