Fundamentals of WiMAX Broadband Wireless Access · PDF file©2007-2008 John Moring page 3 WiMAX Outline May 2008 ÒWiMAX Intro - 1 hour OOverview OWhat is WiMAX? OIndustry activities

© John Moring 2007-2008

Fundamentals ofWiMAX

Broadband Wireless AccessTechnology

May 2008

John Moringwww.moring.net

760-633-1790

John Moringwww.moring.net

760-633-1790

©2007-2008 John Moring page 2

WiMAXMay 2008Objectives

Familiarity with available standards and their scopeUnderstanding of WiMAX related to competing technologiesView of work in progressOverview of features and capabilities


WiMAXMay 2008Outline

WiMAX Intro - 1 hourOverviewWhat is WiMAX? Industry activities

WiMAX Technology - 1 hourTechnology overview 802.16 elements Technology features Equipment characteristics


WiMAXMay 2008Overview

What is WiMAX?Broadband wireless accessCompetition

Industry activities IEEEWiMAX ForumIndustry

Technology overviewSpectrumOSI/IEEE model

IEEE: Institute of Electrical and Electronics EngineersOSI: Open System Interconnect

IEEE: Institute of Electrical and Electronics EngineersOSI: Open System Interconnect



802.16 elementsMAC sublayers• Service-specific convergence• MAC common part• Security

PHY options• Single carrier, OFDM, OFDMA• Line of sight (10+ GHz), • Non-line of sight (<11 GHz)• Licensed, unlicensed

MAC: medium access controlOFDM: orthogonal frequency division multiplexingOFDMA: orthogonal frequency division multiple accessPHY: physical layer

MAC: medium access controlOFDM: orthogonal frequency division multiplexingOFDMA: orthogonal frequency division multiple accessPHY: physical layer



Technology featuresTopology, symmetry, duplex, TDD, FDDQuality of service (QoS)Security• Encryption• AuthenticationReliability• Forward error correction (FEC)• Automatic repeat request (ARQ)• Adaptive modulation and coding

TDD: time division duplexFDD: frequency division duplex

TDD: time division duplexFDD: frequency division duplex



PerformancePropagation & coverageThroughputCapacity, frequency planning

Advanced featuresMesh MobilityMIMOAdvanced antenna systems

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


WiMAXMay 2008What 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


WiMAXMay 2008WiMAX Targets Multiple Markets

Last mile connectivityDSL/cable alternative

BackhaulT-1/microwave alternative

Mobility/portability3G cellular/Wi-Fi alternative


WiMAXMay 2008WiMAX Employs Familiar Components

Base Station (BS)

Downlink (DL)

Backhaul

Fixed Subscriber

Station (SS)

Mobile Subscriber

Station (MS)

Uplink (UL)Infrastructure


WiMAXMay 2008802.16 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 2Can support any higher layer protocols and services

Medium Access Control


WiMAXMay 2008Competition

A number of broadband access technologies existDSLCableT1/T3FiberMicrowaveSatelliteCellularWi-FiProprietary technologies

What distinguishes WiMAX?


WiMAXMay 2008

Bluetooth

802.11

Short rangeZigBee

Wireless Data Landscape

103bps

106bps

109bps

1 m 1 km 1000 kmCOVERAGE ZONE

TH

RO

UG

HPU

T

bps: bits per secondG: generationLEO: low earth orbitVSAT: very small aperture [satellite] terminal

bps: bits per secondG: generationLEO: low earth orbitVSAT: very small aperture [satellite] terminal

Fixed wireless

VSATWiMAX

Microwave

Paging

Wide area

LEO satellite

3G CellularWiMAX

2G Cellular


WiMAXMay 2008Metrics

CapacityThroughputCoverageMobilityQuality of ServiceSecurityReliabilityCostsAvailability/maturity


WiMAXMay 2008What Distinguishes WiMAX?

Wide area, wireless, broadband, point to multipoint

Mobility optionMesh option

Multiple frequency bands, including unlicensedFlexible & efficient use of spectrum

• Advanced, adaptive modulation• Adaptive antenna technologies

Multi-vendor interoperabilityEconomies of scale (expected)Inherent quality of service (QoS)Carrier-grade security


WiMAXMay 2008WiMAX vs Wi-Fi

Longer rangeMore spectrum optionsQuality of serviceMobilityRicher security features


WiMAXMay 2008WiMAX vs Cellular

Better channel efficiencyMore flexible quality of servicePotentially better economies of scale

In the cellular arena, WiMAX faces LTE (Long Term Evolution) being standardized by 3GPP

Chosen by AT&T, Verizon, Ericsson, etc.

3GPP: third generation partnership project3GPP: third generation partnership project


WiMAXMay 2008WiMAX vs Proprietary

Standards-based ConfidenceMulti-vendor interoperabilityEconomies of scale


WiMAXMay 2008Tradeoffs


WiMAXMay 2008Representative 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 channelFixed user devicesAverage shared downlink throughput, per channel, including overhead


WiMAXMay 2008The Many Faces of WiMAX

Fixed / mobileLine of sight / non-line of sight

Different bands and channel bandwidthsLicensed / unlicensed spectrumFrequency division / time division / half-duplex frequency division channel usageSingle carrier / OFDM / OFDMAPlus many configurable options

SecurityReliabilityAdvanced antennasEtc.

“Profiles” collect reasonable feature sets for certification and interoperability

OFDM: orthogonal frequency division multiplexingOFDMA: orthogonal frequency division multiple access



WiMAXMay 2008WiMAX Features Related to Spectrum

NLOSOFDM, OFDMA, SCLicensed, unlicensed

Fixed

LOSSingle carrier

Mostly licensedFixed

6GH

z

66G

Hz

LOS: line of sightNLOS: non-line of sightOFDM: orthogonal frequency division multiplexOFDMA: orthogonal frequency division multiple accessSC: single carrier


2GH

z

MobileOFDMA

11G

Hz

10G

Hz

Added 2004

Added 2005



WiMAX IntroOverview What is WiMAX? Industry activities

WiMAX TechnologyTechnology overview 802.16 elements Technology features Equipment characteristics


WiMAXMay 2008Industry Activities

Institute of Electrical and Electronics Engineers (IEEE)Standards802.3 Ethernet, 802.11 Wi-Fi, etc.802.16 WiMAX

WiMAX ForumIndustry consortium400+ membersPromotes the technology, defines “profiles,” certifies equipment

International bodiesMajor commitments from industry leaders, e.g.,

IntelSprintClearwireMotorolaEtc.


WiMAXMay 2008Three Standards Specify Air Interface

IEEE Std 802.16-2004Encompasses and supercedes

• 802.16-2001, original standard• 802.16a, adds <11 GHz• 802.16c, adds profiles

Sometimes called “802.16d”IEEE Std 802.16-2004/Cor1

Corrigendum, adds correctionsIEEE Std 802.16e-2005

Amendment, adds mobility, etc.

Other amendments cover specific areas


WiMAXMay 2008WiMAX Forum Promotes and Certifies

“The WiMAX Forum® is an industry-led, not-for-profit organization formed to certify and promote the compatibility and interoperability of broadband wireless products based upon the harmonized IEEE 802.16/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 and mobile services. “Along these lines, the WiMAX Forum works closely with service providers and regulators to ensure that WiMAX Forum Certified systems meet customer and government requirements”

www.wimaxforum.org


WiMAXMay 2008WiBro 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 channelsOFDMA, TDDMobility ≤60 km/hrCoverage ≤1 kmPer-user throughput: 128 kbps – 3 Mbps

Nationwide service 4/2007Multiple carriers100,000+ subscribers by 12/2007Price per month ~$20


WiMAXMay 2008802.16 Also Active in Europe

ETSI HiPerMANSubset of IEEE 802.16Fixed, 2 GHz – 11 GHzSeparate test regime from WiMAX

International Telecommunications UnionSubsets of 802.16 proposed/approved for inclusion in the IMT-2000 family of 3G/4G wireless standardsApproval allows deployment in Europe in bands reserved for IMT (traditionally cellular) technologies

3.5 GHz deployments in progressETSI – European Telecommunications Standards InstituteHiPerMAN – high performance metro area networkIMT – International Mobile Telecommunications

ETSI – European Telecommunications Standards InstituteHiPerMAN – high performance metro area networkIMT – International Mobile Telecommunications


WiMAXMay 2008Provider Example: Clearwire

Source: Clearwire website 9/07


WiMAXMay 2008Example: Clearwire

Clearwire Corporation is unwiring Nashville with the introduction of its next-generation wireless broadband solution. The company announced today the official launch of its wireless high-speed Internet access and phone service to the city….Nashville residents and businesses can now have a fast, simple, portable, reliable and affordable alternative to traditional dial-up, cable and DSL. Clearwire service eliminates the confines of traditional cable or telephone wiring, allowing customers to connect at home, a localcoffeehouse, the office or virtually anywhere else in the Clearwire service area. …Simply purchase a modem at … Circuit City, Best Buy or online at www.clearwire.com, and within minutes, Internet access or phone service will be up and running. Clearwire’s next-generation, non-line-of-sight wireless broadband network solution connects customers through licensed or secured spectrum.… Clearwire Internet Phone Service works with a customer’s existing high-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


WiMAXMay 2008Example: Clearwire

Source: Clearwire website 9/07


WiMAXMay 2008Vendor 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 its technical and economic advantages, should help enable mainstreamadoption of personal broadband.“Intel® WiMAX Connection 2250 is a low-cost system-on-chipthat supports IEEE 802.16-2004 and IEEE 802.16e-2005, enabling WiMAX 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


WiMAXMay 2008Provider Quotes: Sprint Nextel

8/8/06. Sprint Nextel Corp. …announced its plans to develop and deploy the first fourth generation (4G) nationwide broadband mobile network. The 4G wireless broadband network will use the mobile WiMAX IEEE 802.16e-2005 technology standard. Working together with Intel, Motorola and Samsung, Sprint Nextel will develop a nationwide network … designed to offer faster speeds, lower cost, and greater convenience and enhanced multimedia quality. The Sprint Nextel 4G mobility network will use the company's extensive 2.5GHz spectrum 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 a network that reaches as many as 100 million people in 2008. Sprint Nextel plans to expand mobile WiMAX network coverage thereafter. The company will continue to invest in and offer access to its current wireless and Sprint PowerVision mobile broadband networks to serve customer communications needs today and into the future. Sprint Nextel is expecting to invest $1 billion in 2007 and between $1.5 billion and $2 billion in 2008Motorola and Samsung will also support Sprint's current and CDMA/EV-DO network technologies by creating multimode devices that will support services on both the 4G network and the 3G network … will provide voice service using the core 3G network.

News services


WiMAXMay 2008Sprint XOHMTM

Aug. 16 2007 -- Sprint announced today that its WiMAX service will be marketed under the XOHMTM ingredient brand (pronounced ZOAM). A soft launch of the WiMAX network is expected by the end of 2007 in the Chicago and Baltimore/Washington markets. XOHM commercial services are expected 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 mobile broadband 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 company currently expects that extending its coverage to approximately 125 million people by year-end 2010 would require an additional capital expenditure of approximately $2.5 billion.….

News services


WiMAXMay 2008Sprint 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 for high-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 2008Cisco Buys WiMAX Infrastructure Player

SAN JOSE, Calif. -- Cisco(R) announced a definitive agreement to purchase Richardson, TX-based Navini Networks, Inc. a leader in the Mobile WiMAX 802.16e-2005 broadband wireless industry. Navini is a pioneer in the integration of "Smart Beamforming" technologies with Multi-Input Multi-Output (MIMO) antennas, a combination that improves the performance and range for WiMAX services and lowers the overall deployment and operational costs for service providers….Cisco also expects that its broadband wireless solution portfolio, that now includes WiMAX products, will play a key role in Cisco´s Country Transformation 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 costs and 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 upon WiMAX have the potential to add millions of new Internet users who cannot 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 new applications and services."

Byteandswitch.com 11/07


WiMAXMay 2008Summary

New entrant to crowded market

Large potentialIndustry backingState of the art technologies

Adaptable to diverse niches4G in developed marketsLast mile in underdeveloped markets



WiMAX Intro - 1 hourWhat is WiMAX? Industry activities

WiMAX Technology - 1 hourTechnology overview 802.16 elements Technology features Equipment characteristics


WiMAXMay 2008The Many Faces of WiMAX

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

Licensed / unlicensed spectrumFrequency division / time division / half-duplex frequency division channel usageFixed / mobileSingle carrier / OFDM / OFDMAPlus many configurable options

SecurityReliabilityAdvanced antennasEtc.




WiMAXMay 2008Spectrum Allocation

3.5 GHzWidely allocated and available for WiMAX in Europe & elsewhere

2.5 GHz In US, mostly licensed by Sprint/ClearwireTo be allocated in Europe in 2008Allocations exist elsewhere

5.8 GHz Licensed-free in the US, parts of Europe

Other bands to watch2.3 GHz used for WiBro in Korea700 MHz, 900 MHz, 3.6 GHz, 5.4 GHz


WiMAXMay 2008WiMAX Features Related to Spectrum

NLOSOFDM, OFDMA, SCLicensed, unlicensed

Fixed

LOSSingle carrier

Mostly licensedFixed

6GH

z

66G

Hz



2GH

z

MobileOFDMA

11G

Hz

10G

Hz

Added 2004

Added 2005


WiMAXMay 2008Mobile Network Model

From WiMAX Forum Network Architecture

Rn designates reference interfaceR1 specified in 802.16

AAA: authentication, authorization, accountingASN: access service networkASP: application service providerCSN: connectivity service networkGW: gatewayHA: home agentNAP: network access providerNSP: network service providerPF: policy function

AAA: authentication, authorization, accountingASN: access service networkASP: application service providerCSN: connectivity service networkGW: gatewayHA: home agentNAP: network access providerNSP: network service providerPF: policy function

ASPR6

R4



WiMAX IntroOverviewWhat is WiMAX? Industry activities

WiMAX TechnologyTechnology overview 802.16 elements

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

• Modulation Technology features Equipment characteristics


WiMAXMay 2008Protocol Models

802.16 Model

Physical

Presentation

Application

Session

Transport

Network

Data Link

Logical Link Control 802.2

Physical

Medium Access Control

Service-Specific Convergence Sublayer

Security Sublayer

MAC Common Part Sublayer

Physical

OSI Model IEEE ModelNote: mappings are approximate


WiMAXMay 2008Service-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 bandwidth allocation; optional header suppressionThere may be multiple CS per MAC/PHY

PHYMAC

CS CS

IP ATM

ATM: asynchronous transfer modeIP: Internet protocolMAC: medium access controlPHY: physical layerQoS: quality of serviceVLAN: virtual local area network

ATM: asynchronous transfer modeIP: Internet protocolMAC: medium access controlPHY: physical layerQoS: quality of serviceVLAN: virtual local area network


WiMAXMay 2008MAC Common Part Sublayer

Core MAC functionsQuality of service (QoS) managementReliability• Dynamic forward error correction (FEC) and

modulation management• Automatic repeat request (ARQ)

Packet fragmentation/defragmentationScheduling

MAC: medium access controlMAC: medium access control


WiMAXMay 2008WiMAX is Connection Oriented

Allows robust QoSConnection-oriented

A connection, session, or association is formed between the communicating end devicesAll circuit technologiesSome packet technologies

• "Virtual circuits"• E.g., TCP, Frame Relay, ATM, WiMAX

vs ConnectionlessNo association, each packet treated individuallyEthernet, IP, UDP

ATM: Asynchronous Transfer ModeIP: Internet ProtocolTCP: Transmission Control ProtocolUDP: User Datagram Protocol

ATM: Asynchronous Transfer ModeIP: Internet ProtocolTCP: Transmission Control ProtocolUDP: User Datagram Protocol


WiMAXMay 2008Security Sublayer

EncryptionProvides user data privacyUses encryption algorithms and crypto keys

Authentication/authorizationVerifies identity of SSVerifies identity of BS (added in 802.16e)Uses certificates, digital signatures, trusted third-party verification

BS: base stationSS: subscriber station



WiMAXMay 2008Security Features

EncryptionProvides user data privacy

• NOT MAC header or most management messagesUses encryption algorithms and crypto keys

• Traffic encryption key (TEK)

Authentication/authorizationVerifies identity of SSVerifies identity of BS (added in 802.16e)Uses certificates, digital signatures, trusted third-party verification

Key exchangeManagement plane

Control message validationBS: base stationSS: subscriber station



WiMAXMay 2008Security Concepts

Crypto suitesTriple 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 2008Modulations used in 802.16

Modulation and coding adjusted to adapt to signal pathBPSK

1 bit/symbol

QPSK2 bits/symbol

16-QAM4 bits/symbol

64-QAM8 bits/symbol

256-QAM16 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 represent 2 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)

phaseam

plitude

BPSK: binary phase shift keyingQAM: quadrature amplitude modulationQPSK: quadrature phase shift keying

BPSK: binary phase shift keyingQAM: quadrature amplitude modulationQPSK: quadrature phase shift keying



WiMAX IntroWhat is WiMAX? Industry activities

WiMAX TechnologyTechnology overview 802.16 elements Technology features

• Topology• Time/frequency division• Quality of service (QoS)• Reliability• Mobility

Equipment characteristics


WiMAXMay 2008Topologies Illustrated

Point to point

Point to multipoint

Mesh

Dynamic mobile mesh

Mesh BS

Nodes

Infrastructurerelay

Mesh BS Nodes

Mesh BS

active


WiMAXMay 2008TDD and FDD

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

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

Good for symmetric trafficMay be full duplex or half duplex at subscriber

TDDSingle shared channel

• Some channel inefficiencies when radio switches between transmit and receive

Half duplexMay use fixed or adaptive slot sizes

• Good for asymmetric traffic


WiMAXMay 2008Single Carrier

One radio channel carries each transmitter’s signal

Pow

er

Frequencyf

Bandwidth (BW)


WiMAXMay 2008OFDM Employs Subcarriers

DataPilot - referenceGuard – interference avoidance

Pow

er

FrequencySubcarriers typically ~10 kHz wideNumber 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)Essentially sends data over several parallel channelsProvides frequency diversityReduces inter-symbol interferenceUsed in 802.11a/g (Wi-Fi) and elsewhereUsers share the channel via time slots

DataSplit to

subcarriers

AntennaRadio


WiMAXMay 2008

Use

r3

Time

OFDM with TDMA

Each transmitter’s signal is carried in a series of related subcarriersOne transmitter on the channel at a time

Pow

er

Frequencyf0 fn

Use

r2U

ser1

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)Subsets of subcarriers are allocated to different users

Uplink and downlinkMultiple users may share the channel simultaneouslyA superior frequency can be chosen for a given user

User 2Data

Split to subcarriers

AntennaRadio

User 1Data

Downlink side illustrated


WiMAXMay 2008OFDMA

Each transmitter’s signal is assigned to a subchannel, i.e., subset of the available subcarriers

Pow

er

Frequency

User4

TimeU

ser2

User5

User1

User4User1

User3

User5

User3


WiMAXMay 2008Quality of Service (QoS)

QoS is required to support the requirements of different traffic typesAccess to the channel is controlled by the BS

Unlike Wi-Fi or Ethernet, which use contention access schemes under control of the stations

BS can efficiently allocate uplink and downlink resources based on requests from SS




WiMAXMay 2008Fundamental QoS Metrics

ThroughputConnection capacity, in bits per second

LatencyConnection delay, in milliseconds (ms)

JitterVariability of delay, in milliseconds

How much…

How quick…

How consistent…


WiMAXMay 2008Robust Reliability Options

Forward error correction (FEC)Code rates adapt to link qualityReed-Solomon (RS)Optional Block Turbo Codes and Convolutional Turbo Codes

Automatic Repeat Request (ARQ)MAC Block basedAcknowledgements (ACKs) can be selective or cumulative; standalone or piggybackedOptional Hybrid ARQ (HARQ)

• Incorporates FEC as well ACKs and resends


WiMAXMay 2008Mobility

802.16e introduces the Mobile Station (MS) class of SSMoving MS may cross BS coverage boundariesHandover: MS migrates from one BS to another

Break-before-makeMake-before-break

• Fast BS switching• Macro diversity handover

ASN-anchored vs. CSN anchored

ASN: access service networkBS: base stationCSN: connectivity service networkSS: subscriber station

ASN: access service networkBS: base stationCSN: connectivity service networkSS: subscriber station



WiMAX IntroWhat is WiMAX? Industry activities

WiMAX TechnologyTechnology overview 802.16 elements Technology features Equipment characteristics


WiMAXMay 2008Equipment Characteristics

Subscriber stationBase stationCertificationAntennas

Alvarion BreezeMAX


WiMAXMay 2008Subscriber Station

FixedIndoor

• Consumer installation• Inexpensive, low performance

Outdoor• Technician mounted• Expensive, high gain, better path

MobileDedicated WiMAX devices (e.g., tablet, phone)Add on (PC card)Embedded in multipurpose devices (e.g., PC, phone)


WiMAXMay 2008Base Station

Comparable to cellular base stationsIndoor equipmentOutdoor equipment

Antenna spec, mountingTechnical features

Band, bandwidth, FDD/TDD, ….Support for optional featuresManagement interface

CapacitySectors, channels, connections, ….

Performance specsPower, sensitivity, ….

Interfaces


WiMAXMay 2008WiMAX Forum Certification

Includes conformance and interoperability testsCertified equipment must conform to

Specific IEEE 802.16 standardA particular defined profileWiMAX 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 2008Certification Stages

Wave 1: Air interface3.5 GHz, 2.3 GHz, other

Wave 2: QoS, security, advanced radio features for outdoor customer premise equipment (CPE) Wave 3: Indoor CPE, PC cards, nomadic serviceWave 4: Handoffs, simple mobilityWave 5: Full mobility

active


WiMAXMay 2008Availability

Certified products*Fixed only

• 2.3 and 3.5 GHz only

10+ companies30+ products

• Base station, subscriber

A number on “WiMAX-class”products are on the market

*As of April 2007


WiMAXMay 2008Antennas

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 DiversityMultiple Input Multiple Output

Essentially sends data over several parallel radios/channelsProvides spatial and frequency diversityUsed in 802.11n and elsewhere

802.16 provides protocol support for MIMOExtended in 802.16eOptions include open loop and closed loop (i.e., with feedback)

Radios AntennasData

Split to subcarriers


WiMAXMay 2008Performance

Can be evaluated using many different criteriaCoverageUser data throughputUser capacityReliabilityCost

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 2008Representative 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 channelFixed user devicesAverage shared downlink throughput, per channel, including overhead


WiMAXMay 2008References

IEEE (specs)WiMAX Forum (white papers, certification)News feeds Texts


WiMAXMay 2008Summary

New entrant to crowded market

Large potentialIndustry backingState of the art technologies

Adaptable to diverse niches4G in developed marketsLast mile in underdeveloped markets

Fundamentals of WiMAX Broadband Wireless Access · PDF file©2007-2008 John Moring page 3 WiMAX Outline May 2008 ÒWiMAX Intro - 1 hour OOverview OWhat is WiMAX? OIndustry activities

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