Fusion-Oriented Sensor Networking ： Network Architectures, Communication Protocols, and Routing Algorithms Dr. Wei Chen

An Example of Sensor Network

Mathematical Model for communication Networks Directed Graph G=(V,E) V={nodes} E={edge (u,v): if node u can transmit data to node v} Nodes with different communication range

Broadcasting using flooding Source How to solve collision problem? -- Randomized algorithm (generate a random number k, 0<k<d, transmit data at kth time slot) How to decide d? It may need long time in a dense network !!! Communication Efficiency (Each node keeps a neighbor list in G) Example: Broadcasting in G=(V,E)

Broadcasting using Euclidean Circle Source (Each node keeps a neighbor list in T) How to solve collision problem? Deterministic algorithm: only one node transmits in one time slot. Communication complexity: Totally 2(n-1) time slots with n nodes It is expensive in a large scale of network!!! Forming a spanning tree T Transmitting data in depth-first style

Cluster-Based Network Architecture Unstructured sensor network Cluster-based Architecture –Network is self-organized to separated clusters. –Each cluster has one head which connected to its members. –Clusters are connected by gateway nodes. –Communication is inefficient –Difficult to embed different levels of data fusion

Example: Broadcasting on cluster-based network s Deterministic algorithm Communication complexity: 2(Number of clusters)

Communication Protocols Backbone communication corresponding to high level data fusion Local Communication corresponding to lower level data fusion What does each node have to keep? Member node: its head id Head node: list of its member id Head/gateway node: list of its neighbor id on backbone

Backbone communication Local Communication Communication Protocols (Continue) More Consideration Assigning a different channel to backbone communication. Using randomized accessing for local communication, and using deterministic accessing with Euclidean circle for backbone communication.

S D Routing Algorithms Fundamental communication tasks Broadcasting, Multi-casting, Peer-peer communication, …. Example: peer-peer communication

Network Reconfiguration Operations for Reconfiguration Node move-in Node move-out Problem: A node is going to die (lower battery) A node is going to join (after charging)

Node move-in algorithms Want to join

Node move-in algorithms Want to join

Clustering structure on Multi-types of sensor nodes Sink Highway (Back bone) Local way (cluster) Primary sensor node Communicable sensor node

Embedded Protocols/Algorithms Hierarchical Communication/routing protocols Highest Level Physical Layer (unstructured Communication Network) Fusion-Oriented Application Layer Lowest Level Communication Tasks Multicasting Broadcasting Global Synchronization Network Maintenance Tasks Network Reconfiguration Structured (Hierarchical) Communication Network Static/Dynamic Grained-Clustering