First in a Three-Part Series on Prioritization
Why will prioritization be important? The Potential for traffic jams.
One of the key differences between the Land Mobile Radio (LMR) networks currently used by public safety and the Long-Term Evolution (LTE) network that FirstNet is building, is the ability to prioritize network traffic. LTE standards contain a complex and well-developed set of mechanisms for guaranteeing quality of service (QoS) by prioritizing certain network traffic during busy periods. Understanding and leveraging these mechanisms will be critical to ensuring that first responders have reliable high-speed data connections when FirstNet experiences heavy traffic. These technical mechanisms may be well established, but the governance structure and planning guidance for implementing them for public safety are not. In the months and years to come, it will be up to the stakeholders, at all levels, to work with FirstNet engineers to ensure that the technical implementation of prioritization on FirstNet meets the operational needs of its users.
In this first of three articles on prioritization, we consider how FirstNet might become congested in the first place – Why will prioritization be important?
Spectrum is a finite resource
FirstNet will be deployed in 20MHz of dedicated spectrum – which is a lot, considering the limited number of public safety users. However, given the expense of launching, maintaining, and periodically upgrading a nationwide LTE network, it is almost a forgone conclusion that FirstNet will monetize excess network capacity – allowing non-public safety users to use FirstNet (or its spectrum) for a fee. We don’t know, at this point, what that arrangement will look like or who the secondary uses will be, but it's safe to assume that traditional first responders will not be the only users on FirstNet.
Balancing secondary users
It will be up to FirstNet and the public safety community to determine the priority and QoS guaranteed (if any) to secondary users. If the secondary users are members of the general public, then they are unlikely to need any QoS guarantee – the public could be freely kicked off the network in an emergency. However, FirstNet’s secondary users might not be members of the general public. Secondary users with a potentially public safety related mission, such as public utility companies, healthcare facilities, animal shelters, etc., might look to FirstNet as a way to get the guaranteed QoS they require during an emergency. Public safety may benefit from maintaining some of these secondary users on the system during large-scale events. It would then be up to our governance structures to determine how to balance the needs of high-priority secondary users and highest-priority first responders.
Furthermore, as first responders crowd event scenes, they could overwhelm network capacity by transmitting live video, biometric sensor feeds, GPS, imaging data, voice, and other data feeds. While the number of responders might be small, the number of critical response data streams could be much larger. For this reason, public safety communications governance bodies will not only need to consider prioritizing first responders over secondary users, but also consider how tough prioritization decisions between competing first responder groups will be made.
Balancing first responder users
When disaster strikes, public safety could very well need all of the network capacity. Events like hurricanes, earthquakes, and power outages often stress LTE networks – both physically, by disabling key network infrastructure, and operationally through increasing capacity demands as users attempt to contact loved ones and retrieve important information. In the face of network overload and service degradation, public safety traffic on FirstNet will need to take priority – preempting secondary user traffic.
FirstNet should plan for congestion and master prioritization. Part 2 of this series will examine some of the technical mechanisms for prioritization that are currently in the LTE standards, as we take a closer look at this powerful tool.
Read Part 2 of "FirstNet Traffic Update: Plan for Congestion"
Read Part 3 of "FirstNet Traffic Update: Plan for Congestion"
By Christopher Webster, JD, @christophersw1
and Max Romanik, JD, MBA, @MaxRomanik
Thanks to Elizabeth Webster, JD, @emw_esq for editing this piece.
Please Note The views expressed by Christopher Webster and Max Romanik on this website are their own and do not represent the views of their employers or clients.