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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.
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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
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
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