Highly-Resilient, Energy-Highly-Resilient, Energy-EEffifficient Multipath Routing cient Multipath Routing ininWireless Sensor NetworksWireless Sensor Networks
Computer Science Department, UCLAComputer Science Department, UCLAInternational Computer Science Institute, BerkeleyInternational Computer Science Institute, Berkeley
ACIRI, BerkeleyACIRI, Berkeley
AboutAboutPeriodic low-rate flooding of data in
order to allow recovery from failure.Multipaths for energy efficient
recoveryDisjoint multipath schemeBraided multipath schemeBraided multipaths are viable
alternative for energy-efficient recovery from isolated and patterned failures
IntroductionIntroductionDirected DiffusionEarlier work has explored the
design of mechanisms for single-path routing in sensor networks
To route around failed nodes, this work assumed periodic, low-rate, flooding of events that enabled local re-routing around failed nodes
IntroductionIntroductionMultipath routingDisjoint multipathBraided multipathResilienceMaintenance OverheadEvaluating the two mechanisms:
isolated node failures and patterned failures
Direct DiffusionDirect DiffusionDirected Diffusion
Direct DiffusionDirect DiffusionUsing directed diffusion to perform
energy-efficient and robust dissemination of surveillance data samples from sources to sinks
Low rate samplesPath reinforcementRecovery from failure along
reinforcement pathThe problem is low-rate flooding
scheme
Direct DiffusionDirect DiffusionDirect Diffusion for energy-
efficient data samples from source to sinks.
Multipath RoutingMultipath RoutingClassic Multipath Routing usageUsing multipath routing in this paperPrimary pathConstruct and maintain a small
number of alternate paths (without periodic flooding)
When primary path is set up, alternate paths also sets up multipaths which data is send low-rate
No network wide flooding needed
Disjoint MultipathsDisjoint MultipathsSmall number of alternate paths
that are node-disjoint with the primary path, and with each other
How do we realize node disjoint multipaths using localized information alone, and not relying on global topology information?
Primary and alternate path reinforcement
Localized disjoint multipaths are differ from idealized multipaths
Construction of Localized Construction of Localized Disjoint PathsDisjoint Paths
Braided MultipathsBraided MultipathsDisjoint multipaths can be energy
inefficientAlternate paths in a braid are partially
disjoint from the primary path, not completely node-disjoint
For each node on the primary path, find the best path from source to sink that does not contain that node
All paths are called idealized braided
Braided MultipathsBraided MultipathsLocalized technique for
constructing braids. Nodes send reinforcement to
route neighbours.The alternate paths can rejoin
the primary path
Braided MultipathsBraided Multipaths
Braided MultipathsBraided Multipaths
Qualitative ComparisonQualitative ComparisonEnergy/resilience tradeoffs of the two
multipath schemesThe energy cost of alternate disjoint
paths depends on the network densityThe resilience of these multipaths to
failure (isolated failures and patterned failures)
Disjoint paths give us independence, but the failure of a single node on each alternate path results in the failure of the multipath.
Qualitative ComparisonQualitative ComparisonBy contrast, in braided multipaths, the
various alternate paths are not independent, and a combination of failures on the primary path could sever all alternate paths
How much additional energy must one expend in order to increase resilience by a fixed amount?
How does the energy/resilience tradeoff vary with density or with the extent and frequency of patterned failures?
How closely do the localized schemes approximate their idealized counterparts?
Evaluation MethodologyEvaluation MethodologyMaintenance overheadResilienceFailure models for which we
evaluated the resilience of our multipath mechanisms
Isolated FailuresPatterned Failures
FailuresFailures
Details of MethodologyDetails of MethodologyThe idealized and localized
constructions of disjoint and braided multipath in ns-2
Uniformly distributing a number of sensor nodes on a finite plane of dimension 400 meters square
Node transmission radius: 40 metersDensityThe spatial separation between source
and sink (represented by the length of the shortest-hop path between the two
Details of MethodologyDetails of MethodologyThe failure probability for isolated
failures pithe arrival rate of patterned failures
is lamda pRadius of patterned failures REach run of our experiment
corresponded to one choice of number of nodes N and and spatial separation between source and sink d
In each run, we randomly selected a large number of source-sink pairs separated by d hops
Simulation ResultsSimulation Results Impact of failure probability on resilience:
400 nodes, 6-hop source-sink separation
Simulation ResultsSimulation ResultsResilience to Isolated Failures
Simulation ResultsSimulation ResultsThe impact of density and
source-sink separation on resilience to isolated failure
Simulation ResultsSimulation ResultsResilience to Patterned Failures
Simulation ResultsSimulation ResultsThe impact of density and source-sink
separation on resilience to patterned failure
Simulation ResultsSimulation ResultsMaintenance Overhead - Density
Simulation ResultsSimulation ResultsMaintenance Overhead – Path
Length
ConclusionsConclusionsMultipath routing for energy-efficient
recoveryNo need network-wide flooding for path
discory on failureDisjoint and braided multipaths are similar,
but braided multipaths have about %50 higher resilience to isolated failures
It is harder to design localized energy-efficient mechanisms for constructing disjoint alternate paths, because the localized algorithms lack the information to find low latency disjoint paths
Increasing the number of disjoint paths does increase the resilince but this needs higher energy cost.
Questions ?Questions ?
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