1. Evaluating Wireless Network Performance David P. Daugherty ITEC 650 Radford University March 23, 2006

2. 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 !!!

3. Sensor Nodes, Sensor Range, Base Stations

4. Star Topology

5. Minimum Spanning Tree Topology

7. 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 nodes All of the above and more +> How to evaluate???

8. 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

9. Star Topology

10. 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.

11. 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

12. 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