Network planning
Planning for transition
Public safety communications
Adobe Stock/ greenbutterfl
As the transition from PMR to mobile broadband draws nearer effective network planning
is needed now more than ever, as Richard Martin discovers
are in a state of flux; we are
in a transition from PMR/
LMR systems to broadband
cellular systems. This is
happening at different speeds across
the world. In some cases, the intent
is to make the transition rapidly, as in
the UK; in others, the transition is a
process of evolution with both working
alongside each other, as in the USA. In
many cases the use of 4G and 5G for
public safety is being trialled or studied,
as is the case in Canada.
In terms of planning for a public
safety network there are several cases
to consider.
First, a dedicated network which
can be a PMR technology such as
TETRA or P25, or a standalone cellular
network such as GSM-R or 3G or
even private LTE. Next, a new cellular
network which may be shared between
public and mission-critical users. The
particular needs of public safety users
will need to be met in terms of coverage
and resilience. In the third case, an
existing public network is offered;
this may need to be expanded into
low-population areas to provide extra
coverage or other enhancements.
In dense urban areas, cell sizes and
capacity will be driven by user numbers;
the addition of public safety users
may not greatly increase traffic but
will require priority service. Frequency
planning and cell capacity calculations
come into play in this case.
The other challenge is the need to
ensure in-building coverage for more
on this topic, see “Building confidence”
in our April issue – Ed.
The site survey may also identify
adaptations to the proposed base station
configurations, the sectors proposed and
the need for special antenna types.
Naturally even the most careful plan
will need to be tested once installed.
A more detailed discussion of this is
covered in Critical Communications
Today’s August 2018 issue.
A bridge from old to new
Our scene shifts to South Korea, where
the country’s Safe-Net mission-critical
broadband network is being rolled out.
To what extent (if any) is it reusing
existing LMR or public cellular
network sites?
“The coverage range of the private
LTE network under construction for
Korea Safe-Net is different than those
With the increasingly rapid roll-out
of 5G we have to ponder how long it
will be before this too is used for critical
communications. 5G is expected to be
deployed in densely populated areas
and use high frequencies – it will pose
network planning challenges of its own.
Planning basics
The basic steps in network planning can
be reduced to the following:
A clear view of service requirements
for the public safety users, including
KPIs. For public safety users, coverage
will be a key factor from the outset,
together with resilience and security.
Fundamental to the planning which
follows will be the budget – high
resilience and secure networks or
network expansions will come at a cost.
Link budgeting will establish the
maximum cell size in rural areas,
particularly when commercial networks
are to be extended to lightly populated
areas. This calculation adds up the losses
from sources in the base station and
the mobile, and this is subtracted from
the base station or mobile transmitter
power. Propagation loss is then included
to calculate cell sizes for the expected
base station configurations.
September 2019 @CritCommsToday 29