Quantifying Link Stability in Ad Hoc Wireless Networks Subject to Ornstein-Uhlenbeck Mobility

The performance of mobile ad hoc networks in general and that of the routing algorithm, in particular, can be heavily affected by the intrinsic dynamic nature of the underlying topology. In this paper, we build a new analytical/numerical framework that characterizes nodes' mobility and the evolution of links between them. This formulation is based on a stationary Markov chain representation of link connectivity. The existence of a link between two nodes depends on their distance, which is governed by the mobility model. In our analysis, nodes move randomly according to an Ornstein-Uhlenbeck process using one tuning parameter to obtain different levels of randomness in the mobility pattern. Finally, we propose an entropy-rate-based metric that quantifies link uncertainty and evaluates its stability. Numerical results show that the proposed approach can accurately reflect the random mobility in the network and fully captures the link dynamics. It may thus be considered a valuable performance metric for the evaluation of the link stability and connectivity in these networks.Comment: 6 pages, 4 figures, Submitted to IEEE International Conference on Communications 201

The Node Distribution of the Random Waypoint Mobility Model for Wireless Ad Hoc Networks

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 nodes moving according to this model is in general non-uniform. However, an in-depth investigation and a closed-form expression of this distribution is still missing. This fact impairs the accuracy of the current simulation methodology of ad hoc networks and makes it impossible to relate simulation results to analytical results on the properties of adhoc networks. To overcome these problems, we present a detailed analytical study of the node distribution resulting from 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\u27s parameters influence the distribution. By describing mobility as a stochastic process, 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 with various settings of the mobility parameters

Orion Routing Protocol for Delay-Tolerant Networks

In this paper, we address the problem of efficient routing in delay tolerant network. We propose a new routing protocol dubbed as ORION. In ORION, only a single copy of a data packet is kept in the network and transmitted, contact by contact, towards the destination. The aim of the ORION routing protocol is twofold: on one hand, it enhances the delivery ratio in networks where an end-to-end path does not necessarily exist, and on the other hand, it minimizes the routing delay and the network overhead to achieve better performance. In ORION, nodes are aware of their neighborhood by the mean of actual and statistical estimation of new contacts. ORION makes use of autoregressive moving average (ARMA) stochastic processes for best contact prediction and geographical coordinates for optimal greedy data packet forwarding. Simulation results have demonstrated that ORION outperforms other existing DTN routing protocols such as PRoPHET in terms of end-to-end delay, packet delivery ratio, hop count and first packet arrival

The Node Spatial Distribution of the Generalized Random Waypoint Mobility Model for Wireless Ad Hoc Networks

In this paper we analyze the node spatial distribution generated by nodes moving according to the random waypoint model, which is widely used in the simulation of mobile ad hoc networks. We extend an existing analysis for the case in which nodes are continuously moving (i.e., the pause time is 0) to the more general case in which nodes have arbitrary pause times between movements. We also generalize the mobility model, allowing the nodes to remain stationary for the entire simulation time with a given probability. Our analysis shows that the structure of the resulting asymptotic spatial density is composed by three distinct components: the initial, the pause and the mobility component. The relative values of these components depend on the mobility parameters. We derive an explicit formula of the one-dimensional node spatial density, and an approximated formula for the two-dimensional case. The quality of this approximation is verified through experimentation, which shows that the accuracy heavily depends on the choice of the mobility parameters