2C04 DECUS IT-Symposium 2006 Andreas-Roos · Consideration of extended and novel security & privacy...
Transcript of 2C04 DECUS IT-Symposium 2006 Andreas-Roos · Consideration of extended and novel security & privacy...
IT-Symposium 2006 17. Mai 2006
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DECUS IT-Symposium 2006 in Neuss – Andreas RoosPotentials and challenges of multi-hop networksMay 17th, 2006, slide 1
DECUS IT-Symposium 2006
Potentials and challenges of multi-hop networks considering as example ad hoc and mesh networks
Andreas Roos, Profn. Sabine Wieland, Michael Flegl
Düsseldorf/NeussMay 17th, 2006
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ContentOverview
� Introduction to wireless multi-hop networks� Ad hoc networks
� Mesh networks
� Benefit of wireless multi-hop networks
� Routing mechanisms
� Application scenarios and existing solutions
� Standardisation activities
� Challenges
� Conclusions
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Wireless multi-hop networksWhat are wireless multi-hop networks?
� Wireless communication between nodes – no wired connectivity.
� Multipoint-to-multipoint communication.
� Communication among nodes.� Single-hop communication – always possible.
� Multi-hop communication – usage of suitable routing protocols.
� Each node contains routing functionalities.
� Self-organizing network structure.� Distributed intelligence – no centralized managing.
� Each node is responsible for routing and connection establishment.
� Dynamic network topology.� Each node can be source, router and destination.
� Technologies for setup multi-hop networks� E.g. Bluetooth, WLAN, WiMAX.
Node (Source)
Node (Destination)
Node
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Wireless multi-hop networksClassification of multi-hop networks
There are different kinds of multi-hop networks with different characteristics and
applications:
� Mobile Ad hoc Networks (MANETs)
� Wireless Mesh Networks (WMNs)
� Sensor networks
Important differences between ad hoc, wireless mesh networks and sensor networks:
� Routing protocols
� Networks equipment
� Energy behaviour
� Mobility support
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InternetInternet
Wireless multi-hop networksAd hoc network – characteristics
Mobile Ad hoc networks (MANETs) – client mesh networks
� Spontaneous formed networks consisting of mobile and wireless devices, e.g.
laptops, PDAs or mobile phones.
� High mobility – mobile and wireless devices.
� Limited energy supply – usage of battery or rechargeable battery.
� No infrastructure equipment necessary, e.g. base station, access point.
� Limited bandwidth.
� Application scenarios� Mainly used for local communications – connectivity to external networks needs special
gateways.
Gateway
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Wireless multi-hop networksMesh network – characteristics
Wireless Mesh Networks (WMNs) – Infrastructure mesh network
� Network consists of infrastructure components, e.g. base stations.
� Low mobility.
� “Unlimited” energy supply – power supply via mains supply.
� Application scenarios� Transport network with connection to external networks, e.g. Internet.
� Separates access network and backhaul network, e.g. user access via 802.11 b/g and backhaul
802.11a.
InternetInternet
Backhaul connection
Access connection
Access networkBackhaul network
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DECUS IT-Symposium 2006 in Neuss – Andreas RoosPotentials and challenges of multi-hop networksMay 17th, 2006, slide 7
Wireless multi-hop networks General characteristics
� Dynamic network topology� Mobility of user devices (ad hoc network).
� Backbone scalability of access network (mesh network).
� Partitioning and merging of networks.
� Changing characteristics of wireless channel (fading).
� Asymmetric / unidirectional connectivity� Quality of connection among source and destination can be different.
� Security mechanisms are difficult to apply� Interception of wireless channel.
� In case of multi-hop routing packets are processed by intermediate nodes.
Consideration of extended and novel security & privacy mechanisms
Consideration Integration of Quality of Service (QoS) mechanisms
Consideration of multi-hop routing mechanisms
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� Low infrastructure costs� Wiring is a cost intensive factor.
� Wiring each Internet access point is expensive.
� Cheap establishment of multi-hop networks, e.g. IEEE 802.11 equipment.
� Multi-hop networks can reduce the number of expensive Internet connections.
� Many multi-hop nodes share few Internet connections.
� Additional multi-hop nodes can be easy installed.
� Reliability and Robustness� Redundant paths within the multi-hop network.
� Low transmit power� Small distances between nodes.
� Energy efficient, min. interference and spatial reuse.
� Easy extensible� No wired installation necessary.
� Auto configuration of multi-hop nodes.
Benefits of multi-hop networks (part 1)Overview
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� Coverage extension of base stations� Intermediate nodes forward packets to the Gateway.
� Far users can be covered.
� Enhancement of network performance� Higher performance for far users
� Poor performance on direct link to the base station.
� Higher performance on short links.� Higher performance for nodes without LOS (Line of Sight)
� Poor direct link because of obstacles.
� Routing around obstacles.
Benefits of multi-hop networks (part 2)Overview
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Routing in multi-hop networksClassification of routing protocols
Proactive Hybrid Reactive
•DSDVDSDVDSDVDSDV
•OLSROLSROLSROLSR
•STARSTARSTARSTAR
•TBRPF TBRPF TBRPF TBRPF
•WRPWRPWRPWRP
•…
•DSRDSRDSRDSR
•AODVAODVAODVAODV
• TORATORATORATORA
• SSRSSRSSRSSR
• …………
Multi-hop routing protocols
•ZRPZRPZRPZRP
•CBRPCBRPCBRPCBRP
•FSRFSRFSRFSR
•CEDARCEDARCEDARCEDAR
•…………
� Proactive: Routing information to all network nodes always available.
� Reactive: Routing information to destination established on demand.
� Hybrid: Combines advantages of proactive and reactive routing protocols.
AODV (Ad hoc On-Demand Distance Vector)
OLSR (Optimized Link State Routing)
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Routing in ad hoc networks (part 1)Considering as example AODV
RREQ
AODV (Ad hoc On-Demand Distance Vector) – part 1:
� Source (orange node) sends Route Request message (RREQ).
� RREQ message is broadcasted within the network (nodes).
� Destination (blue node) receives RREQ message.
Node (Source)
Node (Destination)
Node
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RREP
AODV Route Discovery – part 2:
� Destination (blue node) sends Route Reply message (RREP) to source via unicast.
� RREP is send to source via shortest route.
Node (Source)
Node (Destination)
Node
Routing in ad hoc networks (part 2)Considering as example AODV
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Routing in mesh networks (part 1)Considering as example OLSR
Benefit of Multipoint Relaying within OLSR (Optimized Link State Routing)
� Reduce the number of duplicate retransmissions while forwarding a
broadcast packet.
� Restricts the set of nodes retransmitting a packet from all nodes to a
subset of all nodes.
Multipoint Relay (MPR) selection
� Each node selects and keeps its own set of Multipoint relays.
� Rule of OSLR:� For all 2 hop neighbors n there must exist a MPR m.
� So n can be contacted via m.
Forwarding of traffic
� All nodes registers and maintains their MPR selectors.
� Rule of OSLR:� If OLSR-packet is received from a MPR selector
� Then all messages contained in that packet are to be forwarded if TTL > 0.
m
m
n
n
n
n
m
m
n
n
n
nForwarded traffic
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Routing in mesh networks (part 2)Considering as example OLSR
Distribution of link-state information
� Traditional link-state routing protocols flood the network with link-state information
(Regular flooding).
� OLSR optimises this behaviour – Multipoint Relay flooding (MPR flooding)� Only MPRs selectors are declared in link-state messages – minimises size of link-state messages.
� Only nodes selected as MPRs generate link-state messages – minimises amount of link-state
messages.
� All nodes select their own MPRs� Number of MPR subset depends on network topology.
Regular flooding MPR floodingNetwork structure
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DECUS IT-Symposium 2006 in Neuss – Andreas RoosPotentials and challenges of multi-hop networksMay 17th, 2006, slide 15
Application scenarios of wireless multi-hop networksOverview
Ad hoc networks
� Civil applications� Spontaneous network forming (e.g. Conference, Meetings, Enterprises)
� Rescue missions in disaster areas (e.g. destroyed infrastructure)
� Sensor networks (e.g. observation and monitoring)
� Inter car communication (e.g. FleetNet)
� Personal Area Networks (e.g. mobile phone, camera, printer, laptop).
Mesh networks
� Civil applications� Broadband Internet access
� In-house networking
� Extensions of network structures, e.g. Hotspots, cellular networks.
Ad hoc & mesh networks
� Military application� Communication between mission troops (e.g. soldier, tank).
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Application scenario for ad hoc networksInter car communication
� Car-to-Car Personal Communication � Entertainment, e.g. telephone call, short messaging, chat.
� Car-to-Car Traffic Safety Communication� Warnings, emergency call, traffic jam information, platoon etc..
� Car-to-Infrastructure Personal Communication� Data download via Hotspots, payment of multi-storey car park, Location Based Services etc..
� Car-to-Infrastructure Traffic Safety Communication� Communication with traffic lights, traffic signs or barriers, downloading of actual traffic
information or car diagnostics.
SourceSourceSourceSource: : : : www.carwww.carwww.carwww.car----totototo----car.orgcar.orgcar.orgcar.org SourceSourceSourceSource: Andreas L: Andreas L: Andreas L: Andreas Lüüüübke, Volkswagen AG, Wolfsburgbke, Volkswagen AG, Wolfsburgbke, Volkswagen AG, Wolfsburgbke, Volkswagen AG, Wolfsburg
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Application scenarios of wireless mesh networksBroadband Wireless Internet Access (BWIA)
� Broadband internet access is not available everywhere� In places installed infrastructure does not support broadband internet access like DSL.
� Installing of required infrastructure is expensive.
� Wireless mesh networks offers important advantages� Low costs of Investments – no wired infrastructure needed.
� Customer Coverage – LOS to the base station is not required.
� Fast deployment – usage of wireless equipment.
� Reliability – connectivity via multiple wireless links.
� Communication among mesh nodes, e.g. for community and neighbourhood networking.
� Application scenarios� Providing of wireless DSL in undersupplied DSL areas – wireless technology e.g. WiMAX.
InternetInternet
InternetInternet
In-house networking
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Application scenarios of wireless mesh networksIn-house networking
� In-house coverage is difficult� Interference of propagation due to obstacles – walls, objects, people, etc.
� Dead zones without coverage.
� Full wireless coverage is expensive – every access point (AP) needs wired connection to a central
hub.
� In-house networking with wireless mesh networks� All devices within the home network can share one Internet connection.
� Individual and flexible setup of mesh equipment.
� Mesh APs only need power supply.
� Application scenarios� Building automation – e.g. video observance, measurement value logging.
� Broadband in-house networking – backbone (data backup and storage) and support of
multimedia applications (e.g. video streaming, conferencing, online gaming).
InternetInternet
Mesh networkAccess network
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Application scenarios of wireless mesh networksCellular backhaul
� Bandwidth demand is constantly increasing� Number of users increases.
� Supply of multimedia services and applications increases.
� Mesh networks provides this demand� Flexible scaling and splitting of cells.
� Increasing network capacity and coverage.
� Application scenarios� Flexible connection of cellular BSs to the core network via mesh connections.
� Extension of cellular networks
� Easy and cheap installation of new cell locations
Cellular core
network
Cellular core
network
Backhaul connection
Extension of BackhaulAccess connection to network
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Application scenarios of wireless mesh networksExisting mesh solutions
SourceSourceSourceSource: Microsoft, http://: Microsoft, http://: Microsoft, http://: Microsoft, http://research.microsoft.comresearch.microsoft.comresearch.microsoft.comresearch.microsoft.com/mesh//mesh//mesh//mesh/
BelAir Networks deployment example.
Challenges:� 6 building complexes, 529 rooms, over 23
acres.
� Limited room for deployment on the ocean
side and locations for mounting power
access.
Result:� Full WiFi coverage of the Sheraton property
with only 13 mesh boxes.
SourceSourceSourceSource: BelAir : BelAir : BelAir : BelAir networksnetworksnetworksnetworks, , , , http://http://http://http://www.belairnetworks.comwww.belairnetworks.comwww.belairnetworks.comwww.belairnetworks.com////
Microsoft� Self-Organizing Neighborhood Wireless Mesh
Networks – sharing of Internet access, local
communication.
� Microsoft focus on Software not Hardware.
� Goal is to implement the multihop functionality
in Microsoft Windows
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Standardisation activities – IEEE Wireless multi-hop networks
802.16-2004 (802.16a)802.15.4 (Zigbee)
802.15.5 (WPAN Mesh)
802.11s (ESS Mesh
Networking)Task GroupTask GroupTask GroupTask Group
802.16a ratified in 01/2003
802.16-2004 ratified in 06/2004
802.16e-2005 approved in
12/2005
802.15.4 standardized 11/2003
802.15.5 05/2004
First meeting 06/2004DatesDatesDatesDates
Mesh already included in the
current (802.16-2004) standard
– many limitations and open
issues
Proposals have been submitted
to enhance the 802.16 mesh
New Relay Task Group 802.16j
(03/2006)
802.15.4: native mesh support
802.15.5: Begin of
standardization process:
determine the necessary
mechanisms (in PHY & MAC)
WPANs to enable mesh
networking.
Joint proposal of SEE Mesh and
Wi-Fi Mesh – starting point of
802.11s standard
Standard is targeted to be
approved by 2008
Current Current Current Current
statestatestatestate
Phy & Mac layerPhy & Mac layerPhy & Mac layerFocusFocusFocusFocus
Metropolitan area networks802.15.4: Sensor networks
802.15.5: Wireless Personal area
networks
Local Area networksNetwork Network Network Network
typetypetypetype
802.16802.16802.16802.16802.15802.15802.15802.15802.11802.11802.11802.11
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Standardisation activities – IETFWireless multi-hop networks
� A lot of multi-hop routing protocols are developed, e.g.� AODV (Ad hoc On-Demand Distance Vector)
� DSR (Dynamic Source Routing)
� DSDV (Destination Sequenced Distance Vector), etc.
� The focus of these protocols are mobile ad hoc networks (MANETs) and thus
optimized for:� High mobility
� Dynamic networks
� Less overhead
� Energy efficient
� Low bandwidth
The behaviour of these protocols has to be optimized for WMNs
Currently no standardization activity specialized on mesh routing protocols
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Challenges (part 1)Research activities
Security & privacy
Wireless medium simplifies attacks.
� Secure communication between multi-hop nodes has to be established to provide� Confidentiality – Access to information for allowed users only.
� Integrity – Information is complete and not be changed by a third person.
� Authenticity – A person is assignable to an information.
� Non-repudiation – To ensure that transferred information has been sent by a person claiming to
have transferred this message.
� Privacy – There are different parts of privacy like,
� Communication privacy – Hide exchanged information of person (e.g. voice)
� Location privacy – Hide residence of person (actual location/address).
� Identity privacy – Hide personal information of person (user name, password).
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Challenges (part 2)Research activities
Security & privacy
� Routing protocols for wireless multi-hop networks have to be improved� Avoiding malicious users and freeloaders.
� Guard against Dos (Denial of Service) attacks.
� Congestion of network by malicious users.
� Avoiding of man-in-the-middle attacks.
� Malicious multi-hop node is placed between two valid multi-hop entities.
� Forwarding of manipulated data.
� Changing of routing tables by misuse of routing messages.
� Prevention of passive monitoring.
� Ethernet sniffing and eavesdropping.
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Multi-hop routing
� Route selection� Most of the current routing protocols only consider hop count as metric.
� Further possible metrics: traffic situation, delay, jitter, bandwidth, link quality, error rate, etc.
� Load balancing� Distribution of network traffic – multi-path routing.
� Considering congested network areas.
� Backup routes� Maintenance of communications between nodes.
� Routing Security
Challenges (part 3)Research activities
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Quality of Service (QoS)
� Resource reservation� Problematic of wireless channel
� Fast changing wireless conditions.
� Multi-hop network characteristics
� Unknown behaviour of wireless condition within the next hop.
� Resource allocation – Scheduling� Fairness
� Spatial reuse
� Interference avoidance
� Actual channel conditions.
� Capacity enhancement on PHY layer� Directional and smart antennas
� MIMO (Multiple Input Multiple Output) systems.
Challenges (part 4)Research activities
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Conclusion Wireless multi-hop networks
� Introduction to wireless multi-hop networks� Ad hoc networks
� Mesh networks
� Benefit of wireless multi-hop networks
� Routing mechanisms� AODV – Proactive routing protocol
� OLSR – Reactive rouging protocol
� Application scenarios and existing solutions� Ad hoc networks – Inter car communication
� Mesh networks – Broadband Internet access
– In-house networking
– Extensions of network structures
� Brief overview of standardisation activities� IEEE and IETF
� Issues of challenges� Security & privacy
� Multi-hop routing
� Quality of service
Huge potential of
wireless multi-hop
networks for future
communication
systems,
however, a lot of
developments
have to be done!
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Thank you for your attention!
�Questions & annotations?
Andreas Roos
Office address: Deutsche Telekom Fachhochschule Leipzig
Gustav-Freytag-Straße 43-45
04277 Leipzig
Phone: +49 (0)6151/937-3381
Fax: +49 (0)6151/937-4611
E-mail: [email protected]
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Backup
DECUS IT-Symposium 2006 in Neuss – Andreas RoosPotentials and challenges of multi-hop networksMay 17th, 2006, slide 30
� AODV - Ad hoc On-Demand Distance Vector
� CBRP - Cluster Based Routing Protocol
� CEDAR - Core Extraction Distributed Ad hoc Routing
� DSR - Dynamic Source Routing protocol
� DSDV - Destination-Sequenced Distance Vector
� FSR - Fisheye State Routing protocol
� OLSR - Optimized Link State Routing protocol
� SSR - Signal Stability Routing protocol
� STAR - Source Tree Adaptive Routing protocol
� TBRPF - Topology Broadcast based on Reverse-Path Forwarding routing
protocol
� TORA - Temporally-Ordered Routing Algorithm routing protocol
� WRP - Wireless Routing Protocol
� ZRP - Zone Routing Protocol
AbbreviationsRouting protocols