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Load Balance and Efficient Hierarchical Data-Centric Storage in Sensor Networks. Yao Zhao, List Lab, Northwestern Univ Yan Chen, List Lab, Northwestern Univ Sylvia Ratnasamy, Intel Research. Outline. Background and Motivation Hierarchical Voronoi Graph based Routing Basic routing algorithm

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load balance and efficient hierarchical data centric storage in sensor networks

Load Balance and Efficient Hierarchical Data-Centric Storage in Sensor Networks

Yao Zhao,List Lab, Northwestern Univ

Yan Chen, List Lab, Northwestern Univ

Sylvia Ratnasamy, Intel Research

outline
Outline
  • Background and Motivation
  • Hierarchical Voronoi Graph based Routing
    • Basic routing algorithm
    • Practical design issues
  • Evaluation
  • Conclusions and Future Work
generic storage schemes
Generic Storage Schemes
  • External Storage
  • Local Storage
  • Data-Centric Storage (DCS)
generic storage schemes1

Event

Generic Storage Schemes
  • External Storage
    • Hotspot problem (if no need to store all events )
generic storage schemes2

Event

Generic Storage Schemes
  • Local Storage
    • Overhead of flooding
generic storage schemes3

Event

Generic Storage Schemes
  • Data-Centric Storage [CCR03]
    • Good to avoid hotspots and flooding overhead in some scenarios
motivation
Motivation
  • Routing Primitive for Data-Centric Storage vs Any-to-any Routing
    • DCS doesn’t require any-to-any routing
      • E.g. in pathDCS [NSDI06], not all nodes are routable
    • Any-to-any routing may not be suitable for DCS
      • E.g. BVR[NSDI05] and S4[NSDI07]
    • Only a few any-to-any routing can be DCS routing
      • E.g. VRR [Sigcomm06], GEM[Sensys03]
motivation1
Motivation
  • Routing Primitive for Data-Centric Storage vs Any-to-any Routing
  • Desirable Properties of DCS Routing
    • No GPS (or other location device)
    • Scalability
    • Efficiency
      • Path stretch (routing path length / shortest path length)
    • Load Balancing
      • In routing (forwarding overhead)
      • In Storage
  • Our Goal
    • Design routing primitive for DCS with the above properties
outline1
Outline
  • Background and Motivation
  • Hierarchical Voronoi Graph based Routing
    • Basic routing algorithm
    • Practical design issues
  • Evaluation
  • Conclusions and Future Work
hierarchical voronoi graph based routing
Hierarchical Voronoi Graph based Routing
  • Basic Routing Algorithm
    • Hierarchical coordinate
    • Region oriented routing
    • Name based routing for DCS
  • Practical Issues
    • Landmark selection
    • Path stretch reduction
    • Handling dynamic changes
hierarchical coordinate
Hierarchical Coordinate
  • Divide the network based on the hop distance to landmarks

Irregular borderline in realilty

hierarchical coordinate1
Hierarchical Coordinate
  • Divide the network based on the hop distance to landmarks

In smallest region, nodes know each other

overhead of building coordinate
Overhead of Building Coordinate
  • Initialization Overhead
    • Each Layer
      • O(mN) messages where m is the number landmarks splitting a region, and N is the number of nodes
    • K Layers
      • K ~ O(log N)
    • Total Overhead
      • O(mN·log N) messages
  • Memory Usage
    • Km ~ O(m·log N)
name based routing

d

Name Based Routing

Bypass landmarks

  • S has an event E
    • Take a hash function H1 and get j = H1(E)%3
    • S sends E to the jth 1st level landmark and enter Lj’s region via node a
    • Node a compute H2(E)%3 to determine the next landmark

L2

L1,2

s

L1,2,3

a

L1

L3

load balancing in storage
Load Balancing in Storage
  • Load Balancing Problem
    • In naïve name based routing, non-uniform division of regions causes non-uniform storage distribution
    • To divide regions uniformly is very hard
  • Our Approach: Non-uniform Hash Function
    • Collect the number of nodes in each region
    • Hashed value is proportional to the population of possible sub-regions
outline2
Outline
  • Background and Motivation
  • Hierarchical Voronoi Graph based Routing
    • Basic routing algorithm
    • Practical design issues
  • Evaluation
  • Conclusions and Future Work
evaluation
Evaluation
  • Simulation Setup
    • C++ implementation
    • Simple MAC without collision
    • Unit disk graph model in 2D space (communication range 1)
    • Baseline simulation
      • 3200 nodes
      • Density: 3π neighbors in average
    • Simulate HVGR, HVGR+ and VRR[Sigcomm06]
      • m = 6 (number of landmarks splitting a region)
  • Metrics
    • Path stretch
    • Load balancing: CDF for visualization
    • Route table size
    • Initialization overhead
    • Maintenance overhead
efficiency
Efficiency
  • The stretch of HVGR doesn’t increase as N increase.
scalability
Scalability
  • The route table size and initialization overhead increase logarithmically.
routing load balancing
Routing Load Balancing
  • The routing load balancing feature of HVGR is close to that of shortest path routing.
storage load balancing
Storage Load Balancing
  • The storage load balancing feature of HVGR is close to that of ideal hash based storage.
conclusion
Conclusion
  • Design HVGR/HVGR+
    • Topology based routing (No GPS)
    • Good scalability (log N memory)
    • High efficiency (close to shortest path routing)
    • Balanced load in both routing and storage
  • Future Work
    • Theoretical analysis
    • Tinyos implementation
name based routing for dcs
Name Based Routing for DCS
  • Convert Name to Label
    • Event name S
    • A series of hash functions Hi
    • Order the m landmarks
    • Let j = Hi(S) mod m, the ith level label is the j th landmark
voronoi graph2
Voronoi Graph
  • Divide the regions based on the closest landmark rule.
number of landmark m in each level1
Number of Landmark (m) in Each Level
  • The larger the m, the more overhead. We pick m=6 finally.
desirable properties of dcs
Desirable Properties of DCS
  • DCS without Location Information
    • No GPS or other location devices
  • Scalability
    • Memory usage
    • Control message overhead
  • Efficiency
    • Path stretch (routing path length / shortest path length)
  • Load Balancing
    • In routing (forwarding overhead)
    • In Storage
outline3
Outline
  • Background and Motivation
  • Hierarchical Voronoi Graph based Routing
    • Basic routing algorithm
    • Practical design issues
  • Evaluation
  • Conclusions and Future Work
region oriented routing
Region Oriented Routing
  • From s to d with label (L1, L1,2, L1,2,3)

Bypass landmarks

L1,2

s

d

L1,2,3

a

L1

hierarchical coordinate2
Hierarchical Coordinate
  • Divide the network based on the hop distance to landmarks
ad