Page 160 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks Manmohan Sharma, Lovely Professional University

Notes Unit 10: Wireless MAN Technologies

CONTENTS

Objectives
Introduction
10.1 IEEE 802.11 and Wi-Fi
10.1.1 Wi-Fi Standards
10.1.2 Adaptive Modulation
10.2 IEEE 802.16: Broadband Wireless MAN Standard (WiMAX)

10.2.1 WiMAX and the IEEE 802.16a PHY Layer
10.2.2 IEEE 802.16a MAC Layer
10.6 Summary
10.7 Keywords

10.8 Review Questions
10.9 Further Readings

Objectives

After studying this unit, you will be able to:
z z Understand IEEE 802.11 and Wi-Fi
z z Define IEEE 802.16 and its purpose

Introduction

IEEE 802.11 is a set of physical layer standards for implementing wireless local area
network (WLAN) computer communication in the 2.4, 3.6, 5 and 60 GHz frequency bands.
They are created and maintained by the IEEE LAN/MANStandards Committee (IEEE 802). The
base version of the standard was released in 1997 and has had subsequent amendments. These
standards provide the basis for wireless network products using the Wi-Fi brand

10.1 IEEE 802.11 and Wi-Fi

The 802.11 family consist of a series of half-duplex over-the-air modulation techniques that
use the same basic protocol. The most popular are those defined by the 802.11b and 802.11g
protocols, which are amendments to the original standard. 802.11-1997 was the first wireless
networking standard, but 802.11a was the first widely accepted one, followed by 802.11b and
802.11g. 802.11n is a new multi-streaming modulation technique. Other standards in the family
(c–f, h, j) are service amendments and extensions or corrections to the previous specifications.
802.11b and 802.11g use the 2.4 GHz ISM band, operating in the United States under Part 15 of
the US Federal Communications Commission Rules and Regulations. Because of this choice of
frequency band, 802.11b and g equipment may occasionally suffer interference from microwave
ovens, cordless telephones and Bluetooth devices. 802.11b and 802.11g control their interference
and susceptibility to interference by using direct-sequence spread spectrum (DSSS) andorthogonal
frequency-division multiplexing (OFDM) signaling methods, respectively. 802.11a uses the 5
GHz U-NII band, which, for much of the world, offers at least 23 non-overlapping channels

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