Hardware Reference
In-Depth Information
Mini PCI or PCIe Mini cards are installed inside laptop computers. (They can be removed or
replaced by opening the system.) Because Mini PCI and PCIe Mini cards are installed inside
laptops, they are not usually sold as retail components. However, some vendors sell them as
OEM components, or you can buy them from the laptop vendor's parts department.
Because you can mix and match Wi-Fi-certified products that use the same frequency band, you can
incorporate any mix of desktop and laptop computers into your wireless network.
Although most recent laptop computers include 802.11b/g/n wireless Ethernet or dual-mode
802.11a/b/g/n support through an integrated Mini PCI or PCIe Mini card, you can add support for
other 802.11 wireless networks by either upgrading the internal card or by attaching an additional
card via a CardBus slot, ExpressCard slot, or USB port.
When a Wi-Fi-enabled system receives multiple Wi-Fi signals, client systems lock onto the strongest
signal from access points and automatically roam (switch) to another access point when the signal
strength is stronger and the error level is lower than the current connection. Of course, if you want the
system to lock onto a specific signal, that can be done via the OS or manufacturer-provided software.
Most people use a wireless router as the basis of a wireless network. A wireless router normally
contains a router (which is connected to a cable/DSL modem), switch, and access point. When
looking for a wireless router, I recommend only those that include Gigabit Ethernet switches as well
as a Gigabit Ethernet WAN port for connecting the router to a cable/DSL modem.
Additional hardware you might need to add to your network includes the following:
•
Wireless bridges
—These devices enable you to connect a wired Ethernet device, including
noncomputer items such as video games or set-top boxes, to a wireless network. These are
sometimes called wireless gaming adapters.
•
Wireless repeaters/range extenders
—A repeater can stretch the range of an existing wireless
network. Some can also serve as access points or wireless bridges.
•
Specialized antennas
—The “rabbit ears” antennas used by most access points and routers are
adequate for short distances, but longer distances or problems with line-of-sight reception can
be solved by attaching high-gain replacements for the originals, or by attaching more
specialized directional antennas, possibly on extension cables to mount them higher for greater
range.
•
Signal boosters
—In addition to or as an alternative to replacement antennas, some vendors
also sell signal boosters that piggyback onto an existing access point or router. Note that, in
most cases, these signal boosters are vendor specific.
Wireless Network Logical Topologies
Wireless networks have different topologies, just as wired networks do. However, wireless networks
use only two logical topologies:
•
Star
—The star topology, used by Wi-Fi/IEEE 802.11-based products in the infrastructure
mode, resembles the topology used by 10BASE-T and faster versions of Ethernet that use a
switch (or hub). The access point takes the place of the switch because stations connect via the
access point, rather than directly with each other. This method is much more expensive per unit
but permits performance in excess of 10BASE-T Ethernet speeds and has the added bonus of
being easier to manage.
