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About Wireless LAN Technology
A wireless network connects computers without using network cables.
Computers use radio communications to send data between each other.
You can communicate directly with other wireless computers, or connect
to an existing network through a wireless access point. When you set up
your wireless adapter, you select the operating mode for the kind of wireless
network you want. You can use your Intel(R) PRO/Wireless adapter to connect to other similar
wireless devices that comply with the 802.11 standard for wireless networking.
Choosing a Wireless LAN Mode
Wireless LANs can operate with or without access points, depending on the number of users in the
network. Infrastructure mode uses access points to allow wireless computers to send and receive information.
Wireless computers transmit to the access point, the access point receives the information and rebroadcasts
it to other computers. The access point can also connect to a wired network or to the Internet.
Multiple access points can work together to provide coverage over a wide area.
Peer-to-Peer mode, also called Ad Hoc mode, works without access points and allows wireless computers to send
information directly to other wireless computers. You can use Peer-to-Peer mode to
network computers in a home or small office or to set up a temporary wireless network for a meeting.
Configuring a Wireless LAN
There are three basic components that must be configured for a wireless LAN to operate properly:
- Network Name—Each wireless network uses a unique Network Name to identify the network.
This name is called the Service Set Identifier (SSID). When you set up
your wireless adapter, you specify the SSID. If you want to connect to an existing network, you must
use the name for that network. If you are setting up your own network you can make up your own name
and use it on each computer. The name can be up to 32 characters long and contain letters and numbers.
- Profiles—When you set up your computer to access a wireless network, Intel(R)
PROSet creates a profile for the wireless settings that you specify. If
you want to connect to another network, you can scan for existing networks
and make a temporary connection, or create a new profile for that network.
After you create profiles, your computer will automatically connect
when you change locations.
- Security—The 802.11 wireless networks use encryption to help protect your data.
Wired equivalent privacy (WEP) uses a 64-bit or 128-bit shared encryption key to scramble
data. Before a computer transmits data, it scrambles the data using the
secret encryption key. The receiving computer uses this same key to unscramble
the data. If you are connecting to an existing network, use the encryption key
provided by the administrator of the wireless network. If you are setting up your own
network you can make up your own key and use it on each computer.
Identifying a Wireless Network
Depending on the size and components of a wireless LAN, there are many ways to identify a wireless LAN:
- The Network Name or Service Set Identifier (SSID)—Identifies a wireless network.
All wireless devices on the network must use the same SSID.
- Extended Service Set Identifier (ESSID)—A special case of SSID used to identify
a wireless network that includes access points.
- Independent Basic Service Set Identifier (IBSSID)—A special case of SSID
used to identify a network of wireless computers configured to communicate directly with one another
without using an access point.
- Basic Service Set Identifier (BSSID)—A unique identifier for each wireless device.
The BSSID is the Ethernet MAC address of the device.
- Broadcast SSID—An access point can respond to computers sending probe packets with
the broadcast SSID. If this feature is enabled on the access point, any wireless user can
associate with the access point by using a blank (null) SSID.
Surveying the Site of Your Wireless LAN
Conducting a site survey for your wireless LAN is
the most crucial step in the process of setting up a wireless network. It greatly
reduces the amount of troubleshooting you will have to do once you have the
wireless LAN set up and ready for connection testing. To conduct a site survey,
you will need the following tools:
- An access point (or laptop computer) that is set up to be the
transmitter. It should be mounted near and at the same height as
the designated location of your wireless LAN.
- A laptop that will act as the mobile receiver. It must contain
your site survey software.
- An area or building map, which will be used to plot the strength
of your signals.
Once you have the tools you need, you are ready to survey the
inside of the building. Launch the site survey software on the mobile
receiver laptop and carry it around in the intended wireless LAN area
to test the signal strength. Be sure to also check the signal strength
of each intended access point location. If you encounter problems
while surveying the site, make sure your transmitter laptop is not
located on a wall containing metal, such as an air-conditioning duct,
which will interfere with the range of your signal. Simply move the
transmitter and test the signal strength again. For users to have
seamless coverage when moving from access point to access point, the
signal levels at each point must overlap. There is software available
that will seamlessly hand off changing signal levels from one access
point to another.
Y
our building's infrastructure can sometimes interfere with the
microwave signal, but finding the location and cause of the
interference will allow you to figure out the best place to mount your
access points for optimal area coverage. Microwave signals travel in
all directions, which means there is one access point for a
multi-floor building. However, the range is highly dependent on the
material used to construct the flooring, especially metal materials.
Once your signal strength is strong inside the building, you are ready
to check the strength outside the building. To do so, simply carry the
mobile receiver laptop as far down the street or around the building
as you can go without losing significant signal strength.
If possible, you should be aware of the types of networks being
used by the companies on the floors above and below you, so that you
can work together in harmony. With wireless networks, security is very
important and if you communicate with those around you, you are better
prepared to select the right channels, as well as the best location
for access points.
Factors Affecting Range
Although access points can transmit signals up to 60 feet away in an area with many walled barriers
or as much as 500 feet away in a large open area, the range is affected
by the following factors:
- Building materials, such as steel and drywall, can shorten the range of the radio signals.
- Physical layout of the area can interfere with the signals and cause them to be dropped.
- Electronic noise from cell phones, microwave ovens, or other devices on the same frequency
can interfere with the transmission of the signals.
- Range is inversely proportional to data rate, so the faster that the signals are sent, the
less distance they will travel.
Taking these factors into consideration when you survey the site for your WLAN
is key to providing all of your users with undisturbed mobile connectivity. Using multiple access points
will, of course, reduce the impact of these factors if your area has dividing walls throughout.
Stronger Security
Although wireless networks are easy to use, the main issue lies with
security. Even if you enable the security settings defined in the 802.11b
standard, as well as the security settings of your hardware, your network is still vulnerable.
There are a few things you can do to make it more difficult for outsiders to access your network:
- Change the default network name of your WLAN. Every manufacturer's default
settings are public knowledge.
- Do not allow the name of your network to be broadcasted by your access
points. This makes it more difficult for hackers to identify your network.
- Enable Wired Equivalent Privacy (WEP) encryption, which is the same
security feature used by online shopping websites.
- Change your encryption keys as often as possible. Temporal Key Integrity
Protocol (TKIP), which is being developed by a IEEE task group, will change
the keys automatically.
- Enable MAC address filtering so that each access point can generate a list
of approved MAC addresses for your WLAN.
- If you have a small network, use virtual private network encryption for
additional security. If you have a large network, you may want to install a
gateway between your access points and network clients.
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Copyright (c) 2003 Intel Corporation.