Hello Every One

Page 1 of 14

Hello Every One

By | March 2013
Page 1 of 14
INDEX
· Introduction
· Why WiMAX
· Applications
· WiMAX Spectrum Allocation and Standardization
· PHY Layer Details
· Randomizer
· Forward Error Correction
· Interleaver
· Constellation Mapping
· Frequency Processing
· Time Processing
· Pulse Shaping Filter
· Diversity in WiMAX
· Challenges facing WiMAX

Introduction

WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum. The WiMAX Forum has more than 522 members comprising the major communication players, component and equipment companies in the communications field including Accenture, Agilent, Acer, Intel, Fujitsu, Motorola, Samsung, Sprint and AT&T. The WiMAX forum was formed in April 2001 to promote conformance and interoperability of the IEEE 802.16 standard, officially known as Wireless MAN. The Forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL".

It should be noted that, WiMAX is not a technology that is used but is more specifically a Certification or an Approval stamp given to devices that are in conformity with certain standards of the IEEE 802.16 family of standards. WiMAX supports data rate of up to 75 Mbps and provides a range of about 50 kms for LOS propagation.

Why WiMAX?
Wi-Fi devices operate in the unlicensed ISM band (Industrial Scientific and Medical Band) centered at 2.4GHz. This frequency band is also used by other devices. Hence the Wi-Fi devices are allocated a maximum power limit by FCC which limits their range or coverage. WiMAX was designed keeping in mind a WMAN. It is allocated a licensed frequency band and hence interference from other devices is relatively less. Correspondingly the range for WiMAX is more.

Further, in Wi-Fi, the media access controller ("MAC") uses CSMACA (Carrier Sense Multiple Access Collision Avoidance)...