Query Optimization in Sensor Networks

1. Query Optimization in Sensor Networks Mark Rossman Iris Bass Supervised by: Dr. Fatma Milli

2. Wireless Sensors Networks • Definition: A sensor network consists of many spatially distributed sensors, which are used to monitor or detect phenomena at different locations, such as temperature changes or pollutant levels. • How Sensor Networks are used: • Time Critical Projects • Situations where timeliness and accuracy is more important. • Collect lots of the data immediately because sensors are not needed later. • Monitoring Long Term Projects (our focus) • Get an accurate global model of the environment . • Collecting data throughout a lengthy period of time.

3. Issues • Sensors • Power • Multiple sensors coordinating communication • Changes in the environment • Phenomena / Environmental Monitoring • Accuracy • Redundancy • Space-wise • Time-wise

4. Lengthening The Life of a Network • Rotating which nodes are active • Knowledge about space redundancy • Local information • Local Strategies • Knowledge about time redundancy • Get accurate data • Maximize the life of the network

5. Utility Based Optimization • Terms • Usefulness: Potential Contribution of the node to the query. • Utility: Cost effectiveness of interrogating the node, Usefulness/cost. • Usability: Ability of the node to contribute, Utility * Processing time remaining

6. Process

7. 10 20 30 5 10 Percent 20 40 30 40 Percent 50 50 Results 10 20 10 30 20 Percent 40 30 40 50 50 Percent