tokens: We consider two examples : 1 ) an air quality monitoring application , with low data rate , running on a Low Power Wide Area Network ( LPWAN ) , such as Lora , that generates data every hour , resulting in 24 measurements per day ; 2 ) a heart rate monitoring application ( e.g. , Fitbit ) , with sampling frequency of 1 second and 1 minute corresponding to a high and medium data rate respectively .