VIRTUAL SURROUNDING FACE GEOCASTING IN WIRELESS AND ADHOC SENSOR NETWORKS

AN IMPROVED FACE TRAVERSAL FOR GEOCASTING IN WIRESS ADHOC AND SENSOR NETWORKS By N.A.P.Sivasubramaniyan, ME-CSE, IInd Year Guided By Dr. 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

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. t s

Greedy LBR Fails when a message gets stuck in a dead end. t ? s

Face Routing Derive a planar graph from the network topology

Face Routing Partition into set of faces……..

s t Face Routing Vitrual Surrounding Face Geocasting

t Face Routing Vitrual Surrounding Face Geocasting

Disadvantage: High transmission cost Face Routing Vitrual Surrounding Face Geocasting

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. Vitrual Surrounding Face Geocasting

Geocasting can be easily achieved by flooding the network. Problem: Not energy efficient. Requires atleast ‘N’ transmissions. Three classes of geocasting algorithms exist.

Geocasting Class 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

Geocasting Class II: reduces flooding costs. restricted forwarding zone is intelligently flooded. Drawback: message delivery not guaranteed. Vitrual Surrounding Face Geocasting

Geocasting Class 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. Vitrual Surrounding Face Geocasting

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 Vitrual Surrounding Face Geocasting

s Some concerns: Cost Potential collision Delivery speed RFIFT Basic Vitrual Surrounding Face Geocasting

Another Problem in RFIFT In some cases, RFIFT needs to be modified to guarantee message delivery s Region u y y z Vitrual Surrounding Face Geocasting

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. Vitrual Surrounding Face Geocasting

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. Vitrual Surrounding Face Geocasting

Vitrual Surrounding Face Geocasting Dominating Set - Example

Our Goals Guaranteed message delivery Short delivery time Low transmission cost Avoid potential message collisions Reducing message complexity of RFIFT Vitrual Surrounding Face Geocasting

Proposed Scheme…… Virtual Surrounding Face Geocasting (VSFG) Vitrual Surrounding Face Geocasting

Vitrual Surrounding Face Geocasting 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.

Vitrual Surrounding Face Geocasting Virtual Surround Face (VSF) u v

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. Vitrual Surrounding Face Geocasting

VSFG composed of three tasks. VSF Forwarding VSF Traversal VSF Restricted Flooding Vitrual Surrounding Face Geocasting

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. Vitrual Surrounding Face Geocasting

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. Vitrual Surrounding Face Geocasting

VSF Restricted Flooding: Every node on the boundary of VSF performs DS based Restricted flooding . Vitrual Surrounding Face Geocasting

Vitrual Surrounding Face Geocasting Example of VSF Geocasting s u w

QUERIES…??? Vitrual Surrounding Face Geocasting

VIRTUAL SURROUNDING FACE GEOCASTING IN WIRELESS AND ADHOC SENSOR NETWORKS

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