The current discussion
concerning broadband access to public safety mobile units has been active and
ongoing for years. The primary reason for discussion regarding this issue is
the fact that current dedicated digital authority networks cannot provide the data
capacity required for modern applications. However, capacity limitation seems
to be the last point that discussion participants can agree on. The question of
how to bring the broadband to these vehicles has multiple opposing viewpoints
and conflicts of opinion.
The first and the most obvious
answer to bringing broadband into public safety vehicles is to build dedicated
networks for authorities. The main problem with this solution is the huge cost
involved, along with limited available frequencies. The second solution is to
use a commercial provider with special deals to offer the data capacity
required. Here the main concern is the availability of the data and resilience
of the network. The third option includes several hybrid solutions, either
combining dedicated and commercial networks or using multiple commercial ones.
The key problems with this latest solution are perceived to be resilience and
availability.
Participants in this discussion
are however too often lead astray by either their own personal experiences on
how networks function, by operator promises regarding availabilities, or
dedicated network equipment providers’ denigration of commercial networks. The
only way to know with certainty the availability of any single network or
selected networks together, is to test them in real life environments with the
same applications used by the authorities.
This document shows the results
of several selected pilots or tests conducted in Europe and the USA. The number
was limited for presentation purposes, but very similar or even identical
results have been seen from tens of tests around the world.
Typical testing environment
The selected testing environment
included in all conducted tests contains the following set-up:
Each vehicle was equipped with a
Multi-Channel Router (MCR) with selected available main operators in each case.
A laptop or a tablet was attached to the router. The router created a Mobile IP
tunnel to a server in the cloud and from there the connection to authorities’
back-end systems was created.
We wanted to test against the
clarified customer claims. The first claim was that one network operator is
enough within cities. The second was that out in remote regions there is no
coverage at all.
Cities
We first present the results
from using the hybrid network approach within selected cities. The cities
included here are Brussels, Antwerp and Los Angeles. The test duration for each
of these tests is several hours - long enough to give a clear picture of real
life operation of the networks within the given cities.
As is clear from the example,
the network availabilities of individual network operators are far from the
100% claimed. Over just a few hours there may be more than 50 data
interruptions. It is similarly clear that multiple networks overlap favourably.
The joint coverage with just two operators is always close to 99.5% and often
close to 99.9%.
What is also important is that
the bundled solution practically removed all longer breaks that would have
caused the user to feel an interruption to the service. Looking at the GPS data in heat
maps gives a clear visual representation of the fact that the networks are full
of holes when it comes to delivering broadband to moving vehicles, even in
densely populated cities.
Remote locations
For remote location testing we
selected a third network to ensure we get the maximum coverage. Only in Iceland
did we use two networks due to fewer available operators without network
sharing. We always try to select networks that have as little coverage overlap
as possible. The locations tested include are some of the most remote in
Europe, including Ireland, Norway and Iceland. The results were surprising.
It is understandable that single
network availabilities are significantly lower than in the cities. But
surprisingly they still are very seldom as low as 80%. The number of service
interruptions increases with lower availability and it was noted that some of
the breaks extended from tens of second to minutes and even tens of minutes when
driving. Despite much lower individual network availability in these areas, the
bundled uptime results were excellent. Over 99% is an excellent figure
considering the places where these test routes were driven. Places so sparsely
populated that there are often no inhabitants within a radius of tens of
kilometers.
Even in these remote locations,
the bundled solution offered uninterrupted connectivity as any longer breaks in
data were reduced to zero. The user did not experience any interruptions to the
service, even when some short breaks in the data stream occurred.
Availability heat maps show
clearly how multiple networks combine to provide the high availability
encountered.
Summary
Anecdotal evidence and personal
opinions are especially misleading in this area without accurate data regarding
mobile broadband data coverage. Typically individual opinions have been
influenced by personal experiences and are further confused by operators
marketing messages. The discussion around the need for dedicated broadband
networks is manufactured to some degree by the equipment providers themselves.
Opinions that are not backed up by real data and test based findings should not
form the basis of decisions made in this area.
In every test made, several
parallel networks have been proven to provide greater resilience than a single
one. Tests conducted in various locations across the US and Europe prove two
crucial points. The first is that no city can provide sufficient broadband
availability for public safety vehicles over a single network. The second is
that even the most remote areas can provide availability that is acceptable for
public safety mobile broadband.
It is worth noting that similar
tests are always needed in a new region in order to form valid conclusions. Of
the tens of tests conducted so far, all have yielded very similar results
regardless of locations.
Mikko Kestilä and Juhani Lehtonen
Goodmill Systems Ltd.
