Research On Topology Control Algorithm In Three Dimensional Ad Hoc Networks

With the rapid development of Ad Hoc networks, its applications throughout the space, underwater and underground, e.g. space information networks, underwater acoustic sensor networks and underground sensor networks. A large number of Ad Hoc networks embedded in the physical world is3D where nodes could be deployed at various depths. The increase of dimension brings new research challenges, so new methods and new techniques are needed to solve the great challenges in3D Ad Hoc networks. To design a reasonable topology control algorithm can weigh the demands among connectivity, low power, throughput, and fault tolerance. Hence, topology control is an effective measure of great significance to improve the overall performance of3D Ad Hoc networks.In accordance with the characteristics of three-dimensional deployment, mobility and redundancy of nodes, a topology control algorithm Truncated Octahedron Based Topology Control was proposed. The algorithm is composed of two phases, which are topology control in initial stage and topology maintenance in operation stage. During initial stage, the whole3D network space is divided into identical truncated octahedron cells marked by different ID. On that basis, nodes compute its own cell ID and collect information about active nodes and redundant nodes in the same cell. It is important to find a dynamic mechanism that decreases the redundant nodes by selecting a subset of nodes to act as active nodes in a dynamic and distributed fashion in real time. One simple way to do that is to keep one node active in each cell. Clearly, the smaller the number of active nodes at a time, the higher the energy saving. Then, within each truncated octahedron cell, redundant nodes discover local topology and compute appropriate transmitted powers reaching the active node. Finally, active nodes achieve κ-connecting by schemes of power control and redundant node mobility. During operation stage, dynamic maintenance mechanism composes two parts which are strategies triggered by events and polling mode. Both the topology maintenance mechanisms are realized by schemes of power control and redundant node mobility. The strategies triggered by events occur when network can not meet κ-connecting conditions or network faults. When the topology meets κ-connecting conditions, the performance of the network is evaluated by means of polling, and maintenance strategies adaptively adjust according to the evaluation results.The network simulation software QualNet was used to evaluate the proposed topology control algorithm. Comparing the initial topology with the optimized topology in the respect of validity, scalability and invulnerability, simulation results demonstrate the algorithm can increase network capacity and communication efficiency, and thus optimize network performances.