Abstract:
Energy is the most critical resource in the life of a wireless sensor node. Therefore, its usage must be optimized to maximize the network life. To increase the life time, sensors should stay in energy saving sleep mode as long as possible, because in sleep mode the radio is either shut down or working with less energy. "Sampling" based schemes improve energy efficiency significantly for low traffic. The performance of sampling based protocols deteriorates at medium and high traffic due to presence of hidden terminals. Elimination of the hidden terminal problem, therefore, would result in improved energy efficiency for medium and high traffic.
In this dissertation work, a new sampling based MAC protocol, Sampling and Scheduling Based MAC (SSMAC), is proposed. In SSMAC, time is divided into .time slots during data transmissions. SSMAC minimizes hidden terminals by allowing nodes to transmit in round-robin fashion. The transmitting node initially sends a Wake-Up Frame (WUF) to the destination node to wake it up. The subsequent communication follows CTS/DATA/ACK procedure of 802.11.
SSMAC is simulated in OMNeT++ simulation environment and is compared with WiseMAC, Preamble sampling and SMAC schemes. Simulation results show that SSMAC is most energy efficient in comparison to other schemes. This
