Investigation into the impact of protocol design on energy consumption of low power wireless sensors

This paper proposes a modified communication protocol that uses the knowledge of channel states to transmit packets. It shuts off the energy expensive acknowledgement operation during good channel state while uses all its retransmission attempts in bad channel state to deliver the packets through the channel. The impact of this protocol has been directly studied on the coin cell batteries that are used to power wireless sensors by emulating the loads for the battery and radio channel conditions. The radio channel is modeled as two state Markov chain with FAVORABLE and NON-FAVORABLE states. Three different channel conditions - good, bad and uncertain - are considered based on how often they transit between the FAVORABLE and NON-FAVORABLE states. The results have been compared with a classical communication protocol where communication between nodes takes place on send-acknowledge basis with a fixed number of retransmission attempts when error occurs. Our proposed protocol shows promising improvement in battery lifetime when dealing with good channel and found to be more effective in the other two channel conditions when the receive operation time is high. Analytical results are also used to substantiate our observations.