1. Introduction
2. Background on Calibration
2.1. Calibration Challenges
2.2. Calibration Faults
3. Calibration Model
3.1. Linear Functions
3.4. Choosing a Model
3.5. Open Calibration Data Sets
4. Accuracy of the Model
5. Calibration Approaches and Attributes
5.1. Calibration Area
5.2. Number of Sensors
5.3. Knowledge of Ground-Truth Data
5.4. Position from Ground-Truth Nodes
5.5. Calibration Time and Frequency
5.6. Mode of Operation
5.7. Mode of Calibration Processing
5.8. Combining Calibration Attributes
6. Calibration Guidelines
7. Open Issues
7.1. Open Issues in Calibration Models
7.2. Open Issues in Calibrating Specific Sensor Technologies
7.3. Open Issues in Calibration Approaches
8. Conclusions