QoS in Ad-hoc Networks

8/8/2019 QoS in Ad-hoc Networks

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Presented By: Abbas Agane

ELG 5125 - University of Ottawa

November 29, 2005

Project PresentationQuality of service

in

ad-hoc networks



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Agenda Introduction

Ad-hoc Network definition Overview: Ad-hoc networks Network architecture Applications of ad-hoc networks Ad-hoc networks characteristics

and requirements Overview: QoS

What is QoS ?

The need of QoS in MANETs Why QoS is hard in MANETs

Current Solutions for Support inMANETs Flexible QoS Model for MANETs INSIGNI A-MANETs QoS Signaling Cluster-based Routing Protocol SWAN for MANETs

Ad-hoc QoS interconnectivity withFixed Network

Domain services

Model for QoS ad-hoc

interaction with the hostdomain

Mechanism of operation

Ad-hoc QoS interaction withthe host domain architecture

End-to-end Qos in MANETs

connected to Fixed Networks(DS-SWAN) DS-SWAN for upstream

Conclusions Q&A



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Ad Hoc Network definition Ad Hoc Network definition

An ad-hoc network is a wireless LAN, in which somedevices are part of the network only for the duration ofa communication session or while in some closeproximity to the rest of the network.

A "mobile ad hoc network" (MANET) is an autonomoussystem of mobile routers (and associated hosts)connected by wireless links forming an arbitrary graph.Routers are free to move randomly and organizethemselves arbitrarily; network topology may changerapidly and unpredictably. May operate in a stand-alonefashion, or may be connected to the Internet.

An ad hoc network can be regarded as a spontaneousnetwork: a network that automatically emerges

when nodes gather together



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MANET Mobile Ad hoc NETworks

A

CB

D

- Mobility - Self configuring and healing - Rapid Deployment

- High capacity - Independent of public infrastructure - Relaying

- Internet compatible standards-based wireless systems



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Network Architecture

Flat networkinfrastructure

Multi-layerednetwork

infrastructure

Cluster

Head

Cluster

Head

Cluster

Head



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Applications of Ad Hoc Networks Applications of Ad Hoc Networks

Personal communications

cell phones, laptops

Cooperativeenvironments

taxi cab network

meeting rooms

Emergency operations

policing and fire

fighting Military environments

Battlefield

Network of sensors or

floats over water



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Ad Hoc Networks Characteristics and Ad Hoc Networks Characteristics andRequirementsRequirements

Autonomous and spontaneous nature of nodes Distributed Algorithms to support security, reliability and

consistency of exchanged and stored information

Time-varying network topology (no pre-existing

infrastructure or central administration) Scalable routing and mobility management techniques to

face network dynamics

Fluctuating link capacity and network resources Enhanced functionalities to improve link layer performance,

QoS network support and end-to-end efficiency Low-power devices

Energy conserving techniques at all layers



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What is QoS ?

Hard to agree on a common definition of QoS

A QoS enabled network shall ensure:

That its applications and/or their users have their

QoS parameters fulfilled, while at the same timeensuring an efficient resource usage

That the most important traffic still has its QoSparameters fulfilled during network overload

What are the most important QoS parameters: Throughput, availability, delay, jitter and packet

loss



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The need for QoS in MANETs

Applications have special service requirements

VoIP: delay, jitter, minimum bandwidth

Needs intelligent buffer handling and queueing

High mobility of users and network nodes

Routing traffic is important

No retransmission of lost broadcast messages

Routing contol messages must be prioritized

For use in emergency and military operations

User traffic prioritization is needed

user, role, situation etc

Wireless bandwidth and battery capacity are scarce resources

Need efficient resource usage

E.g. only route high priority traffic through terminals that are low onpower

Need QoS aware routing



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Why QoS is Hard in Mobile Ad HocNetworks?

Dynamic network topology

Flow stop receiving QoS provisions due to pathdisconnections

New paths Must be established, causing data loss and

delays Imprecise state information

Link state changes continuously

Flow states change over time

No central control for coordination

Error-prone shared medium Hidden terminal problem

Limited resources availability

Bandwidth, battery life, storage, processing capabilities

Insecure medium



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Current Solutions for QoS supportin Mobile Ad Hoc Networks

Because of the unique characteristics of the ad-hoc environmentthree models provide some good insight into the issues of QoS inMANETs

These models provide a comprehensive solutions, namely INSIGNI A

FQMM SWAN

FQMMINSIGNIASWAN

Can be integrated

with multiple routingprotocols

Flexibility!



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Flexible QoS Model for MANETs (FQMM)

First QoS Model proposed in 2000 for MANETs by Xiao et al

Proposes a hybrid provisioning that combines the per-flowgranularity on IntServ and per-class granularity of DiffServ

Adopts DiffServ, but improves the per-class granularity to per-flowgranularity for certain class of traffic

Built over IntServ and DiffServ models, it can operate with extranet traffic

Classification is made at the source node

QoS provisioning is made on every node along the path

FQMM Model provisions the traffic into two portions

the highest priority is assigned per-flow granularity.

the rest is assigned per-class granularity.

Three types of nodes defined Ingress (transmit)

Interior (forward)

Egress (receive)

1

2

5

3

4

6 7

i ng ress

egress

core



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INSIGNI A MANETs QoS Signaling

First signaling protocol designed solely for MANETs by Ahn et al.1998 In-band signaling Base and enhanced QoS levels

Per-flow management Resources management adapted as technology Intelligent packet scheduling Flow reservation, restoration and adaptation

QoS reports periodically sent to source node Source node takes action to adapt flows to observed network

condition Routing

Any routing protocol can be used Route maintenance procedure will affect

In-band signaling Establish, adapt, tear down reservations Control information embedded in data packets



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INSIGNI A OPTION Field

Supports in-band signaling by adding a new option field in the IPheader to carry the signaling control

Reservation Mode (REQ/RES): indicates whether there is alreadya reservation for this packet.

If no, the packet is forwarded to INSIGNI A Module which incoordination with a AC may either:

grant resources Service Type = RT (real-time).deny resources Service Type = BE (best-effort).

If yes, the packet will be forwarded with the allowedresources.

Bandwidth Request (MAX/MIN): indicates the requested amountof bandwidth.

The INSIGNIA OPTION field

1 bit

MAX/MIN

Bandwith

Indicator

16 bits

MAX MIN

Bandwith Request

1 bit

REQ/RES

Reservation

Mode

Service

Type

RT /BE

Payload

Indicator

RT /BE

1 bit 1 bit



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INSIGNI A Bottleneck Node

During the flowreservationprocess a nodemay be a

bottleneck:The service willdegrade fromRT/MAX -> RT/MIN.

Ms

M5

M4

M1

M2M

3

MD

r ser ti /ser i e / i t ttleneck node

REQ/RT/MIN

REQ/RT/MAX

REQ/RT/MAX

REQ/RT/MIN

If M2 is heavy-loaded it may also degradethe service level to BE/MIN where there isactually no QoS.



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Cluster-based Routing Protocol forMobile Ad hoc Networks

When network size increase, flat routing schemesbecome infeasible. hierarchical routing

Explicit hierarchy Group nodes geographically close to each other

into explicit clusters Clusterhead

Communicate to other nodes on behalf of thecluster

Clustering is: a distributed, efficient, scalable

protocol Use clustering approach to minimize on-demand

route discovery traffic use local repair to reduce route acquisition delay

and new route discovery traffic

suggest a solution to use uni-directional links



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Cluster Formation

Source

Destination

routing: showing a data path from source to destination



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Cluster Formation

Objective:

Form small, stableclusters with only localinformation

Mechanism: Variations of min-id cluster formation algorithm. Nodes periodically exchange HELLO pkts tomaintain a neighbor table

neighbor status (C_HEAD, C_MEMBER, C_UNDECIDED) link status (uni-directional link, bi-directional link) maintain a 2-hop-topology link state table

Node ID Node tatus

Neighbor ID Neighborstatus

Linkstatus

Adjacent cluster

ID

HELLOmessageformat:



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SWANStateless Wireless Ad Hoc Networks

An alternative to INSIGNI A with improved scalabilities properties Is a stateless network scheme designed specifically for MANETs

with no need to process complex signaling, or to keep per-flowinformation, to achieve scalability and robustness

Promotes rate control system that can be used at each node to

treat traffic either as real-time or best-effort Excessive real-time traffic is automatically demoted to best-effort While provides a model that deals with traffic on a per-class , it

uses merely two level of service, best-effort and real-time traffic Both level of service can be mapped to DCSPs with known PHB

(based on bandwidth requirement) to facilitate extranet QoS

May decide to demote part of the real-time traffic to best-effortservice due to lack of resources The transmission rate for the best-effort traffic is locally estimated

and adjusted to accommodate the bandwidth required by RealTime traffic

Supports source-based admission control and distributedcongestion control for real-time traffic

Uses explicit congestion notification (ECN)



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ad-hoc QoS interconnectivity withfixed network

Ad-Hoc network needs to cling to a host network in order togain access to the internet

Co-operation between ad hoc network and the host network canfacilitate end-to-end QoS support

Framework proposed by Morgan and Kunz defines a solution for

interaction between ad hoc and host networks This framework is not affected by the specific QoS model

implemented on either side Ad-Hoc network may decide to implement INSIGNI A, SWAN, or

FQMM, while host network may decide to implement DiffServ orIntServ

Ad-hoc networks rely on the host network resources andservices in order to access to the outside world

The host network provides support for the ad-hoc by providingaccess to specific domain services and agreements

Domain services are expressed in terms of three majorcomponents



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Domain services Service Level Agreement (SLA): Fixed networks define SLA as a

contract between a customer and service provider thatspecifies, what services the network service provider willfurnish

Ad hoc domain: may decide to use any protocol such as SLP(service Location Protocol ) to locate specific services such

as a mail server, based on individual needs Traffic Conditioning Agreement (TCA): Specifying classifier rules

and any corresponding traffic profiles and metering and shapingrules which are to apply the traffic streams selected by theclassifier

An example of TCA is the DSCP mapping, and packet

fragmentation Ad Hoc network: need to adopt a set of DSCP codes in order

to be able to deal with DiffServ QoS traffic Service Provisioning Policy: how traffic conditioners are

configured on domain boundary nodes and how traffic streamsare mapped to behaviour aggregates to achieve a range ofservices



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Model for QoS ad-hoc interactionwith host domain

Network Elements [1],[2]



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Mechanism of Operation

The GW to the proposed friendly domain can use SLA and TCAproposed by its fixed domain only

GW(A) adopts SLA and TCA proposed by domain DS

While GW(A) adopts SLA and TCA proposed by domain DS

The GW has to achieve a compromise between the costs usingdifferent services

When a GW looses link connectivity during a per-class, extranetpackets have to be rerouted to an alternate GW

Otherwise it will return to the originating node with a propererror code

GWs have to create a table of the in-service DSCP This table provides a way of finding an alternate GW

When a GW looses link connectivity during a per-flow session,extranet packets have to be returned to the sender with anerror report



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Aggregate RS VP

Is used to solve the scalability issues of RS VP protocol It is particular efficient for inter-domain reservations The terminal ad hoc network is good to employ aRS VP Since, all ad-hoc extranet traffic have to pass through an access

network

aRS VP is used to configure an aggregate PHB between nodes A, A, on one hand and D, D on the other hand

All end-to-end reservations that use RS VP will use the sameaggregate if they belong to the same class

All same class reservations will share resources reserved by asingle aRS VP

This raises the problem of dealing with bursty traffic, because itwill simply eat up the resources of other flow Because, Bursty traffic will simply eat up resources of other flows Proved that the performance degradation due to bursty flow comes

with performance enhancement in the form of reduction of delay inthe tail of the delay distribution



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Pro-active and reactive approach

Proactive approach, by allowing the first or best AN to place anaRS VP request to reserve all classes of traffic (i.e. DSCP)

Then other users will use pre-configured services, and only solicit arequest for upgrade when needed

Problem is the reservation of unused resources in anticipation of

future need Unused resources can be released until needed. When needed, they

can simply activated Reactive approach, by reserving services only when needed When services for a new DSCP are needed, the GW will broadcast a

solicit message requiring all ANs to reply with the level of serviceand cost they can obtain from a specified host domain

GW then will apply a selection criteria to choose which AN shouldprovide aRS VP connection

Reactive approach does not reserve unused resources like theproactive one

However, a certain delay is expected to find the right AN, and toperform versus reactive aRS VP reservation can be determined fromthe service policy-provisioning repository



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Ad-hoc QoS interaction withhost domain Architecture

Ad-hoc may employ FQMM, SWAN, or INSIGNI A, and may be usingdRS VP

Ad-hoc will have a traffic forwarding algorithm, which will use theservice policies in order to perform QoS routing

SLA, TCA, and service provisioning policies, are all imported

GW has a common access to SLA, TCA, and service provisioning policies

Architecture Elements [1], [2]



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End-To-End QoS in MANETsConnected to Fixed Networks

DS-SWAN (Diff-SWAN)

New protocol proposed by Remondo, designed to support end-to-end QoS in ad-hoc networks connected to fixed DiffServ domain

DS-SWAN warns nodes in the ad-hoc networks when congestion isexcessive for the correct functioning of real-time applications

These nodes react by slowing down best-effort traffic

DS-SWAN significantly improves end-to-end delays for real-timeflows without starvation of background traffic DS-SWAN, the ingress edge router periodically monitors the

number of Expedited Forwarding (EF) packets that are dropped byits token bucket meter

On the other hand, the corresponding nodes in the fixed IPnetwork periodically monitor the average end-to-end delays of thereal-time flows

DS-SWAN has been designed to combat the effect of congestiondue to excess of best-effort traffic on end-to-end delay real-timeflows



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DS-SWAN for upstream traffic

For Real-time traffic, the DiffServ service class is the Expedite Forwarding

PHB (Peer-Hop Behaviour)

The number of dropped packets at the ingress edge router and the end-to-

enddelay of the real-time connection are associated with the QoS parameters of

the SWAN model in the ad hoc network

If the rate of the best-effort leaky bucket traffic shaper is lower, then best-

effort traffic is more efficiently restricted and real-time traffic is not so much-



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When a destination node detects that the end-to-enddelay of one VoIP flow approached the threshold (i.e.becomes greater than 140ms), it sends a QoS_LOSTwarning to the ingress edge route

When the edge router sends a QoS_LOST to the adhoc network, it sends the message only to the VoIPsources generating flows that have problems to keeptheir end-to-end delay under 150ms, which willobviously also arrive at the intermediate nodes along

the routes All these nodes forward the QoS_LOST message to all

their neighbours because they may be contendingwith them for medium access

DS-SWAN for upstream traffic(cont)



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DS-SWAN for upstream traffic (cont)

The nodes in the ad hoc network usepriority scheduling at the MAC layer toprioritize routing packets and QoS_LOSTpackets

When a node in ad hoc network receivesthe QoS_LOST message, it will react by

modifying the parameter value in the AIMD rate control algorithm Every time that a QoS_LOST message is

received , the node decreases the valueof c by c-bit/s with a certain minimumvalue

When no QoS_LOST message is

received during T seconds the nodeincreases the value of c by c+bit/sunless the initial value of c hasreached

For r is opposite of the above resultsr-> r-bit/s/ c+bit/s



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Conclusion

In this project, I have presented different existing QoSmodel for wireless ad-hoc networks and a proposedframeworks for ad-hoc interconnectivity with fixeddomains

INSIGNI A, SWAN, FQMM and DS-SWAN, each modelprovide the basics for a more comprehensive model

Mobile nodes can connect to the Internet gateways ofdifferent types, providing different QoS

Classified different approach with respect to differentmobility scenarios

Furthermore, I presented existing classified differentlevel of QoS for hybrid fixed networks

In order to achieve an end-to-end QoS approach, QoSinformation in both fixed and ad-hoc networks shouldbe involved

This demands an interaction between the sections



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References

[1] Towards End-to-End QoS in Ad-Hoc Networks Connected to Fixed NetworksDavid Remondo Catalonia Univ. of Technology (UPC)

[2] An architectural framework for MANET QoS interaction with access domains Yasser Morgan and Thomas Kunz, Carleton University

[3]A proposal for an ad-hoc network QoS gateway Yasser Morgan and ThomasKunz, Carleton University

[4] A Glance at Quality of Services in Mobile Ad-Hoc Networks Zeinalipour- YaztiDemetrios ([email protected])

[5] Quality of Service in Ad-Hoc Networks Eric Chi, Antoins Dimakis el([email protected])

[6] QoS in Mobile Ad Hoc Networks Prasant Mohapatra, Jian Li and Chao Gui,University of California

[7] QoS-aware Routing

Based on

Bandwidth Estimation for Mobile Ad Hoc networksLei Chen and Wendi Heinzelman, University of Rochester{chenlei,

wheinzel}@ece.rochester.edu [8] Dynamic Quality of Service for Mobile Ad-Hoc Networks

M. Mirhakkak, N. Schult, D. Thomson, The MITRE Corporation [9] Network Architecture to Support QoS in Mobile Ad Hoc Networks

Lei Chen and Wendi Heizelman, University of Rochester



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Thank You!Thank You!

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Q&AQ&A

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