industrial wireless book special edition - Networking ...

Infrastructure. By using routers as the infrastructure
for clients that connect to them, the
routers form a mesh of self-configuring, selfhealing
links. With their inherent gateway
functionality, mesh routers can also be
connected to the Internet, thereby providing
a backbone for traditional networks while
enabling integration with existing wireless
networks.
Hybrid. A combination of the previous two
architectures, hybrid architecture performs the
functions of infrastructure and client and, as such,
can access the network through mesh routers as
well as communicating with other mesh clients.
This flexibility makes it the most suitable configuration
for a majority of applications.
In addition to these three designs, there are
also three key feature classes that can be
applied to each of them.
Self-healing and Self-forming functions.
Intelligent mesh capabilities with self-healing
and route choosing algorithms (self-forming)
determine their form by a calculation involving
the number of hops and the radio signal quality
for each hop. Each wireless connection in a
mesh network will have a path score to
represent the signal quality between nodes.
The path score calculation includes RSSI
(Received Signal Strength Indication), noise
level and bandwidth flow information in
providing the reference for calculation. The
number of hops from source to destination is
SISO SO
usually a minor consideration in a routing
algorithm.
Multiple hopping functions. Intelligent
wireless mesh systems may have a throughput
of higher than 150Mbps at two hops and can
still transfer data at 100Mbps after as many as
10 hops. These sorts of throughput rate
minimise concern about the carriage of high
bandwidth deterministic traffic such as video
and motion control data. Furthermore, the selfhealing
function may reduce maintenance and
other network management costs. A typical
application might involve monitoring the status
of remote oil fields; each derrick would use a
node with self-healing and self-forming mesh
capability (such as Advantech’s EKI-6351),
transmitting data to an EKI-6340 AP node set
up for direct backhaul to a control centre.
Oil refineries provide an excellent example in
MIMO MO
the use use of self-healing, self forming and
multi hopping algorithms. These sites have
many separate areas that need to be continuously
monitored and managed, but due to the
nature of the business, fires are real possibility
and may destroy the hardware monitoring a
particular section. Once a link has been broken,
routers up or downstream of damaged one
might not be able to send their data back to
the control centre with some conventional
network configurations. Thanks to self-healing
and forming and multiple hopping algorithms,
the data can still get through.
IEEE802.11n explained
802.11n includes many enhancements to the
earlier a/b/g versions of the protocol. These
improvements include an increase in speed,
range and reliability.
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