WiMAX Fixed Vs. Mobile

Mustafa Saad Mustafa

Networks Eng. Dept.

College of Information Engineering

Al-Nahrain University

Agenda

IntroductionOverview Of the IEEE 802.16 Standard &

Mainly (IEEE 802.16-2001)Fixed WiMAXMobile WiMAXFixed Vs. Mobile

Introduction• Stands for “Worldwide Interoperability for

Microwave Access”.• Based on IEEE 802.16 standard.• 802.16 is the IEEE standard for Wireless

Metropolitan Area Network (Wireless MAN).• Specifies the air interface for fixed, portable, and

mobile broadband wireless access (BWA) systems supporting multimedia services.

• Aims to provide wireless broadband services with a target range of up to 31 miles at a transmission rate exceeding 100 Mbps.

Introduction

• It is also to provide a wireless alternative to cable, DSL and T1/E1 for last mile access.

• The term IEEE 802.16 and WIMAX are used interchangeably.

• WiMAX is to IEEE 802.16 where Wi-Fi is to IEEE 802.11

Agenda

IntroductionOverview Of the IEEE 802.16 Standard &

Mainly (IEEE 802.16-2001)Fixed WiMAXMobile WiMAXFixed Vs. Mobile

Overview Of the IEEE 802.16 Standard

• Designed for point-to-point (PTP) and point-to-multipoint (PTM) topologies but mainly deployed for point to multipoint topologies.

• It also support mesh topologies. • IEEE 802.16 has three major versions:

IEEE 802.16-2001.IEEE 802.16d-2004(Fixed).IEEE 802.16e-2005(Mobile).

IEEE 802.16-2001

• Addresses fixed line of sight (LOS) connections and operates in the licensed frequency range between 10 GHz and 66 GHz.

• At these high frequency range (reduced risk of interference)

• Has a maximum coverage of 5km.

IEEE 802.16-2001

• Physical layer• Designed for line-of-sight propagation because the

frequency range is between 10-66 GHz.• Single-carrier modulation is used and the air

interface is called “WirelessMAN-SC”.

IEEE 802.16-2001

• MAC• Supports both Time Division Duplex (TDD) and

Frequency Division Duplex (FDD).• It uses a slotted TDMA protocol scheduled by the base

terminal station to allocate capacity to subscribers.• It also supports different transport technologies such

as IPv4, IPv6, Ethernet, Asynchronous Transfer Mode (ATM).

• Provides mechanisms for authentication, key-sharing and encryption.

Agenda

IntroductionOverview Of the IEEE 802.16 Standard &

Mainly (IEEE 802.16-2001)Fixed WiMAXMobile WiMAXFixed Vs. Mobile

IEEE 802.16d “Fixed”

• Designed to operate in lower frequency range; 2-11 GHz.

• Support Non-line of sight (NLOS) operation.• Operates in both licensed (3.5 GHz) and unlicensed

(5.8 GHz).• Operates with a range of up to 50km and data rates of

up to 75Mbps.

IEEE 802.16d “Fixed”

• PHY• Design for the 2-11 GHz range and is more complex

because of interference. • Three air interfaces are specified for this range, which are;

I. Wireless MAN-SC uses single carrier modulation .II. Wireless MAN-OFDM uses a 256-carrier FDM.

Provides multiple access to different stations through TDMA.

III. Wireless MAN-OFDMA uses a 2,048-carrier OFDM scheme.

Agenda

IntroductionOverview Of the IEEE 802.16 Standard &

Mainly (IEEE 802.16-2001)Fixed WiMAXMobile WiMAXFixed Vs. Mobile

IEEE 802.16e “Mobile”

• Support mobility and will standardize networking between fixed base stations and mobile devices.

• Would enable high-speed signal handoffs necessary for communications with users moving at vehicular speeds which is below 100km/h.

• It will provide 70Mbps.• Operates in the frequency range between 2-6 GHz.

IEEE 802.16e “Mobile”

• PHY• The main technologies used for it’s physical layer

are OFDMA and an improved version called Scalable OFDMA (SOFDMA).

• SOFDMA scales the number of sub-carriers in a channel with possible values of 128, 512, 1024, and 2,048.

IEEE 802.16e “Mobile”

• MAC• It is connection oriented and supports quality of

service (QoS) for stations through adaptive allocation of the uplink and downlink traffic.

Agenda

IntroductionOverview Of the IEEE 802.16 Standard &

Mainly (IEEE 802.16-2001)Fixed WiMAXMobile WiMAXFixed Vs. Mobile

Fixed Vs. Mobile

I. Mobility Management and Hand Offs• The simplest difference between the fixed and

mobile is the fact that the mobile enables a hand-off from one base station to another as the user, in one session, moves from the coverage zone of one base station to another. This is also known as “mobility management”.

Fixed Vs. Mobile

II. OFDM vs. SOFDMA• Orthogonal Frequency Division Multiplexing

(OFDM) breaks the wireless carrier into 256 sub-carriers .

• The two greatest advantages are:

(a) it mitigates inter symbol interference (multipath)

(b) improves propagation of the signal, especially in non-line of sight (NLOS) coverage zones.

Fixed Vs. Mobile

II. OFDM vs. SOFDMA• OFDMA breaks the carrier into even more sub

carriers (up to 2048 sub carriers). • The “mobile” WiMAX uses SOFDMA. • The advantage of this is better propagation and

improved building penetration .• The use of OFDMA should also enable the use of

smaller, less costly subscriber devices including PC cards and USB devices.

Fixed Vs. Mobile

III. QoS• 802.16e introduces Extended Real-Time Polling

Service (ERTPS). ERTPS allows the 802.16e solution to manage traffic rates and transmission policies as well as improving latency and jitter. (VoIP) applications.

Future Works & Problems

• P802.16m (In progress) :Advanced Air Interface with data rates of 100 Mbit/s mobile & 1 Gbit/s fixed.

• With “MIMO” (Downlink 128 Mbps/20 Mhz & Uplink 56 Mbps 20 Mhz)

• Problems:Wimax Availability Problem (DoS)Authentication Problem In WiMAX

(man-in-the-middle attack)Policies (government), infrastructure(poor) and low income

Mainly Security Problem

Also known as Mobile WiMAX Release 2 or

WirelessMAN-Advanced

References• [1]. K. Fazel and S. Kaiser, M. Ergen, “Wikipedia ” ,30.04.2011, URL:

http://en.wikipedia.org/wiki/WiMAX.

• [2]. Sridhar Iyer, “WiMAX: IEEE 802.16 Wireless MANs” , K R School of Information Technology, URL: http://www.it.iitb.ac.in/~sri.

• [3]. AFTAB AHMAD, “WIRELESS AND MOBILE DATA NETWORKS”, Wiley & Sons, Inc., 1st Edition, 2005.

• [4]. Aruleba, Olakunle Michael, “WiMAX (IEEE 802.16)”, B.Sc. Project, University of Windsor, 2007.

• [5]. Frank Ohrtman, “Fixed vs. Mobile WiMAX Mobility Monomania?” , President, WMX Systems, LLC ,URL:http://www.MindCommerce.com, July 2007.

• [6]. White Paper, “WiMAX: E vs. D The Advantages of 802.16e over 802.16d”, URL: http:www.motorola.com/wi4, Motorola, Inc. 2007.

Thank You For Listening

Questions