Rate Selection Approach Based On Battery Model For MANETs

In wireless ad hoc networks, most nodes are operated on batteries to support the service mobility. Since the battery capacity is limited, network nodes powered by batteries can only last for a few hours for work, and thus can not keep up with the increasing power demands from power-intensive application on wireless devices. To solve this problem, manufacturers always have two methods: (1) improve the battery technology to increase the battery capacity; (2) design energy efficient protocols for wireless devices. Actually, with the material technology lagging behind, the capacity of the batteries is difficult to be increased significantly, and thus we should mainly tend to energy efficient protocols to extend the lifetime of the wireless devices. Therefore, carefully scheduling and budgeting battery power in wireless ad hoc networks has become an urgent and critical issue.Battery model has emerged as an important issue in designing energy efficient protocols. But most existing work uses unrealistic battery models and hence fails to conserve network energy. Battery is one kind of energy storage equipment; it can transform the chemical energy or physical energy to the electrical energy through chemical reactions. Recent study in battery technology reveals that the behavior of batteries discharging is nonlinear. Generally speaking, batteries tend to over consume power (i.e. consuming more power than needed) during discharging process, and the over-consumed power is called as the Discharging Loss; but these dissipated energy units can be reimbursed if the battery is allowed to rest (e.g., disconnected from load) for some period. This is known as the battery Recovery Effect.In this thesis, we firstly propose a new mathematical model to capture the battery discharging features, especially the discharging loss. Compared to the existed models, this model can satisfy the 'on-line' requirement due to its low complexity and low computation cost, and thus is practical in real network applications.Taking batteries nonlinear discharging features into account, we further propose an Energy Efficient Rate Selection (EERS) approach for wireless ad hoc netwroks which aims to save battery power and extend network lifetime. When transmitting packets, each node should carefully select an optimal rate according the certain transmission task, the batteries self-recovery rate and the current network condition to minimize the overall energy consumption. Theoretical analyses and numerical results both demonstrate that our approach can implement in a distributive way, and also can guarantee most nodes recover much over-consumed energy, effectively decrease the overall energy depletion and thus prolong network lifetime significantly.