Alternative Positioning Technologies
There is a huge utility to DHS of such a
3D locator system. There are over 2
million emergency responders (ERs) in
the US with the mission to save lives,
while staying alive themselves. Emerging
technologies are critical for meeting
the U.S. Fire Administration’s goal:
reduce firefighter fatalities by 25% in
the next five years. Existing technology
allows first responders to monitor their
own safety, e.g., Personal Alert Safety
System (PASS) and Heads-Up-Display
(HUD) units, and to send and receive
messages from incident command (IC),
however reoccurring failures and user
error have led to fatalities. A lack of status,
condition, location, task, resource,
threat, and exit accessibility information,
or inability to convey this information
among emergency responders
(ERs), Strike Teams, and Incident Command
(IC) can result in civilian and
responder casualties.
The following are some of the
required performance measures
for this locator system:
Locator must send information including
location-related information
Locator must wirelessly transmit inside or
outside of structures and through rubble to
an off-site incident command post, on-site
incident command posts, emergency
responders, and/or other authorized parties
including within teams of responders.
Locator must be self-initializing, self-calibrating,
self-adjusting and must have selfdiagnostic
capabilities to ensure speed and
reliability.
Locator must operate outside all buildings
and inside of almost all buildings, no matter
their structural state and environmental
conditions.
Primary incident command posts should
be able to monitor the status of the locator
and its host from a radial distance from 30
meters to 100 meters (per relay).
Locator must be able to specify the location
of its host in three dimensions within 6
meters (3 meters desired).
The base station software must be able to
display location and identification of personnel.
The base station must be able to display
general-to-specific information (the ability
to drill down from an overall scene to a specific
individual) about an operation/incident
and its emergency responder participants.
The base station must include visualization
tools that :
- Allow incident commanders and
site personnel to easily interpret
incoming displayed information.
- Display the location of an emergency
responder in easy to understand
coordinates. (One form of display
must be a wire-frame like view
of the building structure with the
position of each responder indicated.
The wire-frame view must
include a scale showing grid spaces
of approximately 10 feet in every
direction.)
- Allow the user to identify, group,
and categorize responders as
desired
Optionally, the coordinates returned by the
locator can be input to a Geographic Information
System (GIS) system (including a
building map or equivalent for underground
structures).
EXAMPLE 2: CELL PHONE BASED POSITIONING
INSIDE BUILDINGS
Mobile networks (GSM, GPRS,
UTMS, CDMA) are available everywhere
but the positioning accuracy is
rather low. By calculating the signal’s
time and distance to nearby cell-phone
towers, mobile networks can calculate a
position, but the accuracy is rather low
(50-300 mts). This means that the position
of calls from mobile phones located
in a multi-story building provide
information that will at best identify a
few buildings or the block from which
the call originated. It’s also possible that
a mobile phone (if it’s on the top floors
of a tall building) can be connected to a
transmitter in a neighboring cell, causing
the accuracy to go down to kilometers.
Calls from mobile phones in multistory
buildings provide information
that will identify a few buildings or the
block that the call originated.
Solutions to increase the accuracy of
mobile networks already exist in the
USA, in which mobile clients are located
with the help of supplementary
information (e.g., postal-code information,
streets, town names, etc.). Accuracy
is further improved by using the time
taken by the signal to reach the mobile
device. But due to lack of directional
information, users can be located anywhere
in a circular band (or a section of
a circular band) around a base station,
so uncertainty remains.
It’s important to solve indoor positioning
problems, because by 2005
there will be 184 million U.S. wireless
subscribers (Jupiter Research, 2001).
Moreover, according to the National
Emergency Number Association, more
than 30 percent of 911 calls in the US
originate from mobile phones—a number
expected to soon outpace 911 wireline
calls.
A multitude of applications and services
would benefit from indoor positioning
and navigation. Technologies
such as GPS and initiatives such as the
U.S. Federal Communications Commission’s
E-911 mandate generated a lot
of interest in location-based services
(LBSs). However, despite GPS technology
and the positioning capabilities of
cellular networks, millions of square
meters of indoor space (i.e., office
buildings, airports, convention centers,
etc.) are out of reach.
ROLES AND TYPES OF INFRASTRUCTURE
Building a system that works well
indoors is a challenge, because signals
reflected off walls, floors and ceilings
tend to confuse sensors, and often there
are obstructions between sensors and
objects being tracked. GPS and cellularnetwork-
based positioning aren’t
appropriate for indoor use due to loss of
line-of-sight as well as signal blockage,
fading and shadowing.
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