ARQ Aware Scheduling for the IEEE 802.16 Base StationARQ Aware Scheduling for the IEEE 802.16 Base Station

Alexander Sayenko

Nokia Research Center

Helsinki, Finland

Olli Alanen and Timo Hamalainen

Telecommunication laboratory, MIT department,

University of Jyvaskyla, Finland

ICC 2008

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OutlineOutline

IntroductionARQ Aware SchedulingSimulationConclusions

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IntroductionIntroduction

IEEE 802.16, called WiMAX Point-to-MultiPoint (PMP)

BSSS

Automatic Repeat Request (ARQ) Retransmission

MAC protocol data unit (PDU)

BSBSBSBS

SSSSSSSS SSSSSSSS SSSSSSSS

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IntroductionIntroduction

ARQ aware scheduling for the 802.16 BS ARQ block size ARQ transmission window ARQ block rearrangement

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ARQ Aware SchedulingA. Basics of the 802.16 ARQ mechanismARQ Aware SchedulingA. Basics of the 802.16 ARQ mechanism

If ARQ is enabled for a connection General MAC header (GMH)

Extended fragmentation subheader (FSH)Extended packing subheader (PSH)

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ARQ Aware SchedulingA. Basics of the 802.16 ARQ mechanismARQ Aware SchedulingA. Basics of the 802.16 ARQ mechanism

Subheader Block Sequence Number (BSN)

indicates the first ARQ block number in the PDU

BSN

?802.16d 802.16e

1~2040 bytes 16~1024 bytese.g.,16, 32, 64 …

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ARQ Aware SchedulingB. Basics of the 802.16 schedulingARQ Aware SchedulingB. Basics of the 802.16 scheduling

minimum (Ni

min )

maximum (Ni

max )

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ARQ Aware SchedulingC. ARQ block sizeARQ Aware SchedulingC. ARQ block size

SGMH: GMH size (6 bytes) SFSH : FSH size (2 bytes for the ARQ enabled connection)

SiARQ: the ith connection ARQ block size

SCRC : CRC field size (4 bytes)

Si : slot size (by modulation and coding scheme (MCS))

Uplink connection:+ GMSH size (2 byte)

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ARQ Aware SchedulingD. ARQ transmission windowARQ Aware SchedulingD. ARQ transmission window

SiARQ: the ith connection ARQ block size

Wi : the ARQ transmission window size

FPS : the number of frames per second

DF : the delay factor

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ARQ Aware SchedulingD. ARQ transmission windowARQ Aware SchedulingD. ARQ transmission window

SGMH: GMH size (6 bytes) SFSH : FSH size (2 bytes for the ARQ enabled connection) Si

ARQ: the ith connection ARQ block size Wi : the ARQ transmission window size SCRC : CRC field size (4 bytes) Si : slot size (by modulation and coding scheme (MCS))

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ARQ Aware SchedulingE. ARQ block rearrangementARQ Aware SchedulingE. ARQ block rearrangement

if the BS knows that an SS does not support ARQ block rearrangement

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ARQ Aware SchedulingF. SS uplink schedulerARQ Aware SchedulingF. SS uplink scheduler

BSBSBSBS

SSSS11SSSS11 SSSSmmSSSSmm

CC11CC11 CC22CC22 CCnnCCnn

SSSS22SSSS22

CID

Connection:

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SimulationSimulation NS-2 simulator :802.16 MAC and PHY levels MAC

Frames Bursts Downlink and uplink transmission Connections MAC PDUs

Packing and fragmentation Contention and ranging periods MAC level management messages Dynamic size of the MAP messages ARQ mechanism

ARQ blocks, ARQ transmission window Retransmission with rearrangement All the ARQ feedback types

PHY OFDMa

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SimulationSimulation

Network structure

1 UL BE connection

1 DL BE connection

FTP-like application

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SimulationSimulation

Fixed

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SimulationSimulation

Each simulation lasts for 10 seconds

Applications start to transmit data at the 1.5th second of a simulation run

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SimulationA. ARQ block sizeSimulationA. ARQ block size

Downlink

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SimulationA. ARQ block sizeSimulationA. ARQ block size

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SimulationB. ARQ block rearrangementSimulationB. ARQ block rearrangement

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SimulationB. ARQ block rearrangementSimulationB. ARQ block rearrangement

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SimulationC. ARQ transmission windowSimulationC. ARQ transmission window

ARQ block size is 16 bytes

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SimulationC. ARQ transmission windowSimulationC. ARQ transmission window

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ConclusionsConclusions

ARQ aware resource allocation in the 802.16 networks ARQ block size ARQ transmission window ARQ block rearrangement

A better performance can be achieved Larger ARQ block sizes Create large PDUs Dropped UGS and rtPS classes vs. nrtPS and BE classes

Smaller ARQ block sizes vs. Larger ARQ block sizes

ARQ transmission window To avoid wasting resources on connections

ARQ block rearrangement

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Thank You