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 communicationLocal 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 AlgorithmsFundamental 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 SynchronizationNetwork Maintenance Tasks

Network Reconfiguration

Structured (Hierarchical) Communication Network

Static/Dynamic Grained-Clustering