Robust QoS Control for SinRobust QoS Control for Single Carrier PMP Mode IEEgle Carrier PMP Mode IEE

E 802.16 SystemsE 802.16 SystemsAuthors: Xiaofeng Bai, Abdallah ShaAuthors: Xiaofeng Bai, Abdallah Sha

mi, and Yinghua Yemi, and Yinghua Ye

Published: IEEE TMC April 2008Published: IEEE TMC April 2008

OutlineOutline

IntroductionIntroduction System ModelSystem Model Uplink Request Management AgentUplink Request Management Agent Frame Scheduling UnitFrame Scheduling Unit SimulationSimulation ConclusionConclusion

IntroductionIntroduction

Fixed frame lengthFixed frame length Each connection, excepted UGS, requests Each connection, excepted UGS, requests

bandwidth for next frame before the end of bandwidth for next frame before the end of current frame current frame

ProblemsProblems

How many resource do each connection real How many resource do each connection real need?need?

Is the information received by BS up-to-date?Is the information received by BS up-to-date? How to reduce the control overhead?How to reduce the control overhead?

System ModelSystem Model

Frame Scheduling Unit

Uplink Request Management Agent

Do not concern about UGS services

Uplink Request Management AgentUplink Request Management Agent

Symbol definition Symbol definition Bandwidth request

for bandwidth guaranteed and imminent part

Bandwidth request for bandwidth guaranteed and nonim

minent part

Bandwidth request for bandwidth

guaranteed part Bandwidth request for nonbandwidth guaranteed part

Uplink Request Management AgentUplink Request Management Agent

The connection i’s service timer at ti

me t

The connection i’s eligible bandwidth

request

maxiR

QoS Enforcement ModuleQoS Enforcement Module

The connection i’s bandwidth request

The connection i’s QoS timer at time

t

miniR

SS-Request Generation ModuleSS-Request Generation Module

Frame Scheduling UnitFrame Scheduling Unit

Downlink Request ManagementDownlink Request Management Similarly to Uplink Request Management AgentSimilarly to Uplink Request Management Agent

Resource Allocation ModuleResource Allocation Module Frame Creation ModuleFrame Creation Module

Conversion symbol assignment into timing Conversion symbol assignment into timing informationinformation

Resource Allocation ModuleResource Allocation Module

The symbol need of the The symbol need of the PP0 request is 0 request is considered first, then considered first, then PP1 followed by 1 followed by PP2 2 requests.requests.

If the symbol needs of every SG have been If the symbol needs of every SG have been fully accommodated, the remaining symbols fully accommodated, the remaining symbols are assigned to each SG in proportion to the are assigned to each SG in proportion to the number of connections include in the SG.number of connections include in the SG.

Resource Allocation ModuleResource Allocation ModuleThe Pi request in bytes of the jth SG

The number of bits carried by one modulated symbol of

the jth SG

The Pi request in symbols of the jth S

G

The symbols earned by the Pi reques

t of the jth SG

The extra symbols possibly assigned t

o the jth SG

The integer number of symbols finally assigned to the jt

h SG

SimulationSimulation

UCSA: uncontrolled scheduling UCSA: uncontrolled scheduling algorithmalgorithm

Each uplink connection sends individual bandwidth rEach uplink connection sends individual bandwidth requests over the uplink.equests over the uplink.

The symbol needs are estimated only based on the linThe symbol needs are estimated only based on the link capacity information when each connection is estabk capacity information when each connection is established.lished.

The symbol needs of all rtPS connections are accomThe symbol needs of all rtPS connections are accommodated first, then all nrtPS connections, followed by modated first, then all nrtPS connections, followed by all BE connections.all BE connections.

Any nrtPS connection could be serviced only when eAny nrtPS connection could be serviced only when every rtPS connection queue is evacuated and no BE cvery rtPS connection queue is evacuated and no BE connection could be serviced if any rtPS and nrtPS paconnection could be serviced if any rtPS and nrtPS packet is backlogged. ket is backlogged.

uplink rtPS connection of SS5uplink rtPS connection of SS5

uplink nrtPS connection of SS6uplink nrtPS connection of SS6

uplink BE connection of SS5uplink BE connection of SS5

uplink rtPS connection of SS5uplink rtPS connection of SS5

At time 2.0 second, the links from SS8 to the At time 2.0 second, the links from SS8 to the BS degrade from 64-QAM to QPSK.BS degrade from 64-QAM to QPSK.

At time 4.0 second, the links from SS8 to the At time 4.0 second, the links from SS8 to the BS recover from QPSK to 64-QAMBS recover from QPSK to 64-QAM

uplink rtPS connection of SS8uplink rtPS connection of SS8

uplink nrtPS connection of SS8uplink nrtPS connection of SS8

uplink rtPS connection of SS7uplink rtPS connection of SS7

uplink nrtPS connection of SS9uplink nrtPS connection of SS9

uplink BE connection of SS8uplink BE connection of SS8

uplink rtPS connection of SS8uplink rtPS connection of SS8

ConclusionConclusion

The proposed SCSA scheme enable each connThe proposed SCSA scheme enable each connection’s contracted QoS parameters to control ection’s contracted QoS parameters to control the service provided to the connection, which ethe service provided to the connection, which ensures the per-connection QoS guarantee.nsures the per-connection QoS guarantee.

Signaling overhead is reduced.Signaling overhead is reduced. The proposed scheme is robust against wirelesThe proposed scheme is robust against wireles

s link degradation at a particular SS.s link degradation at a particular SS.