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Wireless Sensor Networks COE 499

Sleep-based Topology Control ITarek Sheltami

KFUPMCCSECOE

http://faculty.kfupm.edu.sa/coe/tarek/coe499.htm

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Outline Overview Constructing topologies for connectivity

BEAC/AFECA GAF, CEC ASCENT SPAN

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Overview Topology control can be defined as the process of configuring or

reconfiguring a network’s topology through tunable parameters after deployment. There are three major tunable parameters for topology control:

1. Node mobility2. Power of transmission3. Sleep scheduling In practice, a limited number of expensive nodes are deployed in

specific locations and must be active at all time. On the other hand, inexpensive nodes are redundant, deployed in remote locations and their precise location is not essential

Over deploying the network may provide some significant advantages:1. Longer lifetime2. Robustness3. Tunable coverage/connectivity

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Constructing topologies for connectivity

1. Basic/adaptive fidelity energy conserving algorithms (BECA/AFECA)

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Constructing topologies for connectivity..

2. Geographic adaptive fidelity (GAF)

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Constructing topologies for connectivity..

2. Geographic adaptive fidelity (GAF).. Deployed in virtual grid topology The priority scheme based on the residual power Each node broadcast its ID, grid ID and residual power The grid cell size, r, is sufficiently small (r< ) A related Cluster-based Energy Conservation (CEC)

eliminates the need of geographic info to setup the virtual grid A node is elected as clusterhead if it has a higher residual

power Gateways are allowed to communicate with more than one

clusterhead Sleep timers are set so that nodes wake-up to run a re-

election before the clusterhead’s energy depleted Node may wake up to send data

R / 5

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Constructing topologies for connectivity..

3. Adaptive self-configuring sensor network topology control (ASCENT)

Unless the number of neighbors > NT or its participation will increase the loss rate

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Constructing topologies for connectivity..

3. Adaptive self-configuring sensor network topology control (ASCENT).. Intended for highly dynamic environment Nodes wakeup to assist in routing depending on the

number of neighbors and the measured data lose in their vicinity

Nodes are expected to be active until they die What are the tunable parameters?

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Constructing topologies for connectivity..

4. Neighborhood coordinators (SPAN)

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Constructing topologies for connectivity..

4. Neighborhood coordinators (SPAN).. Only a subset of nodes, call coordinators nodes are active Non-coordinating nodes go to sleep, waking up

periodically to go to test state, send HELLO messages and check for eligibility to become coordinators: If two neighbors can’t reach each other or via <3

coordinators The eligibility decision is based on the content of HELLO

messages sent by all nodes announcing their coordinators and neighbors

The algorithm ensures that there are coordinators in every radio broadcast range in the network to minimize congestion

Nodes give up their rules as coordinators if they no longer satisfy the eligibility rule or after time period to ensure load balancing