Wireless Energy Sharing for Maximizing Lifetime of Linear Multihop Communications

To extend the lifetime of multihop communication suffering from energy shortages in wireless nodes, we apply the concept of wireless energy sharing (WES) to bidirectional linear multihop transmission and formulate an optimization problem to determine the amount of energy shared in each node that maximizes the lifetime of the multihop path. To solve this problem analytically, we first verify that the lifetimes of multihop nodes have the solidarity property and reveal that the lifetime of the multihop path is maximized when the lifetimes of all the constituting nodes become equal. Based on this property, we then convert the considered optimization problem to a tractable linear programming (LP) problem and obtain the optimal amount of energy shared in each node by solving this LP problem in a centralized manner. Considering the control overhead and complexity in this centralized WES, we also propose a distributed WES operation in which each node autonomously determines the amount of energy shared by matching its lifetime with its neighbors' lifetime without a central coordinator. Thereafter, we prove that the proposed distributed WES algorithm always guarantees convergence, and numerically analyze the control overhead in both centralized and distributed WESs. Intensive simulations in various environments demonstrate that the proposed WES algorithm maximizes the lifetime of the multihop path by equalizing the lifetimes of all the nodes and, thus, increasing the path lifetime almost twice as much as that of the typical one-way wireless energy transfer. Moreover, distributed WES achieves a near-optimal performance and exhibits a smaller control overhead than centralized WES as the number of hops increases.