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Real-Time Deployment of Mesh Networks

Overview

The goal of real-time deployment is the rapid establishment of a wireless mesh network to support communications in hard-to-reach areas.  Intended applications are primarily emergency response communications in areas where traditional wireless solutions are problematic:  inside large buildings, underground tunnels and mines, and urban canyons. Beyond two-way communications, ancillary services may include location tracking of emergency responders, environmental sensing, and physiological sensing of responders.

In a typical scenario, a first responder (FR) equipped with a two-way radio and several small relay nodes enters a building.  As the FR goes further into the building, the radio signal from incident command (IC) weakens.  Before losing radio connectivity with IC, a relay node is deployed, providing two-hop connectivity between the FR and IC.  This process repeats whenever any FR is about to lose radio signal, creating a multi-hop mesh network in real time to maintain connectivity with IC.

NIST work on real-time deployment of mesh networks is focused in three areas:

  1. Link Quality Measurement to support rapid assessment of wireless mesh links
  2. Modeling and Simulation of mesh networks and real-time deployment protocols
  3. Prototyping, Testing and Evaluating implementations of rapidly-deployable mesh networks
Publications and Related Work		 Mesh Network

Link Quality Measurement

Link quality measurement is needed by the deployment protocol to determine when a new node needs to be added to the network to maintain connectivity as it expands.  Of utmost importance to efficient deployment of mesh network resources is detecting the onset of a marginal link before it occurs.  NIST is studying various approaches to rapid and efficient measurement of the reliability of time-varying links in packet-switched wireless networks.
 
Linear positioner used to induce time-varying channel
Linear positioner
Plots of SNR and Packet Success Rate versus time
SNR and Packet Success Rate versus time

Modeling and Simulation

NIST is developing models and simulation tools to evaluate the performance of mesh networks and deployment protocols in RF-challenging environments. Specific efforts include:
Simulation graphical user interface

Prototyping, Testing, and Evaluation

NIST has developed two prototypes demonstrating real-time deployment of a multihop wireless network between a fixed incident command station and a mobile user: 
  1. 900 MHz system based on TinyOS motes
  2. 2.4 GHz system based on IEEE 802.11
These systems have been used for testing, evaluation and feasibility analysis.
Features of Real-Time Deployment Prototypes 900 MHz System 2.4 GHz System
Rapid link quality measurement X X
Automated deployment indication X X
Local placement assistance X X
Full-duplex voice   X
Two-way text messaging X X
Centralized monitoring of sensor data X X
Location tracking using RFID-Assisted Localization X X

2.4 GHz prototype relay node
 2.4 GHz prototype relay
Certain commercial equipment, instruments, or materials are identified in order to specify the experimental procedure adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the materials or equipment identified are necessarily the best available for the purpose.

Publications and Related Work

Real-time Deployment Link Quality Measurement Prototyping, Testing, and Evaluation Related Efforts NIST Contact:  Nader Moayeri, +1 (301) 975-3767, moayeri at nist.gov