Adding Public Safety Services to a DAS
In many municipalities across the country, legislation is in the works to require buildings to meet a minimum signal requirement for public safety first responders inside the building. There are two ways to meet this requirement, either the building has sufficient coverage from the outdoor repeater sites, or the property owner must enhance the service using a Distributed Antenna System (DAS). If you are already planning on installing a DAS in your building, it is a good idea to make sure it will support public safety channels in case they are needed in the future.
Understanding the Spectrum Requirements
The frequencies used for public safety can vary greatly from county to county and even from agency to agency. In the same city, the police may operate in one band, fire department in another and Emergency Medical Services (EMS) in a third. Before developing your DAS requirements, make sure you understand the channels used by all first responders in your area and which of these channels can be supported by any DAS. Even if you are not planning to support public safety services immediately, you can ensure that all the components of your DAS will support the required channels if you decide to add them later.
Covering the Entire Building
The coverage area requirements vary greatly between Wireless Service Providers (WSPs) and public safety agencies. While it may be acceptable to the WSPs to provide service over 90% of the building and completely neglect mechanical spaces and stairwells, these may be critical coverage areas for the fire department. It will be significantly less expensive to design for these areas upfront than trying to augment coverage at a later date.
A public safety DAS is useless if it isn’t operational in the event of a disaster. For this reason, public safety agencies usually have more stringent requirements for survivability than WSPs. These may include centralized power with battery backup, installing cables in conduit and equipment in NEMA enclosures. All of these items are difficult and costly to retrofit, but relatively easy to incorporate in the initial system.
If you are feeling overwhelmed by all of these new requirements for your DAS, the best thing to do is contact an expert. Planning ahead will avoid many problems down the road if you need to add public safety channels to your DAS.