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