Wireless Technology
Wireless Basics and General Information:
Basic Wireless Principles
The following information is designed to provide you with a basic
overview of Wireless technology, including the components that make
up a Wireless system and the information you need to properly configure
a Wireless system. This information is largely focused on the 2.4GHz
Wireless offering, but also touches on 902MHz.
2.4Ghz is the default Wireless Offering. Approximately 90% of
new Wireless projects are using 2.4Ghz (Wireless Ethernet)
Principles of Wireless:
The basic principles of Wireless are the same regardless of the
manufacturer. Wireless terminals (hand-held, truck mount, stationary,
pen based) send out data through the radio. Some type of identification
accompanies the data so the host knows which terminal sent it. A
transceiver (902MHz) or access point (2.4GHz) receives that data.
The data is then sent to the host computer to perform the desired
task. The host application program performs the task and returns
the needed data to the originating Wireless terminal.
802.11 Standard
The IEEE 802.11 represents the first standard for WLAN products
from an internationally recognized, independent organization. With
this standard wireless communication can be interoperable between
manufacturers. This means an Intermec wireless device can communicate
to a Symbol access point and vise versa, or any other manufacturer
products that are 802.11 compliant.
802.11 refers to 1 and 2 MB offerings. 802.11b refers to 11-MB
offerings. This may also be referred as High Rate (HR).
802.11b will start at 11MB and will decrease to 5.5MB, 2MB, and
1MB if needed. Coverage range will decrease as MB increases. Special
considerations will need to be made to insure constant 11MB coverage.
You will need to insure a site survey is performed with specific
instructions that 11MB throughput is required.
An 802.11 1-2MB radio can connect to an 802.11b radio system but
the system will only operate at the slower 1-2 MB rate. An 802.11b
11MB HR radio can connect to an 802.11 1-2MB radio system but the
system will only operate at the slower 1-2 MB rate.
An 802.11 Direct Sequence device will not communicate with an 802.11
Frequency Hopping device and vise versa.
Types of Wireless Offerings:
2.4 GHz:
This offering operates in the frequency range of 2.4GHz and uses
industry standards of Ethernet and TCP\IP. This is sometimes referred
to as "Wireless Ethernet" or "Wireless LAN." The Access Point attaches
to the same Ethernet LAN as the host computer and serves two purposes:
- Sends and Receives Wireless data for the Wireless devices.
- Acts as a bridge between the wired Ethernet and the Wireless
Ethernet the Wireless devices are using.
Transport of data is accomplished in the same method as any other
device attached to an Ethernet LAN using TCP\IP addressing.
An Ethernet connection to the host will not require a Network Control
Unit (NCU). Since industry standards of Ethernet and TCP\IP are
used, connectivity is simple when you follow standard networking
principles. Having a connectivity other than Ethernet (ie: Token
Ring, Twinax, SDLC) will require a NCU. A variety of devices can
be included in a 2.4 GHz Wireless Ethernet system, including portable
data terminals, pen-based devices, printers, laptops, and desktop
PCs.
900 MHz:
This offering operates in the frequency range of 902-928 MHz. This
offering deals with proprietary protocols regardless of the manufacturer.
A Network Control Unit (NCU) is required as the interface between
the host system and the Wireless equipment. Generally, some type
of serial connection is initially made from the NCU and the first
transceiver. From the first transceiver to additional transceivers,
connections vary depending on the manufacturer.
Host System and Software
There are many different types of host computers in the industry.
The most commonly used in "Wireless Ethernet" systems are:
Unix
Host There are many different types of UNIX systems running various
versions of UNIX. It is important to determine whether the Unix
host has Ethernet TCP\IP support and can accept a telnet session.
This will usually be the case with Unix systems, but there are exceptions.
Most of the time the remote Wireless device will run a VT emulation
program, which allows the Wireless device to appear as a wired terminal
on the wired Ethernet LAN. Therefore, the remote Wireless device
can access existing programs on the Unix host. This is accomplished
through a telnet session from the Wireless device and the Unix host.
Sometimes the remote Wireless device will have a smaller display
area than the host program was written for. You will need to reduce
the software application screens to adapt to the smaller display
of the Wireless device. The most common method for accomplishing
this involves reformatting the host application to the screen size
of the Wireless device.
AS400
You can connect to an AS400 by loading 5250 emulation software in
the Wireless device. The AS400 must have Ethernet and TCP/IP support
along with TN5250 support. Most AS400 with version V3.51 or better
have this support, but it may need to be activated. The 5250 emulation
software makes the Wireless device appear as a wired terminal on
the wired Ethernet LAN. This is accomplished through a telnet session
from the Wireless device and the AS400. Note that the remote Wireless
device will probably have a smaller display area than the host program
was written for. The software application screens will need to be
reduced to adapt to the smaller display of the Wireless device.
The most common method of accomplishing this involves reformatting
the host application to the screen size of the Wireless device.
IBM Host
You can connect to an IBM host by loading 3270 emulation software
in the Wireless device. The IBM host must have Ethernet and TCP/IP
support along with TN3270 support. The 3270 emulation software makes
the Wireless device appear as a wired terminal on the wired Ethernet
LAN. This is accomplished through a telnet session from the Wireless
device and the IBM host. Note that the remote Wireless device will
probably have a smaller display area than the host program was written
for. The software application screens will need to be reduced to
adapt to the smaller display of the Wireless device. The most common
method of accomplishing this involves reformatting the host application
to the screen size of the Wireless device.
Windows Based PCs
As the popularity and power of the PC market grows, more Windows
95 and Windows NT PC's are being used as host computers. Connectivity
issues are the same as connecting to either a Unix or AS400 host,
but the software issues can be more challenging.
Client \ Server: In a client server software option, software will
need to be written or provided for both the host computer and Wireless
device. T&W Enterprises has the experienced programmer to develop
the desired applications.
Software Development Tools: Software tools are designed to allow
users with little or no programming experience to generate software
applications for their Wireless projects. Most generators are based
on a GUI interface, which will be familiar to Windows users. Most
generators are limited to the complexity of applications that can
be generated. This should not be a problem since most Wireless applications
are simple and are used to track product movements.
Telnet Servers: Unlike the Unix, AS400, and IBM host, there is
no PC emulation. There is a way that a Wireless device could simulate
a VT terminal to allow users to access existing applications on
the PC. Loading a "Telnet Server" on a Windows NT PC will allow
a Wireless device, running a VT Emulation Client, to Telnet into
the PC much like connecting to a Unix host. After satisfying the
Login and Password fields from the Telnet Server, you can execute
your software application. You'll need to purchase Telnet Servers
from a third party. This is valid only with Windows NT.
System and Antenna Diagrams
Plane Antenna
 The
Plane antenna mounts using Velcro. Coverage is best when mounted
horizontally on the topside of a flat surface rather than vertically
on a side surface. It is ideal for most PC or POS devices in areas
with good coverage.
Ceiling Mount Dipole Antenna
 The
Ceiling Mount Dipole antenna mounts with a screw or with a clamp
to frames for acoustical ceiling tiles. This antenna provides excellent
coverage in industrial or large retail environments. It is also
the ideal choice when using Symbol's universal wall mounting bracket.
Rubber Duck Dipole Antenna
 The
Rubber Duck Dipole antenna connects directly to the Spectrum24 device.
The antenna swivels for best positioning. This antenna is best used
for desktop devices, temporary setups or small retail environments.
This antenna is not recommended for VRC units, i.e. VRC3940, VRC4040.
Yagi Antenna
 The
Yagi antenna mounts with screws to a flat surface/wall or with a
U-bolt to a pole/mast. This is the highest gain antenna Symbol offers.
The antenna provides coverage to narrow areas or for outdoor point-to-point
links over long distances.
The Wireless Checklist will help you gather the information you
need - Square Footage of facility i.e. 60,000, Type of Host: AS400,
IBM, UNIX, PC, Host Connectivity: Ethernet, Token Ring, Twinax,
SDLC, and Serial Software Needs (This is applicable if TE (Terminal
Emulation) is not being used) to build your Wireless system using
T&W Enterprise's "Product Configurator." The "Product Configurator"
is an online configuration tool that builds valid systems - complete
with pricing - in minutes. You will need a log-in and password to
access "Product Configurator."
T&W Enterprises can custom design a wireless solution
tailored for your specific business needs.
or
Click here to be redirected to the Product
Configurator.
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