Abstract
Mobile ad hoc networks (MANETs) have inherently dynamic topologies. Under these difficult circumstances, it is essential to have some dependable way of determining the reliability of communication paths. Mobility metrics are well suited to this purpose. Several mobility metrics have been proposed in the literature, including link persistence, link duration, link availability, link residual time, and their path equivalents. However, no method has been provided for their exact calculation. Instead, only statistical approximations have been given. In this paper, exact expressions are derived for each of the aforementioned metrics, applicable to both links and paths. We further show relationships between the different metrics, where they exist. Such exact expressions constitute precise mathematical relationships between network connectivity and node mobility. These expressions can, therefore, be employed in a number of ways to improve performance of MANETs such as in the development of efficient algorithms for routing, in route caching, proactive routing, and clustering schemes.
Highlights
Mobile ad hoc networks (MANETs) are comprised of mobile nodes communicating via wireless links
Having established definitions for each of the mobility metrics of interest, we develop generic expressions for each of the mobility metrics, using a Markov chain model. (Using a Markov chain model allows for random mobility models for which no closed-form expression may be found for the PDF of the mobility, which is most often the case.) These expressions may be applied to any particular random mobility model by substituting in the appropriate PDF
Frequent changes in network topology caused by mobility in mobile ad hoc networks impose great challenges for developing efficient routing algorithms
Summary
Mobile ad hoc networks (MANETs) are comprised of mobile nodes communicating via (potentially multihop) wireless links. Our framework can be applied to any mobility model that admits a Markov process describing node separation. This theoretical approach is in contrast to most research to date which has been based on simulation results and empirical analysis of mobility metrics. The main contributions of this paper are (1) introduction of notion of link (path) persistence and its calculation method, (2) expressions for the expected link (path) duration and its PDF, (3) expressions for the expected link (path) residual time and its PDF which are derived using a random mobility model rather than a nonrandom travelling pattern (straight-line mobility model), (4) an exact expression for link (path) availability which matches the simulation data well for any given time interval.
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