March 17, 2022
Blocking Out the Noise in Wireless Networking
Noise is an unavoidable disturbance in our personal lives, and it’s no less true in wireless networking. In public safety communication, noise interference is an often understated problem that isn’t a tangible issue for authority having jurisdictions (AHJ) until it becomes a major one. It takes an innate understanding of how noise aggregates across many emergency responder communication enhancement systems (ERCES) in a particular region that can dramatically impact the ability for first responders to connect with each other.
What is noise interference and how does it impact public safety communication?
Every ERCES, whether a distributed antenna system (DAS) or bi-directional amplifier (BDA), brings a certain level of uplink noise that can impact the ability for other devices to communicate. Noise impact doesn’t just come from ERCES, it can come from any electronic device, which is why the problem is only getting worse as we become more reliant on technology. For example, UHF/VHF is a popular public safety frequency band for first responder land mobile radio (LMR) communication and common devices such as smart TVs and LED lighting emit noise that can interfere with this signal. Additionally, new public safety codes from the IFC and NFPA, as well as legislative bodies, are requiring more public safety systems in buildings, adding to the collective number of devices emitting noise.
A single building using a public safety system that adds 7 decibels (dB) of noise, for example, is no big deal. But what happens when AHJs allow this level of noise for many different buildings in a jurisdiction over time? The collective noise can negatively impact the way first responders communicate with each other and effectively eliminate the purpose of an ERCES in the crucial moments they are needed. Certain venues are generally at a higher risk of noise interference like airports, casinos and high-rise buildings that require a substantial public safety system and have many other electronic devices producing noise. Fortunately, ADRF uses a series of technologies within its own public safety solutions, such as digital filtering and squelch, to keep the noise level to an industry-low <3.55dB for UHF/VHF BDAs. Digital filtering works to weaken certain signals that create noise and amplifies others, while the squelch works as a “noise gate” to suppress those weak signals even further.
How can AHJs mitigate the chances of suffering from a noise issue?
If a region accumulates too much noise, or a single ERCES begins to oscillate, it can create a chain reaction of interference across many devices. To remediate the issue, an AHJ would have to enter every building with a spectrum analyzer and find the source of the problem which could take countless hours and resources. AHJs must be mindful of an acceptable level of noise in each ERCES and standardize it across the region.
There is cause for optimism as certain groups are championing the effort to spread awareness of the noise issue. One example is the No Noise Task Force, which is a working group within the Safer Buildings Coalition (SBC). They’re working diligently to help AHJs and other local representatives understand the seriousness of uplink noise.