Wireless sensor network (WSN) is a network consisting of a large number of low energy sensor nodes. The main objective in WSN is the maximization of network lifespan through efficient utilization of energy. Low Energy Clustering Hierarchy Protocol (LEACH) is a protocol which balances the energy consumption all the sensor nodes in a sensor network. Recent variants of LEACH are Fixed LEACH and N-LEACH clustering routing protocol. Static Base station balances energy consumed in data relaying to extend the network lifespan. Base station (BS) mobility increase the sensor lifespan even further in certain network configurations. Furthermore, utilization of multiple mobile BSs extends WSN lifespan still further as compared to single BS case. It has been observed by researchers that optimal mobility patterns of multiple mobile BSs can be employed for achieving the maximum lifespan in WSNs. In recent literature, four representative patterns Grid, Random, Spiral, and Gaussian). It has been developing a novel mixed integer programming (MIP) framework to characterize network lifespan under different mobility patterns for multiple mobile B.S.