Transcript Directed Diffusion: A Scalable and Robust Communication

Directed Diffusion:
A Scalable and Robust Communication
Paradigm for Sensor Networks
Intanagonwiwat, Govindan, Estrin
USC, Information
Sciences Institute, UCLA
Carl Hartung
CSCI 7143: Secure Sensor Networks
Overview

Directed Diffusion






Conventions and Terms
Interest Propagation
Data Propagation
Reinforcement
Summary
Evaluation of Directed Diffusion

Impacts of node failures, etc..
Directed Diffusion

A Data Driven routing protocol

The basics:





A node (sink) broadcasts out Interests
If a node measures something of interest, send it
back to interested node.
Every node thinks all neighbors are End Points
Localized repair and reinforcement
Multi-path delivery for different sinks
Naming

Task descriptions are named by Attribute-Value
pairs

Query/interest:
1.
2.
3.
4.

Type=four-legged animal
Interval=20ms (event data rate)
Duration=10 seconds
Rect=[-100, 100, 200, 400]
// detect animal location
// send back events every 20 ms
// for the next 10 seconds
// from sensors within rectangle
Reply:
1.
2.
3.
4.
5.
6.
Type=four-legged animal
Instance = elephant
Location = [125, 220]
Intensity = 0.6
Confidence = 0.85
Timestamp = 01:20:40
// type of animal seen
// instance of this type
//location of node sensing
// signal amplitude measure
// confidence
// event generation time
Interests and Gradients



Interests injected into network by (possibly
arbitrary) node– now called sink.
Interests are cached by all nodes for
time=duration, then purged
Interests are periodically refreshed by the
sink.


Low initial data rate
Higher if found something of interest
Interests cont’d



Nodes cache many interests
Cached interests do not contain info
about the sink – only node it received
interest from
Interest entry contains possibly many
gradient fields
Gradients



Contain a data rate field requested by the
specified neighbor
Also contains timestamp and expiresAt
One per neighbor per Interest

Each interest can have many gradients (one
per neighbor)
Interest Propagation (flooding)
C
A
F
D
B
G
E
Interest Propagation (flooding)
C
A
F
Interests
D
Sink
B
G
E
Interest Propagation (flooding)
C
A
F
Interests
D
Sink
B
G
E
Interest Propagation (flooding)
C
A
F
Interests
D
Sink
B
G
E
Interest Propagation (flooding)
C
A
F
Interests
D
Sink
B
G
E
Data Propagation
Sensed something that matched
an interest
C
A
F
D
Sink
B
G
E
Data Propagation
C
A
F
D
Sink
B
G
E
Data Propagation
C
A
F
D
Sink
B
G
E
Data Propagation (ignored)
C
A
F
D
Sink
B
G
E
Data Propagation (ignored)
C
A
F
D
Sink
B
G
E
Reinforcement
C
A
F
Re-send Interest with
smaller interval
D
Sink
B
G
E
Reinforcement
C
A
F
Re-send Interest with
smaller interval
D
Sink
B
G
E
Reinforcement
C
A
F
Primary path
D
Sink
B
G
E
Design Choices
Diffusion Element
Design Choices
Interest
Propagation
Flooding
Data
Propagation
Reinforcement
Data caching
and aggregation
For
Reinforcement
Rules
Constrained
or directional flooding based on location
Directional Propagation based on previously cached data
to single path delivery
Multipath Delivery with selective quality along different paths
Multipath delivery with probabilistic forwarding
robust data delivery in face of node failure
For coordinate sensing and data reduction
For directing interests
for deciding when to reinforce
Rules for how many neighbors to reinforce
Negative reinforcement mechanisms and rules
Summary





Data-centric communication
All communication neighbor to neighbor,
not end-to-end
All neighbors appear to be ‘end’ to each
node
Routes are established ‘on demand’
Message cache used to avoid loops
Analysis

Used 2 metrics to measure

Average dissipated energy


Average Delay


Measures the ratio of total dissipated energy per
node in the network to the number of distinct
events seen by sinks
Measures the average one-way latency observed
between transmitting an event and receiving it at
the sink
Simulation uses a 1.6Mbps 802.11 MAC layer
Analysis

Compared Directed Diffusion to 2 other
protocols

Flooding


All events are flooded to every node in the network
Omniscient Multicast

Each source transmits events along shortest-path
multicast tree to all sinks
Average Dissipated Energy
Average Delay
Average Dissipated Energy (w / node failures)
Average Delay (w / node failures)
Event Delivery Ratio (w / node failure)
Problems?



Interest timeouts while data is en-route to sink.
Congested network?
Can the network satisfy small event data
intervals?


Multiple?
Security – nodes temporarily disabled cause
data to loop?

Cache size / Timeouts
Conclusion




Directed Diffusion has potential for
significant energy efficiency
Robust in dynamic sensor networks
Self Configuring
A good start

Need better evaluation