The Design Space of Wireless Sensor Networks Xin-Xian Liu 2005 03 22.
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The Design Space of Wireless Sensor Networks
Xin-Xian Liu
2005 03 22
Outline
Background Performance Metrics Sensor Network Architecture Design Space Conclusion
Background
Initial research into WSN was mainly motivated by military application
A de facto definition of WSN as a large-scale, ad hoc, multihop, tiny, resource-constrained
Sensor network
The components of a sensor node
Performance Metrics
Energy efficiency / system lifetime Latency Accuracy Fault-tolerance Scalability
Sensor Network Architecture
The network protocol is responsible for supporting all communication between the sensors and the observer
The performance of the protocol will be highly influenced by the network dynamics and by the specific data delivery model employed
Communication Models
Communication within a sensor network can be classified into two categories– Application communication– Infrastructure communication
Application communication is related to the transfer of sensed data with the goal of informing the observer about the phenomena
Communication Models
Within application communication, there are two models:– Cooperative– Non-cooperative
Communication Models
Infrastructure communication refers to the communication needed to configure, maintain and optimize operation
In sensor networks, an initial phase of infrastructure communication is needed to set up the network
Data Delivery Models
Sensor networks can be classified in terms of the data delivery required by the application interest as:– Continuous– Event-driven– Observer-initiated– hybrid
Data Delivery Models
Continuous– The sensors communicate their data continuously
at a prespecified rate Event-driven
– The sensors report information only if an event of interest occurs
Observer-initiated– The sensors only report their results in response t
o an explicit request from the observer
Data Delivery Models
The actual flow of data packets between the sensors and the observer– Flooding– Unicast– Multicast
Network Dynamics Models
The approach to construct and maintain a path between observer and phenomenon will differ depending on the network dynamics, which we classify as – Static sensor networks– Dynamic sensors networks
Static Sensor Networks
In static sensor networks, there is no motion among communication sensor, the observer and the phenomenon
Dynamic Sensor Networks
In dynamic sensor networks, either the sensors themselves, the observer, or the phenomenon are mobile
Dynamic sensor networks can be further classified by considering the motion of the components– Mobile observer– Mobile sensors– Mobile phenomena
Design Space
We informally characterize each of the dimension and, where appropriate, identify property classes in order to support a coarse-grained classification of sensor network application
Design Space
Deployment– Random vs. Manual– One-time vs. Iterative
Mobility– Immobile vs. Partly vs. All– Occasional vs. Continuous– Active vs. Passive
Design Space
Cost – The cost of a single device may vary from
hundreds of Euros to a few cents
Size– The form factor of a single sensor node may vary
from the size of a shoebox to a microscopically small particle
Design Space
Resources and Energy– Varying size and cost constrains directly result in
corresponding varying limits on the energy available, as well as on computing, storage and communication resources
– We partition sensor nodes roughly into four classes based on their physical size
brick, matchbox, grain, and dust
Design Space
Heterogeneity– Homogeneous vs. Heterogeneous
Communication Modality– Radio vs. Light vs. Inductive vs. Capacitive vs.
Sound
Infrastructure– Infrastructure vs. Ad Hoc
Design Space
Network Topology– Single-hop vs. Star vs. Networked Start vs. Tree
Coverage– Sparse vs. Dense vs. Redundant
Connectivity– Connected vs. Intermittent vs. sporadic
Design Space
Network Size– The network size may vary from a few nodes to
thousands of sensor nodes or even more
Lifetime– Depending on the application, the required
lifetime of a sensor network may range from some hours to several years
Design Space
Other QoS Requirement– Depending on the application, a sensor network
must support certain QoS aspects such as Real-time Robustness Tamper-resistance Eavesdropping resistance
Conclusion
Clearly, a single hardware platform will most likely not be sufficient to support the wide range of possible applications
A modular approach, where the individual components of a sensor node can easily exchanged
References
[1] S. Tilak, N. B. Abu-Ghazaleh, and W. Heinzelman, “A Taxonomy of Wireless Micro-Sensor Network Models,”MR2C, vol. 6, no. 2, Arp.2002, pp. 28-36
[2] Kay Romer and Friedemann Mattern, ETH Zurich, “The Design Space of Wireless Sensor Networks,” IEEE Communications Magazine, pp.54-61,December 2004
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