A general framework to construct stationary mobility models for the simulation of mobile networks

Electr. Eng. & Comput. Sci. Dept., Michigan Univ., Ann Arbor, MI, USA
IEEE Transactions on Mobile Computing (Impact Factor: 2.54). 08/2006; 5(7):860- 871. DOI: 10.1109/TMC.2006.89
Source: IEEE Xplore


Simulation has become an indispensable tool in the design and evaluation of mobile systems. By using mobility models that describe constituent movement, one can explore large systems, producing repeatable results for comparison between alternatives. In this paper, we show that a large class of mobility models - including all those in which nodal speed and distance or destination are chosen independently - have a transient period in which the average node speed decreases until converging to some long-term average. This speed decay provides an unsound basis for simulation studies that collect results averaged over time, complicating the experimental process. In this paper, we derive a general framework for describing this decay and apply it to a number of cases. Furthermore, this framework allows us to transform a given mobility model into a stationary one by initializing the simulation using the steady-state speed distribution and using the original speed distribution subsequently. This transformation completely eliminates the transient period and the decay in average node speed and, thus, provides sound models for the simulation of mobile systems.

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Available from: Mingyan Liu, Mar 15, 2014
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    • "Since the performance tests should be done in the steady states, the non-steady states should be minimized for efficient simulations. For this purpose, several analytical techniques have been proposed [18]–[23]. In Ref. [18], Yoon et al. have focused on the node velocity distribution in the RWP model and shown the presence of the harmful effects before the convergence. "
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    ABSTRACT: In mobile wireless networks such as WSNs, WMNs and MANETs, movement of sensor nodes, clients and relay nodes has a great impact on the performance. Nevertheless, geography is too simplified in random-based mobility models such as RWP, while it is unrealistic to prepare trace-based mobility patterns for potential combinations of geography and mobility. To fulfill the gap, this paper provides a new method to automatically generate natural mobility patterns realizing designated node distributions. The goal of this work is to synthesize the movement patterns that can capture real (or intentional) node distributions. The method determines the probabilities of choosing waypoints from the subregions, satisfying the given node distributions. For this purpose, the relationship between the probabilities and node distributions is analyzed. Based on the analysis, the problem is formulated as an optimization problem of minimizing the error from the designated node distribution. Since the problem has non-linear constraints, a heuristic algorithm is designed to derive the near-optimal solutions. Several experiments have been conducted to show that a variety of node distributions could be realized in the proposed mobility model where the maximum error from the given node distributions was around 0.5%. Additionally, a case study has been conducted to show the applicability of the method.
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    • "Though this is critical to our analysis, it is not an unreasonable assumption. It is well-known that a mobility model is meaningful for network evaluation only if it exhibits stationarity [20]. In particular, it is obvious that the random-walk, the random-waypoint model, and their variants are known to be stationary under proper choice of parameters. "
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    ABSTRACT: Consider an intermittently-connected mobile network consisting of n relay nodes, a single source node, and m destination nodes exhibiting a stochastic model for mobility. Each mobile relay node is also equipped with finite storage. We seek to analyze the performance of Multicast enabled by Network Coding in such a network under the store, carry, and forward paradigm, and compare its performance to a simple custodial-multicast scheme. Though accurate analysis of network-coded multicast is very complicated, we derive a provable way to obtain tight bounds on the performance. We then develop a queuing-theoretic framework to analyze the steady-state throughput performance of the network-coded scheme under this setup, which is then solved iteratively. The framework developed thus enables speedy evaluation of the communication protocols described. Our analytical results, supported by simulation studies, show that the network-coding-based scheme offers considerable improvement for the case when the storage size of the relay nodes is small and when the number of destination nodes is large.
    Preview · Conference Paper · Jul 2010
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    • "Note that authors unaware of this problem have tested communication protocols under such conditions [3], [7], [8], [9], [10]. Previous works have proposed general frameworks to design mobility models with stable average node speed [12], [13], [14]; however, they did not present the impacts over networking performance metrics. In addition, the main features of the resultant models deviated from the principal characteristics of the RWP model, e.g., the average velocities of the used distributions for choosing node speed differ from the average value "
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    ABSTRACT: It has been recently shown that the instantaneous average node speed for the random waypoint (RWP) mobility model may not reach a steady state regime due to velocity gradual decaying which can cause inaccurate results in simulations and communication protocol validations for mobile ad hoc networks (MANETs). This paper presents a modification to the RWP model, in which we propose to choose node speeds from a BETA(2,2) distribution, demonstrating analytically and by simulations that our idea stabilizes the instantaneous average node speed and consequently other important network metrics, like control overhead, number of dropped data packets and delivery delay. The proposal of alteration not only eliminates the decaying problem of the average node speed but also provides average values closer to the commonly supposed average velocity (V<sub>max</sub> + V<sub>min</sub>)/2 than those of the original RWP model. In addition, the proposed change for the RWP model can be readily incorporated into network simulators.
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