Random waypoint mobilitymodel National Institute of 随机点移动模型的国家研究所.pptVIP

Empirical Analysis of the Mobility Factor for the Random Waypoint Model 1542 Case Studies Introduction Evaluation of performance of various wireless ad hoc network routing protocols Largely done via simulation Node mobility model One aspect of a simulation scenario Determines how frequently links change Relates to the performance (e.g., affects overhead traffic for maintenance of routes) Need a mobility measure to characterize the motion of nodes and to compare simulations → Mobility Factor (MF) In this paper, OPNET simulations are performed for random waypoint mobility model Used a slightly modified equation for MF of Larsson and Hedman [7] Provide useful guidance for designing simulation scenario for ad hoc network Random Waypoint Mobility Model Operation Select a random destination (within the specified area) Select a random speed (0 v ≤ max_speed) Move After reaching the destination, pause a random time (0 p ≤ max_pause_time) Process Model Mobility Factor (MF) Mi MF for node i Average change of the distance to all other nodes during a sample time (Dt) T = KDt N: Number of nodes dij(t): Distance between nodes i and j at time t MF Average MF of the nodes in the network where dij(t) is the distance between nodes i and j at time t and N is the number of nodes. Simulation and Results Simulation Parameters Results Relationship between MF and the maximum node speed Results for single-hop connectivity Results for multi-hop connectivity MF vs. Maximum Speed of Nodes Each symbol represents an independent simulation run. “Average” is the mean value of 20 independent runs. MF is almost a linear function of speed. Results for Single-Hop Connectivity (1/3) Analytical Results Node distribution of random waypoint mobility model Not uniform distribution [12] Peak in the middle of the area Decrease to zero at the border of the area Symmetric in all directions from the center Density function of node’s position: where D ? D squar