Node density and connectivity properties of the random waypoint model

Abstract

A frequently used mobility model for mobile ad hoc network (MANET) simulations is the random waypoint (RWP) model. We study the properties exhibited by RWP, with a focus on the impact of the rectangular boundary and the speed of the mobile nodes moving within the boundary. The most notable result is that the average node density within the rectangle is non-uniform, contrary to what is frequently assumed. The density, in fact, does depend on the speed of the nodes. Only at high mobility speeds, and in the asymptotic sense, does the density become approximately uniform. The direct implications of the non-uniformity are studied from the point of view of network connectivity. It is found that higher mobility speed results in better connectivity. We also find that irrespective of the speed, when multiple connected components are present, they typically consist of a very large component and (potentially several) extremely small ones, alluding to similarities to the ‘giant component’ in random graphs. We finally comment on the impact of RWP simulations on the design and evaluation of MANET routing protocols.