Transcript View File - University of Engineering and Technology, Taxila

Mobile and Ad hoc Networks
Background of Ad hoc
Wireless Networks
Wireless Communication
Technology and Research
Ad hoc Routing and
Mobile IP and Mobility
Wireless Sensor and Mesh
Networks
Student Presentations
QoS in Ad Hoc
http://web.uettaxila.edu.pk/CMS/SP2012/teAWNms/
Overview
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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
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Current Solutions for Support in MANETs
 Flexible QoS Model for MANETs
 INSIGNIA-MANETs QoS Signaling
 SWAN for MANETs
Conclusions
Q&A
Ad Hoc Network definition
 An ad-hoc network is a wireless LAN, in which some devices are part
of the network only for the duration of a communication session or
while in some close proximity to the rest of the network.
 A "mobile ad hoc network" (MANET) is an autonomous system of
mobile routers (and associated hosts) connected by wireless links
forming an arbitrary graph. Routers are free to move randomly and
organize themselves arbitrarily; network topology may change
rapidly and unpredictably. May operate in a stand-alone fashion, or
may be connected to the Internet.
 An ad hoc network can be regarded as a “spontaneous network”: a
network that automatically “emerges” when nodes gather together
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MANET – Mobile Ad hoc NETworks
B
C
A
D
- Mobility
- Self configuring and healing
- High capacity
- Independent of public infrastructure - Relaying
- Internet compatible standards-based wireless systems
- Rapid Deployment
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Network Architecture
 Flat network
infrastructure
 Multi-layered network
infrastructure
Cluster
Head
Cluster
Head
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Cluster
Head
Applications of Ad Hoc Networks
 Personal communications
 Cell phones, laptops
 Cooperative environments
 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
Requirements
 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 time ensuring an
efficient resource usage
 That the most important traffic still has its QoS parameters
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 on power
 Need QoS aware routing
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Why QoS is Hard in Mobile Ad Hoc Networks?
Video frame without QoS Support
Video frame with QoS Support
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Why QoS is Hard in Mobile Ad Hoc Networks?
 Dynamic network topology
 Flow stops receiving QoS provisions due to path disconnections
 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 support in Mobile
Ad Hoc Networks
 Because of the unique characteristics of the ad-hoc environment three
models provide some good insight into the issues of QoS in MANETs
 These models provide a comprehensive solutions, namely
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FQMM
INSIGNIA
SWAN
FQMM
INSIGNIA
SWAN

Can be integrated
with multiple routing
protocols
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
Flexibility!
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-flow granularity on IntServ
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and per-class granularity of DiffServ
Adopts DiffServ, but improves the per-class granularity to per-flow granularity 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.
core
 Three types of nodes defined
 Ingress (transmit)
 Interior (forward)
 Egress (receive)
ingress
2
4
3
1
egress
6
5
13
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Comparison
Best-Effort
Diffserv
Intserv
Service
• Connectivity
• No isolation
• No guarantees
• Per aggregation
isolation
• Per aggregation
guarantee
• Per flow isolation
• Per flow guarantee
Service Scope
• End-to-end
• Domain
• End-to-end
Complexity
• No set-up
• Long term setup
• Per flow setup
Scalability
• Highly scalable
• (nodes maintain
only routing state)
• Scalable (edge
• Not scalable (each
routers maintains
router maintains
per aggregate state; per flow state)
core routers per
class state)
INSIGNIA – MANETs QoS Signaling
 First signalling 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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INSIGNIA – OPTION Field
 Supports in-band signaling by adding a new option field in the IP header to carry
the signaling control
 Reservation Mode (REQ/RES): indicates whether there is already a reservation for
this packet.
 If “no”, the packet is forwarded to INSIGNIA Module which in coordination
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 allowed resources.
 Bandwidth Request (MAX/MIN): indicates the requested amount of bandwidth.
Reservation
Mode
Service
Type
Payload
Indicator
Bandwith
Indicator
REQ/RES
RT/BE
RT/BE
MAX/MIN
1 bit
1 bit
1 bit
1 bit
Bandwith Request
MAX
MIN
16 bits
The INSIGNIA OPTION field
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INSIGNIA – Bottleneck Node

During the flow
reservation process a node
may be a bottleneck:
The service will degrade
from RT/MAX -> RT/MIN.
reservation/service/bandwidth
bottleneck node
REQ/RT/MAX
REQ/RT/MIN
MD
REQ/RT/MAX
M2
M3
M1
Ms
REQ/RT/MIN
M4
M5

If M2 is heavy-loaded it may also degrade the service level to
BE/MIN where there is actually no QoS.
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SWAN - Stateless Wireless Ad Hoc Networks
 An alternative to INSIGNIA with improved scalabilities properties
 Is a stateless network scheme designed specifically for MANETs with no need to
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process complex signaling, or to keep per-flow information, 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 DSCPs with known PHB (based on
bandwidth requirement) to facilitate extranet QoS
May decide to demote part of the real-time traffic to best-effort service due to lack
of resources
The transmission rate for the best-effort traffic is locally estimated and adjusted to
accommodate the bandwidth required by Real Time traffic
Supports source-based admission control and distributed congestion control for
real-time traffic
Uses Explicit Congestion Notification (ECN)
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Ad hoc QoS interconnectivity with fixed
network
 Ad-Hoc network needs to cling to a host network in order to gain access to
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the internet
Co-operation between ad hoc network and the host network can facilitate
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 INSIGNIA, SWAN, or FQMM,
while host network may decide to implement DiffServ or IntServ
Ad-hoc networks rely on the host network resources and services in order
to access to the outside world
The host network provides support for the ad-hoc by providing access to
specific domain services and agreements
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Conclusion
 In this lecture, we have discussed different existing QoS model for
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wireless ad-hoc networks
INSIGNIA, SWAN and FQMM, each model provide the basics for a
more comprehensive model
Mobile nodes can connect to the Internet gateways of different types,
providing different QoS
Classified different approach with respect to different mobility
scenarios
In order to achieve an end-to-end QoS approach, QoS information in
both fixed and ad-hoc networks should be involved
This demands an interaction between these sections
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References
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[1] Towards End-to-End QoS in Ad-Hoc Networks Connected to Fixed Networks, David
Remondo Catalonia Univ. of Technology (UPC)
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[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 Thomas Kunz,
Carleton University
[4] A Glance at Quality of Services in Mobile Ad-Hoc Networks, Zeinalipour-Yazti
Demetrios ([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 networks, Lei
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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Assignment #10
 Write note on the topics highlighted in Yellow.
Q&A
 ?