Project 25
more feature-rich.” He adds that the
goal of federal grant programmes
is interoperability. Th ey also favour
regional applications that encompass
multiple small agencies because these
can benefi t more than one agency,
while also delivering economies of
scale as a secondary benefi t.
Rehbehn points out that agencies
end up with more functionality
and excellent interoperability, and
a sustainable economic model, if
they join a larger, interconnected
system. “It is a sensible way to
progress. Otherwise you have a lot
of small fragmented systems, which
do not deliver on the promise of
interoperability and require far more
core network infrastructure, which
increases costs.”
Michigan’s Motorola statewide P25
system has been in place for 25 years,
and over that period has slowly added
more jurisdictions. In contrast, Iowa’s
state system only went live less than a
year ago, but already the capital, Des
Moines, and 20 counties have signed
up. “Michigan took a long time to get
everyone on board, but I have never
seen so many jurisdictions sign up
so fast as with the Iowa P25 system,”
says Lonnett.
North Dakota has also just signed
a $90m contract with Motorola
Solutions for a state system
following a competitive tender. “It
is a collaborative procurement with
both state and local jurisdictions
participating at the same time and it
is designed with both in mind,” says
Lonnett. “So, customers continue to
invest in P25 systems.”
The DMO issue
Another reason public safety is not
abandoning P25 is the lack of an
adequate talk-around or direct mode
operation (DMO) feature on LTE
devices. “DMO is still an issue for
MCPTT,” says Elder.
“3GPP’s ProSe equivalent is not
really being adopted by the chipset
vendors and there are all the problems
with lack of range.”
3GPP has recently indicated that
5G New Radio’s Vehicle-to-Everything
(V2X) capabilities might provide
the basis for an improved DMO
solution for public safety. Rehbehn
has his doubts, pointing out that fi rstresponders
need DMO to transmit
in and out of buildings and over long
range in forest fi res.
“Direct mode is a more demanding
set of requirements than V2X,” he
argues. “Abandoning P25 solutions is
not practical until that DMO gap
is closed. Reliance on one device
with an LTE direct mode capability is
some way off .”
A more immediate solution is that
off ered by the Sonim LMR Enabled
Detachable (SLED) P25 accessory
paired with the Sonim XP8 rugged
PTT smartphone. Rather than
incorporating a P25 radio into the
XP8, a separate P25 accessory provides
the direct mode solution.
Th ere are other reasons public safety
continues to rely on P25 for missioncritical
voice for the time being. Davis
cites the much longer equipment
budgetary cycles for public safety
agencies, as well as their desire not
to have to depend on others for their
critical communications.
“Pricing and equipment lifecycles
for FirstNet remain to be seen.
Reliability is still a reason to go for
P25 continues to serve
a very important role
thanks to its strong
interoperability feature set
P25, but as FirstNet proves itself on
that front, people will fi nally move
over,” says Davis.
Rehbehn concurs, noting: “P25
continues to serve a very important
role in the public safety community
thanks to its strong interoperability
feature set. Th e data limitations
remain a signifi cant issue and many
agencies operate LTE capabilities
in parallel.”
FirstNet may be gathering
steam, but it is this kind of parallel
deployment of traditional P25 voice
services and LTE voice and data
services that we are likely to see
operating in public safety for some
years to come.
Before public
safety agencies
can migrate to
mission-critical
broadband, the
challenge of direct
mode must be
addressed
Adobe Stock/Ton Forio
P25 systems in use
PTIG has identi ed a total of 2,351 P25 systems worldwide including both conventional and
trunking. Of these, 1,017 are trunking and 1,334 are conventional systems. Another major trend
identi ed by PTIG includes a strong migration from P25 Phase 1 FDMA systems to P25 Phase 2
TDMA systems.
P25 Phase 1 systems are down from 728 to 652 systems, while Phase 2 systems are up from
188 to 364 known systems. In addition, 93 P25 systems have been merged or consolidated into
larger regional or statewide P25 systems and are no longer listed as standalone systems. The net
total with consolidations removed is up 101 systems from the 2017 list.
Public safety remains the primary user type, with the US Department of Defense and federal
agencies being the other primary user groups. Additional P25 systems were recognised for public
works, utilities, corrections (non-federal), business, airport/transportation and universities. There are
37 statewide P25 trunking systems recognised.
Frequency bands in use remain dominated by 800MHz, 700MHz and UHF LO (380-420MHz).
Source: The Project 25 Technology Interest Group (PTIG): Updated P25 Trunking Systems List,
31 May 2019
July 2019 @CritCommsToday 19