Algorithm 1: Time interval selection and operation algorithm for an end device.

Data: ZigBee communication-initiation phase is over. Time intervals TI for priorities are configured.

Input: Received Offer message at the time T.

Output: Selected time interval TI(P).

1 application selects a suitable priority P from the Offer message

2 if Selection not sent then

3  send Selection with priority P

4 Sleep time = (TI(P) − time required for data processing)

5 sleep while time < (T + Sleep time)

6 repeat

7  process data

8  send data

9  wait for Acknowledgement

10   sleep for (Sleep time − time actually waited for Acknowledgement)

11 until another Offer message received