Energy Management in WSN: IEEE 802.15.4 Unslotted Mode

Wireless Sensor Networks suffer from many problems but energy efficient always presents the most critical trouble in this field. Many approaches and technologies were invented in order to reduce the energy consumed such as the IEEE 802.15.4. The IEEE 802.15.4 is invented for low power and Low Rate Wireless Personal Area Networks (LRWPANs). It has been updated many times in order to provide a suitable solution for this problem. It presents two different modes which are the beacon enabled mode and the non beacon enabled mode. This work is interested in the non beacon enabled mode. The paper proposes a new model to compute the energy consumed by the node in the CSMA/CA protocol specially in the unslotted algorithm. Then an auto-adaptation process is enabled. So the last quantity of energy in the battery is adapted to the activity period of the node in the network by intervening in its duty cycle in order to postpone its death. The simulation results prove both the efficiency of our consumption energy model in addition to the performance of our intervention which lead to reduce the consumed energy by node and to increase its lifetime.