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Wireless Sensor Networks
Transcript of Wireless Sensor Networks
• 1970’s: Wired sensors connected to central location
• 1980’s: Distributed wired sensor networks
• 1993: LWIM project at UCLA (University of California, Los Angeles)
• 1999-2003: DARPA SensIT project: UC Berkeley, USC, Cornell etc.
• 2001: Intel Research Lab at Berkeley focused on WSN
• 2002: NSF Center for Embedded Networked Sensing
• 2001-2002: Emergence of sensor networks industry; startup
companies including Sensoria, Crossbow, Ember Corp, SensiCast
plus established ones: Intel, Bosch, Motorola, General Electric,
• 2003-2004: IEEE 802.15.4 standard, Zigbee Alliance. Berkeley Mote (MICAz MPR 2400 Series) Requirements Environmental Monitoring Applications Industrial applications Traditional single-sink WSN and A more general Scenario !! 2-Structural Health Monitoring 1-Environmental Monitoring 3-Energy Monitoring 4-Machine Condition Monitoring 5-Transportation 6-Industrial Monitoring And It is important to underline that the application strongly affects the choice of the wireless technology to be used. 7-Distributed Temperature Monitoring Applications Classification:- Event detection (ED) spatial process estimation (SPE). sensors are deployed to detect an event,
for example a fire in a forest, a quake SPE the WSN aims at estimating a given physical phemenon for e.g:-
1- the atmospheric pressure in a wide area
2.the ground temperature variations in a small volcanic site And each of these application has it’s own requirements A WSN can be defined as a network of devices, denoted as nodes, which can sense the environment
and communicate the information gathered from the monitored field (e.g., an area or volume) through
wireless links . The data is forwarded, possibly via multiple hops, to a sink (sometimes denoted as
controller or monitor) that can use it locally or is connected to other networks (e.g., the Internet) through
a gateway. The nodes can be stationary or moving. They can be aware of their location or not. They can
be homogeneous or not. coordinate actions over a shared channel Multi hop is a critical for WSN….??
Solutions were the INTERNET and MANET routing techniques??!
But…they didn’t perform well in our case!!!
These differences have necessitated the invention of new solutions..!!
Building tables for neighbor
Once the tables exist, in most WSN routing algorithms messages are directed from a source location to
a destination address based on geographic coordinates, not IDs….!!!
Additional key issues for WSN…??
• Integrating with wake/sleep schedules,
• Unicast, multicast and anycast semantics,
• Congestion. Node localization is a function of many problems and requirements which make it very complex!!!!
Issues to consider:
1-the cost of extra localization hardware
2-is it a 2D or 3D localization problem
3-is the system indoors/outdoors
their solutions!!! clocks is WSN should read the same time ….since clocks drift over a time…they must be re-synchronized
why synchronization is very important??!!!
NTP protocol used to solve this issue…RBS
Accuracies are around 30 microseconds for 1 hop……..
BUT THIS DIDN’T ADRESS MULTI HOP SYSTMES..it’s extended in TPSN It’s aim is to increase life time of node…..
How could this be achieved??!!
Hard ware level
Soft ware level
Solutions for sleep/wake-up patterns :-
duty-cycle Tepology Formation Other Technologies Questions