Pre-Process RSSI Value
Because RSSI values are unstable even in a controlled environment, outliers must first be removed. Ten RSSI values are taken and stored. Then the mean and standard deviation for these ten values are calculated. Any single value that falls below \(mean-2\cdot standarddeviation\) is removed from the ten stored values. The average value of the remaining RSSI values is calculated and used as the pre-processed value in the next step.