SEARCH & RESCUE
WIRELESS TECHNOLOGY REFERENCE GUIDE
CDMA Code-Division Multiple Access.
CDMA is a digital wireless technology. CDMA is a "spread
spectrum" technology, which means that it spreads the information
contained in a particular signal of interest over a much greater
bandwidth than the original signal. Unlike many competing
technologies, CDMA has no hard limit for the number of users who
may share one base station (tower). Instead, with CDMA, additional users can connect until the
base station determines that call quality would suffer behind a set limit. CDMA networks operate
in the 800 and 1900 MHz frequency bands.
GSM- Global System for Mobile Communication. (originally-Groupe Spécial Mobile)
GSM is the most popular standard for mobile phones in the world. Cingular and T-Mobile use
GSM. Sprint and Verizon use CDMA. GSM is more prevalent in most other parts of the world, and
especially in Europe. GSM phones are completely incompatible with CDMA networks, and vice-
versa. GSM phones utilize a SIM card which identifies the user on the network.
TDMA- Time-Division Multiple Access.
TDMA is a digital mobile phone technology. In TDMA, the frequency band is split into a number of
channels, which are stacked into short time units, so that several calls can share a single channel
without interfering with one another. Put another way, TDMA allows several devices to share the
same frequency band at the same time, by letting each device "take turns" sending digital data.
Each "turn" is called a "time slot". TDMA, is the basis for several major wireless standards,
including GSM, iDEN, and IS-136. IS-136.
PDE (Position Determining Equipment)
Location Technologies Technology Performance
E-CID Derives additional timing advance
Works with any phone and
provides improved accuracy over
Enhanced Cell ID and power measurements from
Cell-ID in areas of high-cell site
(200m to 500m)* the wireless network.
*Depending on cell site density. density.
A-GPS Utilizes modified handsets that
contain a GPS receiver and a
Works well in rural and suburban
Assisted Global Positioning areas that provide an unobstructed
System special network server to assist in
view of the sky.
(sub 30m) location calculation.
U-TDOA Utilizes low-cost location
measurement units installed in the
Works with any phone — existing
Uplink Time Difference of Arrival or future. Works well in urban,
operators' base stations to
(sub 50m) suburban, and obstructed
precisely calculate location using
(Considered Best Option) environments.
AOA Utilizes two or more antennas
containing multiple element
Works with any wireless phone —
existing or future. Supports space
Angle of Arrival
arrays, allowing the exact location cell site density or where cell sites
(100m to 500m)
of each AOA element to be are arranged linearly, for example,
precisely calculated. along a stretch of highway.
Wireless Location Sophisticated pattern-matching
approach for determining the
Signatures (WLS™) location of a mobile phone. Works with any phone — existing
Reports are compared against an or future. Works well in urban or
established geo-referenced suburban areas.
database that models the radio
Hybrid Any combination of E-CID, A-
GPS, U-TDOA, or AOA to achieve Highest Quality of Service for all
optimal performance for any applications.
A-GPS (Assisted GPS). Handset-based position location technology. Phone takes
readings from both GPS satellites and nearby cellular base stations (towers), with the
help of a location server on the network. The location server on the network is required
to tell the phone which satellites to look for, and also to perform the complex calculations
that provide precise location information. This technology provides better accuracy than
GPS-only and network-based technologies. Since the database containing satellite
positions and timing is very large, it would be infeasible to contain that information within
the phone. A-GPS uses a separate server at a precisely known location.
Cellular and digital PCS providers by ZIP code http://www.wirelessadvisor.com
Cell phone tower locations http://www.cellreception.com
Cellular terminology glossary http://www.phonescoop.com/glossary/
GSM providers & maps http://www.gsmworld.com/roaming/gsminfo/cou_us.shtml
Phone number query to determine provider http://www.fonefinder.net/
Number Portability Query- NeuStar- North American Numbering Plan Administrator
CALEA- Communications Assistance for Law Enforcement Act
of 1994. Defines statutory obligation of telecommunications carriers to
assist law enforcement in executing electronic surveillance pursuant to
court order or other lawful authorization.
ASKCALEA Law Enforcement Forum http://www.askcalea.net/
Cellular site database
CALEA contact list for wireless providers
18 U.S.C. § 2702- Voluntary disclosure of customer communications or records
(b) Exceptions for disclosure of communications— A provider described in
subsection (a) may divulge the contents of a communication—
(8) to a Federal, State, or local governmental entity, if the provider, in good
faith, believes that an emergency involving danger of death or serious
physical injury to any person requires disclosure without delay of
communications relating to the emergency.
(c) Exceptions for Disclosure of Customer Records.— A provider described in
subsection (a) may divulge a record or other information pertaining to a subscriber to or
customer of such service (not including the contents of communications covered by
subsection (a)(1) or (a)(2))—
(4) to a governmental entity, if the provider reasonably believes that an
emergency involving immediate danger of death or serious physical injury
to any person justifies disclosure of the information;
18 U.S.C. § 2703. - Required disclosure of customer communications or records
Investigation of a crime- requires a search warrant
47 U.S.C. § CHAP 5 SUBCHAPTER II Part I § 222. Privacy of customer information
Privacy safeguarding by wireless carrier (protects liability of carrier)
(c) (2) Disclosure on request by customers “ …..shall disclose…to any person designated
by the customer.“
(d) (4)(A) ……to respond to the user’s call for emergency services
(B) to inform the user’s legal guardian or members of the user’s immediate family of
the user’s location in an emergency situation that involves the risk of death or
serious physical harm.
-KPhillips, Grand Canyon National Park SAR (03-2007)