Directed Diffusion for

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21 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Directed Diffusion for
Wireless Sensor Networking

C. Intanagonwiwat, R. Govindan, D. Estrin, J. Heidemann,
F. Silva


Mobicom 2000

Routing Schemes
-

Anycast


Anycast


data is routed to the
“nearest” or “best” destination


Destinations identify a set of host


Only one is chosen

Routing Schemes
-

Broadcast


Broadcast


data is routed to
everyone


Used with Discovery Protocols


Can only be sent to nodes on that
network segment

Routing Schemes
-

Multicast


Multicast


data is delivered to
everyone in the group


Destinations identify a set of host


Data is delivered to the whole set


Used with IRC, Video Streaming

Routing Schemes
-

Unicast


Unicast


Data is sent to one
destination


Used with Http, SMTP, POP, SSH,
most services


Directed Diffusion
-

Interests


Interests: a query which specifies what
a user wants by naming the data.


Sink periodically broadcasts interest
messages to each neighbor
.


Includes the rectangle and duration
attributes from the request.


Includes a larger interval attribute


All nodes maintain an interest cache

Interest Cache

Sensor Node


Receives interest packet


Node is within the rectangle
coordinates


Task the sensor system to generate
samples at the highest rate of all the
gradients.


Data is sent using unicast

Data Return

Exploratory versus Data


Exploratory use lower data rates


Once the sensor is able to report the
data a reinforcement path is created


Data gradients used to report high
quality/high bandwidth data.

Positive Reinforcement


Sink re
-
sends original interest message with smaller
interval


Neighbor nodes see the high bandwidth request and
reinforce at least one neighbor using its data cache


This process selects an empirically low
-
delay path.

Multiple Sources & Sinks


The current rules work for multiple
sources and sinks

Repair


C detects degradation


Notices rate of data significantly lower


Gets data from another neighbor that it hasn’t
seen


To avoid downstream nodes from repairing their
paths C must keep sending interpolated location
estimates.

Negative Reinforcement


Repair can result in more than one path
being reinforced


Time out gradients


Send negative reinforcement message

Compared to traditional methods


Routes are established on command


No attempts to find a pre
-
determined
loop
-
free path


Message caches are used for loop
avoidance