WI-MAX

GROUP MEMBERS

SHAHEER SHAHBAZ HYDERAIBAD AHMED ALI HABIB USAMA AHFAZ

CONTENTS

INTRODUCTION WIMAX ARCHITECTURE QOS CLASSES MULTIPLEXING TECHNIQUES MODULATION SCHEMES WIMAX RADIOS APPLICATIONS

INTRODUCTION

BACKGROUND PROJECT DEVELOPMENT ON WIMAX WAS

START IN 1998.

WHY WIMAX????? Wi-Fi signals can not cover more than a

hundred meters. Both LOS and NLOS support. Higher data rate than former technologies. Fewer base stations.

CONT….

WIMAX refers to interoperable implementations of the IEEE 802.16 family of wireless-networks standards ratified by the WiMAX Forum.

There were some earlier version of Wimax that were used for testing purposes:

802.16a ,802.16b ,802.16c .

The current versions are 802.16d(FIXED) and 802.16e(MOBILE).

CURRENT DEPLOYMENT IN PAKISTAN:

Pakistan is the first country with world’s largest nationwide installed WiMAX network

Providers: Wi-Tribe, Wateen (3.5GHz), Mobilink Infinity, Qubee.

WiMAX could potentially be deployed in a variety of spectrum bands: 2.3GHz, 2.5GHz, 3.5GHz, and 5.8GHz

Operates in both licensed and un-licensed bands

WIMAX NETWORK CHARACTERISTICS

There are two scenarios for a wireless deployment: point-to-point and point-to multipoint.

Point to Point (P2P): Point to point is used where there are two points of interest: one sender and onereceiver.

As the architecture calls for a highly focused beam between two points range and throughput of point-to pointradios will be higher than that of point-to-multipoint products.

CONT...

Point-to-Multipoint (PMP):

One base station can serve hundreds of dissimilar subscribers in terms of bandwidth and services offered.

LINE OF SIGHT (LOS) OR NON-LINE OF SIGHT (NLOS):

WiMAX functions best in line of sight situations. Buildings between the base station and the subscriber diminish the range and throughput, but in an urban environment, the signal will still be strong enough to deliver adequate service.

WiMAX ability to deliver services non-line-of-sight, the WiMAX service provider can reach many customers in high-rise office buildings to achieve a low cost per subscriber because so many subscribers can be reached from one base station.

WIMAX ARCHITECTURE END-TO-END REFERENCE MODEL

NSP

NAP

R1 R3

MSS

R2

ASN CSN

ASP Netw ork ORInternet

R4

Another ASN

DECOMPOSED ASN INTO BS AND ASN GW ENTITIES

CPE OR MS

CPE and MS are end-user products which integrates with user devices

Like laptops, mobile phones. it also includes USB modem, PCMCIA cards

Can be fixed or mobile

BASE STATION

It provides connectivity to the consumer equipments

Base station consist of wireless electronic tower

Coverage area theoretically up to 50km but practically 10 km

Additional functions are: handoff triggering, QoS policy enforcement, DHCP etc

BS can be point-to point or point-to-multipoint BS are LOS as well as NLOS

ENTITIES OF THE WIMAX NETWORK

ASN: Access Serving Network

Logical representation of the functions of a NAP, e.g. 802.16 interface network entry and handover Radio Resource Management & Admission ctrl. L2 Session/mobility management QoS and Policy Enforcement Foreign Agent (FA) Forwarding to selected CSN

ASN-GW

Access service network-Gate Way acts as a layer 2 traffic aggregation points within an ASN.

management, network optimization, and forwarding of all subscriber traffic, routing to the selected CSN , AAA client functionality.

CSN

Connectivity service network provides: AAA servers that support authentication

for the devices Operations tools IP & traffic management QoS & Policy Pre paid billing Billing control support for roaming between different NSPs

CONT....

AUTHENTICATION, AUTHORIZATION AND

ACCOUNTING AAA refers to Authentication, Authorization and

Accounting.

The AAA server provides the following services to WiMAX:

Authentication Services These include MS, user, or combined MS and user

authentication. Authorization Services

These include the delivery of information to configure the session for access, mobility, QoS and other applications.

Accounting Services These include the delivery of information for the purpose

of billing (both prepaid and post paid billing) and information that can be used to audit session activity by both the home NSP and visited NSP.

INTERNETWORKING WITH 3GPP

Scope:

WiMAX-3GPP Interworking refers to the integration of a WiMAX Access Network to an existing 3GPP core network.

3GPPCard

WiMAXCard

UE

Loosely-CoupledInternetworking

3GPP AccessNetwork

RNC

GCSN

SGSN

3GPP CoreNetwork

WAG

PDGBilling Server

Home AAA

Internet

Home Agent

WiMAX NetworkService Provider

Local AAA

WiMAX Base Stations

WiMAX ASN

WIMAX REFERENCE POINTS

QOS CLASSES

Five QOS services are supported in WIMAX:

UGS (Unsolicited Grant Service) RT-VR (Real-Time -Variable Rate Service) NRT-VR (Non-Real Time -Variable Rate service) BE (Best Efforts) ERT-VR (Extended Real-Time Variable Rate)

UNSOLICITED GRANT SERVICE (UGS) support real-time data streams consisting of

fixed-size data packets issued at periodic intervals Such as T1/E1 and Voice over IP without silence

suppression

VoIP

REAL-TIME POLLING SERVICE (RTPS) support real-time data streams consisting of

variable-sized data packets that are issued at periodic intervals Such as moving pictures experts group (MPEG)

video.

NON-REAL-TIME POLLING SERVICE (NRTPS)

support delay-tolerant data streams consisting of variable-sized data packets for which a minimum data rate is required such as FTP

BEST EFFORT (BE) support data streams for which no minimum

service level is required and therefore may be handled on a space-available basis.

EXTENDED REAL-TIME VARIABLE RATE (ERT-VR)

SERVICE support real-time applications with variable

data-rates, which require guaranteed data and delay, for example VoIP with silence suppression.

MULTIPLEXING TECHNIQUES

OFDM OFDM divides the bandwidth into multiple

frequency sub-carriers. In OFDM sub-carriers are orthogonal to

each other. OFDM also uses multiple sub-carriers but

the sub-carriers are closely spaced to each other without causing interference, removing guard bands between adjacent sub-carriers.

For fixed devices Orthogonal sub carriers produce no signal

power in adjacent sub carriers

BASEBAND OFDM SYSTEM

CONT....

As a reminder, IFFT (Inverse Fast Fourier Transform) is used in a WiMAX transmitter to create an OFDM waveform from modulated data streams, while FFT (Fast Fourier Transform) is used in a WiMAX receiver to demodulate the data streams.

WHY IS OFDM SO POPULAR FOR NEW BROADBAND

SYSTEMS?

Most broadband systems are subject to multipath transmission Conventional solution to multipath is an equalizer in the

receiver With OFDM there is a simple way of dealing with multipath

relatively simple DSP algorithms. It uses cyclic prefix to avoid residual ISI

If multipath delay is less than the cyclic prefix

-no intersymbol or intercarrier interference

-amplitude may increase or decrease

OFDMA: OFDMA employs multiple closely spaced sub-carriers,

which are divided into groups of sub-carriers. For mobile services Point-to-point systems are OFDM, and do not support

OFDMA. Point-to-multipoint fixed and mobile systems use OFDMA.

CONT....

(OFDMA) is a multi-user version of the popular (OFDM) digital modulation scheme

Assigns different subset of sub-carriers to individual user

Bandwidth options 1.25, 5, 10, or 20 MHz Entire bandwidth divided into 128, 512, 1024 or2048

sub carriers

SOFDMA:

SOFDMA is used for mobile Wi-Max mode. It adjusts the size of FFT while fixing the sub-

carrier frequency Smaller FFT size is given to lower bandwidth

channels, while larger FFT size to wider channels

Capacity of each individual sub-channel remain constant

By making the sub-carrier frequency spacing constant, SOFDMA reduces system complexity of smaller channels and improves performance of wider channels.

CONT....

SUB-CHANNELIZATION

Defines sub-channels that can be allocated to subscriber stations (SSs)

Depends on : Channel Conditions Data requirement

Base Station (BS) can allocate : more transmit power to user devices (SSs) with

lower SNR like for indoor SSs. less power to user devices with higher SNR.

Subchannelization in the uplink can save a user device transmit power because it can concentrate power only on certain sub-channel allocated to it.

Picture. Uplink Subchannelization in WiMAXIn OFDM, only one SS transmits in one time slot.

In OFDMA, several SS's can transmit at the same time slot over several sub-

channels.

MODULATION SCHEMES

In Wimax the modulation schemes used are: Qpsk (Quadrature Phase Shift Keying) QAM-16, 64, & 256

QPSK uses four points on the constellation diagram

In QPSK the phase is changed in 4 ways for sending data bits.

QPSK can encode two bits per symbol.

CONT....

QAM is a technique in which the amplitude and phase varies simultaneously for sending higher data rate

QAM is a combination of ASK and PSK.

In QAM-16, 4 bits are send on each single change with the phase change of 22.5 degree

In QAM-64, 6 bits are send on each single change with the phase change of about 5.5 degree

Same as for QAM-256 , 8 bits are send.

Constellation diagram for QAM-16 and QAM-64

WI-MAX RADIOS

A radio contains both a transmitter (sends) and a receiver

(receives). WiMAX antennas, just like the antennas for

car radio, cell phone, FM radio, or TV, are designed to optimize performance for a given application.

OMNI DIRECTIONAL ANTENNAS Omni directional antennas are used for point-to-

multipoint configurations. Omni directional antenna broadcasts 360 degree from

the base station. Omni directional antennas are good for situations where

there are a lot of subscribers located very close to the base station.

SECTOR ANTENNAS

A sector antenna, by focusing the beam in a more focused area, offers greater range and throughput with less energy.

Many operators will use sector antennas to cover a 360-degree service area rather than use an omni-directional antenna due to the superior performance of sector antennas over an omni-directional antenna.

PANEL ANTENNAS Panel antennas are most often used for point-to-point

applications Panel antennas are usually a flat panel of about one foot

square.

APPLICATIONS

WIMAX VOIP Voice over Internet Protocol (VoIP) offers a wider range of

voice services at reduced cost to subscribers and service providers alike.

The diagram below illustrates a typical solution where a WiMAX service provider can obtain wholesale VoIP services (no need for the WiMAX service provider to install and operate a VoIP soft switch) at about $5/number/month and resell to enterprise customers at $50.