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Random Waypoint Mobility Model is comparable to the random walk model. However, it includes pause times that occur between changes in direction and speed. If pause time is zero, random way point model is similar to random walk model. A mobile node starts at one location where it stays for a certain period of time. This is actually the pause time. After the expiry of pause time, the mobile node chooses a different destination randomly alongside a new speed which ranges from nil to the stipulated maximum [0,speedmax]. Subsequently, it travels towards the new destination at the chosen speed. When it arrives at the destination, it takes a break (pause time) before starting the procedure again. This is continuously repeated as long as the mobile node is range of connectivity (Mohd Saad & Zukarnain, 2009).

 

In this model, a number of uniformly distributed fixed points are used as targets and are referred to as waypoints. Nodeds move from one waypoint to another in segments that represent straight lines. The waypoints are chosen in such a way that information can be retrieved by the mobile nodes from anywhere in the domain as they move along their designated paths at predefined speeds (Schmidt, 2011). A comparison of mobility models reveals that the random way point model has the highest delivery ratio of packets in wireless networks besides having the lowest end-to-end delay and hop count (Unhelkar, 2006).

 

Figure 2: Random waypoint model diagram

 

Source: Klaus & Gross

 

Common problems have been observed with this model however. For instance, zigzag trajectories in the model make the paths followed by mobile nodes to appear unnatural. Moreover, any practical mechanism needs to be robust and provide reasonable performance alongside multiple moving patterns particularly similar to random waypoint model. In addition, the velocity distribution of the random waypoint model presents a common problem in simulation studies. Its velocity distributions range from zero to maximum which create situations of stationary states where each node stops moving (Hyytiä, 2005).

 

Applications

The random waypoint model bears a number of parameters that can easily be adjusted to match certain scenarios. Its versatility makes it useful in modeling networks and algorithms especially mobile users in wireless networks. It is applied in the location of arbitrary packets in a multi-hop network. Therefore it can be used in the study of the effects of mobility in the performance of cellular networks. The fact that users behave independently in a system is used to determine total handover rates into a cell as well as the mean number of handovers during a call. The relationship between mobility factor and maximum speed of a node may also be analyzed in this mobility model. Therefore, simulation evaluations of ad hoc routing protocols can be performed more efficiently with the random way point mobility model.本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。