12-06-2013, 03:24 PM
Wireless Mesh Network Concepts and Best Practices Guide
Wireless Mesh Network.pdf (Size: 729.29 KB / Downloads: 88)
Networks are Evolving
Within the past 40 years, networking technology has undergone
significant changes, and yet the primary mission of a network has
remained the same, to share information.
When IBM introduced the SNA architecture, we saw the network as a
means to record and distribute information from a large central
mainframe. We typed in an entire page of information using a “dumb”
terminal and pressed the Enter key to deliver it while we waited for the
mainframe to respond with a new page of fields and values.
Later, as PCs were introduced and became more powerful, the concept
of a de-centralized distributed network was considered a more flexible
architecture. Networks of servers and workstations could be small,
medium or large, and provide all the software applications, tailored to a
company’s, institution’s, or organization’s needs.
LANs
When many of us boot up our computer, we are automatically
connected to our company’s or organization’s LAN. Most LANs cover a
small geographical area, such as a building or campus, and include
individual PCs and workstations that are referred to as nodes. Each
node has its own CPU and can execute programs individually, while
also having the option of using programs and accessing data from
servers anywhere on the network.
LANs are capable of transmitting data at very fast rates, but the
distances are limited, and there is also a limit to the number of
computers that can be attached to a single LAN.
Internet
The Internet is a network of networks in which users at any one
computer can, if they have permission, send and receive information to
or from any other computer connected to the Internet.
The Internet is a public, cooperative, and self-sustaining facility
accessible to hundreds of millions of people worldwide. Physically, the
Internet uses a portion of the existing public telecommunications
networks.
Technically, the Internet uses a set of protocols called TCP/IP
(Transmission Control Protocol/Internet Protocol). Private sections of
the Internet, such as intranets and extranets, also use the TCP/IP
protocol.
Wireless Terminology
Wireless technology is based upon embedding RF components (lowcost,
low-power radios and microcontrollers) directly into a product.
Embedded RF uses high quality, low-cost, radio frequency integrated
circuit (RFIC) technology.
Network Topologies
A wireless network can have different topologies, or organizations,
depending on the ways in which messages need to flow from one node
to another. A topology is established, based on answers to fundamental
questions, such as:
Will a number of sensors report their controller data to an
aggregation point?
What happens if a message destination is out of range of the
message originator?
Wireless Repeater
As a Wireless Repeater, the device is used to provide redundant links
between Wireless Adapters connected to field bus controllers. When
used as a Wireless Repeater, the device is not connected to a controller,
and can be installed anywhere.
A repeater may be needed when there are long distances between
wireless-enabled controllers, to add additional network paths for
redundancy, or to compensate for obstacles, such as pipes or walls that
can attenuate or weaken the wireless signal between controllers.