Energy Conserving Protocol Design And Optimization In Wireless Sensor Networks

For wireless sensor networks, energy is usually wasted in the processes of collision, overhearing, control packet overhead and idle listening. In this paper, we proposed a novel protocol termed periodically hybrid MAC protocol (PH-MAC). PH-MAC is designed to minimize the waste of energy in all the above processes. Besides energy efficiency, through PH-MAC, we are able to guarantee throughput and bandwidth utilization by allocating timeslots effectively in the contention period. PH-MAC proposes a new architecture of MAC protocol for data communication. PH-MAC is contention-based at allocation period and TDMA-based at the TDMA period. It uses contention period to allocate the timeslot to every node that needs to transmit data, and the TDMA part to transmit actual data. For every node at TDMA period, it just needs to transmit data or receive data when the incoming data coming or outgoing data outgoing. What we want to do is to get the boring contention work done once and forever, though we could not keep it forever, just a moment (period) is enough for us. As we also need to deal with network changes and clock drift, so the PH-MAC runs periodically to adjust to those changes online. The simulation results show that, PH-MAC not only improve the throughput of the network, but also save nearly half of the energy that T-MAC usually consumes.In wireless sensor networks, a clustering scheme is helpful in reducing the energy consumption by aggregating data at intermediate sensors. In the second section we discusses the important issue of energy optimization in hierarchically-clustered wireless sensor networks to minimize the total energy consumption required to collect data. We propose a comprehensive energy consumption model for multi-tier clustered sensor networks, in which all the energy consumptions not only in the phase of data transmissions but also in the phase of cluster head rotations (or cluster setup) are taken into account. By using this new model, we are able to obtain the solutions of optimal tier number and the resulted optimal clustering scheme on how to group all the sensors into tiers by the suggested numerical method. This then enables us to propose an energy-efficiency optimized distributed multi-tier clustering algorithm for wireless sensor networks. This algorithm is theoretically analyzed in terms of time complexity. Simulation results are provided to show that, the theoretically calculated energy consumption by the new model matches very well with the simulation results, and the energy consumption is indeed minimized at the optimal number of tiers in the multi-tier clustered wireless sensor networks.