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By : Prajwal PanchmahalkarNishant Reddy Kommidi

Fault tolerant Energy aware data

dissemination protocol in sensor networks

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Introduction Problems Related Research

◦ LEACH◦ POACH◦ SAFE◦ TTDD◦ SPIN

SPMS (Shortest Path Minded SPIN)◦ Design◦ Failure free case ( Example and Design)◦ Evaluation

Delay Analysis Energy Analysis

Content

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Sensor Networks, a particular class of wireless ad-hoc networks in which the nodes have sensors

Sensor nodes gather and disseminate data about the physical conditions.

Introduction

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Sensor nodes are battery powered and usually run out of battery◦ Reducing energy consumption is an important

design consideration Node failures is evident – due to battery

drain or due to physical condition of their deployment environment

Problems

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Low Energy Adaptive Clustering Hierarchy  Communicates directly with the respective cluster

head and cluster heads communicate with base station.

Does not consider end-to-end latency Assumes that base station is within communicating

distance of all nodes. Economic feasibility and the scalability of

solutions.

LEACH

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Power Aware Caching Heuristics Determine the servers in the sensor

network at which the data should be cached.

Aimed at minimizing the cost of data dissemination from the sink node.

What if the data cache fails?

POACH

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Motivated by two problems◦ Implosion – broadcast ◦ Overlap – redundant data

Use high level descriptors – metadata Nodes exchange metadata prior to data

exchange

What about the cost of dissemination ?

SPIN Protocol

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SPIN didn’t consider node failure in the network.

Adjust of power level with respect to distance to the neighbor

Emergence of SPMS

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Energy spent in wireless network is directory proportional to dα

d – distance between source and destination α – constant between 2 and 4 SPMS uses multi-hop model for data transmission among nodes with

variable transmission power levels

Shortest Path Minded SPIN (SPMS)

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Consider the following multihop routing between A to C

A

B

C

Zone of A

1 1

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Destination

via COST

C - 5

C B 2

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Knowing the route to destination

Dealing with failures of intermediate nodes

Two Challenges Faced:

??

?

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Node neighbor zones are considers◦ A region that the node can reach by transmitting

at maximum power level. Each node has a routing table for each of its

zone neighbors◦ Distributed Bellman Ford algorithm is used

Design:

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Motivated by SPIN1. Meta-data exchange within zone neighbors 2. The node sends REQ packet to the source using the

shortest path.3. If the source is not the next 1 hop neighbor the REQ is

sent through multiple hops4. Relaying between nodes is used and meanwhile the

destination nodes wait for the ADV from the 1 hop neighbors before sending the REQ

5. Energy is saved here compared to the transmission directly to source node

Implementation

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If the destination node doesn’t receive ADV from the relay node before the timer the timer expires it sends REQ to the source through the shortest path

A timer Tadv is used to wait for ADV Expended Energy in SPIN = 2nEr Expended Energy in SPIN = 2kEr (k- relay nodes) Ratio of Reception leads to n>k

Another timer TDAT is used to wait for DATA REQ is resent if the timer expires before reception of the

data.

Implementation Cont.

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Failure Free Case

A

B

C

adv

adv

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Failure Free Case

A C

REQ

Waits Tadv to receive ADV from B

B

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Failure Free Case

A C

DATA

Waits Tadv to receive ADV from B

B

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Failure Free Case

A C

ADVB

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Failure Free Case

A C

REQB

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Failure Free Case

A C

DATAB

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At each stage, the destination node maintains a Primary Originator Node (PRONE) and Secondary Originator Node (SCONE).

PRONE is the primary choice for the REQ , if PRONE fails SCONE is considered.

Design for Failure Case

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Design for Failure Case

D

CB

A

Destination

Source

REQ

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Design for Failure Case

D

B

A

Destination

Source

REQ

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SPMS is cost and energy effective compared to SPSM

It reduces end-to-end data latency SPMS shortest distance multi-hop routing

for the data transfers which allows energy savings.

Conclusion