6
May 2017
c
oVer
s
torY
ARM or x86?
Qseven modules for LPWAN gateways
By Zeljko Loncaric,
congatec
The FlexGate Low-Power
Wide-Area Network (LPWAN)
gateway from the French IoT and
embedded systems engineering
specialists EXPEMB is based on
Qseven Computer-on-Modules from
congatec. This gives the vendor the
freedom to pick any ARM or x86 low
power processor customers demand.
n
Connected distributed sensor and control-
ler networks formonitoring,management and
maintenance purposes are the driver behind
the IoT. One of the major challenges is pro-
viding reliable connectivity and data exchange
with distributed sensors and controllers over
long distances from a few hundred meters up
to several kilometers. This challenge is two-
fold: To meet the ultra-low power consump-
tion requirements of the distributed sensors
and controllers while enabling reliable and
cost-efficient data exchange. Local wireless
technologies don’t have the broadcast range.
Cellular technologies are too expensive and
consume too much energy. Thus, new tech-
nologies are needed for these Low-Power
Wide-Area (LPWA) connections in rural as
well as urban areas that are major drivers of
the progressive high growth rates of M2M
and IoT applications.
While the total number of M2M connections
will only grow from 5 billion in 2014 to 27
billion in 2024 at a CAGR of 18%, LPWA
is a market that is expected to grow at 93%
CAGR during 2016-2022 to reach 14% of
the overall M2M connections in 2024. Today,
Western Europe has the largest share of the
LPWA market as the countries in this region
were early adopters of these information
systems. But major smart city projects in
China, Singapore and India are also driving
the growth. LPWA connections can be made
available via different technologies. One path
is based on a cellular type infrastructure with
telecom like base stations. Examples are Sigfox
or Huawei (Cellular IoT) which get deployed
as open networks for usage of everybody. But
most commercial users prefer private net-
works due to security concerns. One of the
technologies for this market segment is LoRa.
It uses a star topology for a bi-directional con-
nection between devices like sensors or actu-
ators, and one or several gateways that can
– if supported –immediately forward all data
via standard IP technology to a central cloud
server. The data rate between the devices and
gateways ranges from 0.3 kbps to 50 kbps.
LoRa also encrypts all data via AES encryp-
tion technology by using a 64 bit unique net-
work key, a 64 bit unique application key and
a 128 bit device specific key. The single-hop
wireless connection uses the unlicensed 868
MHz frequency band in Europe and 915 MHz
in North America. By this, operators do not
have to pay for third party infrastructures and
licenses, which help to reduce cost.
The maximum capacity of accessible end
devices or nodes for a LoRa gateway depends
on the number of packets the gateway has to
manage in a given time frame. A LoRa build-
ing block for a gateway with 8 channels can
process up to 62,500 packets per hour. This
equals the maximum amount of devices a
gateway can handle if it is configured to send
only one packet per hour. The maximum
range in urban environments with no direct
line of sight and deep indoor coverage ranges
from 2 to 10 km. In suburban areas, up to 15
km can be achieved and 40 km for areas with a
direct line of sight and little interferences.
To balance battery life and signal strength, the
LoRa network server uses an Adaptive Data
Rate (ADR) algorithm to automatically define
the optimal performance under the local
environmental conditions. The algorithm is
based on advanced information such as Signal
Noise Ratio (SNR), Received Signal Strength
Indication (RSSI) and different channels to
optimize signal strength and power consump-
tion for each end device individually. By this,
end devices can achieve a battery life of up to
105 months with a 2000 mAh battery, which
is about 10 times more than current cellular
based protocols offer. Besides the technolog-
ical aspects, LoRa also receives great indus-
try support, which helps to accelerate its roll
out across the world. In July 2016, for exam-
ple, KPN made its LoRa network throughout
the Netherlands available for IoT applica-
tions. LPWAN specialist Actility also supports
