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Modeling, Simulation and Performance Evaluation for Future Public Safety Networks

University of Washington

This project is exploring fundamental aspects of demand modeling for Public Safety Communications (PSC) networks, in terms of the key network Quality of Service (QoS) metrics: network capacity etc. This work hopes to shed light on key questions such as: what should be done from a network planning and resource scheduling perspective for Long Term Evolution (LTE) network to account for location and scale of various for emergency/ public safety events so as to meet capacity, coverage and QoS (latency, data rates, loss and service prioritization) requirements.

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A second objective in support of performance evaluation of PSC scenarios over LTE networks is creation of a public safety simulation module within the open source ns-3 network simulator intended for the broader research community. The objective includes implementations and/or integrations of essential 3GPP features into ns-3, inclusive of

  • proximity services and mission critical push-to-talk over group communications
  • LTE Direct Mode Operation for device-to-device communications

Researchers will be able to use this tool (when tested and released formally) to conduct performance analysis studies of future public safety networks, with a high degree of modeling fidelity.

Quick Resources

Analysis and Simulation of Migration of PTT Services to 4G LTE_On-Demand Session
Analysis and Simulation of Migration of PTT Services to 4G LTE_On-Demand Session
The performance of Mission-Critical Push-To-Talk (MCPTT) in future public safety networks based on LTE and 5G will be a key driver of operational success and safety. MCPTT is being implemented by many vendors and tested at interoperability events such as the ETSI Plugtest events, but large-scale experimentation with real equipment is often limited by factors such as equipment availability and field testing costs. For these reasons, a high-fidelity simulation model of MCPTT for the popular ns-3 discrete-event network simulation framework has been initiated by NIST Wireless Networks Division and further developed in this PSIAP-funded project. We will describe specifically how the off-network MCPTT simulation models from NIST have been extended to model on-network MCPTT operation over a simulated LTE radio access network and core, and how these models can be used in large-scale simulation experiments such as have been authored by NIST. Key performance indicators (KPIs) such as access time latency and mouth-to-ear latency are supported by performance traces from the simulation models, and the models will allow researchers to explore issues such as scheduling policies and robustness to intermittent links in a controlled, reproducible simulation environment. Simulation tests and documentation are also published as part of the open-source software dissemination of the models.

Meet the Team

Principle Investigator: Sumit Roy
University of Washington

Project Overview

This project ties together modeling using analysis and simulation along with open-source software development to deliver a demand modeling framework for emerging LTE-based public safety networks, developed in coordination with City of Seattle in the midst of a significant transition of its PSC network. The project utilizes a two-phased approach: developing first baseline stochastic approach to demand modeling, followed by validation and additional modeling that leverages the body of data provided by City of Seattle as it confronts an exponential increase in public safety wireless video traffic.

A key question the team will focus on is under what emergency scenarios can the requirements be expected to exceed the capacity of the allocated public safety spectrum in the 700 MHz band, and what should be done from a network planning and resource scheduling perspective to compensate for various scenarios so as to meet capacity, coverage and QoS (latency, data rates, loss and service prioritization) requirements. As a result, the team will work to act as neutral arbiters regarding public safety communications technology and network planning for the City of Seattle and their vendor chain.

Future public safety services over LTE networks will require progress on several key topics.  At the MAC layer within the radio access network (RAN), the team will pursue network planning and resource scheduling of the RAN for group call bearers, bearer retention schemes and emergency service flow prioritization in a public safety context, and analysis of LTE RAN scheduling options and their impact on QoS.  Further, link level analysis of LTE Direct Mode Operations (DMO) for device-to-device (D2D) communications will be conducted. Specifically, the team will explore relaying strategies while incorporating realistic D2D channel models for canonical operating scenarios via MATLAB link simulations, as inputs to subsequent network-level analysis.

In response to the call for packet-level simulation research infrastructure, the team offers an ns-3 public safety simulation module, including implementations and/or integrations of essential 3GPP features (cf. Proximity Services and MCPTT over GCSE) for public safety networks, public safety scenario support, models from the above tasks, and underlying LTE enhancements, in the packet-level open source ns-3 simulator. Outputs from the above two research thrusts will be integrated with the essential PSCR model and scenario support of this task

<< Back to the PSIAP 2017 - Public Safety Mission Critical Voice Page

Created September 28, 2017, Updated July 18, 2022