department of information engineering university of padova, italy

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Department of Information EngineeringUniversity of Padova, ITALY

On Providing Soft-QoS in On Providing Soft-QoS in

Wireless Ad-Hoc NetworksWireless Ad-Hoc Networks

{andrea.zanella, daniele.miorandi, silvano.pupolin}@dei.unipd.it

Andrea Zanella, Daniele Miorandi, Silvano Pupolin, Paolo Raimondi

WPMC 2003, 21-22 October 2003

Special Interest Group on NEtworking & Telecommunications

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Outline of the contents

Motivations & Purposes

Soft-QoS & Call Admission Control

Path creation & maintenance

Results

Conclusions

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

What & Why…

Motivations &Purposes

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Motivations

Ad-hoc networks are a valuable solution to

Extend in a multi-hop fashion the radio access to wired networks

Interconnect wireless nodes without any fixed network structure

In these contexts, providing QoS is a key issue

audio/video streaming

interactive games

multimedia

Classic QoS support methods involve

QoS-routing

Call-Admission-Control (CAC) mechanisms

MAC-layer Resource Reservation (MRR) strategies

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Aim of the study

Providing basic Soft-QoSSoft-QoS support over low-profilelow-profile

ad-hoc wireless networks

No hard QoS guarantees Soft QoSSoft QoS

Simple QoS routing algorithm modified AODVmodified AODV

Simple CAC mechanism distributed statistical CACdistributed statistical CAC

No static MRR statistical MRRstatistical MRR

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Introduction to QoS issues

Soft QoS & CACSoft QoS & CAC

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Hard & Soft QoS

Widely used in wired

networks

Integrated Services: flow

based (RSVP)

Differentiated Services:

class based

Suitable for wireless

networks

Applications may work

even if, for short periods of

time, QoS requirements

are not satisfied

Deal with limited bandwidth

and radio channel

Hard-QoS Soft-QoS

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

QoS parameters required per link

Minimum peak band: Br

End-to-End Delay: Dr

Soft QoS parameter: Target Satisfaction indexTarget Satisfaction index

r = percentage of pcks expected to satisfy QoS constrains

r = 1 hard QoS

r = 0 pure best-effort

Path Service Levels P = (p1,…, pN)

Path Peak Bandwidth

Path Delay

Soft-QoS parameters

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WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Call-Admission Control

Path is feasible if Bandwidth constrained requests

Delay constrained requests

Using Gaussian approx, Bandwidth and Delay statistic is

determined by mean and standard deviation

Bandwidth constrained requests

Delay constrained requests

rrP BB Pr

rrP DD Pr

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br

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1

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Statistical Resource Reservation

Bandwidth-constrained

Delay-constrained Extra-delay margin given to

each link along the path is inversely proportional to the mean link delay

Resource bounds Minimal residual resources that should be guaranteed

to preserve QoS levels of accepted connections

j

j

jjb

brrbrb

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ˆ 1

ˆ1ˆ 1 QDmPP DrD

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Actual SatisfactionResource bounds

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Path creation & maintenance Soft-QoS routing is largely inspired to AODV

Each Route Request (RREQ) packet gathers statistical information on the minimum bandwidth and maximum delay along that portion of the path

RREQ is propagated only whether bandwidth request is satisfied

The destination node back propagates a Route Reply (RREP) packet along the selected path

RREP acquaints intermediate nodes with new resource bounds and updates maximum sustainable traffic rate

Source node is required to respect the maximum sustainable traffic rate limit or to refuse the connection

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Simulation Results

Simulation of Soft-QoS Simulation of Soft-QoS routing algorithmrouting algorithm

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Simulation Scenario

Bluetooth Scatternet Round Robin Polling Gateways spend 50 slots in each piconet

Poisson packets arrival process Mixed packet formats with average length of 1500 bits

Delay-constrained requests

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Gaussian Approximation Local slave-to-slave connections

in each piconet Data rate=9.6 Kbit/s 1 hop

6 hops

Gaussian approx is fairly closefairly close to empirical delay CDF

Gap increases for long-distance and high traffic connection

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Simulation setup Target connection c1

Dr = 50 ms

r = 0.2 r = 20 kbit/s

Target connection c2

Dr = 200 ms

r = 0.9 r = 30 kbit/s

Target connection c3

Dr = 200 ms

r = 0.9 r = 20 kbit/s

Target connection c4 Dr = 50 ms r = 0.2 r = 60 kbit/s

Transversal connections Starting after 20 s, last for 10 s On average 1 request/s Random source, destination & QoS

requests Rate: 520 kbit/s

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Satisfaction & Delay dynamics Satisfaction Delay

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Conclusions We have proposed a basic Soft QoS routing algorithm for low-profile

ad hoc networks

Provides Soft-QoS guarantees

Requires

basic nodes’ functionalities

statistical link state monitoring (mean and standard deviation)

Does not require

service differentiation

static resource reservation

Drawbacks

Lower resource utilization

Higher rate of connection request rejection

WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

Department of Information EngineeringUniversity of Padova, ITALY

On Providing Soft-QoS in On Providing Soft-QoS in

Wireless Ad-Hoc NetworksWireless Ad-Hoc Networks

{andrea.zanella, daniele.miorandi, silvano.pupolin}@dei.unipd.it

Andrea Zanella, Daniele Miorandi, Silvano Pupolin, Paolo Raimondi

WPMC 2003, 21-22 October 2003

Special Interest Group on NEtworking & Telecommunications