Advances in broadband wireless technologies developed by standard developing organizations (SDOs) such as 3GPP and IEEE 802 offer unprecedented capabilities that have the potential to improve the effectiveness of first responders. Our efforts are aimed at evaluating whether or not those emerging solutions meet current public safety needs, and what improvements are necessary to meet future needs.
We provide the public safety community with the performance analysis tools needed to better understand emerging network technologies and facilitate:
- the evaluation of worst/best case network deployment scenarios,
- the investigation of how well new technologies support public safety requirements,
- the development of quantitative requirements for public safety communications.
- the development of next generation network standards in support of public safety communication needs.
Current efforts are focused on the following 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 to ensure that functionalities support the public safety requirements.
The situations under which first responders are communicating necessitate more stringent performance and availability 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) and Group Communication System Enablers for LTE (GCSE_LTE). In collaboration with public safety partners such as FirstNet, we are contributing to the 3GPP standard development process to ensure that the public safety requirements are clearly defined and that specifications have the potential to meet those requirements. A major focus has been on off-network MCPTT mode over LTE, where users communicate using ProSe without accessing the network. An extensive set of scenarios was created to cover most of the possible combinations of call control and floor control procedures. We have been able to verify the protocols’ correctness and provide solutions to issues identified using modeling and simulation. During our research, we evaluated the time required for users to be able to talk, also called access time, under various scenarios. We developed analytical and simulation models that provide insights regarding parameter configurations and ensure that the solutions will deliver the best possible performance for first responders. As our efforts continue, we are investigating in-coverage and partial-coverage scenarios in both LTE and 5G technologies.
Open-source simulation tool
While we employ a variety of commercial modeling and simulation software to conduct our research, we have made extensive use of the open-source simulation tool called ns-3. Using open-source software accelerates collaboration by making it easily accessible to other researchers in both industry and academia. We have developed several public-safety oriented modules to enable simulation of ProSe and off-network MCPTT protocols. Additional models for Unmanned Arial Vehicle (UAV) energy consumption, video applications, and scenarios have also been included and released publicly (https://github.com/usnistgov/psc-ns3). Thanks to the Public Safety Innovation Accelerator Program (PSIAP) Funding Opportunity, we have been able to collaborate with other universities to further expend the simulation capabilities such as proper management of radio link failures, wireless backhaul, and mmWave communication.
This work is part of the Public Safety Communications Research program.