Evaluating Wireless Network Performance

David P. DaughertyITEC 650

Radford UniversityMarch 23, 2006

WSN Characteristics• Large numbers of low-cost sensors each having short-range

wireless transmitter, simple on-board processor & internal battery• One or more base stations to receive collected sensor data• Individual sensors may be positioned randomly or manually placed• Sensors usually immobile after initial placement• Transmitter may be directional• Transmitter power may be adaptive• No individual addresses assigned; may use coordinates as proxy for

address • Communication via many short hops• Designed to be fault-tolerant

Energy consumption is biggest issue• Sensor Energy Consumed ≈

constant × (bits transmitted to next node) × (distance to next node)P

• P is in range of 2 to 4; doubling hop distance +> 16 X Power !!!

Sensor Nodes, Sensor Range, Base Stations

Star Topology

Minimum Spanning Tree Topology

Minimum Spanning Tree Topology

Energy Management Strategies

• Consolidate & redundant data before forwarding• Use multiple sensor modes:

– sleep– monitor– active

• Keep routing & protocol calculations simple• Use adjustable and directional transmitters• Use many-hop routing protocols• Adapt routing to off-load depleted nodesAll of the above and more +> How to evaluate???

Comparing Strategies

• Requires a model and a simulation tool to calculate average behavior of WSN over lifetime for many random initial placements

• Need to include routing reconfiguration as individual SN deplete their batteries

• Trade-off between forwarding traffic and self-generated sensor data makes model complicated

This proposal is to build a Java-based simulator that can be used for future research studies

Star Topology

Tool Capabilities

• User input of key WSN parameters– Average sensor density– Sensor deployment dispersion– Sensor range– Base station to sensor node ratio– Internal battery capacity– Transmission energy vs. inter-node distance

and bit traffic.

Tool Capabilities

• For each set of input parameters, automatically set up and run performance simulations for entire WSN lifetime

• Collect performance curves vs. time for:– Nodes connected : total node count– Actual area coverage vs. theoretical maximum

area– Bit traffic received– Energy consumption

Guidelines & Schedule• Implemented in Java• Deployed as JAR for standalone execution• Self-documented code via Sun Javadoc • Simple user interface: parameter input & results

summary through text fields• Save full simulation data to files; no database connection