Directed Diffusion for Wireless Sensor Networking

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Directed Diffusion for Wireless Sensor Networking

• C. Intanagonwiwat, R. Govindan, D. Estrin, J.
  Heidemann, F. Silva
• Mobicom 2000

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Routing Schemes - Anycast

• Anycast data is routed to the nearest or
  best destination
• Destinations identify a set of host
• Only one is chosen

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Routing Schemes - Broadcast

• Broadcast data is routed to everyone
• Used with Discovery Protocols
• Can only be sent to nodes on that network segment

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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

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Routing Schemes - Unicast

• Unicast Data is sent to one destination
• Used with Http, SMTP, POP, SSH, most services

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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

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Interest Cache
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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

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Data Return
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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.

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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.

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Multiple Sources Sinks

• The current rules work for multiple sources and
  sinks

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Repair

• C detects degradation
• Notices rate of data significantly lower
• Gets data from another neighbor that it hasnt
  seen
• To avoid downstream nodes from repairing their
  paths C must keep sending interpolated location
  estimates.

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Negative Reinforcement

• Repair can result in more than one path being
  reinforced
• Time out gradients
• Send negative reinforcement message

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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