Wireless Sensor Network Protocol: Directed Diffusion
This protocol for WSN is a data
centric query-based protocol where sink floods a query into the network through
several routes between the sink and source. The sink supports one of those
routes and receives data from that path within shorter time interval.
Therefore, multipath delivery can be realized and significant achievement can
be attained by adapting subset of network.
Directed diffusion protocol builds path on need-basis and
stores the data in attribute value pairs. Interest messages are broadcast
(flooded) when sink requires data. This is added to neighbor’s interest cache
and each neighboring node has gradients corresponding the ones that transmitted
the interest. When a node generates data matching that interest, it is sent
back to sink using gradients. The sink then reinforces shortest path and the
intermediate nodes send the reinforcement by checking the local cache of the
sent messages.
Advantages
- It is data centric. The communication uses interests to identify named data.
- It performs neighbor to neighbor communication without node addressing mechanism. Every node specifies an end in the sensor network thus eliminating the need of routers and every node interprets data and interest messages.
- Each node is capable of performing caching and aggregation along with sensing thus saving energy and reducing delay substantially. Unlike IP-based sensor network, where a collection of specialized servers collect and process the sensor data, the network with directed diffusion protocol performs coordinated sensing close to the sensed phenomena thus providing robustness and scalability.
- Nodes require to distinguish between neighbors but are independent of unique addresses or identifiers.
- Global network topology is not required here and directed diffusion routing protocol is energy efficient.
Limitations
Data progressing takes place in
intermediate nodes thus increasing the transmission latency in the directed
diffusion protocol. Energy utilization is high in the protocol with respect to
flooding and data processing. It uses directional flooding to set multiple
paths. Data messages are transmitted redundantly through those paths. It then
observes the path performance and reduces the path multiplicity. Thirdly,
loop-free paths are not guaranteed through gradient setup mechanisms.
References
Handziski V., Köpke A., Karl H., Frank C., Drytkiewicz W. (2004) Improving the Energy Efficiency of Directed Diffusion Using Passive Clustering. In: Karl H., Wolisz A., Willig A. (eds) Wireless Sensor Networks. EWSN 2004. Lecture Notes in Computer Science, vol 2920. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-24606-0_12
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