Is GPRS reliable enough for intruder and/or fire alarm transmission?
This discussion was started by Jerzy from Poland and is very relevant for many people in the security and fire alarm monitoring business today. The question posed by Jerzy was:
Some operators/ central stations are enthusiastic, others disappointed. Probably the best measure of alarm transmission path/system reliability is availability as defined in IEC 60839-5-1 Alarm systems - Part 5: Requirements for alarm transmission systems - Section 1: General requirements for systems and then in EN 50136-1 standards. Required availability levels specified in these two standards are based on reliability of PSTN based systems, measured 20 years ago. But what is availability of GPRS based alarm transmission systems? Do you know what the real availability of your GPRS based alarm transmission system is? Do you measure availability and report it to any external body?
A well known UK based provider of GPRS monitoring solutions responded:
I do think GPRS has improved a lot in past 10 years for coverage and availability in the UK.
Vodafone UK and other operators are making big investments into M2M communications. We see on
our Gemini Network over 400 million calls per month. These are static sites and give us all
the reasons to believe that GPRS is right path for Intruder/Fire Alarm delivery.
Jerzy was seeking a little more detailed information and continued:
I also would like to think and believe but I would prefer to know the real availability of
GPRS based alarm transmission systems. EN 50136-1-1 standard gives definition of Alarm
transmission system availability and equations which allow to calculate it. This standard also
advises us that availability records shall be open to inspection by a representative from an
accredited body. Do you collect information and calculate availability of your networks or
transmission paths?
The UK provider added:
The information you are looking for will depend on Network provider and country you are
in. In UK we use Vodafone and my reason to believe in GPRS is bases on the information we
gather from our Gemini network and calculate availability by location.
Then came an Australian perspective:
I run a company here in Australia that manufactures
a GPRS solution for the last 8 years. We have been quite successful and our product has been
independently tested & certified according to our nationally based standard (AS2205.5 Part
2008). Part of this standard requires us to deliver a solution with the required 'uptime /
network availability', which we have easily achieved with a 99.8% result. Our solution uses
dual SIM cards connected to Australia's 2 main telco networks (Optus & Telstra), and our
hardware automatically switches between these networks as required. We have overseas partners
in many regions around the world offering our solution and always on the lookout for more!
Steve Nutt, the owner of group commented that Jerzy had asked a simple question which any potential alarm monitoring subscriber should have the right to ask to the governing body in any region. What is the point of all these standards if the equipoment and networks are not monitored for performance?
Jerzy still wasn't getting the answer he was looking for and continued:
You have just indirectly confirmed that GPRS is not so reliable or at least that you were not so
convinced designing your system. Did you demonstrate 99,8% availability during certification
tests or calculate it after one year or one month of operation of your whole monitoring
network? You have very specific alarm transceivers with access to two GPRS networks. What
is availability of each of these networks calculated separately? Do you observe correlated
fluctuations of availability eg cased by popular events?
I know that in many cases GPRS is the only possibility. Unfortunately, service providers/ central station managers do not want any discussion on reliability of GPRS based solution. Do they have something to hide? Do you present information of availability of your alarm transmission system to any external body? Is it required in USA, Australia or in any other country?
Someone from the US pointed out a flaw with GPRS based signaling solutions:
When one can
purchase equipment on the internet that will successfully overcome any GPRS for less than
$100, and in addition to the above noted vulnerabilities, why does there remain any question
of significant vulnerability?
The UK provider responded:
It is same as someone cutting PSTN line which is outside house
or business or burn down PSTN exchange. Communication devices delivering alarms need to be
intelligent and identity what is an attack and what is Radio Base station/Network issue.
Not one to hold back, Jerzy upped the ante:
Are you ready to sign SLA agreement with your
customers offering 99,98% availability? Several years ago when we were drafting EN 54-21
standard on fire alarm transmission we intentionally excluded GPRS as a not reliable medium
for transmission of safety of life information. Nowadays GSM/UMTS providers are even more
interested in data than voice transmission and have to offer better service. But: bandwidth
is limited and is not growing, traffic is changing, mains from time to time are down for
different reasons etc. ,etc. Drafting EN 50136-1 (like AS 2205-5) I would like to know
where we really are, what we can expect, what we should require from GPRS providers. Our
electronic communication administration provides fields test of GSM/UMTS networks of all
operators. Unfortunately they do not cover such features like availability. Maybe in other
countries you have more information from your telecom administration.
A well known industry leader from New York suggested an alternative approach:
It easy to
show all the faults with any communicatins technology, maybe the better question for the
group should be: Which of todays communications technologies is the most reliable for alarm
transmission and why?
Steve Nutt said:
Now that is a good question, but I think the answer would vary on a
country by country basis. If the PSTN is 100% analog, then it's a clear winner, but in places
like the US, Canada and the UK where VoIP can creep in without notification, then that
obviously changes things. In North America, AES Intellinet may be justified in claiming the
title of "most reliable for alarm transmission".
The UK provider commented:
I agree with Mark which communications technologies are best
in todays environment and we have only 3 paths to look at PSTN, IP LAN and GPRS.
PSTN is still very reliable but can it hand calls every minute and what should be the second
path? This brings back to GPRS. Also with BT 21CN changes will this method still be available
future in its current form? IP LAN is good in managed network environment but to get a leased
line the minimum cost is 6,000. Setting up firewall to allow communication outside company
environments is concern and cost for any IT Department. ADSL broadband is up and down most
of the nights and there are no stats available on its availability and no ISP in UK is
providing SLA for ADSL. My own home broadband I have been resetting my router every day as
links keep dropping off and provider cannot see any issues. GPRS is good on coverage and
ease of install. Do not have to wait for PSTN line to be installed or IP RJ45 connections to
be available these are all additional costs to end user. If and when in the future new
communication technology becomes available which offers more reliable and cost effective
communications then we will be sure to offer these to our customers. At this moment we see
GPRS is the best and most reliable for Alarm communications.
At the time of writing, Steve Nutt had made the last comment:
I have no problem with your
GPRS + PSTN combo as a viable solution for replacing Redcare systems, but you can forget the
digicom market because dual path solutions are too expensive. The only viable solution there
is IP-only, using existing infrastructure. Oh and don't take your eye off that domestic
market as it accounts for 50% of the overall market in the UK. No 6,000 leased lines or
corporate firewalls in that market, just plain old DSL Internet connections.
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