Worldwide Interoperability for Microwave Access

WiMAX(IEEE 802.16)

by

E. Kishore Kumar

Out line

• 1.History

• 2.Specification

• 3.Architectur

• 4.Physical layer

• 5.MAC layer

• 6.Opetation Network

• 7.Application

• 8.Advntage &Disadvantage

• 9.Conclusion

Why we need broadband wireless access?

• Fill the gap and high data rate wireless LAN and mobile cellular networks.

• Provide high-speed mobile data and telecommunications services

Wireless networks

• Wireless PANs (Bluetooth – IEEE 802.15)– very low range– wireless connection to printers etc

• Wireless LANs (WiFi – IEEE 802.11)– infrastructure range– home/office networking

• Wireless MANs (WiMAX-802.16)– Similar to cellular networks– traditional base station

infrastructure systems

Standards• IEEE 802.16 (2001)

– Air Interface for Fixed Broadband Wireless Access System MAC and PHY Specifications for 10 – 66 GHZ (LoS)

– One PHY: Single Carrier– Connection-oriented, QoS, Privacy

• IEEE 802.16a (January 2003)– Amendment to 802.16, MAC Modifications and Additional PHY Specifications for 2 –

11 GHz (NLoS)– Three PHYs: OFDM, OFDMA, Single Carrier– Additional MAC functions: OFDM and OFDMA PHY support, Mesh topology support,

ARQ

• IEEE 802.16d (July 2004)– Combines both IEEE 802.16 and 802.16a– Some modifications to the MAC and PHY

• IEEE 802.16e (2005)– Amendment to 802.16-2004 – MAC Modifications for limited mobility

Introduction

Coverage range up to 50km and speeds up to 70Mbps(shared among users).

Specification

802.16 802.16a 802.16-2004 802.16e-2005

Date Completed

December 2001 January 2003 June 2004 December 2005

Spectrum 10-66 GHz < 11 GHz < 11 GHz < 6 GHz

Operation LOS Non-LOS Non-LOS Non-LOS and Mobile

Bit Rate 32-134 Mbps Up to 75 Mbps

Up to 75 Mbps

Up to 15 Mbps

Cell Radius 1-3 miles 3-5 miles 3-5 miles 1-3 miles

Architecture

Physical Layer

• Five physical layer modes

802.16d

802.16e

Designation Applicability

WirelessMAN-SC 10 -66 GHz

WirelessMAN-SCa Below 11GHzLicensed bands

WirelessMAN-OFDM Below 11GHzLicensed bands

WirelessMAN-OFDMA Below 11GHzLicensed bands

WirelessHUMAN Below 11GHzLicensed-exempt bands

Orthogonal Frequency Division Multiplexing (OFDM)

• Multiplexing technique that divides the channel into multiple orthogonal sub channels

• Input data stream is divided into several sub streams of a lower data rate and each sub stream is modulated and simultaneously transmitted on a separate sub channel

• High spectral efficiency, resilient to interference, and low multi-path distortion

Conventional FDM and OFDM

Orthogonal Frequency Division Multiple Access (OFDMA)

• Multiple-access/multiplexing scheme– multiplexing operation of data streams from multiple users– Dynamically assign a subset of sub channels to individual

users• Wireless MAN-OFDMA based on scalable OFDMA

(SOFDMA) – Support scalable channel bandwidths from 1.25 to 20 MHz

MAC Layer

Service Specific Convergence Sublayer

MAC Common Part Sublayer

Privacy Sublayer

Interface to higher layer protocols, classifies incoming data, etc.

Core MAC functions (i.e., scheduling, connection maintenance, fragmentation), QoS control

Encryption, authentication, secure key exchange

Network Operation

Applications

• According to WiMax Forum it supports 4 classes of applications:

1. Multi-player Interactive Gaming.

2. Video Conference.

3. Web Browsing and Instant Messaging.

4. Media Content Downloads.

Advantage

• Low cast.• It can support: NLOS(non line of set)&LOS. Mesh Network. Point to Multipoint. Handoff Technique.• Coverage:50Km.• Max Data Rate:70Mpbs.

Disadvantage

• Interference issues.

• It is not work proper in weather.

Features

• Use wireless link with microwave or millimeter wave radios.

• Use licensed spectrum

• Use point-to-multipoint architecture, tower-mounted antennas

• Provide broadband and QoS, data transmissions.

Conclusions

• WiMax becomes the dominant Wireless MAN in the world market.

• The end-users will have to be extremely easy to install.

• Focus is too often on technologies – Subscribers pay for services, not

technologies – Broadband capabilities are important, but

bandwidth is not the only meter to assess service

Querries?

Thank u.

References

• IEEE802.16

• Alcatel White Paper: WiMAX, making ubiquitous high-speed data services a reality

• Intel White Paper: Understanding WiMAX and 3G for Portable/Mobile Broadband Wireless

• WiMAX Forum: www.wimaxforum.com

• http://en.wikipedia.org/wiki/WiMax