By The FirstNet CTO Technology Planning and Development Team
FirstNet was established to ensure the deployment and operation of the Nationwide Public Safety Broadband Network (NPSBN) using 20 Megahertz of Long Term Evolution (LTE) spectrum in the 700 MHz band. Once built, the network will act as a “wide-open freeway” providing pubic safety users with the bandwidth and capacity they need to communicate and share information during both emergencies and daily operations.
In addition, during times of heavy usage, FirstNet is developing priority and preemption capabilities so public safety voice, video, and data communications won’t get caught in any “traffic jams” caused by network congestion. As part of our work in this area, FirstNet is coordinating with the Public Safety Advisory Committee (PSAC) to help develop a Quality of Service, Priority and Preemption (QPP) framework for the NPSBN. The Public Safety Communications Research (PSCR) program has also been instrumental in testing efforts on QPP.
The QPP framework seeks to ensure that the NPSBN remains a “wide open freeway” for public safety. Furthermore, when public safety traffic increases, the NSPBN should, as quickly and seamlessly as possible, move non public safety traffic onto other network roadways. A more detailed description of the key elements of the framework is provided below.
- Quality of Service (QOS) is needed to ensure that Public Safety users have access to their mission critical services and applications at the required level of quality, corresponding to their individual needs. QoS requires discriminatory assignment of properties such as bandwidth guarantees, usage limits, latency, accuracy, accessibility and retention.
- Priority is the means by which users, applications, traffic streams or individual packets take precedence over others in setting up a service session or forwarding packets during periods of congestion in the network. Public Safety users will require priority access to the NPSBN resources to make their communications (at the required level of QOS) an effective tool in their management of incidents and emergencies.
- Preemption is used together with priority to control use of resources by removing active sessions of lower priority users and allow allocation of resources to higher priority users, when network resources are scarce or fully occupied.
The QPP framework has exploited features and settings that are standard in 3GPP technology, including incorporation of additional interfaces, systems and tools as needed, and provides a holistic solution requiring device, applications, operations, and policy elements. Importantly, the QPP framework provides alignment with Local Control (http://firstnet.gov/newsroom/blog/local-control-and-npsbn) where PSEs influence network QPP behavior through the administration of their users, services, devices, and applications.
FirstNet has authored a white paper on this Quality of Service, Priority and Preemption, which is available in our Reading Room: http://www.firstnet.gov/resources/request-reading-room-access. This paper serves as a reference to the providers of the NPSBN, explaining FirstNet’s vision regarding QPP, so that providers may develop proposals around these principles.