Hardware Reference
In-Depth Information
Table 17.3
compares the standard and optional speeds supported by the different wireless standards
discussed in this chapter.
Table 17.3. Wireless Network Speeds
Note
For more information about 802.11ac and how it differs from 802.11n, see the Cisco document
“802.11ac: The Fifth Generation of Wi-Fi Technical White Paper” at
713103.html
.
Bluetooth
Bluetooth is a low-speed, low-power standard originally designed to interconnect laptop computers,
PDAs, cell phones, and pagers for data synchronization and user authentication in public areas such
as airports, hotels, rental car pickups, and sporting events. Bluetooth is also used for a variety of
wireless devices on PCs, including printer adapters, keyboards, mice, headphones, DV camcorders,
data projectors, and many others. A list of Bluetooth products and announcements is available at the
official Bluetooth wireless information website:
www.bluetooth.com
.
Bluetooth devices also use the same 2.4GHz frequency range that most Wi-Fi devices use. However,
in an attempt to avoid interference with Wi-Fi, Bluetooth uses a signaling method called
frequency
hopping spread spectrum (FHSS)
, which switches the exact frequency used during a Bluetooth
session 1,600 times per second over the 79 channels Bluetooth uses. Unlike Wi-Fi, which is designed
to allow a device to be part of a network at all times, Bluetooth is designed for ad hoc temporary
networks (known as
piconets
) in which two devices connect only long enough to transfer data and
then break the connection. The basic data rate supported by Bluetooth is currently 1Mbps (up from
700Kbps in earlier versions), but devices that support enhanced data rate (EDR) can reach a transfer
rate up to 2.1Mbps.
The current version of Bluetooth is 4.0; however, versions 2.1 and later support easier connections
between devices such as phones and headsets (a process known as
pairing
), longer battery life, and
improved security compared to older versions. Version 3.0 adds a high-speed mode based on Wi-Fi,
