Public Safety Communications

Current efforts are focused on the following three topic areas.

Device-to-Device (D2D) Communication

The ability for public safety personnel responding to an incident to communicate is critical to the success of the operations. In certain situations, the coverage provided by the network infrastructure (i.e. cell towers) may be missing or insufficient and therefore it is crucial for public safety devices to be able to connect directly with each other. This feature is added to LTE starting with Release 12 via the Proximity Services (ProSe). We are extending the ns-3 simulation platform to evaluate the D2D capabilities of Release 12 and to ensure that functionalities added in Release 13 and later releases support the public safety requirements.

Mission-Critical Communications

Public safety personnel are currently using commercial broadband network to support applications not available in LMR systems. However, during an emergency, the availability and performance of those applications are not guaranteed. The situations under which first responders communicates necessitate more stringent requirements compare to non-emergency personnel. To enable the mission-critical communications, whether it is voice, video, or data, new architectures are proposed, such as Mission Critical Push-To-Talk (MCPTT) in 3GPP Release 13. Using modeling and simulation, we are able to verify the protocols’ correctness and optimize parameter configurations to ensure that the solutions will deliver the best possible performance for first responders.

Priority and Preemption

Historical data has shown that cellular networks experience congestion and outages during large incidents (e.g. 911, Boston marathon bombings) and large events (e.g. inaugurations, sporting events). Even with 20 MHz of dedicated spectrum for public safety, it is anticipated that these situations will occur and traffic will have to be prioritized in order to ensure that the critical communication paths are maintained. In this task, we evaluate the features available in LTE to define priorities among users and applications. Our focus will be on bearer management and scheduling in order to maintain the Quality of Service (QoS) of the high priority traffic.

You can also found additional information on our prior work, including P25 ISSI modeling.