Increasing Lifetime of Wireless Sensor Networks Using Controllable Mobile Cluster Heads

This paper proposes a scheme for improvement of network lifetime and delay by employing a connected group of mobile cluster heads in a wireless sensor network (WSN). As data sensing is triggered by an event, the sensors relaying the aggregated data to the base station run out of energy at a much faster rate than sensors in other parts of the network. This gives rise to an unequal distribution of residual energy in the network, making the nodes with lower remaining energy level to die much faster than others. To distribute the remaining energy more evenly in the network, some energy-rich nodes are designated as cluster heads which move in a controlled manner toward locations rich in energy and data. This reduces the transmission energy required by the static sensors to send data and thus increases the overall lifetime of the network. Along with transmission energy, time taken for transmitting data to the BS is also reduced as the CHs follow a connectivity strategy to always maintain a connected path to the BS. Simulation shows that lifetime of the network can be increased by 42% over existing scheme by making the CHs always move towards a stable equilibrium point, i.e., a point where the total residual energy of the network and data are concentrated. Our connectivity algorithm also provides 40% improvement in the transmission delay as compared to existing schemes.