Waypoint

About: Waypoint is a research topic. Over the lifetime, 1728 publications have been published within this topic receiving 30100 citations. The topic is also known as: way point.

Random waypoint considered harmful

Abstract: This study examines the random waypoint model widely used in the simulation studies of mobile ad hoc networks. Our findings show that this model fails to provide a steady state in that the average nodal speed consistently decreases over time, and therefore should not be directly used for simulation. We show how unreliable results can be obtained by using this model. In particular, certain ad hoc routing metrics can drop by as much as 40% over the course of a 900-second simulation using the random waypoint model. We give both an intuitive and a formal explanation for this phenomenon. We also propose a simple fix of the problem and discuss a few alternatives. Our modified random waypoint model is able to reach a steady state and simulation results are presented.

The node distribution of the random waypoint mobility model for wireless ad hoc networks

Abstract: The random waypoint model is a commonly used mobility model in the simulation of ad hoc networks It is known that the spatial distribution of network nodes moving according to this model is, in general, nonuniform However, a closed-form expression of this distribution and an in-depth investigation is still missing This fact impairs the accuracy of the current simulation methodology of ad hoc networks and makes it impossible to relate simulation-based performance results to corresponding analytical results To overcome these problems, we present a detailed analytical study of the spatial node distribution generated by random waypoint mobility More specifically, we consider a generalization of the model in which the pause time of the mobile nodes is chosen arbitrarily in each waypoint and a fraction of nodes may remain static for the entire simulation time We show that the structure of the resulting distribution is the weighted sum of three independent components: the static, pause, and mobility component This division enables us to understand how the model's parameters influence the distribution We derive an exact equation of the asymptotically stationary distribution for movement on a line segment and an accurate approximation for a square area The good quality of this approximation is validated through simulations using various settings of the mobility parameters In summary, this article gives a fundamental understanding of the behavior of the random waypoint model

Multivariable sliding mode control for autonomous diving and steering of unmanned underwater vehicles

Abstract: A six-degree-of-freedom model for the maneuvering of an underwater vehicle is used and a sliding-mode autopilot is designed for the combined steering, diving, and speed control functions. In flight control applications of this kind, difficulties arise because the system to be controlled is highly nonlinear and coupled, and there is a good deal of parameter uncertainty and variation with operational conditions. The development of variable-structure control in the form of sliding modes has been shown to provide robustness that is expected to be quite remarkable for AUV autopilot design. It is shown that a multivariable sliding-mode autopilot based on state feedback, designed assuming decoupled modeling, is quite satisfactory for the combined speed, steering, and diving response of a slow AUV. The influence of speed, modeling nonlinearity, uncertainty, and disturbances, can be effectively compensated, even for complex maneuvering. Waypoint acquisition based on line-of-sight guidance is used to achieve path tracking. >

Stochastic properties of the random waypoint mobility model

Abstract: The random waypoint model is a commonly used mobility model for simulations of wireless communication networks. By giving a formal description of this model in terms of a discrete-time stochastic process, we investigate some of its fundamental stochastic properties with respect to: (a) the transition length and time of a mobile node between two waypoints, (b) the spatial distribution of nodes, (c) the direction angle at the beginning of a movement transition, and (d) the cell change rate if the model is used in a cellular-structured system area. The results of this paper are of practical value for performance analysis of mobile networks and give a deeper understanding of the behavior of this mobility model. Such understanding is necessary to avoid misinterpretation of simulation results. The movement duration and the cell change rate enable us to make a statement about the "degree of mobility" of a certain simulation scenario. Knowledge of the spatial node distribution is essential for all investigations in which the relative location of the mobile nodes is important. Finally, the direction distribution explains in an analytical manner the effect that nodes tend to move back to the middle of the system area.