Data Dissemination in Sensor Networks

Challenges and Solutionsby

Sovrin Tolia

Presentation Outline Overview of Sensor Networks Directed Diffusion, A Scalable and

Robust Communication Paradigm for Sensor Networks

SPIN, Adaptive Protocols for Information Dissemination in Wireless Sensor Networks

Research Efforts Directed Diffusion

USC/ISI Institute Deborah Estrin, Ramesh Govindan

et al SPIN Protocols

MIT Balakrishnan, Joanna Kulik et al

Challenges in Sensor Networks

Sheer Numbers Unattended deployment Device failures Frequent Change Heterogenity of Tasks

Sensor Nodes Capability of Sensor Nodes Distributed Microsensing Sensor Networks are task specific Autonomous Operation

Sensor Network Applications

Monitoring Remote Geographic Locations and terrains

Toxic Urban Locations Less Accessible environments like

large Industrial Plants and Aircraft Interiors

Directed Diffusion Motivated by Scalability, Energy

Efficiency and and robustness Data Centric Application Aware Energy Efficient Remote Surveillance Sensor

Network

Directed Diffusion Naming

Directed Diffusion Interests and Gradients

Sink Nodes Periodic Broadcasts Interest Cache in every node (distinct

interests)Two Way Gradient establishedGeneralized Interest Propagation means

Directed Diffusion Data Propagation location satisfied, finds Interest

Match from cache computes the highest data rate in

gradients present in the interest cache

Intermediate Node base their decision based on Data cache

“Downconversion”

Directed Diffusion Reinforcement

Data Driven Rules for deciding which node(s) to reinforce

Explicitly send a high data rate Interest message

What do the neighboring nodes do Extreme Reactivity and Negative

Reinforcements

Directed Diffusion Explained

In Essence No mention of target detection algos The usage is not restricted to

interests-gradients-drawing data. All Communication uses interests to

specify named data Neighbor-Neighbor (Not End-to-End) No routers, governed by task

specificity No Need for globally unique identifiers

Is It Routing ? Kind of Reactive, Routes on Demand No Attempt to find one loop free

route Constrained Flooding is used Message Cache is used to avoid loops

They did carry out some preliminary results

Future Research here Target Detection Algorithm Simulate Congestion in the network Experiment the non-aggressive

reinforcement strategy and less conservative negative reinforcements

Sensor Networks are at a stage where Internet was three decades ago

SPIN, Sensor Protocols for Information via Negotiation Overcomes Implosion, Overlap and

Resource Blindness in conventional approaches

Advocates Negotiation and Resource-adaptation

SPIN Naming Using Meta Data SPIN Messages

ADV,REQ,DATA Resource Management Implementation 3-stage handshake Participation only when it can complete

all the three stages

SPIN Working

SPIN Architecture

Performance Compared against flooding, gossiping

and ideal protocol Metric is amount of data disseminated

over time and energy consumed SPIN-1 higher throughput than gossip

but same as flooding, less energy usage

SPIN-2 ideal amount of data per unit energy

Food for Thought If Ad-hoc networks are not yet a

reality, can we ever expect Sensor Networks to be deployed

Are they really required ?

ANY QUESTIONS