IT-3303-3 Broadband Networks

Punjab University College of Information Technology,University of the Punjab.

Wireless MAN (IEEE 802.16) cont.

Lecture - Objectives

• WiMAX (IEEE 802.16)• IEEE 802.16 Standards• Wi-Fi vs. WiMAX

• WiMAX (Worldwide Interoperability for Microwave Access) is a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL.

• The technology is specified by the Institute of Electrical and Electronics Engineers Inc., as the IEEE 802.16 standard.

WiMAX

WiMAX Standards

• The 802.16a standard is a wireless metropolitan area network (MAN) technology that will provide a wireless alternative to cable, DSL and T1/E1 for last mile broadband access. It will also be used as complimentary technology to connect 802.11 hot spots to the Internet.

• IEEE Std 802.16-2004, approved 2004, addresses only fixed systems. An amendment 802.16e is in the works which adds mobility components to the standard.

WiMAX Standards

• IEEE 802.16-2005, approved December, 2005 (named as 802.16e or Mobile WiMAX). The WiMAX mobility standard is an improvement on the modulation schemes stipulated in the original (fixed) WiMAX standard. It allows for fixed wireless and mobile Non Line of Sight (NLOS) applications primarily by enhancing the OFDMA (Orthogonal Frequency Division Multiple Access).

WiMAX Standards  802.16/c 802.16a/REVd/2004 802.16e

Spectrum 11-66 GHz 2-11 GHz 2-6 GHz

Channel Conditions

LOS LOS, NLOS NLOS

Bit Rate 32-124 Mbps 1-70 Mbps Up to 50 Mbps

Modulation QPSK, 16QAM and 64QAM

OFDM 256 sub-carriers, QPSK, 16QAM and 64QAM

SOFDMA

Mobility Fixed Fixed, Portable Mobile (upto 120Km/h)

Channel Bandwidths

20, 25 and 28 MHz

Selectable channel bandwidths between 1.5 and 20 MHz

Selectable channel bandwidths between 1.25 and 20 MHz

Typical Cell Radius

1-3 miles 3-5 miles Maximum range 30 miles based on the tower height

1-3 miles

Wi-Fi Standards Standard Throughput Range Frequency

802.11a Up to 54 Mbps Up to 300 ft Between 5 and 6 Ghz

802.11b Up to 11 Mbps Up to 300 ft 2.4 Ghz

802.11g Up to 54 Mbps Up to 300 ft 2.4 Ghz

Wi-Fi Vs WiMax

802.11 802.16a/eScalability Wide (20MHz) frequency

channelsMAC designed to support 10’s of users

Channel bandwidths can be chosen by operator 1.5 MHz to 20 MHz width channels.•MAC designed to support thousands of users.

Channel Bandwidth

20 MHz 1.5 – 20 MHz

Maximum Data Rate

54 Mbps 100 Mbps

Maximum bps/Hz

2.7 bps/Hz 5.0 bps/Hz

Wi-Fi Vs WiMax

802.11 802.16aRange Optimized for ~100

metersNo “near-far” compensation

Optimized for up to 50 KmDesigned to handle many users spread out over kilometers

Coverage Optimized for indoor performance

Optimized for outdoor NLOS performance

Security 802.11i standard is in progress that will provide security

Standard by default support security

Quality of Service

Contention-based MAC (CSMA/CA) => no guaranteed QoS

Grant-request MAC Designed to support Voice and Video from ground up

P2MP Architecture

Reference Material

• Wireless Communications and Networks (Ch 11)

by William Stallings

• WiMAX Forum