Wireless Sensor Networks (WSN) is an active area of research and given below is a case study of a WSN term project done at Indian Institute of Technology (IIT) Madras using NetSim, titled “Estimation of Carrier Sense Range and its effect on IEEE 802.15.4 Sensor Networks”
- Building probability models: The attenuation of IEEE 802.15.4 signals was to be observed and probability models for decoding range and carrier sense range were to be developed.
- Estimating decoding range: This is the threshold below which packets sent from the transmitter are always received, and was to be estimated in terms of the probability that two devices separated by a distance are in decoding range.
- Developing custom code: Source C files, Sensor.c, CheckRoute.c and CCA.c of NetSim WSN library were modified. These codes were linked and debugged using NetSim’s project work environment.
- Modeling network configurations: Custom Sensor network configurations were created using NetSim’s XML based network configuration files
- Generating performance metrics: Packet and event traces were used for analyzing network performance metrics such as Throughput, Probability of packet discard, Average service rate and Mean Backoff duration
- Creating dependency graphs
- These are directed graphs representing the probability of link establishment between sensors.These graphs were generated by sampling the probability model for each link.
- Statistically analyzing performance: Variation in network performance, from simulation, for different dependency graphs were plotted for the 10 most likely and 10 least likely DG’s
- Establishing confidence interval: This provides the probability that a network will operate in a corresponding range. The confidence interval for operation of the 802.15.4 Wireless Sensor network with limits of performance, i.e. throughput and packet failure probability, was established.