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Sunday 29 January 2012

Super-Diffusive Behavior of Mobile Nodes and its Impact on Routing Protocol Performance


1.  ABSTRACT :

                               Mobility is the most important component in mobile ad-hoc networks (MANETs) and delay-tolerant networks (DTNs). In this project, we first investigate numerous GPS mobility traces of human mobile nodes and observe super-diffusive behavior in all GPS traces, which is characterized by a ‘faster-than-linear’ growth rate of the mean square displacement (MSD) of a mobile node. We then explains a large amount of access point (AP) based traces, and develop a theoretical framework built upon continuous time random walk (CTRW) formalism, in which one can identify the degree of diffusive behavior of mobile nodes even under possibly heavy-tailed pause time distribution, as in the case of reality. We study existing synthetic models and trace based models in term of the capability of producing various degrees of diffusive behavior, and use a set of L'evy walk models due to its simplicity and flexibility. In addition, we show that diffusive properties make a huge impact on contact-based metrics and the performance of routing protocols in various scenarios and that existing models such as random way point, random direction
model or Brownian motion lead to overly optimistic or pessimistic results when diffusive properties are not properly captured. Our work in this paper thus suggests that the diffusive behavior of mobile nodes should be correctly captured and taken into account for the design and comparison study of network protocols.

 
  2.EXISTING SYSTEM :

        The mobility pattern directly impacts time-varying contact/inter-contact dynamics among mobile nodes, which in turn affect the performance of any protocol built over these mobility patterns . Mobility models that fail to capture key characteristics in the movement pattern of mobile nodes will result in misleading guidelines on the design of new protocols and their performance evaluations and thus prevent us from making a right decision on our choice.
Numerous approaches have been put forth, ranging from various synthetic mobility modelings with certain desired properties, to the numerical study of MANET protocols using mobility traces obtained from real-world measurements. Synthetic mobility models , such as random way point models, random direction models, random walk or Brownian motion on a square or a sphere, and their variations, have been developed mainly for the purpose of simplicity and the ease of analysis, but subsequently been criticized for their unrealistic behaviors.

          Another common approach is to rely on real mobility traces  and use them as inputs to a simulator for the study and comparison of protocols . This approach, however, suffers from lack of the amount of available traces on a fine time/space scale; most existing traces show only partial or ‘filtered’ information about the real trajectories of mobile nodes such as access point (AP) association information or just contact duration with others, not the actual spatial-temporal information of the mobile users on a fine scale. Existing synthetic models and trace based models are studied to find out whether these models can produce varying degrees of super-diffusive behavior as observed from all GPS-based mobility traces as well as AP-based traces, and show that each model can generate only a limited range of diffusive properties or cannot be conveniently used to produce different degrees of diffusive property in practice.


  3. PROPOSED SYSTEM :

                                        Super-diffusive behavior is the common characteristic in the movement of mobile nodes. We have investigated a large number of GPS-based traces as well as AP-based traces available in the literature. Our approach via the use of MSD coupled with CTRW formalism, allows us to statistically and theoretically identify the (possibly hidden) degree of diffusive behavior of mobile nodes. A numerous GPS-based mobility traces as well as AP-based traces are examined to find out key characteristics in movement patterns of mobile nodes. The location of mobile nodes and how it changes over time is specifically focused. We then find that there is a common and distinctive characteristic observed in all mobility traces, super-diffusive movement pattern, which is characterized by a ‘faster-than-linear’ growth curve of the mean square displacement (MSD)

                                      A set of  L'evy walk models  which is  simple, easy-to-generate, yet still versatile mobility models. The L´evy walk model is an isotropic two-dimensional random walks, whose super-diffusive behavior (super-linear growth in MSD) is easily controlled via a single parameter – the exponent of its power-law step-length distribution.
  4.HARDWARE REQUIREMENTS:

         System                : Pentium IV 2.4 GHz.
         Hard Disk            : 40 GB.
         Floppy Drive       : 1.44 MB.
         Monitor                : 15 VGA Colour.
         Mouse                 : Logitech.
         Ram                     : 256 MB.



   5.SOFTWARE REQUIREMENTS:

         Operating System       : - Windows XP Professional.
         Front End                               : - Asp .Net 2.0.
         Coding Language       : - Visual C# .Net.








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