ISSI Network Simulation Tool

Project Description

SNAPSHOT

The PSCR program is developing a tool that models the P25 ISSI protocols to evaluate system performance for various deployment configurations. The goal is to provide users with insight as to how the ISSI works and offer a mechanism for simulating deployment configurations and parameter settings without setting up expensive test beds and demonstrations.

BACKGROUND

Because LMR systems from some manufacturers use proprietary protocols that are not capable of communicating with another manufacturer’s LMR system, the P25 ISSI was developed by TIA in conjunction with the P25 Steering Committee. The ISSI enables RFSSs from different manufacturers to be connected together.

As more testing and demonstration events are planned for ISSI prototypes and products, a simulation tool that models the behavior of the ISSI may be handy for planning these experiments. The simulation tool can provide feedback on overall system performance including the audio quality and latency in setup. The tool is especially helpful for large deployment topologies where experimental setups and demonstrations may be too costly to realize.

AN INNOVATIVE APPROACH

We are developing a model for the ISSI as an extension to the NS-2 simulation platform. NS-2 is a discrete event simulator for networking research. NS-2 contains models for many of the existing network technologies and protocols upon which new protocols can be added, or existing ones extended or modified. Some example protocols that already exist for NS-2 that can be used to support the P25 ISSI model are Ethernet, IPv4, UDP, SIP, and RTP.

Our ISSI model (an NS-2 extension) includes the call control manager, mobility manager, and transmission control manager as specified in TIA-102.BACA-A, as well as extensions to existing NS-2 SIP models.

• The call control manager enables the establishment and termination of talk group calls and SU-to-SU calls, as well as the various configuration parameters (e.g., priority, availability check, emergency call/non-emergency call).

• The mobility manager handles the movement of the SUs from RFSS to RFSS.

• The transmission control manager handles the transmission of the RTP (e.g., voice) packets.

The Java-based server manages user authentication, retrieves the script file, launches the simulation, monitors the simulation’s progress, and provides the result files.

VALUE TO PUBLIC SAFETY

Emergency response agencies can use the ISSI simulation tool to model (or emulate) the behavior of the ISSI to help answer a multitude of configuration and parameter issues before, during, and after deployment. The tool can:

• Be used for network planning purposes to produce network-satisfying solutions based on application requirements

• Help troubleshoot potential issues in an experimental setup to forecast application expectations in a physical network

RESULTS

The ISSI simulation tool’s user interface displays an animated topology that highlights the paths of active calls and lists link capacity. The tool facilitates quantitative and qualitative network performance analysis with user-specified incident scenarios.

• Quantitative — Measurements for applications, RFSSs, network devices, and links revealing:

o Congestion on the link due to limited bandwidth

o High number of packets dropped

• Qualitative — Capability to listen to audio conversations revealing:

o High latency

o Poor audio quality

. . .

Right-click ISSI Network Simulation Tool to save or download this one-page project summary PDF file. Click here for more detailed resources concerning this project. See also Interoperability Press.

For more information, contact: Nada Golmie.