AN IMPROVED FACE TRAVERSAL FOR GEOCASTING IN WIRESS
ADHOC AND SENSOR NETWORKS
ByN.A.P.Sivasubramaniyan,
ME-CSE, IInd Year
Guided ByDr. E.Baburaj
Problem Definition
• GEOCASTING– a task to deliver a message from a source node to all
nodes within a given geographic region.
• It requires ensured message delivery with low transmission cost.
• Limited energy of sensors requires geocasting to consume a little energy
as possible.
• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
Vitrual Surrounding Face Geocasting 3
• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
Vitrual Surrounding Face Geocasting 4
Location Based Routing
• Every node in network knows its location and its neighbors.
• Routing made based on destination location and location of neighbors.
• Nodes don’t maintain routing tables.
Greedy LBR• Each node choses the neighbor closest to the destination as next forwarding node.
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Greedy LBR• Fails when a message gets stuck in a
dead end.
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• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
Vitrual Surrounding Face Geocasting 8
• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
Vitrual Surrounding Face Geocasting 9
Face RoutingDerive a planar graph from the network topology
Face RoutingPartition into set of faces……..
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Face Routing
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Face Routing
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Face Routing
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Face Routing
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Face Routing
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Face Routing
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Face Routing
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Disadvantage:
High transmission cost
Face Routing
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• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
Vitrual Surrounding Face Geocasting 20
• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
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Greedy Face Routing
• Combines greedy LBR and Face Routing.
• Generally uses greedy routing.
• When a void is reached, uses Face Routing.
Drawback in existing Face Routing
Though x is a direct neighbor of v, message is sent from v to w and then to x, introducing an extra transmission.
In dense networks, this may be significant compared with the total number of transmissions for face traversal.
Solution: We propose a SKIP method to allow skipping of such nodes.
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• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
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• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
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Geocasting
• can be easily achieved by flooding the network.
• Problem: Not energy efficient.
Requires atleast ‘N’ transmissions.
• Three classes of geocasting algorithms exist.
GeocastingClass I: limits the scope of flooding by creating a restricted forwarding zone.
minimum rectangle containing source and geocasting region is chosen as forwarding zone.
restricted flooding is performed.
Drawback:forwarding zone larger than geocasting region.
Flooding cost don’t go down.
message delivery not guaranteed.Vitrual Surrounding Face Geocasting 28
Geocasting
Class II: reduces flooding costs.
restricted forwarding zone is intelligently flooded.
Drawback:message delivery not guaranteed.
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GeocastingClass III:
phase 1: message sent from source node to a node in geocasting region.
phase 2: performs restricted flooding.
Reduces transmission cost.
Drawback:message delivery not guaranteed.
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Some algorithms combine location based unicasting and restricted flooding with face traversal to guarantee message delivery.
• Depth First Face Tree Traversal
• Restricted Flooding with Intersected Face Traversal
• Entrance Zone Multicasting based Geocasting
Drawbacks :
Complex, longer delivery time, high message cost, potentially series contention.
RFIFT: Restricted Flooding with Intersected Face Traversal
Phase 1: Uses GFG to deliver a geocasting message to a node in geocasting region R.
Phase 2: Performs restricted flooding within R and traverses all the faces intersecting R. Each face traversal determined by two nodes:
an internal border node
an external border node
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Some concerns:• Cost• Potential collision• Delivery speed
RFIFT Basic
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Another Problem in RFIFT
• In some cases, RFIFT needs to be modified to guarantee message delivery
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Region
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• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
Vitrual Surrounding Face Geocasting 35
• Location Based Routing
• Face Routing
• Greedy Face Greedy Routing
• Geocasting Algorithms
• Broadcasting Algorithms
Existing Approaches for Routing
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Broadcasting
• It is a process to send a message to all nodes in a network.
• Efficient broadcasting can be modified to reduce the cost of restricted flooding in geocasting.
• Drawbacks:
high cost, contention, message collision.
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Broadcasting
• based on domain set based algorithms.
• a connected domain set(CDS) is defined, such that for every node in the network, the node either belongs to CDS or has a direct neighbor in CDS.
• flooding performed only by the nodes belonging to the CDS.
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Vitrual Surrounding Face Geocasting 39
Dominating Set - Example
Our Goals
• Guaranteed message delivery
• Short delivery time
• Low transmission cost
• Avoid potential message collisions
• Reducing message complexity of RFIFT
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Proposed Scheme……
Virtual Surrounding Face Geocasting (VSFG)
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Basic Idea of VSF: Virtual Surrounding Face
For any two faces that share an edge, if the shared edge is ignored, the two faces can be merged into one face with a larger area.
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Virtual Surround Face (VSF)
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Overview of VSFG
• VSFG algorithm based on VSF acheives geocasting with guaranteed message delivery.
• SKIP algorithm let nodes skip some intermediate nodes during face traversal.
• DS based restricted flooding reduces the number of transmissions.
• RFIFT reduces the transmission cost.
• We assume that all nodes donot change their locations during the geocasting task.
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VSFG• composed of three tasks.
VSF Forwarding
VSF Traversal
VSF Restricted Flooding
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VSFG• composed of three tasks.
VSF Forwarding
VSF Traversal
VSF Restricted Flooding
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VSF Forwarding:
A source node transmits a geocasting message containing the specification of the region to a node on the boundary of the VSF by LBR or GFG.
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VSFG• composed of three tasks.
VSF Forwarding
VSF Traversal
VSF Restricted Flooding
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VSFG• composed of three tasks.
VSF Forwarding
VSF Traversal
VSF Restricted Flooding
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VSF Traversal:
Node which received the message starts double directional face traversal.
Thus messages will never collide.
Traversal is also aided by SKIP algorithm to reduce the number of transmissions.
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VSFG• composed of three tasks.
VSF Forwarding
VSF Traversal
VSF Restricted Flooding
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VSFG• composed of three tasks.
VSF Forwarding
VSF Traversal
VSF Restricted Flooding
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VSF Restricted Flooding:
Every node on the boundary of VSF performs DS based Restricted flooding.
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Example of VSF Geocasting
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QUERIES…???
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