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Archive
ViewsLetter on
Provisioning 14 Jan
2005 #43
Provisioning automation--from chips to
the business layer.
PROJECT 25 DEVELOPMENTS:
RADIO FOR FIRST RESPONDERS
By V. Kaminsky, Associate Editor
We continue our series on Public Safety Radio. This issue is devoted to
the Project 25, a standard, which is accepted by the U.S. agencies
responsible for public safety and emergencies.
Project 25 (P25) radio is new generation radio, which supports a digital
format and is backwards compatible with existing analog network
infrastructure. P25 carries voice and data communications, uses
spectrum efficiently, and is easy to use. Gradual adaptation of
P25 by
the U.S. public safety communications community will allow all first
responders to communicate--among agencies as well as within
agencies.
RQUIREMENTS OF PUBLIC SAFETY RADIO
To do their jobs well, Public safety radio users require specific
functions:
--Control of group communications and dispatching, with purpose-built
security, dynamic management of talk groups, emergency calls,
talk-around capability (ad hoc calls between handsets without
involvement of a base station), prioritization of communications,
etc.
--"Instant" connections, with voice call set-up time in the range 0.3 to
1 second; 0.5 second often is cited.
--Seamless radio coverage throughout the geographic area, including
guaranteed coverage under the harsh environments of disasters.
Handsets
can relay connections when events take out network base stations.
--Ability to provision additional radio capacity during major incidents
automatically, while guaranteeing that capacity for rescue and law
enforcement.
--Uncompromising voice quality to allow a listener to recognize the
speaker, regardless of the background noise.
When talking about Public Safety and Security, these functions are
mandatory.
Initially, the Association of Public-Safety Communications Officials,
International (ARCO) led the development with the ARCO Project 25, a
standard for first response radio. Project 25 is now a joint
effort,
with the participation of local, state, and federal governments.
Many
security and technical organizations also support the initiative,
including the U.S. Telecommunications Industry Association (TIA) which
adopted the standards developed through Project 25 and published them as
TIA-102.
The primary objectives are to provide high quality digital, narrowband
radios that meet public safety user needs and maximize
interoperability. Additional objectives include optimizing radio
spectrum efficiency and ensuring market competition among multiple
vendors based on standards throughout the life of systems.
Although developed in the United States, Project 25 standards were
designed for the global marketplace. P25 radios are produced for
any
VHF or UHF public safety band to economically satisfy agencies with
small number of users.
PHASED APPROACH
Project 25 considered various access technologies in an attempt to make
the best use of the available radio frequency spectrum. Under
Phase I
of P25, upgrades moved the existing equipment from analog technology
with a 25 kHz bandwidth to digital technology with a 12.5 kHz bandwidth.
The modulation selected for Project 25 is C4FM, which is a modified,
four-level, frequency-shift keying (FSK), with a raised cosine filter to
minimize inter-symbol interference. TIA-102 requires new
equipment to
be "backward compatible" with the analog equipment to allow for a smooth
transition.
In Phase II, more spectrum-efficient equipment using Frequency and Time
Division Multiple Access (FDMA and TDMA) will need no more than
6.25
kHz per voice channel. This equipment will also be backward
compatible
with Phase I. Additionally, P25-II allows support compatibility
with
TETRA radios (originally Trans-European Trunked Radio, renamed
Terrestrial Trunked Radio).
Project 25 defines both Trunked and Conventional operating modes
for
Digital Two-Way Radio. It offers much richer set of features than
traditional FM radio and gives the immediate advantage that voice can
easily be encrypted, and mixed with other data transmissions.
Project 25 mission includes these key digital standard attributes:
--Backward compatibility and graceful migration. Project 25
enables
system migration, which is backward compatible with existing public
safety communications systems, and allows forward compatibility with
next-generation radios. These features contribute to...
--Interoperability. With all phases compatible, Project 25
promotes
communication among groups in an agency, among agencies (local,
state,
and federal), and with neighboring jurisdictions. This is
important for
mutual aid where resources are gathered from many different
sources.
--Scalable Trunked and Conventional capabilities. Project 25
systems
scale from a single channel (conventional) to high-capacity
trunking of
many voice channels on one RF carrier via frequency division
multiplexing (FDM). Trunked radios add a number of features, such
as
priority call, and they can be configured in voting, multicast, and/or
simulcast communications, and still include the talk-around capability
required by public safety agencies. Of course, these advantages
affect
the cost.
--High-level security
--Reliability.
The Project 25 standards has the following major objectives:
--Obtain maximum radio spectrum efficiency: system migration from
25
kHz to 12.5 kHz and then 6.25 kHz or equivalent spectral efficiency to
support more calls and more users without more RF spectrum.
--Ensure competition in system life cycle procurements:
choice among a
variety of vendors and solutions to keep costs competitive and maximize
features.
--Provide "user friendly" equipment: ease of use, minimal training
costs, and a shorter learning curve so users quickly can take advantage
of all system features to enhance their productivity.
--Rapid Deployment: creation of active voice and data networks at
emergency sites, with or without the presence of base stations.
--Support both digital and analog testing: although common in the
cellular world, this is a new requirement in the public safety
communications environment.
In addition to the voice encoding method, the P25 specifications define
the following open interfaces and equipment definitions. Any
manufacturer could supply equipment on either side of these interfaces:
-Common air interface (CAI)
-RF sub-system
-Inter-system interface
-Telephone interconnect interface
-Network management interface
-Host and network data interfaces.
Implementations can take the form of software-defined radios, which
means the same hardware can in principal upgrade from phase 1 to phase 2
and possibly later versions with new firmware.
-- Call us for a vendor-neutral network architecture and strategy for
expansion or convergence. We know voice AND data--and how to avoid
expensive bear traps on the migration path, such as security
arrangements.
--Working on product positioning or a marketing message for telecom?
Yes, we've done that--for hardware products and carrier services.
--Need an Expert Witness? Associates at Flanagan Consulting have
aided
in many legal proceedings involving telecom intellectual property and
technology.
--For RFP preparation, bid analysis, proposal evaluation--call
us. We
have current experience in Federal network procurement processes that
produced a network award without a formal protest.
"In Converged Networking, We Have the Experience."
Special thanks for supporting
ViewsLetter to www.webtorials.com, your
best source for communications tutorials and white papers.
"Flanagan Consulting" and "ViewsLetter"
are Service Marks of W. A. Flanagan, Inc.
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