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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Luca Leschiutta
Politecnico di Torino, Italy
www.adhocsys.org
A pragmatic QoS solution inwireless mesh networks: the
ADHOCSYS approach
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Agenda
Why ADHOCSYS?
Project objectives
Architecture and scenarios
QoS issues
Concluding remarks
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Objectives Provide a reliable broadband Internet
access solution to people who live in rural
and mountain regions where ADSL is notavailable or non-profitable
Consider also people living outside towns
and villages
Consider also occasional visitors
Cheap solution: ability to use off-the-shelf
hardware equipments; open source
software
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Network architecture The ADHOCSYS network consists of two levels of
network hierarchy
An access network in each town/village connectingall inhabitants
A backbone connecting together towns and villages
The backbone network consists of few longwireless links while the access network consists of
many short links
Internet gateways might be connected directly to
the backbone or the access network
Depending on some external factors this general
architecture may lead to different scenarios
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Architecture illustration
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
QoS goal and solutions Goal: guarantee access to an essential set of
services under all conditions while maximizingnetwork utilization for other types of services
Two implementation directions
identification and implementation of mechanisms to
be used to guarantee the availability of essential
services to all ADHOCSYS end-users, includingpriority classification, Connection Admission
Control (CAC), traffic monitoring, and QoS metrics.
selection and implementation of application-level
techniques for multimedia services, to maximizethe perceived quality based on network load and
link status
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Eight QoS classes
Class I: applications which require strong latency
constraints and low bandwidth such as VoIP and
chatting applications (jabber, Yahoo! Messenger, etc). Class II: applications requiring high throughput such
as transaction-processing applications.
Class III: interactive and best-effort type applications
like web-browsing and e-mail.
Class IV: routing and battery information.
Class V: emergency calls.
Class VI: high throughput and latency constraint suchas streaming video.
Class VII: peer-to-peer (P2P) applications.
Class VIII: other types of traffic (unclassified).
QoS Classification
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
The traffic sources could be located eitheroutside or inside the ADHOCSYS network.The first case is more common
The framework is composed of thefollowing mechanisms, which are part ofthe functions of the Access Points
Traffic flow identification Scheduling and buffer management
Traffic load and channel congestion status
measurement
CAC (Connection Admission Control)
Rate adaptation
Traffic Management
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Congestion Management Based on the measurement of the
approximated congestion level the AP node
decides whether the request is accepted ornot
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
802.11e The new EDCA
(Enhanced DCF
Channel Access)mechanism definedin 802.11eimplements four
different queues atMAC layer, and canbe used as amechanism to
provide unequalerror protection todifferent trafficpatterns
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Packet classificationand queueing
START (packet P received)
END (send packet)
P comes from an
ADHOCSYS node?
Tag P (IP TOS)
Linux queueing (HTB)
WMM queueing
P has been tagged?
Y N
N
Y
Deterministic QoS byHTB (HierarchicalToken Bucket)
Probabilistic QoS by
MMM (WirelessMultimedia)
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Structure of the HTB tree Mapping between application classes, application categories
and WMM Access Categories
Root
A B C
I VIIIII IIVIIV VIII
Category
Class
3 (Highest Priority)IV, VA, B
2IIIA
1I, VIB
0 (Best Effort)II, VII, VIIIC
WMM ACClassCategory
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Ns-2 Simulations Several metrics are considered, includingsystem and MAC throughput, delay atnetwork level and PSNR at application level
The main effort, in this context, has beendevoted to develop the tools to process andanalyze data from the Ns-2 simulationframework.
Our analysis shows that the new EDCA(Enhanced DCF Channel Access)mechanism defined in 802.11e allows to
achieve higher throughput for higher prioritytraffic, and that smart techniques todynamically adapt the retry limit to thenetwork conditions can lead to an increaseof the overall throughput
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Multimedia trafficmanagement
Maximize the perceived quality of multimediaservices without affecting the performance of the
whole network Algorithms for multimedia compression and
transmission often do not consider themechanisms provided by the lower layers for error
protection, scheduling, resource management We have developed a multimedia service cross-
layer framework suitable for ad-hoc networking,for jointly adapting different strategies available at
the various layers, taking into account variousmetrics, such as multimedia quality, consumedpower, and spectrum utilization
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
The following issues are also studied in
the project OLSR Optimization
Security and authentication
Auto-configuration, self-healing andreliability
Standalone power supply and renewable
power supply system Installation
Open source
Other issues in the project
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16th IST Mobile & Wireless Communications Summit
Budapest, Hungary 1-5 July 2007
ADHOCSYS Project IST-2004-026548
Concluding remarks The objective of the ADHOCSYS project is to
provide a reliable broadband Internet accesssolution to people who live in rural and mountainregions where ADSL is not available
The goal for QoS provisioning in ADHOCSYS isto guaranteeing access to an essential set ofservices under all conditions while maximizing
network utilization for other types of services Flow identification, scheduling and queuing
using 802.11/WMM, load measurement, CACare mechanisms used for our QoS solution
Currently, we have finished the implementationphase
A complete real-life pilot network is beingdeployed in Northern Italy