Energy Efficiency of Five Broadcast-based ARQ Protocols in Multi-hop WSNs

Achieving reliable and energy-saving broadcast is the main issue discussed in this study. Firstly, a multi-hop broadcast model is introduced, and the energy consumption and reliability of the network are defined in this study. Then five broadcast-based automatic repeat request (ARQ) protocols (automatic retransmission N times, stop-and-wait end-to-end-ARQ, stop-and-wait hop-by-hop-ARQ, stop-and-wait hop-by-hop oriented implicit ARQ, stop-and-wait hop-by-hop implicit and explicit ARQ) are proposed to realise the reliable transmission. Secondly, based on five protocols, the relationship between the system reliability and the number of retransmissions of the root node is established analytically, and the maximum number of retransmissions is solved under the required system reliability. Thirdly, the energy consumptions of the root node are calculated, and then the analytical expressions of the minimum system energy consumption are obtained separately according to five broadcast-based retransmission mechanisms. Finally, the relationships between the maximum number of retransmissions, energy consumption and reliability, the broadcast probability and feedback probability are discussed in the numerical analysis. Specially, for better energy-saving, the modulation technique should be adopted to choose suitable protocol based on a dynamic hop threshold.