CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [425]
Wireless networking is not limited to PCs. Most handheld computers, PDAs, and smartphones have wireless capabilities built-in or available as add-on options. Figure 24-4 shows a smartphone accessing the Internet over a Wi-Fi connection.
Figure 24-1 Infrared transceiver ports on a laptop and PDA
Figure 24-2 Wireless PCI add-on card
Figure 24-3 External USB wireless NIC
Figure 24-4 Smartphone with wireless capability
Essentials
To extend the capabilities of a wireless Ethernet network, such as connecting to a wired network or sharing a high-speed Internet connection, you need a wireless access point (WAP). A WAP centrally connects wireless network nodes in the same way that a hub connects wired Ethernet PCs. Many WAPs also act as switches and Internet routers, such as the Linksys device shown in Figure 24-5.
Figure 24-5 Linksys device that acts as wireless access point, switch, and router
Wireless communication via Bluetooth comes as a built-in option on newer PCs and peripheral devices, or you can add it to an older PC via an external USB Bluetooth adapter. Figure 24-6 shows a Bluetooth adapter with a Bluetooth-enabled mouse and keyboard.
Figure 24-6 External USB Bluetooth adapter, keyboard, and mouse
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EXAM TIP Wireless Access Points are commonly known as WAPs, APs, or simply wireless routers.
Wireless Networking Software
Wireless devices use the same networking protocols and client that their wired counterparts use, and they operate by using the carrier sense multiple access/collision avoidance (CSMA/CA) networking scheme. The collision avoidance aspect differs slightly from the collision detection standard used in wired Ethernet. Wireless nodes listen in on the wireless medium to see if another node is currently broadcasting data. If so, it waits a random amount of time before retrying. So far, this method is exactly the same as the method used by wired Ethernet networks. Because wireless nodes have a more difficult time detecting data collisions, however, they offer the option of using the Request to Send/Clear to Send (RTS/CTS) protocol. When enabled, a transmitting node that determines that the wireless medium is clear to use sends an RTS frame to the receiving node. The receiving node responds with a CTS frame, telling the sending node that it’s okay to transmit. Then, once the data is sent, the transmitting node waits for an acknowledgment (ACK) from the receiving node before sending the next data packet. Very elegant, but keep in mind that using RTS/CTS introduces significant overhead to the process and can impede performance.
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EXAM TIP Wireless networks use the carrier sense multiple access/collision avoidance (CSMA/CA) standard, while wired Ethernet networks use carrier sense multiple access/collision detection (CSMA/CD).
In terms of configuring wireless networking software, you need to do very little. Wireless network adapters are plug and play, so any modern version of Windows immediately recognizes one when installed, prompting you to load any needed hardware drivers. You will, however, need a utility to set parameters such as the network name.
Windows XP and later built-in tools for configuring these settings, but for previous versions of Windows, you need to rely on configuration tools provided by the wireless network adapter vendor. Figure 24-7 shows a typical wireless network adapter configuration utility. Using this utility, you can determine your link state and signal strength, configure your wireless networking mode (discussed next), and set security encryption, power saving options, and so on.
Wireless Network Modes
The simplest wireless network consists of two or more PCs communicating directly with each other without cabling or any other intermediary hardware. More complicated wireless networks use a WAP to centralize wireless