355
Yadi Ma and Maggie Cheng
4.2 Performance Metrics
The performance metrics we used are: message overhead, cluster size, energy
e?±ciency and cluster stability in a mobile environment.
??? Message Overhead: The total number of control messages used during the
cluster formation. This is an important metric for scalability.
??? Energy E?±ciency: Energy dissipation on data transmission after the clusters
are established.
??? Cluster Size: The number of clusters, the average cluster size and the
standard deviation of cluster sizes. These are important measures of load
distribution.
??? Stability in Mobile Environments: The percentage of nodes that change
their cluster membership in the sensor network when some node moves.
This metric reflects the stability of the network. Because clusters are used
as a lower layer infrastructure to support upper layer operations such as
routing or data gathering, the stability of a cluster itself is very important.
4.3 Simulation Results
Message Overhead
In the simulation study, we define the message overhead as the total number
of control messages used during clustering formation. We assume the total
number of nodes in the network is n, and the maximum node degree is ??.
In LEACH, each node has a probability 1 to become a cluster head for
every 1
P rounds. So there will be Pn cluster heads per round on average. Each
node that has elected itself a clusterhead for the current round will broadcast
an advertisement message to the rest of the nodes within its communication
range.
Pages:
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569