WiMax-Architecture[1].pdf

8/9/2019 WiMax-Architecture[1].pdf

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IEEE 802.16 Network Architecture

Wireless Communication NetworksWWAN


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802.16 Standards History

802.16a(Jan 2003)

• Extension for 2-11 GHz: Targeted for non-line-of-sight, Point-to-Multi-Pointapplications like “last mile” broadband access

802.16(Dec 2001)

• Original fixed wireless broadband air Interfacefor 10 – 66 GHz: Line-of-sight only, Point-to-Multi-Point applications

802.16c(2002)

802.16 AmendmentWiMAX System Profiles

10 - 66 GHz

802.16REVd

(802.16-2004)(Oct 2004)

• Adds WiMAX System Profiles and Errata for2-11 GHz

802.16e(802.16-2005)

(Dec 2005)

• MAC/PHY Enhancements to supportsubscribers moving at vehicular speeds

• First standard based on proprietary implementations of DOCSIS/HFCarchitecture in wireless domain

IEEE 802.16 StandardsIEEE 802.16

Air interface on 10-66 GHz licensed bandsLight-of-sigh (LOS) transmission, point-to-point delivery

IEEE 802.16aOperations on 2-11 GHz licensed/non-licensed bandsNon-Light-of-sigh (NLOS) transmission, point-to-multipointdelivery

IEEE 802.16eOperation on 2-6 GHz licensed bands

Support mobilityPromoted by WiMAX World-wide Interoperability forMicrowave Access

IEEE 802.16 Standards IEEE 802.16 Applications

Provide broadband Internet access withtransmission rates over >2 Mb/sReplace DSL or cable

DSL can deliver up to 6 Mb/s at distances upto 18,000 feetIEEE 802.16 can deliver up to 120 Mb/s atdistances up to 30 km

Provide local multipoint distributedservices (LMDS)


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IEEE 802.16 Applications IEEE 802.16 Features

Use wireless links with microwave or millimeter

wave radiosUse licensed spectrum Are metropolitan in scaleProvide public network service to fee-payingcustomersUse point-to-multipoint architecture withstationary rooftop or tower-mounted antennas

Antenna with a variety of radiation patterns are used(e.g., directional or Omni-directionalProvide broadband and QoS guarantee datatransmissions

WLAN vs. WMAN

WLAN WMAN

Typical max.coverage Inferior to 100 m 12 ~ 15 km (LOS), 1~2 km (NLOS)

Optimisation For indoor short range spacesFor NLOS environments (2-11 GHzband). Supports advanced antennatechniques

Scalability

LAN application. The numberof users can vary between oneto several tens, with asubscriber per CPE

Efficient support of hundreds of SSs witha limited number of users per SS.

Flexible bandwidth channels ranging 1.5-20 MHz.

Bit RateMaximum spectral efficiency2,7 b/s/Hz.

54 Mb/s in 20 MHz channels.

Maximum spectral efficiency 5 b/s/Hz.

100 Mb/s in 20 MHz. channels

QoS Without QoS supportNative MAC QoS support.

Service differentiation levels

IEEE 802.16 Example


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IEEE 802.16 Network Architecture IEEE 802.16 Network Architecture

BS: base station RS: relay stationSS: subscriber station TE: terminal equipment

IEEE 802.16 Network Architecture

IEEE 802.16 specifies the air interface(PHY and MAC between STS and BTS

Components and Data Path

IEEE 802.16 architecture consists of twokinds of fixed (non-mobile) stations

Subscriber stations (SS)Base station (BS)

The communication path between SS andBS has two directions

Uplink (from SS to BS)

Downlink (from BS to SS)


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Protocol Architecture Protocol Architecture

Physical and transmission layer functions:Encoding/decoding of signalsPreamble generation/removalBit transmission/reception

Medium access control layer functions:On transmission, assemble data into a frame withaddress and error detection fields

On reception, disassemble frame, and performaddress recognition and error detectionGovern access to the wireless transmission medium

Protocol Architecture

Convergence layer functions:Encapsulate PDU framing of upper layers intonative 802.16 MAC/PHY framesMap upper layer’s addresses into 802.16addressesTranslate upper layer QoS parameters intonative 802.16 MAC format Adapt time dependencies of upper layertraffic into equivalent MAC service

IEEE 802.16 Bear Services

Digital audio/video multicast: one-way(broadcast radio and video) or two-way(teleconferencing)Digital telephony: multiplexed digital telephonestreams

ATM: transfer ATM cellsInternet protocol: transfer IP datagramsBridged LAN: transfer data between two LANsBack-haul: provide wireless trunks for wireless

telephone base stationsFrame relay: transfer variable-length frames


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Services and QoS Requirements

Circuit basedCircuit-switching capabilityConnections are set up to subscribers acrossa core network

Variable packetIP and frame relay

MPEG videoFixed-length cell/packet

For ATM

Protocol Structure MAC Protocol

Convergence sublayer Handle the higher-layer protocols

Common part sublayer Channel access, connection establishmentand maintenance, and QoS

Security sublayer Authentication, secure key exchange, and

encryption


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MAC Protocol MAC PUD Transmissions

Convergence Sublayer

The service specific convergence sublayer (CS) provides any transformation ormapping of external network data,received through the CS service accesspoint (SAP)Object : classifying external networkservice data units (SDU) and associating

them to the proper service flow identifiedby the connection identifier (CID

Convergence Sublayer

Functions:Classification, possible

processing of higher-layer PDUsDelivery to proper MAC SAPReceives CS PDUs from peer

Two specifications ATM and packetThe higher layers will predominantly be ATM andIEEE 802.3 Ethernet

Each vendor can develop a difference convergencesublayer


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ATM Convergence Sublayer

ATM cells mapped to MAC framesDifferentiates Virtual Path switched /Virtual Channel switched ATMconnections

Assigns channel ID (CID)Can perform Payload Header Suppression(PHS)

The process of suppressing the repetitiveportion of payload headers at the sender andrestoring the headers at the receiver

Packet Convergence Sublayer

used for all packet-based protocols,such as IPv4, IPv6, Ethernet, and VLANSimilar functions as ATM convergencesublayer, including PHS

MAC Common Part Sublayer

Defines multiple-access mechanismFunctions :system access, bandwidthallocation, connection establishment, andconnection maintenance

MAC Common Part Sublayer

Connection-oriented protocol Assign connection ID (A16-bit value thatidentifies a connection to equivalent peers inthe MAC) to each service flow

Each service flow (uniquely identified by aSFID, 32-bit value) has it own QoSparameter setting (latency, jitter, and

throughput)BS grants the bandwidth allocation


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Security Sublayer

The MAC security sublayer has twocomponent protocols:

Encapsulation protocol for data encryptiondefines cryptographic suites i.e. pairings of data

encryption and authentication algorithmsthe rules for applying those algorithms to a MAC

payload

Privacy key management (PKM)describes how the BS distributes keys to client SS

Physical Layer Summary

IEEE 802.16 Operation Bands

Licensed bands between 10GHz~66GHzSingle-carrier PHY

Frequency band is large (25~28MHz) Allow data rate over 120Mb/s

LOS (line-of-sight) between transmit and receiveantennas (trend to be blocked)Multipath is not an issue and the thermal noise andinterference are the main limited factorsFor outdoor setting

Rain will increase the attenuation


Licensed bands between 2GHz~11GHzSingle and multi-carrier PHYsNLOS (non-line-of-sight) between transmitand receive antennas

received signal power can vary significantly Advanced power management technique

Multipath can be significant andretransmission may be necessary


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Unlicensed bands between 2GHz~11GHzPhysical characteristics are the same asaboveOther users may cause interferences andregulations limit the output power

Dynamic frequency selection and powermanagement

Adaptive PHY

(burst(burst --byby --burstburst adaptivityadaptivity not shown)not shown)

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WiMax-Architecture[1].pdf