Distributed Event Detection in Sensor Networks
March 25, 2008
Presented by Chinh Vu
by Fernando Martincic, Loren Schwiebert
Introduction
Sensors periodically send data to BS. Sensors send data to BS when threshold
is exceeded. (reactive method)
Sensors collaboratively detect object How: appl. defines event signature and
disseminates to network.
SYSTEM MODEL
Nodes are assumed to be stationary and location-aware.
Node distribution is uniform and the network is 1-connected.
Communication links between nodes are assumed to be relatively stable.
Cell-membership
Nodes know which cell they belong to. Nodes know neighboring nodes which
are within the same cell. Periodically update cell membership
Each cell elects a leader node Cell leadership is rotated between
nodes
Sensing value Each cell member publishes a
timestamped cell value. Leader calculates a weighted
average (e.g., majority vote) of all cell members.
Disseminate to all members Disseminate to adjacent cells
Matching signatures An event signature is an r×s matrix (r≤p, s≤q) To detect an event
A node “overlays” an event signature over its cell sub-matrix
performs a cell by cell comparison.
Simulation
Using TinyOS A lossless communication model was
employed Sensing value (payload) is 8-bit. Message header is negligible Area is clustered into 4×4-unit cells