wimax technonlogy: presented julian kamberi

7/31/2019 WiMAX Technonlogy: Presented Julian Kamberi

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WiMAX: Broadband Wireless Access

Presented: Julian Kamberi

Wireless Networks Spring 2012-Ing.Julian Kamberi


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802.16 Standards Development Use wireless links with microwave or millimeter

wave radios

10-66 GHz 802.16a extension to 2-11 GHz Use licensed spectrum (unlicensed too in

802.16a) Metropolitan in scale Provide public network service to fee-paying

customers Point-to-multipoint architecture with rooftop or

tower-mounted antennas


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802.16 Standards Development

Provide efficient transport of heterogeneoustraffic supporting QoS

Capable of broadband transmissions (2-75Mbps) Accommodate both continuous and bursty traffic

Mobile extensions: 802.16e


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IEEE 802.16 Protocol ArchitectureWireless NetworksSpring 2007


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Protocol Architecture

Physical layer functions: Encoding/decoding of signals

Preamble generation/removal Bit transmission/reception

Medium access control layer functions: On transmission, assemble data into a frame with

address and error detection fields On reception, disassemble frame, and perform addressrecognition and error detection

Govern access to the wireless transmission medium


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Protocol Architecture

Convergence layer functions: Encapsulate PDU framing of upper layers into

native 802.16 MAC/PHY frames Map upper layers addresses into 802.16 addresses Translate upper layer QoS parameters into native

802.16 MAC format

Adapt time dependencies of upper layer trafficinto equivalent MAC service


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IEEE 802.16 Services

Digital audio/video multicast

Digital telephony

ATM

Internet protocol

Bridged LAN

Back-haul Frame relay


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Burst Profiles

Each subscriber station negotiates a burst profilewith the base station

Burst profiles decided based on QoS needs andchannel conditions Harsher environment demands more robust profiles

Favorable environment allows efficient profiles


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IEEE 802.16.1 Frame Format

Header - protocol control information Downlink header used by the base station

Uplink header used by the subscriber to conveybandwidth management needs to base station

Bandwidth request header used by subscriber torequest additional bandwidth

Payload either higher-level data or a MACcontrol message

CRC error-detecting code


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Physical Layer: Uplink

Stations transmit in in their assigned allocationspecified in an initial map

Uplink sub-frame may also contain contention-based allocations for initial system access

Uses a DAMA-TDMA technique

Error correction uses Reed-Solomon codes Modulation scheme based on QPSK, 16-QAM or

64-QAM


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Physical Layer: Downlink

Continuous downstream mode For continuous transmission (audio/video) Simple TDM scheme is used for channel access

Frequency division duplex (FDD)

Burst downstream mode For bursty transmission (IP-based traffic)

DAMA-TDMA scheme for channel access

FDD with adaptive modulation, frequency shift division

duplexing (FSDD), time division duplexing (TDD)

Wireless NetworksSpring 2007


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Medium Access Control (MAC)

Connection-oriented

All services inherently connectionless mapped to aconnection

Connections referenced using a 16-bitconnection identifier (CID)

Management channels and transport channelsfor contracted services


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Radio Link Control Power control and paging Transition among burst profiles

Downlink burst profile change Subscriber station monitors downlink quality Requests a new profile Granted if base station judges possible

Uplink profile change Base station monitors the uplink signal quality Specifies the new profiles usage code when granting

subscriber bandwidth in a frame


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Bandwidth Requests & Grants

Two kinds of subscribers Grant per connection (GPC)

Grant per subscriber (GPSS)

Both classes request bandwidth per connection

for QoS guarantees For GPC, bandwidth explicitly guaranteed to

connection

For GPSS, bandwidth aggregated into a singlegrant for SS

Wireless NetworksSpring 2007


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Requesting Bandwidth

Unsolicited grants No need to request bandwidth for services that

generate fixed units of data periodically

Negotiated at connection setup time

Send a bandwidth request MAC packet Piggyback request within MAC data packet

Polling by base station


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MAC Management Messages

Uplink and downlink channel descriptor

Uplink and downlink access definition

Ranging request and response

Registration request, response and acknowledge

Privacy key management request and response

Dynamic service addition request, response andacknowledge


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wimax technonlogy: presented julian kamberi

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