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Wave Relay: Multi-hop Wireless Ad hoc Network Baruch Awerbuch, David Holmer, Herbert Rubens {baruch...
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Transcript of Wave Relay: Multi-hop Wireless Ad hoc Network Baruch Awerbuch, David Holmer, Herbert Rubens {baruch...
Wave Relay:Wave Relay:Multi-hop Wireless Ad hoc NetworkMulti-hop Wireless Ad hoc Network
Baruch Awerbuch, David Holmer, Baruch Awerbuch, David Holmer, Herbert RubensHerbert Rubens
{baruch dholmer herb}@cs.jhu.edu
Johns Hopkins UniversityDepartment of Computer Science
www.cnds.jhu.edu/archipelago/
Goals: Design a system that…Goals: Design a system that… Supports a large number of nodesSupports a large number of nodes
thousandsthousands Moving at high speeds Moving at high speeds
greater then 40 mphgreater then 40 mph In an urban environmentIn an urban environment
High multi-path, rapidly fluctuating channelsHigh multi-path, rapidly fluctuating channels Running real-time applicationsRunning real-time applications
Voice, video, interactive distributed applicationsVoice, video, interactive distributed applications With or without help from fixed infrastructureWith or without help from fixed infrastructure
If its available use it to be more efficientIf its available use it to be more efficient
Wave Relay Test-bedWave Relay Test-bed Over 50 Wave Relay Routers deployed Over 50 Wave Relay Routers deployed
across JHU Campusacross JHU Campus Urban City EnvironmentUrban City Environment Internet Access, Ad hoc Access Points, Internet Access, Ad hoc Access Points,
Voice over IPVoice over IP Mobility testing from automobilesMobility testing from automobiles
System tested at Holcim Industrial Plant System tested at Holcim Industrial Plant (Chicago, IL)(Chicago, IL)
Complex propagation environment Complex propagation environment Massive multi-pathMassive multi-path Enabled real-time industrial process Enabled real-time industrial process
controlcontrol Currently Deployed Custom ApplicationsCurrently Deployed Custom Applications
Military Distributed Battlefield MappingMilitary Distributed Battlefield Mapping GPS based interactive mapGPS based interactive map Eventual reliabilityEventual reliability
Locality Specific Messaging SystemLocality Specific Messaging System GPS based messaging systemGPS based messaging system Messages targeted to any user at a Messages targeted to any user at a
specific locationspecific location
Wave Relay DeviceWave Relay Device
Pulse Protocol Pulse Protocol [Infocom’04, Milcom’04, WONS’05][Infocom’04, Milcom’04, WONS’05] Scalable ad hoc routing protocolScalable ad hoc routing protocol Active path trackingActive path tracking Based on Tree Routing strategyBased on Tree Routing strategy
Medium Time Metric Medium Time Metric [MONET,WONS’04][MONET,WONS’04] High Throughput Path SelectionHigh Throughput Path Selection Increased Path ElasticityIncreased Path Elasticity Efficient Multi-rate OperationEfficient Multi-rate Operation
Leader Election Algorithm Leader Election Algorithm Handles merge, partition, failureHandles merge, partition, failure
Embedded Linux Distribution Embedded Linux Distribution Less then 8 MB storage requirementLess then 8 MB storage requirement
Linux Kernel Module 2.4 and 2.6 compatibilityLinux Kernel Module 2.4 and 2.6 compatibility Operates at layer 2Operates at layer 2 Distributed virtual switch architecture provides Distributed virtual switch architecture provides
seamless bridgingseamless bridging
Embedded Single Board ComputerEmbedded Single Board Computer NS Geode SC1100 266 MHz ProcessorNS Geode SC1100 266 MHz Processor 64 Mb Ram onboard64 Mb Ram onboard 2 mini-PCI interfaces2 mini-PCI interfaces 1 Compact flash interface1 Compact flash interface Serial portSerial port 10/100 Ethernet10/100 Ethernet Hardware WatchdogHardware Watchdog Power over EthernetPower over Ethernet
+7V to +18V DC Input+7V to +18V DC Input Atheros 802.11g/b Wireless CardAtheros 802.11g/b Wireless Card
400 mW (26 dBm) output power400 mW (26 dBm) output power 16 MB Industrial Compact Flash16 MB Industrial Compact Flash
Stores OS & Wave Relay softwareStores OS & Wave Relay software Garmin GPS 16 receiverGarmin GPS 16 receiver Li-Ion Battery PackLi-Ion Battery Pack
~20 hours continuous runtime~20 hours continuous runtime Industrial NEMA 67 EnclosureIndustrial NEMA 67 Enclosure
4 N-type antenna mounts4 N-type antenna mounts 2 Ethernet Ports2 Ethernet Ports (6) protection against dust(6) protection against dust (7) water submersible(7) water submersible
Software Hardware
Existing ApproachesExisting Approaches
0 200 400 600 800 1000 1200 1400 1600 1800 2000-40
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5
10
0 200 400 600 800 1000 1200 1400 1600 1800 2000-40
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0 200 400 600 800 1000 1200 1400 1600 1800 2000-20
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0 200 400 600 800 1000 1200 1400 1600 1800 2000-20
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Source
Receivers
Destination
• Multi-path fading & shadowing
• Rapidly changing channel conditions
• On-demand protocols have no knowledge of channels conditions
• A RREQ packet provides only a single sample of a complex distribution
On-Demand Protocols (AODV, DSR)
• Channel is continuously changing
• Continuous flooding from every node in the network
Link State Protocols (OLSR, TBRPF)
Urban Channel Environment
You can not accurately track channel with control packets!
The Pulse ProtocolThe Pulse Protocol Proactive ComponentProactive Component
Tracks minimum amount of information to avoid flooding for Tracks minimum amount of information to avoid flooding for route establishment and maintenanceroute establishment and maintenance
Periodic flood operation (similar to Hello Protocol)Periodic flood operation (similar to Hello Protocol) Rebuilds spanning treeRebuilds spanning tree Estimates neighbors, density, SNR, loss rates, capabilities, Estimates neighbors, density, SNR, loss rates, capabilities,
number of radios, MTM metricnumber of radios, MTM metric On-Demand ComponentOn-Demand Component
Route establishmentRoute establishment Using only UNICASTS!Using only UNICASTS!
Gratuitous mechanismGratuitous mechanism Neighbors promiscuously monitor packetsNeighbors promiscuously monitor packets Metric tracked at the speed of data packets NOT control packets!Metric tracked at the speed of data packets NOT control packets! Path switches as metrics changePath switches as metrics change Local changes in connectivity only generate Local changes in connectivity only generate locallocal traffic traffic
Unlike BOTH on-demand and link state protocolsUnlike BOTH on-demand and link state protocols
Ad hoc NodesAd hoc Nodes
Network ConnectivityNetwork Connectivity
Pulse FloodPulse Flood
Spanning TreeSpanning Tree
Source and Destination Need to Source and Destination Need to Establish a PathEstablish a Path
Pulse Response Sent to RootPulse Response Sent to Root
Destination Paged on Next PulseDestination Paged on Next Pulse
Destination Sends Pulse ResponseDestination Sends Pulse Response
Initial Path: Tree ShortcutInitial Path: Tree ShortcutTree Shortcut Path
3 HopsShortest Path
2 Hops
This is the initially selected path of the Pulse protocol.
Path Optimization: Gratuitous ReplyPath Optimization: Gratuitous ReplyOptimized Path
2 HopsShortest Path
2 Hops
Node sends gratuitous reply
Proactive Route MaintenanceProactive Route Maintenance
Proactive Route MaintenanceProactive Route Maintenance
Proactive Route MaintenanceProactive Route Maintenance
Pulse Protocol ConceptsPulse Protocol Concepts AggregationAggregation – for – for scalabilityscalability
Spanning tree represents a compressed view of the network Spanning tree represents a compressed view of the network topologytopology
Pro-active component maintains the minimum amount of Pro-active component maintains the minimum amount of information to allow efficient route establishmentinformation to allow efficient route establishment
De-AggregationDe-Aggregation – for – for efficiencyefficiency The routing metric is tracked at the speed of the data flowThe routing metric is tracked at the speed of the data flow Changes to the metric are only reported locallyChanges to the metric are only reported locally Routes are continuously adjusted as the metrics changeRoutes are continuously adjusted as the metrics change High speed accurate route tracking is essentially an on-demand High speed accurate route tracking is essentially an on-demand
decompression of the topologydecompression of the topology However, it occurs ONLY in areas of the network with active data However, it occurs ONLY in areas of the network with active data
flowsflows Result: a scalable routing structure which tracks paths at Result: a scalable routing structure which tracks paths at
the speed of the data flowthe speed of the data flow
Future WorkFuture Work Security (NDSS 2005)Security (NDSS 2005)
Wormholes, black-holes, flood rush, replayWormholes, black-holes, flood rush, replay ProvideProvide
Node authenticationNode authentication End-to-end encryptionEnd-to-end encryption Broadcast/Routing EncryptionBroadcast/Routing Encryption Efficient node addition/removalEfficient node addition/removal
Distributed commit (CNDS-02)Distributed commit (CNDS-02) Consistent, persistent, group communicationConsistent, persistent, group communication e.g. coordinated battlefield view and controle.g. coordinated battlefield view and control
Opportunistic Gradient ForwardingOpportunistic Gradient Forwarding
Thank You!Questions??
http://www.cnds.jhu.edu/archipelago/
(baruch,dholmer,herb)@cs.jhu.edu
Wave Relay Ad hoc Networking Test-bedhttp://www.cnds.jhu.edu/research/networks/archipelago/testbed/testbed.html
Secure Ad hoc Networking for Industrial Process Controlhttp://www.cnds.jhu.edu/research/networks/archipelago/industrial/industrial.html
Baruch Awerbuch, David Holmer, Herbert RubensBaruch Awerbuch, David Holmer, Herbert Rubens
Minimum Hop MetricMinimum Hop Metric(Traditional Technique)(Traditional Technique)
Not designed for multi-rate networksNot designed for multi-rate networks A small number of long slow hops provide A small number of long slow hops provide
the minimum hop paththe minimum hop path These slow transmissions occupy the These slow transmissions occupy the
medium for long times, blocking adjacent medium for long times, blocking adjacent senderssenders
Selecting nodes on the fringe of the Selecting nodes on the fringe of the communication range results in reduced communication range results in reduced reliabilityreliability
New Approach:New Approach: Medium Time Metric (MTM) Medium Time Metric (MTM)
Assigns a weight to each link proportional Assigns a weight to each link proportional to the amount of medium time consumed to the amount of medium time consumed by transmitting a packet on the linkby transmitting a packet on the link
Enables the Pulse protocol to discover the Enables the Pulse protocol to discover the path that minimizes total transmission timepath that minimizes total transmission time
MTM ExampleMTM Example
Source
Destination
11 Mbps
5.5 Mbps
2 Mbps
1 Mbps
1 0.85 Mbps
2.5ms
3.7ms
7.6ms
13.9ms
11 Mbps
5.5 Mbps
2 Mbps
1 Mbps
13.9ms
Medium Time Usage
4.55 Mbps
3.17 Mbps
1.54 Mbps
0.85 Mbps
Path ThroughputPath Medium Time Metric (MTM)
= 13.9 ms
Link Throughput
MTM ExampleMTM Example
Source
Destination
11 Mbps
5.5 Mbps
2 Mbps
1 Mbps
5.5 + 2
1
1.04 Mbps
0.85 Mbps
2.5ms
3.7ms
7.6ms
13.9ms
11 Mbps
5.5 Mbps
2 Mbps
1 Mbps
7.6ms3.7ms
13.9ms
= 11.3 ms
Medium Time Usage
4.55 Mbps
3.17 Mbps
1.54 Mbps
0.85 Mbps
Path ThroughputPath Medium Time Metric (MTM)
= 13.9 ms
Link Throughput
MTM ExampleMTM Example
Source
Destination
11 Mbps
5.5 Mbps
2 Mbps
1 Mbps
11 + 2
5.5 + 2
1
1.15 Mbps
1.04 Mbps
0.85 Mbps
2.5ms
3.7ms
7.6ms
13.9ms
11 Mbps
5.5 Mbps
2 Mbps
1 Mbps
2.5ms 7.6ms
7.6ms3.7ms
13.9ms
= 10.1 ms
= 11.3 ms
Medium Time Usage
4.55 Mbps
3.17 Mbps
1.54 Mbps
0.85 Mbps
Path ThroughputPath Medium Time Metric (MTM)
= 13.9 ms
Link Throughput
MTM ExampleMTM Example
Source
Destination
11 Mbps
5.5 Mbps
2 Mbps
1 Mbps
11 + 11
11 + 2
5.5 + 2
1
2.38 Mbps
1.15 Mbps
1.04 Mbps
0.85 Mbps
2.5ms
3.7ms
7.6ms
13.9ms
11 Mbps
5.5 Mbps
2 Mbps
1 Mbps
2.5ms 2.5ms
2.5ms 7.6ms
7.6ms3.7ms
13.9ms
= 5.0 ms
= 10.1 ms
= 11.3 ms
Medium Time Usage
4.55 Mbps
3.17 Mbps
1.54 Mbps
0.85 Mbps
Path ThroughputPath Medium Time Metric (MTM)
= 13.9 ms
Link Throughput
MTM AdvantagesMTM Advantages Paths which minimize network utilization, Paths which minimize network utilization,
maximize network capacitymaximize network capacity Global optimum under complete interferenceGlobal optimum under complete interference Excellent heuristic in even larger networksExcellent heuristic in even larger networks
Avoiding low speed links inherently Avoiding low speed links inherently provides increased route stabilityprovides increased route stability High speed links operate with greater margin High speed links operate with greater margin
and are more elastic under changesand are more elastic under changes