EHMBA: An energy efficient hybrid MAC multihop broadcast protocol for asynchronous duty-cycled wireless sensor networks

In this paper, we propose an energy efficient hybrid MAC multihop broadcast protocol for asynchronous duty-cycled wireless sensor networks called EHMBA, where each node independently wakes up according to their own schedule and incorporated the concept of hybrid MAC and power transmission adjustment to reduce the delay and to increase the energy efficiency in the network. The working of EHMBA is based on two different techniques: one is forwarder's guidance and overhearing of broadcast messages and ACKs and the other is with the incorporation of hybrid MAC and power transmission adjustment mechanism. The forwarder's guidance presents how to forward the broadcast message and significantly reduces redundant transmission and collision. Overhearing reduces the number of transmissions and minimizes the number of active nodes. The broadcast message has to wait till the node wakes up as each node has its own time slot in asynchronous duty-cycled protocols. The proposed protocol can overcome this problem, where within the same network, we can have different frequencies and multiple transmissions can be carried out at the same time slot and hence reduces delay. The transmission power adjustment mechanism helps to suitably vary the transmission power in order to reduce energy consumption.