Wi Max Delmar 08

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© John Moring 2007-2008

Fundamentals of

WiMAX

Broadband Wireless AccessTechnology

May 2008

John Moring

www.moring.net

760-633-1790

John Moring

www.moring.net

760-633-1790


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©2007-2008 John Moring page 2

WiMAXMay 2008

Objectives

Familiarity with available standards and their scope

Understanding of WiMAX related to competingtechnologies

View of work in progress

Overview of features and capabilities


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WiMAXMay 2008

Outline

WiMAX Intro - 1 hour

Overview

What is WiMAX?

Industry activities

WiMAX Technology - 1 hour

Technology overview

802.16 elements

Technology featuresEquipment characteristics


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WiMAXMay 2008

Overview

What is WiMAX?

Broadband wireless access

Competition

Industry activities

IEEE

WiMAX Forum

Industry

Technology overviewSpectrum

OSI/IEEE model IEEE: Institute of Electrical and Electronics Engineers

OSI: Open System Interconnect

IEEE: Institute of Electrical and Electronics Engineers

OSI: Open System Interconnect


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WiMAXMay 2008

Overview

802.16 elements

MAC sublayers

• Service-specific convergence

• MAC common part

• Security

PHY options

• Single carrier, OFDM, OFDMA

• Line of sight (10+ GHz),• Non-line of sight (


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WiMAXMay 2008

Overview

Technology features

Topology, symmetry, duplex, TDD, FDD

Quality of service (QoS)

Security• Encryption

• Authentication

Reliability• Forward error correction (FEC)

• Automatic repeat request (ARQ)

• Adaptive modulation and coding

TDD: time division duplex

FDD: frequency division duplex

TDD: time division duplex

FDD: frequency division duplex


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WiMAXMay 2008

Overview

Performance

Propagation & coverage

Throughput

Capacity, frequency planning

Advanced featuresMesh

MobilityMIMO

Advanced antenna systems

MIMO: multiple input, multiple output MIMO: multiple input, multiple output


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WiMAXMay 2008

What is WiMAX?

A marketing term…

WiMAX Forum

“Worldwide Interoperability for Microwave Access”

…representing the IEEE 802.16 standards…

“Air Interface for Fixed and Mobile Broadband

Wireless Access Systems”

“WirelessMAN®”

…for a broadband wireless access (BWA)technology supporting multimedia services


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WiMAXMay 2008

WiMAX Targets Multiple Markets

Last mile connectivityDSL/cable alternative

BackhaulT-1/microwave alternative

Mobility/portability3G cellular/Wi-Fi alternative


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WiMAXMay 2008

WiMAX Employs Familiar Components

Base

Station

(BS)

D o w n l i n k ( D L )

Backhaul

Fixed

Subscriber

Station

(SS)

Mobile

Subscriber

Station

(MS)

U p l i n k

( U L )

Infrastructure


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WiMAXMay 2008

802.16 Covers Lowest 1.5 OSI Layers

User/program interface

User information format

Management of sessions

End to end reliability

(e.g., TCP)

End to end delivery(e.g., IP)

Point to point delivery

Electrical, mechanical 1. Physical

6. Presentation

7. Application

5. Session

4. Transport

3. Network

2. Data Link

802.16

802.16 specifies layers 1 (PHY) and part of Layer 2

Can support any higher layer protocols and services

Medium Access Control


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WiMAXMay 2008

Competition

A number of broadband access technologies exist

DSL

Cable

T1/T3

Fiber

Microwave

Satellite

Cellular

Wi-Fi

Proprietary technologies

What distinguishes WiMAX?


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WiMAXMay 2008

Bluetooth

802.11

Short range

ZigBee

Wireless Data Landscape

103 bps

106 bps

109 bps

1 m 1 km 1000 km

COVERAGE ZONE

T H R O U

G H P U T

bps: bits per second

G: generation

LEO: low earth orbit

VSAT: very small aperture [satellite] terminal

bps: bits per second

G: generation

LEO: low earth orbit

VSAT: very small aperture [satellite] terminal

Fixed wireless

VSAT

WiMAX

Microwave

Paging

Wide area

LEO

satellite

3G Cellular WiMAX

2G Cellular


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WiMAXMay 2008

Metrics

Capacity

Throughput

Coverage

Mobility

Quality of ServiceSecurity

Reliability

Costs

Availability/maturity


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WiMAXMay 2008

What Distinguishes WiMAX?

Wide area, wireless, broadband, point tomultipointMobility option

Mesh option

Multiple frequency bands, including unlicensedFlexible & efficient use of spectrum

• Advanced, adaptive modulation• Adaptive antenna technologies

Multi-vendor interoperability

Economies of scale (expected)Inherent quality of service (QoS)

Carrier-grade security


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WiMAXMay 2008

WiMAX vs Wi-Fi

Longer range

More spectrum options

Quality of service

Mobility

Richer security features


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WiMAXMay 2008

WiMAX vs Cellular

Better channel efficiency

More flexible quality of service

Potentially better economies of scale

In the cellular arena, WiMAX faces LTE

(Long Term Evolution) being

standardized by 3GPPChosen by AT&T, Verizon, Ericsson, etc.

3GPP: third generation partnership project 3GPP: third generation partnership project


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WiMAXMay 2008

WiMAX vs Proprietary

Standards-based

Confidence

Multi-vendor interoperability

Economies of scale


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WiMAXMay 2008

Tradeoffs


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WiMAXMay 2008

Representative Performance

Source: WiMAX Forum

“WiMAX Deployment Considerations for Fixed Wireless Access in the 2.5 GHz and 3.5 GHz Licensed Bands”

Simulation results for 3.5GHz band, paired 3.5 MHz FDD channel

Fixed user devices

Average shared downlink throughput, per channel, includingoverhead


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WiMAXMay 2008

The Many Faces of WiMAX

Fixed / mobile

Line of sight / non-line of sightDifferent bands and channel bandwidths

Licensed / unlicensed spectrum Frequency division / time division / half-duplex

frequency division channel usage

Single carrier / OFDM / OFDMA

Plus many configurable optionsSecurity

Reliability

Advanced antennasEtc.

“Profiles” collect reasonable feature sets forcertification and interoperability

OFDM : orthogonal frequency division multiplexing

OFDMA: orthogonal frequency division multiple access




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WiMAXMay 2008

WiMAX Features Related to Spectrum

NLOS

OFDM, OFDMA, SC

Licensed, unlicensed

Fixed

LOS

Single carrier

Mostly licensed

Fixed

6 G H z

6 6 G H z

LOS: line of sight

NLOS: non-line of sight

OFDM: orthogonal frequency division multiplex


SC: single carrier

LOS: line of sight




SC: single carrier

2 G H z

Mobile

OFDMA

1 1 G H z

1 0 G H z

Added

2004

Added

2005


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WiMAXMay 2008

Outline

WiMAX Intro

Overview

What is WiMAX?Industry activities

WiMAX Technology

Technology overview

802.16 elements

Technology features

Equipment characteristics

WiMAX


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WiMAXMay 2008

Industry Activities

Institute of Electrical and Electronics Engineers (IEEE)Standards

802.3 Ethernet, 802.11 Wi-Fi, etc.

802.16 WiMAX

WiMAX ForumIndustry consortium

400+ members

Promotes the technology, defines “profiles,” certifies equipment

International bodies

Major commitments from industry leaders, e.g.,

IntelSprint

Clearwire

Motorola

Etc.

WiMAX


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WiMAXMay 2008

Three Standards Specify Air Interface

IEEE Std 802.16-2004

Encompasses and supercedes

• 802.16-2001, original standard• 802.16a, adds


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WiMAXMay 2008

WiMAX Forum Promotes and Certifies

“The WiMAX Forum® is an industry-led, not-for- profit organization formed to certify and promote thecompatibility and interoperability of broadband

wireless products based upon the harmonized IEEE802.16/ETSI HiperMAN standard.

“A WiMAX Forum goal is to accelerate the

introduction of these systems into the marketplace. “WiMAX Forum Certified™ products are fully

interoperable and support broadband fixed, portable andmobile services.

“Along these lines, the WiMAX Forum works closelywith service providers and regulators to ensure thatWiMAX Forum Certified systems meet customer andgovernment requirements”

www.wimaxforum.org

WiMAX


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WiMAXMay 2008

WiBro Uses 802.16 in Asia

Korean WiBro = Wireless Broadband

“must comply with IEEE 802.16-2004 and

IEEE 802.16e/Draft3 or later versions.”

2.3 GHz band, 8.75 MHz channels

OFDMA, TDD

Mobility ≤60 km/hr

Coverage ≤1 kmPer-user throughput: 128 kbps – 3 Mbps

Nationwide service 4/2007

Multiple carriers100,000+ subscribers by 12/2007

Price per month ~$20

WiMAX


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WiMAXMay 2008

802.16 Also Active in Europe

ETSI HiPerMAN

Subset of IEEE 802.16

Fixed, 2 GHz – 11 GHzSeparate test regime from WiMAX

International Telecommunications Union

Subsets of 802.16 proposed/approved for inclusionin the IMT-2000 family of 3G/4G wireless standards

Approval allows deployment in Europe in bandsreserved for IMT (traditionally cellular)

technologies

3.5 GHz deployments in progress

ETSI – European Telecommunications Standards Institute

HiPerMAN – high performance metro area network IMT – International Mobile Telecommunications

ETSI – European Telecommunications Standards Institute

HiPerMAN – high performance metro area network IMT – International Mobile Telecommunications

WiMAX


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WiMAXMay 2008

Provider Example: Clearwire

Source: Clearwire website 9/07

WiMAX


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May 2008

Example: Clearwire

Clearwire Corporation is unwiring Nashville with the introduction of itsnext-generation wireless broadband solution. The company announcedtoday the official launch of its wireless high-speed Internet access andphone service to the city….

Nashville residents and businesses can now have a fast, simple, portable,reliable and affordable alternative to traditional dial-up, cable andDSL. Clearwire service eliminates the confines of traditional cable ortelephone wiring, allowing customers to connect at home, a localcoffeehouse, the office or virtually anywhere else in the Clearwireservice area.

…Simply purchase a modem at … Circuit City, Best Buy or online atwww.clearwire.com, and within minutes, Internet access or phone servicewill be up and running.

Clearwire’s next-generation, non-line-of-sight wireless broadbandnetwork solution connects customers through licensed or securedspectrum.

… Clearwire Internet Phone Service works with a customer’s existinghigh-speed Internet access and provides unlimited local and long-distance calling from a regular telephone.

Clearwire press release 9/07

Note: Clearwire uses Motorola Expedience “WiMAX-class” technology

WiMAX


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May 2008

Example: Clearwire

Source: Clearwire website 9/07

WiMAX


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May 2008

Vendor Quotes: Intel

“Intel currently plans to integrate WiMAX and WiFi into its

notebook platforms based on Intel® Centrino® Mobile

Technologies. Pairing the two will help bring users the ultimate in

high-speed mobile broadband. Intel believes that WiMAX, with itstechnical and economic advantages, should help enable mainstream

adoption of personal broadband.

“Intel® WiMAX Connection 2250 is a low-cost system-on-chip

that supports IEEE 802.16-2004 and IEEE 802.16e-2005, enablingWiMAX modems for use with fixed or mobile networks.

“The Intel NetStructure® WiMAX Baseband Card integrates

control plane, MAC and PHY processing in a single standards-

based card, ….”

Source: Intel website 9/07

WiMAXM 2008


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May 2008

Provider Quotes: Sprint Nextel

8/8/06. Sprint Nextel Corp. …announced its plans to develop and deploy the firstfourth generation (4G) nationwide broadband mobile network. The 4G wireless broadband network will use the mobile WiMAX IEEE 802.16e-2005 technologystandard.

Working together with Intel, Motorola and Samsung, Sprint Nextel will develop a

nationwide network … designed to offer faster speeds, lower cost, and greaterconvenience and enhanced multimedia quality.

The Sprint Nextel 4G mobility network will use the company's extensive 2.5GHzspectrum holdings, which cover 85 percent of the households in the top 100 U.S.markets …

The company's deployment plans target a launch of the advanced wireless

broadband services in trial markets by the end of 2007 with plans to deploy anetwork that reaches as many as 100 million people in 2008. Sprint Nextel plans toexpand mobile WiMAX network coverage thereafter.

The company will continue to invest in and offer access to its current wireless andSprint PowerVision mobile broadband networks to serve customer communicationsneeds today and into the future.

Sprint Nextel is expecting to invest $1 billion in 2007 and between $1.5 billion and$2 billion in 2008

Motorola and Samsung will also support Sprint's current and CDMA/EV-DOnetwork technologies by creating multimode devices that will support services on both the 4G network and the 3G network … will provide voice service using thecore 3G network.

News services

WiMAXMay 2008

S i O TM


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May 2008

Sprint XOHMTM

Aug. 16 2007 -- Sprint announced today that its WiMAX servicewill be marketed under the XOHMTM ingredient brand(pronounced ZOAM). A soft launch of the WiMAX network isexpected by the end of 2007 in the Chicago and

Baltimore/Washington markets. XOHM commercial services areexpected to be available beginning in the first half of 2008.

... partners have committed to embed 50 million WiMAX chipsetsin devices. The company expects to begin offering 4G mobilebroadband services up to two years ahead of other national

wireless carriers. Sprint Nextel expects to invest approximately $2.5 billion in

capital for WiMAX through year-end 2008. Beyond 2008, network build is expected to be increasingly success-based. The companycurrently expects that extending its coverage to approximately 125

million people by year-end 2010 would require an additionalcapital expenditure of approximately $2.5 billion.….

News services

WiMAXMay 2008


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May 2008

Sprint Quiet on WiMax Launch Date

April 2008 -- Sprint Nextel says provisioning of backhaul is the primary

hold-up to the operator's nationwide deployment of mobile WiMAX.

Sprint, which was supposed to launch its Xohm network this month, is

having difficulty finding high-capacity transport links to connect cell sites

as typical T-1 lines that feed today's mobile networks are inefficient forhigh-speed wireless broadband data, said Xohm President and Sprint

Chief Technology Officer Barry West in an interview with Telephony.

To build the network, Sprint is provisioning fiber where economically

feasible, West said. In other areas, Sprint is using microwave. The entire process has moved slower than what Sprint expected, causing the delay of

the commercial launch.

"Clearly I wanted to hit the April date," West said. "Having missed that

date, I want to make sure we come out with a robust service. Right now

I'm building sites."

WiMAXMay 2008

Ci B WiMAX I f Pl


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May 2008

Cisco Buys WiMAX Infrastructure Player

SAN JOSE, Calif. -- Cisco(R) announced a definitive agreement to purchase Richardson, TX-based Navini Networks, Inc. a leader in theMobile WiMAX 802.16e-2005 broadband wireless industry. Navini is a

pioneer in the integration of "Smart Beamforming" technologies withMulti-Input Multi-Output (MIMO) antennas, a combination that improves

the performance and range for WiMAX services and lowers the overalldeployment and operational costs for service providers….

Cisco also expects that its broadband wireless solution portfolio, that nowincludes WiMAX products, will play a key role in Cisco´s CountryTransformation and "Digital Inclusion" initiatives to drive broadband

penetration to consumers and business in emerging countries. "Emerging country service providers are in expansion mode, building out

broadband wireless networks and are concerned about deployment costsand the availability of skilled resources," said Brett Galloway, vice

president and general manager of the Wireless Networking Business Unit,Cisco. "Around the world broadband wireless networks based uponWiMAX have the potential to add millions of new Internet users whocannot be reached economically using copper or fiber infrastructures.Additionally, WiMAX networks will help drive the transition to open IP-

based broadband wireless architectures and accelerate the rollout of newapplications and services."

Byteandswitch.com 11/07

WiMAXMay 2008

S


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May 2008

Summary

New entrant to crowded market

Large potentialIndustry backing

State of the art technologies

Adaptable to diverse niches

4G in developed marketsLast mile in underdeveloped markets

WiMAXMay 2008

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May 2008

Outline

WiMAX Intro - 1 hour

What is WiMAX?

Industry activitiesWiMAX Technology - 1 hour

Technology overview

802.16 elements

Technology features


WiMAXMay 2008

Th M F f WiMAX


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y

The Many Faces of WiMAX

Line of sight / non-line of sightDifferent bands and channel bandwidths

Licensed / unlicensed spectrum

Frequency division / time division / half-duplexfrequency division channel usage

Fixed / mobile

Single carrier / OFDM / OFDMA

Plus many configurable optionsSecurity

ReliabilityAdvanced antennas

Etc.OFDM : orthogonal frequency division multiplexing




WiMAXMay 2008

Spectrum Allocation


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y

Spectrum Allocation

3.5 GHzWidely allocated and available for WiMAX in

Europe & elsewhere

2.5 GHzIn US, mostly licensed by Sprint/Clearwire

To be allocated in Europe in 2008

Allocations exist elsewhere5.8 GHzLicensed-free in the US, parts of Europe

Other bands to watch2.3 GHz used for WiBro in Korea

700 MHz, 900 MHz, 3.6 GHz, 5.4 GHz

WiMAXMay 2008



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NLOS

OFDM, OFDMA, SC

Licensed, unlicensed

Fixed

LOS

Single carrier

Mostly licensed

Fixed

6 G H z

6 6 G H z

LOS: line of sight




SC: single carrier

LOS: line of sight




SC: single carrier

2 G H z

Mobile

OFDMA

1 1 G H z

1 0 G H z

Added

2004

Added

2005

WiMAXMay 2008

Mobile Network Model


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Mobile Network Model

From WiMAX Forum Network Architecture

Rn designates reference interface

R1 specified in 802.16

AAA: authentication,

authorization, accounting

ASN : access service network

ASP: application service provider

CSN : connectivity service network

GW : gateway

HA: home agent

NAP: network access provider

NSP: network service provider

PF: policy function

AAA: authentication,

authorization, accounting

ASN : access service network

ASP: application service provider

CSN : connectivity service network

GW : gateway

HA: home agent

NAP: network access provider

NSP: network service provider

PF: policy function

ASP

R6

R4

WiMAXMay 2008

Outline


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Outline

WiMAX IntroOverview

What is WiMAX?

Industry activitiesWiMAX TechnologyTechnology overview

802.16 elements

• Protocol model – Service-Specific Convergence Sublayer – MAC Common Part Sublayer

– Security Sublayer

– Physical layer

• ModulationTechnology features


WiMAXMay 2008

Protocol Models


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Protocol Models

802.16 Model

Physical

Presentation

Application

Session

Transport

Network

Data Link

Logical Link

Control 802.2

Physical

Medium

Access

Control

Service-SpecificConvergence Sublayer

Security Sublayer

MAC Common

Part Sublayer

Physical

OSI Model IEEE Model

Note: mappings are approximate

WiMAXMay 2008

Service-Specific Convergence Sublayer


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Service-Specific Convergence Sublayer

Service-Specific Convergence Sublayer (CS)Supports higher layer “services”

• ATM

• Packet – IPv4

– IPv6

– Ethernet

– VLAN

Classify data to the proper MAC connection, preserve or enable QoS, and enable bandwidthallocation; optional header suppression

There may be multiple CS per MAC/PHY

PHYMAC

CS CS

IP ATM

ATM : asynchronous transfer mode

IP: Internet protocol MAC : medium access control

PHY : physical layer

QoS: quality of service

VLAN : virtual local area network

ATM : asynchronous transfer mode

IP: Internet protocol

MAC : medium access control

PHY : physical layer

QoS: quality of service

VLAN : virtual local area network

WiMAXMay 2008

MAC Common Part Sublayer


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MAC Common Part Sublayer

Core MAC functions

Quality of service (QoS) management

Reliability• Dynamic forward error correction (FEC) and

modulation management

• Automatic repeat request (ARQ)

Packet fragmentation/defragmentation

Scheduling

MAC: medium access control MAC: medium access control

WiMAXMay 2008

WiMAX is Connection Oriented


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WiMAX is Connection Oriented

Allows robust QoS

Connection-oriented

A connection, session, or association is formed between the communicating end devices

All circuit technologies

Some packet technologies• "Virtual circuits"

• E.g., TCP, Frame Relay, ATM, WiMAX

vs Connectionless

No association, each packet treated individuallyEthernet, IP, UDP

ATM : Asynchronous Transfer Mode

IP: Internet ProtocolTCP: Transmission Control Protocol

UDP: User Datagram Protocol

ATM : Asynchronous Transfer Mode

IP: Internet Protocol

TCP: Transmission Control Protocol

UDP: User Datagram Protocol

WiMAXMay 2008

Security Sublayer


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Security Sublayer

Encryption

Provides user data privacy

Uses encryption algorithms and crypto keys

Authentication/authorization

Verifies identity of SS

Verifies identity of BS (added in 802.16e)

Uses certificates, digital signatures, trusted third-

party verification

BS: base station

SS: subscriber station

BS: base station


WiMAXMay 2008

Security Features


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Security Features

EncryptionProvides user data privacy

• NOT MAC header or most management messages

Uses encryption algorithms and crypto keys• Traffic encryption key (TEK)

Authentication/authorizationVerifies identity of SS

Verifies identity of BS (added in 802.16e)

Uses certificates, digital signatures, trusted third-partyverification

Key exchangeManagement plane

Control message validation

BS: base station


BS: base station


WiMAXMay 2008

Security Concepts


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Security Concepts

Crypto suites

Triple Data Encryption Standard (3DES)

Advanced Encryption Standard (AES)• Counter Mode with Cipher Block Chaining with Message

Authentication Code Protocol (CCMP)

Privacy Key Management (PKM)

PKMv1PKMv2

• RSA (Rivest, Shamir, Aldeman)

• EAP (Extensible Authentication Protocol)Security Associations (SA)

Holds security info (e.g., keys) for each connection

WiMAXMay 2008

Modulations used in 802.16


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Modulations used in 802.16

Modulation and coding adjusted to adapt to signal path

BPSK

1 bit/symbol

QPSK

2 bits/symbol

16-QAM

4 bits/symbol

64-QAM

8 bits/symbol

256-QAM

16 bits/symbol

-1.5

-1

-0.5

0

0.5

1

1.5

- 1.5 -1 - 0.5 0 0.5 1 1.5

Example: BPSK uses phase shift(here 45º and -135º) to represent2 values

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

- 2 - 1.5 - 1 - 0.5 0 0.5 1 1.5 2

Example: 16-QAM uses both

phase (angle from horizontal) and

amplitude (distance from origin)

phase

a m p l i t u

d e

BPSK : binary phase shift keying

QAM : quadrature amplitude modulationQPSK : quadrature phase shift keying

BPSK : binary phase shift keying

QAM : quadrature amplitude modulation

QPSK : quadrature phase shift keying

WiMAXMay 2008

Outline


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WiMAX Intro

What is WiMAX?

Industry activities

WiMAX Technology

Technology overview

802.16 elements

Technology features• Topology

• Time/frequency division

• Quality of service (QoS)

• Reliability

• Mobility


WiMAXMay 2008

Topologies Illustrated


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p g

Point to point

Point to multipoint

Mesh

Dynamic mobile mesh

Mesh BS

Nodes

Infrastructure

relay

Mesh BS Nodes

Mesh BS

a c t i v e

WiMAXMay 2008

TDD and FDD


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WiMAX includes support for both Frequency DivisionDuplexing (FDD) and Time Division Duplexing (TDD)

FDD

Requires paired channels• Usually licensed• Each unit requires dual transceivers

Good for symmetric traffic

May be full duplex or half duplex at subscriber

TDDSingle shared channel

• Some channel inefficiencies when radio switches betweentransmit and receive

Half duplexMay use fixed or adaptive slot sizes

• Good for asymmetric traffic

WiMAXMay 2008

Single Carrier


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g

One radio channel carries each

transmitter’s signal

P o w e r

Frequency f

Bandwidth (BW)

WiMAXMay 2008

OFDM Employs Subcarriers


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p y

Data

Pilot - reference

Guard – interference avoidance

P o w e r

Frequency

Subcarriers typically ~10 kHz wide

Number of subcarriers related to Fast Fourier Transform (FFT) size

Bandwidth (BW)

OFDM: orthogonal frequency

division multiplexing

OFDM: orthogonal frequency

division multiplexing

WiMAXMay 2008Orthogonal Frequency Division

Multiplexing (OFDM)


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Multiplexing (OFDM)

Essentially sends data over several parallel channels

Provides frequency diversity

Reduces inter-symbol interference

Used in 802.11a/g (Wi-Fi) and elsewhere

Users share the channel via time slots

Data

Split to

subcarriers

AntennaRadio

WiMAXMay 2008

OFDM with TDMA


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U s e r 3

T i m e

Each transmitter’s signal is carried in a series ofrelated subcarriers

One transmitter on the channel at a time

P o w e r

Frequency f 0 f n

U s e

r 2

U s e r 1

OFDM: orthogonal frequency division multiplexingTDMA: time division multiple access

OFDM: orthogonal frequency division multiplexingTDMA: time division multiple access

WiMAXMay 2008Orthogonal Frequency Division Multiple

Access (OFDMA)


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Access (OFDMA)

Subsets of subcarriers are allocated to different usersUplink and downlink

Multiple users may share the channel simultaneously

A superior frequency can be chosen for a given user

User 2Data

Split to

subcarriers

AntennaRadio

User 1

Data

Downlink side illustrated

WiMAXMay 2008

OFDMA


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Each transmitter’s signal is assigned to a subchannel ,

i.e., subset of the available subcarriers

P o w e r

Frequency

User4

T i m e

U s e r 2

User5

User1

User4User1

User3

User5

User3

WiMAXMay 2008

Quality of Service (QoS)


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QoS is required to support the requirements of

different traffic types

Access to the channel is controlled by the BSUnlike Wi-Fi or Ethernet, which use contention

access schemes under control of the stations

BS can efficiently allocate uplink and downlinkresources based on requests from SS

BS: base station


BS: base station


WiMAXMay 2008

Fundamental QoS Metrics


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Throughput

Connection capacity, in bits per second

LatencyConnection delay, in milliseconds (ms)

Jitter

Variability of delay, in milliseconds

How much…

How quick…

How consistent…

WiMAXMay 2008

Robust Reliability Options


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Forward error correction (FEC)

Code rates adapt to link quality

Reed-Solomon (RS)

Optional Block Turbo Codes and Convolutional Turbo Codes

Automatic Repeat Request (ARQ)

MAC Block based

Acknowledgements (ACKs) can be selective or cumulative;standalone or piggybacked

Optional Hybrid ARQ (HARQ)

• Incorporates FEC as well ACKs and resends

WiMAXMay 2008

Mobility


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802.16e introduces the Mobile Station (MS)

class of SS

Moving MS may cross BS coverage boundariesHandover: MS migrates from one BS to another

Break-before-make

Make-before-break • Fast BS switching

• Macro diversity handover

ASN-anchored vs. CSN anchored

ASN: access service network

BS: base station

CSN: connectivity service network SS: subscriber station

ASN: access service network

BS: base station

CSN: connectivity service network


WiMAXMay 2008

Outline


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WiMAX Intro

What is WiMAX?

Industry activitiesWiMAX Technology

Technology overview

802.16 elementsTechnology features


WiMAXMay 2008

Equipment Characteristics


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Subscriber station

Base station

Certification

Antennas

Alvarion BreezeMAX

WiMAXMay 2008

Subscriber Station


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Fixed

Indoor

• Consumer installation

• Inexpensive, low performance

Outdoor

• Technician mounted

• Expensive, high gain, better path

Mobile

Dedicated WiMAX devices (e.g., tablet, phone)

Add on (PC card)

Embedded in multipurpose devices (e.g., PC, phone)

WiMAXMay 2008

Base Station


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Comparable to cellular base stations Indoor equipment

Outdoor equipment

Antenna spec, mounting Technical featuresBand, bandwidth, FDD/TDD, ….

Support for optional features

Management interface CapacitySectors, channels, connections, ….

Performance specsPower, sensitivity, ….

Interfaces

WiMAXMay 2008

WiMAX Forum Certification


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Includes conformance and interoperability tests

Certified equipment must conform to

Specific IEEE 802.16 standard

A particular defined profile

WiMAX Forum test documentation

• System Profiles

• Test Suite Structure (TSS) and Test Purposes (TP)• Protocol/Profile Implementation Conformance Statements (PICS)

Tests must be performed by a Designated Certification

Laboratory

AT4 Wireless (Spain), Telecommunications Technology

Association (Korea), China Academy of Telecommunication

Research (China)

WiMAXMay 2008

Certification Stagesa cti


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Wave 1: Air interface

3.5 GHz, 2.3 GHz, other

Wave 2: QoS, security, advanced radiofeatures for outdoor customer premiseequipment (CPE)

Wave 3: Indoor CPE, PC cards, nomadicservice

Wave 4: Handoffs, simple mobilityWave 5: Full mobility

ac t i v e

WiMAXMay 2008

Availability


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Certified products*

Fixed only

• 2.3 and 3.5 GHz only

10+ companies

30+ products

• Base station, subscriber

A number on “WiMAX-class”

products are on the market

*As of April 2007

WiMAXMay 2008

Antennas


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802.16 offers protocol support for advanced

antenna options under 11 GHz

Adaptive antenna systems (AAS)

• AKA “smart antennas,” “beam forming”

Multiple input/multiple output (MIMO)

Space time coding (STC)

Line of sight systems above 11 GHz do not get

much benefit from these features

WiMAXMay 2008MIMO Exploits

Spatial & Frequency Diversity


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Multiple Input Multiple OutputEssentially sends data over several parallel radios/channels

Provides spatial and frequency diversity

Used in 802.11n and elsewhere

802.16 provides protocol support for MIMOExtended in 802.16e

Options include open loop and closed loop (i.e., with feedback)

RadiosAntennas

Data

Split to

subcarriers

WiMAXMay 2008

Performance


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Can be evaluated using many different criteriaCoverage

User data throughput

User capacity

Reliability

Cost

TNSTAAFLOptimizing one aspect of performance generally

impacts performance in other areas

TNSTAAFL: There’s no such thing as a free lunch!TNSTAAFL: There’s no such thing as a free lunch!

WiMAXMay 2008

Representative Performance


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©2007-2008 John Moring page 75Source: WiMAX Forum

“WiMAX Deployment Considerations for Fixed Wireless Access in the 2.5 GHz and 3.5 GHz Licensed Bands”

Simulation results for 3.5GHz band, paired 3.5 MHz FDD channel Fixed user devices

Average shared downlink throughput, per channel, includingoverhead

WiMAXMay 2008

References


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IEEE (specs)

WiMAX Forum (white papers,

certification) News feeds

Texts

WiMAXMay 2008

Summary


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New entrant to crowded market

Large potentialIndustry backing

State of the art technologies

Adaptable to diverse niches

4G in developed marketsLast mile in underdeveloped markets

Documents

Wi Max Delmar 08