Page 66 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks

Notes 2.4 GHz ISM band. Maximum transmission speed is 11Mbps and approximate wireless range is
100-200 feet indoors and 802/11g: operates in the 2.4 GHz ISM band. Maximum transmission
speed is 54Mbps and approximate wireless range is 100-200 feet indoors.
The ISM (Industrial, Scientific and Medical) band, which is controlled by the FCC in the US,
generally requires licensing for various spectrum use. To accommodate wireless LAN’s, the FCC
has set aside bandwidth for unlicensed use including the 2.4Ghz spectrum where many WLAN
products operate.
Wi-Fi stands for Wireless Fidelity and is used to define any of the IEEE 802.11 wireless standards.
The term Wi-Fi was created by the Wireless Ethernet Compatibility Alliance (WECA). Products
certified as Wi-Fi compliant are interoperable with each other even if they are made by different
manufacturers. Access points can support several or all of the three most popular IEEE WLAN
standards including 802.11a, 802.11b and 802.11g.

4.1 Types of Wireless Networks

There are three primary usage scenarios for wireless connectivity :
1. Wireless Personal Area Networking (WPAN)
2. Wireless Local Area Networking (WLAN)

3. Wireless Wide Area Networking (WWAN)
4.1.1 WPAN (Wireless Personal Area Network)

WPAN describes an application of wireless technology that is intended to address usage scenarios
that are inherently personal in nature. The emphasis is on instant connectivity between devices
that manage personal data or which facilitate data sharing between small groups of individuals.
An example might be synchronizing data between a PDA and a desktop computer. Or another
example might be spontaneous sharing of a document between two or more individuals. The
nature of these types of data sharing scenarios is that they are ad hoc and often spontaneous.
Wireless communication adds value for these types of usage models by reducing complexity (i.e.
eliminates the need for cables).
A wireless personal area network (WPAN) is a personal area network — a network for
interconnecting devices centered around an individual person’s workspace — in which the
connections are wireless. Wireless PAN is based on the standard IEEE 802.15. The two kinds of
wireless technologies used for WPAN are Bluetooth and Infrared Data Association.

A WPAN could serve to interconnect all the ordinary computing and communicating devices that
many people have on their desk or carry with them today; or it could serve a more specialized
purpose such as allowing the surgeon and other team members to communicate during an
operation.
A key concept in WPAN technology is known as “plugging in”. In the ideal scenario, when any
two WPAN-equipped devices come into close proximity (within several meters of each other)
or within a few kilometers of a central server, they can communicate as if connected by a cable.
Another important feature is the ability of each device to lock out other devices selectively,
preventing needless interference or unauthorized access to information.
The technology for WPANs is in its infancy and is undergoing rapid development. Proposed
operating frequencies are around 2.4 GHz in digital modes. The objective is to facilitate seamless
operation among home or business devices and systems. Every device in a WPAN will be able
to plug into any other device in the same WPAN, provided they are within physical range of one
another. In addition, WPANs worldwide will be interconnected.

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