Doughnut Effect in Wireless Sensor Network and its Solution

The sensor nodes in a network are connected to the outer world via a base station. Base stations (BS) have some back up power and it is not suppose to fail due to shortage of battery power. The nodes which are away from the base station communicate to it via the nodes which are in proximity of BS. Thus the nodes which are nearer to BS have additional communication responsibilities of forwarding data of distant nodes. Thus the nodes which are in proximity of BS will run out of battery very soon and create bottleneck for communication. In this paper we have proposed that if the density of sensor nodes increases as we move towards base station this effect can be minimized. We found the exact density of the sensor nodes at a particular distance from BS to avoid bottleneck phenomenon around it. We have considered the real life scenario (i) sensor nodes are dropped from the aeroplane with possible error in its position from predetermined coordinates and (ii) nodes generates data only when there is an event of interest with a given probability of occurrence. The main contribution of this paper with our proposed strategy is lifetime offered per unit cost of deployment is almost double