Algorithm 2. Pseudo code at the sensor node for resubmission of unsuccessfully transmitted packets

1: Call the required libraries, waspXBee, waspSensorPro

2: While (time < 13 min and Stack is not empty) do

3:   Read message from the Stack (SD card)

4:   Send the message to the gateway

5:   If no acknowledgement received or timeout then

6:      Go to line 3

7:   Else

8:      Remove message from Stack

9:   End if

10: End while