SMALL WORLD

It is well known that mobility increases the capacity of mobile ad hoc networks (MANETs) by reducing the number of relays for routing, prolonging the lifespan of wireless sensor networks (WSNs) by using mobile nodes in place of bottleneck static sensors, and ensuring network
connectivity in delay-tolerant networks (DTNs) using mobile nodes to connect different parts of a disconnected network. Trajectory planning and the coordination of mobile nodes
are two important design issues aiming to optimize or balance several measures, including delay, average number of relays, and moving distance. In this paper, we propose a new
controlled mobility model with an expected polylogarithmic number of relays to achieve a good balance among several contradictory goals, including delay, the number of relays,
and moving distance. The model is based on the small-world model where each static node has “short” link connections to its nearest neighbors and “long” link connections to other
nodes following a certain probability distribution. Short links are regular wireless connections whereas long links are implemented using mobile nodes. Various issues are
considered, including trade-offs between delay and average number of relays, selection of the number of mobile nodes, and selection of the number of long links. The effectiveness
of the proposed model is evaluated analytically as well as through simulation.