Hardware Reference
In-Depth Information
• Wireless network cards
An
access point
is a bookend-size device that uses one or more 8P8C (RJ-45) ports to attach to a
10BASE-T or 10/100/1000 Ethernet network (if desired) and contains a radio transceiver,
encryption, and communications software. It translates conventional Ethernet signals into wireless
Ethernet signals that it broadcasts to wireless NICs on the network and then performs the same role in
reverse to transfer signals from wireless NICs to the conventional Ethernet network.
Most people wouldn't buy an access point as a separate stand-alone item; instead, they would
purchase a router that has an access point built in. Wireless routers normally include a router, switch,
and wireless access point but may also include a cable/DSL modem, file/print server, and other
features.
Note
In SOHO networks that provide Internet access, the access point is usually incorporated into a
wireless router that also includes an Ethernet switch.
For coverage of a large area, you can use two or more access points and connect them to an Ethernet
switch. This enables users to roam inside a building without losing contact with the network. Some
access points can communicate directly with each other via radio waves, enabling you to create a
wireless backbone that can cover a wide area (such as a warehouse) without the need to run network
cabling. You can also purchase a wireless Ethernet range extender that can receive and boost weak
Wi-Fi signals. Some access points are designed to be used as either access points or range extenders.
Some range extenders are designed only to work with the same brand of access point or router.
Access points are not necessary for direct peer-to-peer networking (also called
ad hoc mode
), but
they are required for a shared Internet connection or a connection with another network. When access
points are used, the network is operating in
infrastructure mode
.
Note
Wireless clients running in ad hoc mode cannot connect to the Internet unless one of the stations
on the network is connected to a bridge or uses another network adapter as a bridge.
NICs equipped for wireless Ethernet communications have a fixed or detachable radio antenna.
Wireless NICs come in four forms:
• CardBus (32-bit PC Card) or ExpressCard (PCIe) cards for use in laptop computers that do not
include “integrated” wireless support
• Mini PCI or PCIe Mini cards that provide wireless and wired Ethernet and dial-up modem
support for laptop computers
• PCI or PCIe cards for use in desktop computers with PCI or PCIe slots
• USB adapters for use in both desktop and laptop computers
Most laptop computers with Wi-Fi hardware onboard use the Mini PCI or PCIe Mini interface for the
wireless adapter and place the antenna inside the display housing.
Note
