MOBILITY MODELS FOR DELAY TOLERANT NETWORK : A SURVEY <s> Random Direction (RD) Mobility Model <s> We propose a new routing protocol, the Zone Routing Protocol (ZRP), for the reconfigurable wireless networks, a large scale, highly mobile ad-hoc networking environment. The novelty of the ZRP protocol is that it is applicable to large flat-routed networks. Furthermore, through the use of the zone radius parameter, the scheme exhibits the adjustable hybrid behavior of proactive and reactive routing schemes. We evaluate the performance of the protocol, showing the reduction in the number of control messages, as compared with other reactive schemes, such as flooding. <s> BIB001 </s> MOBILITY MODELS FOR DELAY TOLERANT NETWORK : A SURVEY <s> Random Direction (RD) Mobility Model <s> An ad hoc mobile network is a collection of nodes, each of which communicates over wireless channels and is capable of movement. Wireless nodes have the unique capability of transmission at different power levels. As the transmission power is varied, a tradeoff exists between the number of hops from source to destination and the overall bandwidth available to individual nodes. Because both battery life and channel bandwidth are limited resources in mobile networks, it is important to ascertain the effects different transmission powers have on the overall performance of the network. This paper explores the nature of this transmission power tradeoff in mobile networks to determine the optimum node density for delivering the maximum number of data packets. It is shown that there does not exist a global optimum density, but rather that, to achieve this maximum, the node density should increase as the rate of node movement increases. <s> BIB002 </s> MOBILITY MODELS FOR DELAY TOLERANT NETWORK : A SURVEY <s> Random Direction (RD) Mobility Model <s> The Pareto probability distribution is widely applied in dierent fields such us finance, physics, hydrology, geology and astronomy. This note deals with an application of the Pareto distribution to astrophysics and more precisely to the statistical analysis of masses of stars and of diameters of asteroids. In particular a comparison between the usual Pareto distribution and its truncated version is presented. Finally, a possible physical mechanism that produces Pareto tails for the distribution of the masses of stars is presented. <s> BIB003
The random direction distribution overcomes the problem of non-uniform distribution found in RWP BIB002 . In the RD model, a mobile node gets a movement degree randomly and moves in a particular direction until it touches the destination boundary of simulation area with a specified speed. When it travels to boundary area, it stops for a specified pause time before choosing a new direction to move again. This model is more consistent in comparison with other random models and offers quantitatively even distribution of nodes in the simulation area. Many variants of the RD mobility model have been developed. The first variant proposed by Royer et al. BIB001 assign a travel duration to each node before it starts to move with a random speed in a random direction. It then stops and changes its direction if the assigned travel duration expires before it reaches the border of the simulation area. In such a case, a new direction is uniformly chosen in [0, 2π]. The second variant of the RD mobility model was presented by Haas BIB003 . In his work, when a node reaches a boundary of the simulation area, it instantaneously re-enter into the simulation area from the opposite boundary. It then continues to move with the previous speed and direction. The third variant presented by Bettstetter added that node would bounce off and continue to move with the previous speed in a new direction when a node reaches a boundary of the simulation area BIB002 .