Applications and communication patterns

for WSN

N. Reijers

Consensus day TU Delft February 7, 2003

WSN applications and traffic MAC simulation requires generating

realistic WSN traffic

Routing Data aggregation OS

Expected to have special characteristics

Application scenarios Intruder detection Forest fire detection Cattle herd Battle field Fire rescue Environmental monitoring Condition based maintenance Airconditioning sensors

Application types

3 types of applications Detection Tracking

Active Passive

Monitoring Push Pull

Communication Event Periodic/event

Periodic Query/response

Example:Sheep tracking Farmers want to know:

Rough location of their sheep When a sheep wanders off from the

herd When a sheep is lying on its back

Sensor nodes spread throughout the meadow

Sheep carry a node that periodically sends a beacon pulse

Sheep tracking approaches Raw data to sink

Very inefficient Active node

Cheap in terms of communication Rough location estimate

Local triangulation More expensive in terms of

communication More accurate location

Active node

Sink

Sheep

Active node

Sink

Sheep

Local triangulation

Sink

Sheep

WSN application characteristics

Activity is often very localized both in space and time

High latency is tolerable Available bandwidth >> required

bandwidth Messages

local or node->sink sink->node are rare

Application model Capture charateristics in application

scenarios Generate traffic which is typical for WSN Scenario description

Network description Traffic generation Active areas

Network model Number of nodes Placement of nodes

Random Grid

Radio range Number of sinks Placement of sinks

Center / edge / corner

Traffic generation (1) Generate random messages

Rate (msgs/sec) Type, selected according

to given ratio Local broadcast Local unicast Node -> sink Sink -> node Sink -> all

86

38 %50 %12 %0 %0 %

Traffic generation (2) For each message type, specify

Message size Allowed latency

For node->sink messages specify aggregation type None Concatenation Averaging

Active areas Active areas appear randomly

Rate (new areas/sec) Avg lifetime Avg size

2nd set of parameters for active areas

Traffic generated for active areas is added to normal traffic

Conclusion Specific characteristics of WSN applications

localized activity latency available bandwidth >> required bandwidth messages

local or node->sink sink->node are rare

Traffic generation algorithm to model these