Psiber Data Systems RF3D Fundamentals of Wireless Network Planning

manual

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Fundamentals of Wireless Network Planning

To plan an efﬁcient wireless network, it helps to understand a little radio communica-

tion theory. In this document we can only provide a brief summary with regard to wire-

less networks. For more detailed information, please consult the specialist literature.

In designing standards for wireless networks as they are used in the industry today, the

IEEE built on the Ethernet standard, IEEE 802.3. Like Ethernet, an IEEE WLAN functions

as a shared medium with a decentralized access control mechanism. Every station

competes for access with all other stations, and is responsible for regulating its own

use of the medium. In this situation, the CSMA/CD access protocol (Carrier Sense Mul-

tiple Access with Collision Detection) ensures that every station gets an opportunity

to transmit data over the medium. Because it uses the same media access technique,

802.11 WLAN is often called “wireless Ethernet”.

The IEEE 802.11 standard deﬁnes several different Ethernet-based wireless networks.

The most common of these are 802.11a, b, g and h. In general, two different radio

techniques are used in two different frequency bands. The 2.4 GHz ISM band is most

often used. This band is reserved worldwide for license-free industr ial, scientiﬁc and

medical applications. The frequency band used can vary from one country to an-

other, however. For example, eleven channels can be used in the 2.4 GHz band in the

United states, while up to 14 channels are available in other parts of the world. The

other frequency band used for wireless Ethernet is around 5 GHz. In addition to the fre-

quency bands, the IEEE standards also specify transmitter power, data rates, packet

structure, management packets, and much more.

The wireless Ethernet standard IEEE 802.11b, adopted in late 1999, is the ﬁrst such

standard to be widely supported for both industrial and home use. Networking com-

ponents that support this standard communicate in the 2.4 GHz band. The speciﬁed

data transfer rates are 1, 2, 5.5 and 11 Mbit/s.