An energy efficient Odd-Even round number based data collection using mules in WSNs

Energy efficient data collection is the major challenging task in the Wireless Sensor Network (WSN). Since, batteries are the main power sources of sensor nodes which has limited energy. In multi hop clustering, Base Station's neibourhood nodes have overload compare to far nodes because nearer nodes transmit their own data as well as other nodes data. As a result, the Base Station (BS) nearby nodes die first and transmission stopped, though maximum sensor nodes have sufficient energy to communicate. This problem is called energy hole or hot spot problem in WSN. In order to reduce the hot spot problem and increase the lifetime of WSN, we propose an energy efficient data collection in hierarchical clustering through multi hop routing using Odd-Even round numbers. In this proposed protocol, sensing area is divided into rectangular levels and further these levels are divided into fixed square shaped Grids (clusters). The square grids are divided in such a way that transmission distance between two grids are always less than the threshold distance of free space propagation model. In each cluster, the BS assigns a number serially to each sensor node based on the centroid distance. Based on these numbers sensor nodes became CH in each round, which reduces the message overhead. In every round the BS informs about round number to all CHs. Based on the round number CHs route their data to the BS through Mules. For Odd round number (ORN) CHs route their data from right to left and for Even round number (ERN) CHs transfer their data left to right in their respective levels. Two Mules are used to collect data from all leftmost and rightmost CHs in all levels. Most of the proposed algorithms for multi-hop data collection in hierarchical clustring have used vertical and one way communications for data collection. Due to this one way and vertical communications, nearer nodes of the BS suffers from hot spot problem. This proposed protocol decreases the hot spot problem with better load balancing and horizontal communications in WSN.